Category Archives: Forestry Info Publications

Well-Read-Robyn_4_24_15

Compilation by Robyn Darbyshire

Nielsen-Pincus, M., R. G. Ribe, et al. (2015). “Spatially and socially segmenting private landowner motivations, properties, and management: A typology for the wildland urban interface.” Landscape and Urban Planning 137: 1-12.

Throughout North America, rapid exurban development is increasing the spatial extent and population density of the wildland urban interface (WUI), exacerbating problems of wildfire risk and biodiversity loss. To address these issues, policy and planning tools need to be targeted toward different types of WUI landowners in the different types of landscape locations they occupy. We developed a typology of WUI landowners in the Willamette Valley foothills of Oregon, USA. We used market segmentation techniques on mail survey data (n = 939) to develop a typology of four types of WUI landowners in the Willamette Valley foothills of Oregon, USA. We identify differences in each type’s land management strategies and property characteristics and use commonly available GIS data to project where different landowner types are likely to occur in the landscape. We conclude with a discussion of the importance of social and spatial heterogeneity in the WUI for strategically targeted policy and planning efforts intended to manage wildfire risk and promote ecological restoration.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0169204614002886

 

Wagenbrenner, J. W. and P. R. Robichaud (2014). “Post-fire bedload sediment delivery across spatial scales in the interior western United States.” Earth Surface Processes and Landforms 39(7): 865-876.

Post-fire sediment yields can be up to three orders of magnitude greater than sediment yields in unburned forests. Much of the research on post-fire erosion rates has been at small scales (100 m2 or less), and post-fire sediment delivery rates across spatial scales have not been quantified in detail. We developed relationships for post-fire bedload sediment delivery rates for spatial scales up to 117 ha using sediment yield data from six published studies and two recently established study sites. Sediment yields and sediment delivery ratios (SDRs; sediment delivered at the catchment scale divided by the sediment delivered from a plot nested within the catchment) were related to site factors including rainfall characteristics, area, length, and ground cover. Unit-area sediment yields significantly decreased with increasing area in five of the six sites. The annual SDRs ranged from 0.0089 to 1.15 and these were more closely related to the ratio of the plot lengths than the ratio of plot areas. The developed statistical relationships will help quantify post-fire sediment delivery rates across spatial scales in the interior western United States and develop process-based scaling relationships.

FULL TEXT LINK: http://dx.doi.org/10.1002/esp.3488

 

Beschta, R. L., J. Boone Kauffman, et al. (2014). “Long-term livestock grazing alters aspen age structure in the northwestern Great Basin.” Forest Ecology and Management 329: 30-36.

We determined the age structure of quaking aspen (Populus tremuloides) over the period 1850–2009 in Hart Mountain National Antelope Refuge riparian areas to evaluate potential influences of (a) livestock herbivory and (b) climate on aspen demography. We found a significant decline in aspen recruitment (p < 0.05) in the late 1800s, coincident with the onset of high levels of Euro-American livestock grazing. Although livestock use was regulated following establishment of the refuge in 1936, low levels of aspen recruitment continued. After termination of livestock grazing in 1990, aspen recruitment on the refuge increased (p < 0.05) by more than an order of magnitude in comparison to levels occurring during the previous half-century of regulated grazing. Climate variables (i.e., Palmer Drought Severity Index, annual precipitation, and annual temperature) appeared to have little influence on long-term patterns of aspen recruitment. Overall, results are consistent with top–down forcing by livestock herbivory as the major factor associated with a century of reduced aspen recruitment on HMNAR. Where long-term declines in aspen are currently underway on grazed lands in the western US, land managers need to carefully consider the potential effects of livestock and alter, as needed, management of these ungulates to ensure retention of aspen woodlands and their ecosystem services.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714003818

 

Jenkins, M. E., T. L. Bell, et al. (2014). “Pyrogenic carbon: the influence of particle size and chemical composition on soil carbon release.” International Journal of Wildland Fire 23(7): 1027-1033.

In many countries, prescribed or planned burning is increasingly used as a management strategy to reduce the risk and negative effects of wildfires. As a by-product of this practice, ash, charcoal and partially charred material (referred to here as pyrogenic carbon, PC) is created. The amount and type of PC produced and fate of this form of carbon is uncertain. PC is often assumed to be resistant to chemical and microbial degradation and therefore potentially persistent in soils for hundreds or thousands of years. As a result, PC has been proposed as a sink for carbon and promoted for its storage potential in soil. We hypothesised that the differing components of PC would interact differently with soil processes and have varying potential for carbon storage. We analysed the chemical composition of PC produced by prescribed fire in a eucalypt forest and measured its effect on soil respiration. A laboratory incubation experiment showed that when PC of differing size fractions was added to soil, only the smallest size fraction (<1 mm; ash) increased rates of soil respiration, whereas larger fractions (charcoal) had little effect. The carbon contained in charcoal was resistant to microbial degradation and had little effect on microbial processes such as respiration. In general, fires of greater intensity will produce greater proportional amounts of smaller size particles and will likely result in faster rates of respiration than fires of lesser intensity. Therefore, lower intensity fires may ultimately have a greater capacity for soil carbon sequestration than those of higher intensity.

FULL TEXT LINK: http://www.publish.csiro.au/paper/WF13189

 

Lefèvre, F., T. Boivin, et al. (2014). “Considering evolutionary processes in adaptive forestry.” Annals of Forest Science 71(7): 723-739.

Managing forests under climate change requires adaptation. The adaptive capacity of forest tree populations is huge but not limitless. Integrating evolutionary considerations into adaptive forestry practice will enhance the capacity of managed forests to respond to climate-driven changes. Focusing on natural regeneration systems, we propose a general framework that can be used in various and complex local situations by forest managers, in combination with their own expertise, to integrate evolutionary considerations into decision making for the emergence of an evolution-oriented forestry. We develop a simple process-based analytical grid, using few processes and parameters, to analyse the impact of forestry practice on the evolution and evolvability of tree populations. We review qualitative and, whenever possible, quantitative expectations on the intensity of evolutionary drivers in forest trees. Then, we review the effects of actual and potential forestry practice on the evolutionary processes. We illustrate the complexity of interactions in two study cases: the evolutionary consequences for forest trees of biotic interactions and of highly heterogeneous environment. Evolution-oriented forestry may contribute adapting forests to climate change. It requires combining short-term and long-term objectives. We propose future lines of research and experimentation.

FULL TEXT LINK: http://dx.doi.org/10.1007/s13595-013-0272-1

 

 

Well-Read-Robyn_4_17_15

Compilation by Robyn Darbyshire

Dietz, M. S., R. T. Belote, et al. (2015). “The world’s largest wilderness protection network after 50 years: An assessment of ecological system representation in the U.S. National Wilderness Preservation System.” Biological Conservation 184: 431-438.

Protected areas, such as wilderness, form the foundation of most strategies to conserve biological diversity. However, the success of protected areas in achieving conservation goals depends partly on how well ecological diversity is represented in a network of designated lands. We examined how well the world’s largest highly-protected conservation network—the U.S. National Wilderness Preservation System (NWPS)—currently represents ecological systems found on federal lands in the contiguous United States and how ecological system representation has accumulated over the 50-year tenure of the Wilderness Act (passed in 1964 and giving the U.S. Congress authority to establish wilderness areas). Although the total area of NWPS has risen fairly steadily since 1964, the diversity of ecological systems accumulated in wilderness areas (436 ecological systems) reached an asymptote 30 years ago that is well below the total pool of ecological systems available (553) on federal lands. Thus, NWPS currently under-represents ecological system diversity. Additionally, only 113 ecological systems are represented at more than 20% of federal land area. As the designation of new wilderness areas becomes more difficult, it is important to increase the ecological representation of those areas to achieve greater protection of biological diversity. Over the next 50 years of the Wilderness Act, federal land-management agencies and the U.S. Congress could increase the ecological diversity of wilderness areas by prioritizing under-represented ecological systems in new wilderness legislation.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0006320715000944

 

Wiebe, K. L. (2014). “Responses of cavity-nesting birds to fire: testing a general model with data from the Northern Flicker.” Ecology 95(9): 2537-2547.

Census-based studies document changes in population size of animal species in response to wildfires, but mechanisms involving behavior of individuals and the effects on reproductive success are usually unknown. I developed a conceptual model explaining the persistence of cavity-nesting birds on the landscape after fires depending on carrying capacity (food supply) of the habitat and the philopatry and territoriality of the species. The breeding density, nest site characteristics, and reproductive success of Northern Flickers Colaptes auratus was studied before and after low- to moderate-severity fires on replicated plots. The density and spatial distribution of nests did not change in a consistent way after fires, but the rates of cavity excavation increased and characteristics of nest sites changed as such decay class of the tree. Laying dates were delayed and clutches were smaller in freshly excavated vs. reused cavities on the burned sites. Breeding philopatry caused a shift to older age classes in the population. Depredation of nests by small mammals increased during the first three years after fires, reducing the number of young produced per nest attempt on burned plots. The study shows that, even when fire does not reduce the density of breeding pairs, there may be detrimental effects detected only by monitoring the behavior and reproduction of individuals.

FULL TEXT LINK: http://dx.doi.org/10.1890/13-1711.1

 

Chaffin, B., R. Mahler, et al. (2015). “The Role of Agency Partnerships in Collaborative Watershed Groups: Lessons from the Pacific Northwest Experience.” Environmental Management 55(1): 56-68.

Collaborative watershed group experiences reveal commonalities in their approaches to facilitate decentralized and inclusive watershed planning and management in the United States, and increasingly around the world. Although watershed groups are widely recognized in the United States for positive accomplishments across local, state, and regional scales, the role of government agencies as watershed group partners often remains ambiguous and inconsistent. This paper details results of a survey used to determine the status of Pacific Northwest (PNW) watershed group-agency partnerships relative to planning and management. Specific inquiry was directed toward: (1) the role of technical information flow; and (2) watershed group needs. Mail surveys were administered to 304 watershed group participants in Idaho, Oregon, and Washington. Sixty-nine percent of the surveys were completed and returned. Based on the collected survey data, PNW watershed groups rely heavily on agency officials for technical watershed information. Respondents perceive support of state government to be the highest relative to federal agencies, local governments, and university Extension offices. However, evidence from the survey suggests that partnerships are underutilized across all agencies and organizations concurrently vested in watershed planning and management in the PNW. Sustained operational funding, increased group participation, and baseline watershed data are the most pressing needs of PNW watershed groups and present a significant opportunity for expanding watershed group-agency partnerships.

FULL TEXT LINK: http://dx.doi.org/10.1007/s00267-014-0367-y

 

Zhang, C.-B., L.-H. Chen, et al. (2014). “Why fine tree roots are stronger than thicker roots: The role of cellulose and lignin in relation to slope stability.” Geomorphology 206: 196-202.

Plant roots help to reinforce the soil, increase slope stability and decrease water erosion. Root tensile strength plays an important role in soil reinforcement and slope stabilization. The relationship between tensile strength and internal chemical composition of roots is unknown due to limited studies. Thus, it is difficult to determine why root tensile strength tends to decrease with increasing root diameter. In this study, biomechanical and biochemical tests were performed on the roots of Chinese pine (Pinus tabulaeformis) to determine the relationships among tensile strength and the contents of the main chemical composition: cellulose, alpha-cellulose and lignin in the roots with different diameters. Our results confirmed that the tensile strength of Chinese pine roots decreased with increasing root diameter, and this relationship might be a power function. The chemical contents of the roots and root diameter were also related to each other with significant power regression. With increasing root diameter, the cellulose content and alpha-cellulose content increased, but the lignin content decreased. In addition, the lignin content exhibited a significantly positive relationship with tensile strength. Furthermore, the ratios of lignin/cellulose and lignin/alpha-cellulose decreased with increasing root diameter following significant power regressions, and they also demonstrated a positive relationship with tensile strength. Taken together, these results may be useful for studies on root tensile strength, soil reinforcement and slope stability.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0169555X13004984

 

Rideout, D. B., P. S. Ziesler, et al. (2014). “Valuing fire planning alternatives in forest restoration: Using derived demand to integrate economics with ecological restoration.” Journal of Environmental Management 141: 190-200.

Assessing the value of fire planning alternatives is challenging because fire affects a wide array of ecosystem, market, and social values. Wildland fire management is increasingly used to address forest restoration while pragmatic approaches to assessing the value of fire management have yet to be developed. Earlier approaches to assessing the value of forest management relied on connecting site valuation with management variables. While sound, such analysis is too narrow to account for a broad range of ecosystem services. The metric fire regime condition class (FRCC) was developed from ecosystem management philosophy, but it is entirely biophysical. Its lack of economic information cripples its utility to support decision-making. We present a means of defining and assessing the deviation of a landscape from its desired fire management condition by re-framing the fire management problem as one of derived demand. This valued deviation establishes a performance metric for wildland fire management. Using a case study, we display the deviation across a landscape and sum the deviations to produce a summary metric. This summary metric is used to assess the value of alternative fire management strategies on improving the fire management condition toward its desired state. It enables us to identify which sites are most valuable to restore, even when they are in the same fire regime condition class. The case study site exemplifies how a wide range of disparate values, such as watershed, wildlife, property and timber, can be incorporated into a single landscape assessment. The analysis presented here leverages previous research on environmental capital value and non-market valuation by integrating ecosystem management, restoration, and microeconomics.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S030147971400173X

 

 

 

Well-Read-Robyn_4_10_15

Compilation by Robyn Darbyshire

Mooney, P. (2014). “A Systematic Approach to Incorporating Multiple Ecosystem Services in Landscape Planning and Design.” Landscape Journal 33(2): 141-171.

This paper uses a contemporary perspective on ecosystem services to propose a method by which projects designed for sustainability may more fully capture or enhance ecosystem services. A comprehensive Ecosystem Services Evaluation Matrix is used to evaluate three designed landscapes, at different scales. The matrix is then incorporated into a revised sustainable landscape planning and design process. This approach uses evaluative tools within a decision making process to incorporate a broader range of ecosystem services in landscape planning and design.

NO FULL TEXT LINK: full text available from FS Library Services http://fsweb.wo.fs.fed.us/library/document-delivery.htm

 

Halofsky, J. S., J. E. Halofsky, et al. (2014). “Dry forest resilience varies under simulated climate-management scenarios in a central Oregon, USA landscape.” Ecological Applications 24(8): 1908-1925.

Determining appropriate actions to create or maintain landscapes resilient to climate change is challenging because of uncertainty associated with potential effects of climate change and their interactions with land management. We used a set of climate-informed state-and-transition models to explore the effects of management and natural disturbances on vegetation composition and structure under different future climates. Models were run for dry forests of central Oregon under a fire suppression scenario (i.e., no management other than the continued suppression of wildfires) and an active management scenario characterized by light to moderate thinning from below and some prescribed fire, planting, and salvage logging. Without climate change, area in dry province forest types remained constant. With climate change, dry mixed-conifer forests increased in area (by an average of 21-26% by 2100), and moist mixed-conifer forests decreased in area (by an average of 36-60% by 2100), under both management scenarios. Average area in dry mixed-conifer forests varied little by management scenario, but potential decreases in the moist mixed-conifer forest were lower with active management. With changing climate in the dry province of central Oregon, our results suggest the likelihood of sustaining current levels of dense, moist mixed-conifer forests with large-diameter, old trees is low (less than a 10% chance) irrespective of management scenario; an opposite trend was observed under no climate change simulations. However, results also suggest active management within the dry and moist mixed-conifer forests that creates less dense forest conditions can increase the persistence of larger-diameter, older trees across the landscape. Owing to projected increases in wildfire, our results also suggest future distributions of tree structures will differ from the present. Overall, our projections indicate proactive management can increase forest resilience and sustain some societal values, particularly in drier forest types. However, opportunities to create more disturbance-adapted systems are finite, all values likely cannot be sustained at current levels, and levels of resilience success will likely vary by dry province forest type. Land managers planning for a future without climate change may be assuming a future that is unlikely to exist.

FULL TEXT LINK: http://dx.doi.org/10.1890/13-1653.1

 

Toman, E., B. Shindler, et al. (2014). “Public Acceptance of Wildland Fire and Fuel Management: Panel Responses in Seven Locations.” Environmental Management 54(3): 557-570.

Wildland fire affects both public and private resources throughout the United States. A century of fire suppression has contributed to changing ecological conditions and accumulated fuel loads. Managers have used a variety of approaches to address these conditions and reduce the likelihood of wildland fires that may result in adverse ecological impacts and threaten communities. Public acceptance is a critical component of developing and implementing successful management programs. This study examines the factors that influence citizen support for agency fuel reduction treatments over time—particularly prescribed fire and mechanical vegetation removal. This paper presents findings from a longitudinal study examining resident beliefs and attitudes regarding fire management and fuels treatments in seven states: Arizona, Colorado, Oregon, Utah, Michigan, Minnesota, and Wisconsin. The study was implemented in two phases over a 6-year period using mail surveys to residents of communities adjacent to federal lands in each location. Questions replicated measures from the original project as well as some new items to allow a more in-depth analysis of key concepts. The study design enables comparisons over time as well as between locations. We also assess the factors that influence acceptance of both prescribed fire and mechanical vegetation removal. Findings demonstrate a relative stability of attitudes toward fuels management approaches over time and suggest that this acceptance is strongly influenced by confidence in resource managers and beliefs that the treatments would result in positive outcomes.

FULL TEXT LINK:

http://dx.doi.org/10.1007/s00267-014-0327-6

 

DellaSala, D. A., M. L. Bond, et al. (2014). “Complex Early Seral Forests of the Sierra Nevada: What are They and How Can They Be Managed for Ecological Integrity?” Natural Areas Journal 34(3): 310-324.

Complex early seral forests (CESFs) occupy potentially forested sites after a stand-replacement disturbance and before re-establishment of a closed-forest canopy. Such young forests contain numbers and kinds of biological legacies missing from those produced by commercial forestry operations. In the Sierra Nevada of California, CESFs are most often produced by mixed-severity fires, which include landscape patches burned at high severity. These forests support diverse plant and wildlife communities rarely found elsewhere in the Sierra Nevada. Severe fires are, therefore, essential to the region’s ecological integrity. Ecologically detrimental management of CESFs, or unburned forests that may become CESF’s following fire, is degrading the region’s globally outstanding qualities. Unlike old-growth forests. CESFs have received little attention in conservation and reserve management. Thus, we describe important ecological attributes of CESFs and distinguish them from early seral conditions created by logging. We recommend eight best management practices in CESFs for achieving ecological integrity on federal lands in the mixed-conifer region of the Sierra Nevada.

FULL TEXT LINK: http://dx.doi.org/10.3375/043.034.0317

 

 

Christensen, N. L. (2014). “An historical perspective on forest succession and its relevance to ecosystem restoration and conservation practice in North America.” Forest Ecology and Management 330: 312-322.

Eugene Odum’s 1969 paper, The Strategy of Ecosystem Development, marks a watershed moment in approaches to the study of succession, ecosystem change caused by discrete disturbances. He argued that succession is unique from other kinds of change with regard to mechanisms (modification of the physical environment by the community), trajectory (orderly, directional and predictable), and endpoint (a stable climax ecosystem in which “maximum biomass and symbiotic function between organisms are maintained per unit energy flow”). Odum also argued that understanding successional change was central to the management of a great variety of environmental challenges. Given the important role of disturbance in these ecosystems, this is particularly true for management aimed at restoration and conservation of forests. Although there was considerable debate among ecologists regarding successional mechanisms, trajectories and endpoints in the decades preceding his exegesis, the views outlined by Odum generally prevailed. These significantly influenced answers to three central restoration and conservation questions during that era. (1) What should we restore and conserve? Climax ecosystems. (2) How should boundaries be set for restoration and conservation areas? This was not an important matter. (3) How should restoration and conservation be accomplished? Because succession would inexorably lead to the ultimate climax goal, forest ecosystems should be protected from disturbance. Over the past five decades, virtually every aspect of succession theory as presented by Odum (1969) has come into question. We now understand that there is no single unique or unifying mechanism for successional change, that successional trajectories are highly varied and rarely deterministic, and that succession has no specific endpoint. Answers to the three restoration and conservation questions have changed accordingly. (1) Restoration and conservation goals should include the full range of variation in species diversity and composition associated with disturbance and the succession that proceeds from it. (2) Pattern, scale and context influence patterns of both disturbance and succession, and preserve design really does matter. (3) Restoration and conservation practice must be tailored to the unique mechanisms and post-disturbance ecological legacies that determine the trajectory and tempo of successional change in each particular ecosystem. The search for a grand unified theory of succession apart from other kinds of ecosystem change is futile. Nevertheless, the change caused by discrete disturbances remains an important matter for concern for restoration and conservation practitioners.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714004617

 

 

Well-Read-Robyn_4_3_15

Compilation by Robyn Darbyshire

Halpern, C. B., J. A. Antos, et al. (2014). “Vegetation Recovery in Slash-Pile Scars Following Conifer Removal in a Grassland-Restoration Experiment.” Restoration Ecology 22(6): 731-740.

A principal challenge to restoring tree-invaded grasslands is the removal of woody biomass. Burning of slash piles to reduce woody residues from forest restoration practices generates intense, prolonged heating, with adverse effects on soils and vegetation. In this study, we examined vegetation responses to pile burning following tree removal from conifer-invaded grasslands of the Oregon Cascades. We quantified the longevity and magnitude of fire effects by comparing ground conditions and the cover and richness of plant species in burn-scar centers (higher-intensity fire) and edges (lower-intensity fire) with adjacent unburned vegetation 7 years after treatment. We interpreted patterns of recovery through the responses of species with differing growth forms, habitat affinities, and clonality. Cover of bare ground remained elevated at the centers, but not at the edges of scars; however, much of this effect was due to gopher disturbance. Total plant cover, consisting entirely of native species, was comparable in and adjacent to scars. However, richness remained depressed at the scar centers. Cover of grass, meadow, and non-clonal species was comparable in and adjacent to scars, but cover of forb, sedge, residual forest, and clonal species was reduced at the centers. Although scar centers had a simpler community structure (fewer but more abundant species) than the adjacent vegetation, they remained free of exotics and recovered quickly, aided by the soil-disturbing activities of gophers and the regenerative traits of native, disturbance-adapted species. Pile burning can be a viable and efficient approach to fuel reduction in the absence of exotics.

FULL TEXT LINK: http://dx.doi.org/10.1111/rec.12130

 

Vicente-Serrano, S. M., J. J. Camarero, et al. (2014). “Diverse responses of forest growth to drought time-scales in the Northern Hemisphere.” Global Ecology and Biogeography 23(9): 1019-1030.

Aim To identify the main spatiotemporal patterns of tree growth responses to different time-scales of drought at a hemispheric scale using a climate drought index and tree-ring records, and to determine whether those patterns are driven by different climate and forest features. Location Northern Hemisphere. Methods We used a large-scale dendrochronological data set of tree-ring width series from 1657 sites and a time-dependent drought index which incorporates information on precipitation and temperature variability (standardized precipitation–evapotranspiration index, SPEI). Correlation analysis was used to quantify how tree growth responds to different drought time-scales. Variation in the correlations was summarized using principal components analysis (PCA) and the contribution of the various environmental factors was estimated using predictive discriminant analysis (PDA). Results The period between the water shortage and the impact on tree growth differs noticeably among forest types and tree families. There is a gradient in the response of growth to drought including: (1) forests that do not respond to drought, such as those located in cold and very humid areas; (2) forests located in semi-arid areas characterized by responses to long-term droughts; (3) forests that respond to medium- to long-term droughts subjected to subhumid conditions; and (4) forests that dominate humid sites and respond to short-term droughts. Main conclusion Forests that experience semi-arid and subhumid conditions tend to respond over longer time-scales than those located in more humid areas. The characteristic time-scale at which forest growth mainly responds to drought is a proxy for drought vulnerability, reflecting the trees’ ability to cope with water deficits of different durations and severities.

FULL TEXT LINK: http://dx.doi.org/10.1111/geb.12183

 

Gray, A. N. and T. R. Whittier (2014). “Carbon stocks and changes on Pacific Northwest national forests and the role of disturbance, management, and growth.” Forest Ecology and Management 328: 167-178.

The National Forest System (NFS) of the United States plays an important role in the carbon cycle because these lands make up a large proportion of the forested land in the country and commonly store more wood per unit area than other forest ownerships. In addition to sustaining natural resources, these lands are managed for multiple objectives that do not always align with maximizing carbon (C) sequestration. The objectives of this study were to determine C stocks and flux in measured pools on Pacific Northwest Region NFS lands and the major ecological drivers of C flux. We compiled tree, dead wood, and understory vegetation data from 11,435 systematically-placed inventory plots and estimated growth, mortality, decay, removals, and disturbance events based on two full measurements spanning 1993–2007. The area of NFS-administered lands increased by 0.3% during this period and the area in formally-designated protected status increased by 0.7%. There was 1293 Tg C (±11.2 Tg standard error) in non-soil C stocks at the first measurement, which increased by 45 ± 2.2 Tg (3.4%), with 59% of the increase in the live tree pool and the remainder in the dead tree pools. C stocks followed broad regional patterns in productivity while C flux varied at local scales. Fires affected <1% of the forested area per year and were most prevalent in Wilderness areas. Fires reduced C stocks on burned plots by only 9%, and had a negligible effect on the region as a whole. Most tree harvest on NFS lands in the region consisted of partial harvest and had comparable impacts to fire during this period. C sequestration rates were higher (1.2 ± 0.09 Mg/ha/yr) on the west side of the Cascade Mountains, and primarily stayed in the live tree pool, compared to lower rates (0.5 ± 0.04 Mg/ha/yr) east of the Cascades where most of the increase was seen in the down wood pool. We discuss challenges to estimating forest ecosystem carbon stocks, which requires the application of a large number of equations and parameters for measured and unmeasured components, some with scant empirical support. Improved measurements and biomass models applied to networks of permanent plots would enable improved ground-based estimates of the drivers and components of regional changes in C.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S037811271400303X

 

Rohlf, D. J., C. Carroll, et al. (2014). “Conservation-Reliant Species: Toward a Biology-Based Definition.” BioScience 64(7): 601-611.

The concept of conservation-reliant species has become increasingly prominent, particularly with species listed or under consideration for listing under the US Endangered Species Act (ESA). We have concerns about the trend toward what we see as an overly broad definition of conservation reliance. In addition to being of limited practical utility, overuse of the conservation reliant label can mask important legal and policy issues associated with species recovery and delisting. We propose a biology-based definition of conservation-reliant species—specifically, one based on the degree to which a species needs direct and ongoing human manipulation of its life cycle or environment in order to persist in the wild. This definition could assist managers in developing recovery priorities and allocating scarce recovery funds. In addition, a biological definition of conservation reliance could assist society and policymakers in considering whether the ESA’s focus on self-sufficiency in the wild remains relevant as a definition of conservation success.

FULL TEXT LINK: http://bioscience.oxfordjournals.org/content/64/7/601.abstract

 

Rota, C. T., M. A. Rumble, et al. (2014). “Space-use and habitat associations of Black-backed Woodpeckers (Picoides arcticus) occupying recently disturbed forests in the Black Hills, South Dakota.” Forest Ecology and Management 313: 161-168.

Black-backed Woodpeckers (Picoides arcticus) are a disturbance-dependent species that occupy recently burned forest and mountain pine beetle (MPB) infestations. Forest management practices that reduce the amount of disturbed forest may lead to habitat loss for Black-backed Woodpeckers, which have recently been petitioned for listing under the Endangered Species Act. We studied home range size and resource selection of Black-backed Woodpeckers occupying habitat created by summer wildfire, fall prescribed fire, and MPB infestations in the Black Hills, South Dakota. We studied home range size and resource selection by attaching radio-transmitters to adult Black-backed Woodpeckers. We estimated home range size using fixed kernel density techniques (n = 28 in habitat created by summer wildfire, n = 19 in habitat created by fall prescribed fire, and n = 27 in MPB infestations). We evaluated resource selection with a random-effects discrete choice model in a Bayesian framework (n = 5 in habitat created by summer wildfire, n = 16 in habitat created by fall prescribed fire, and n = 8 in habitat created by MPB infestations). Home range size was smallest in 1–2 year post summer wildfire habitat (mean home range size = 79 ha) and 2-year post fall prescribed fire habitat (mean home range size = 143 ha). Home range size was intermediate in MPB infestations (mean home range size = 307 ha) and was greatest in 3–4 year post fire habitat (mean summer wildfire home range size = 430 hectares, mean fall prescribed fire home range size = 460 ha). The relative probability that a Black-backed Woodpecker used a tree increased with increasing diameter at breast height (DBH) and basal area and was greatest on disturbance-killed trees. These results suggest 1–2 year post summer wildfire habitat may have the greatest relative value to Black-backed Woodpeckers and that MPB infestations may be more important as post-fire habitats age. We recommend retaining patches of 1–2 year post summer wildfire habitat that are at least 200 ha by exempting portions of recently burned forest from salvage logging. This recommendation can be accomplished by exempting salvage logging in summer wildfires <200 ha and retaining at least 50% of summer wildfires >400 ha. Ideally, recently burned forest patches should be composed of ⩾27 m2 basal area/ha of trees that burned at moderate or high severity, with at least 40% of the basal area composed of trees ⩾27 cm DBH.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112713007354

 

 

Well-Read-Robyn_3_27_15

Compilation by Robyn Darbyshire

Monroe, M. C. and S. Lauretta (2014). “Perceptions of Forest Health among Preservice Educators and Implication for Teaching Youth.” Applied Environmental Education & Communication 13(1): 5-14.

The objectives of this study were to (a) determine preservice educators’ perceptions of forest health, (b) define the experiences which may have influenced their understanding, and (c) identify the approaches they might use to convey forest health information. Twelve interviews were conducted with preservice science and agriculture education students at the University of Florida who are likely to teach about forest ecosystems. Results suggest that many respondents understand ecosystem function, the importance of insects, and the effects of invasive species. Most respondents demonstrated little knowledge of diseases, fungi, and appropriate ways to use the analogy of human health. Several findings suggest these perceptions are related to the types of experiences respondents had with forests.

FULL TEXT LINK: http://dx.doi.org/10.1080/1533015X.2014.913960

 

Cambi, M., G. Certini, et al. (2015). “The impact of heavy traffic on forest soils: A review.” Forest Ecology and Management 338: 124-138.

Forest soils can suffer from various threats, some of which are human induced. Although mechanized harvesting allows for high productivity, it may also seriously damage forest soils. In recent decades, the use of powerful and heavy machinery in forest management has increased exponentially. The extent, degree, and duration of direct and indirect effects of heavy traffic on soils depend on several factors, such as soil texture, moisture, and organic matter content, slope of the terrain, type and size of vehicles, wheel inflation pressure, tire shape, and number of vehicles trips. Topsoil compaction and the alteration of ground morphology are crucial direct effects of forest harvesting carried out using heavy equipment. Soil compaction results in reduced porosity, which implies limitations in oxygen and water supply to soil microorganisms and plants, with negative consequences for soil ecology and forest productivity. Compaction, especially when confined in ruts, also has dramatic ramifications in terms of runoff and erosion of the most fertile soil compartment (i.e., the top soil). In compacted soils, forest regeneration can be impeded or even prevented for long time periods. A detailed review of the abundant although still insufficient literature on machinery-induced negative effects on forest soils and their ramifications for forest ecology and management is provided here, along with recommendations for best practices to limit such damage.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714006884

 

Wilkerson, M. L., K. L. Ward, et al. (2014). “Diminishing Returns from Higher Density Restoration Seedings Suggest Trade-offs in Pollinator Seed Mixes.” Restoration Ecology 22(6): 782-789.

Native forbs have become a more central component of restoration programs, especially because of their role in supporting crop pollinators. This study evaluates the success of different native forb mixes and seeding rates using shared goals of restoration practitioners and agroecologists, namely percent native species cover, floral resources, native diversity, and cost-effectiveness. At 6 sites with hedgerows adjacent to agricultural lands in California’s Central Valley, we planted 3 native forb seed mixes at 3 seeding rates and monitored germination, percent cover, and floral resources for 2 to 3 years. We also evaluated the cost of the mixes based on seeding rates and original seed prices. More than mix type, relative seeding rate strongly affected germination, cover, and floral resource success. The relative benefits of seeding with more species diminished at higher seeding rates, especially when cost was considered. Cover increased significantly over the years but diversity declined sharply after the first year. Increased cover of target species was mainly due to the effect of 1 dominant species Grindelia camporum, common gumplant. We summarize data from a similar forb restoration study showing that the species that dominated in our mix-and-rate experimental sites also attracted the greatest diversity and abundance of pollinators. These findings highlight trade-offs and balance-points within restoration and pollination services goals. We offer suggestions on how to weigh those trade-offs, given particular priorities and how native forb plantings can support combined goals of pollination services and restoration.

FULL TEXT LINK: http://dx.doi.org/10.1111/rec.12141

 

Waltz, A. E. M., M. T. Stoddard, et al. (2014). “Effectiveness of fuel reduction treatments: Assessing metrics of forest resiliency and wildfire severity after the Wallow Fire, AZ.” Forest Ecology and Management 334: 43-52.

Landscape-scale wildfire has occurred in higher frequencies across the planet. Fuel reduction treatments to fire-adapted systems have been shown to reduce the impact to human values-at-risk. However, few studies have examined if these treatments contribute to ecosystem resilience, or the capacity of a system to absorb perturbation and return to a similar set of structures or processes. We defined short-term metrics of resiliency to test the hypothesis that fuel reduction treatments in mixed conifer forests increased a fire-adapted system’s resiliency to uncharacteristically severe wildfire. In addition, we tested the hypothesis that fuel reduction treatments reduced burn severity, thereby increasing protection for adjacent human communities. We examined a mixed conifer forested landscape in the southwestern U.S. that was burned by a landscape-scale “mega-fire” in 2011; fuel reduction treatments had been established around communities in the 10 years prior to the fire. Fire effects were highly variable in both treated and untreated forests. However, analysis of resiliency metrics showed that: (a) treated units retained a higher proportion of large trees and had post-fire tree densities within the natural range of variability; (b) the understory herbaceous community had significantly higher cover of native grasses in the treated units, but no significant differences in nonnative cover between treated and untreated units; and (c) high-severity patch sizes were significantly larger in untreated stands and covered a larger proportion of the landscape than historical reference conditions. Fire severity, as defined by overstory mortality and basal area loss, was significantly lower in treated units; on average, trees killed per hectare in untreated units was six times the number of trees killed in treated units. Fuel reduction treatments simultaneously reduced fire severity and enhanced short-term metrics of ecosystem resiliency to uncharacteristically severe fire.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714005155

 

Sunday, J. M., A. E. Bates, et al. (2014). “Thermal-safety margins and the necessity of thermoregulatory behavior across latitude and elevation.” Proceedings of the National Academy of Sciences 111(15): 5610-5615.

Physiological thermal-tolerance limits of terrestrial ectotherms often exceed local air temperatures, implying a high degree of thermal safety (an excess of warm or cold thermal tolerance). However, air temperatures can be very different from the equilibrium body temperature of an individual ectotherm. Here, we compile thermal-tolerance limits of ectotherms across a wide range of latitudes and elevations and compare these thermal limits both to air and to operative body temperatures (theoretically equilibrated body temperatures) of small ectothermic animals during the warmest and coldest times of the year. We show that extreme operative body temperatures in exposed habitats match or exceed the physiological thermal limits of most ectotherms. Therefore, contrary to previous findings using air temperatures, most ectotherms do not have a physiological thermal-safety margin. They must therefore rely on behavior to avoid overheating during the warmest times, especially in the lowland tropics. Likewise, species living at temperate latitudes and in alpine habitats must retreat to avoid lethal cold exposure. Behavioral plasticity of habitat use and the energetic consequences of thermal retreats are therefore critical aspects of species’ vulnerability to climate warming and extreme events.

FULL TEXT LINK: http://www.pnas.org/content/111/15/5610.abstract

 

 

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Compilation by Robyn Darbyshire

Dodson, E. K., J. I. Burton, et al. (2014). “Multiscale Controls on Natural Regeneration Dynamics after Partial Overstory Removal in Douglas-Fir Forests in Western Oregon, USA.” Forest Science 60(5): 953-961.

We examined natural regeneration following operational-scale variable density retention treatments in 40‐60-year-old Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests at seven sites for a decade following treatment. Treatments included residual overstory densities of 300, 200, and 100 trees/ha, with leave islands and gaps of three sizes (0.1, 0.2, and 0.4 ha) and an untreated control (~600 trees/ha). Natural regeneration was influenced by factors from multiple spatial scales including broad-scale differences in overstory composition among sites, mesoscale variability in topographic position, and fine-scale variability in overstory and understory competition. High local basal area (BA) decreased the probability of seedling establishment, though some seedlings established even under high BA, particularly shade-tolerant western hemlock. In contrast, recruitment of saplings (> 1.37 m height) required lower residual overstory density (i.e., 100 trees/ha), especially for shade-intolerant Douglas-fir. Understory vegetation had little effect on saplings but was negatively related to seedling densities, particularly when overstory density was low. Variable density prescriptions can take advantage of the importance of fine-scale variability to promote regeneration of desired species mixtures, though other factors such as site overstory species composition and variation in topographic position will also influence regeneration dynamics. Including heavy overstory removal or gap creation could facilitate rapid recruitment of saplings, especially for shade-intolerant Douglas-fir.

FULL TEXT LINK: http://www.ingentaconnect.com/content/saf/fs/2014/00000060/00000005/art00014

 

Stephenson, N. L., A. J. Das, et al. (2014). “Rate of tree carbon accumulation increases continuously with tree size.” Nature 507(7490): 90-93.

Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle—particularly net primary productivity and carbon storage—increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree’s total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.

FULL TEXT LINK: http://dx.doi.org/10.1038/nature12914

 

Merschel, A. G., T. A. Spies, et al. (2014). “Mixed-conifer forests of central Oregon: effects of logging and fire exclusion vary with environment.” Ecological Applications 24(7): 1670-1688.

Twentieth-century land management has altered the structure and composition of mixed-conifer forests and decreased their resilience to fire, drought, and insects in many parts of the Interior West. These forests occur across a wide range of environmental settings and historical disturbance regimes, so their response to land management is likely to vary across landscapes and among ecoregions. However, this variation has not been well characterized and hampers the development of appropriate management and restoration plans. We identified mixed-conifer types in central Oregon based on historical structure and composition, and successional trajectories following recent changes in land use, and evaluated how these types were distributed across environmental gradients. We used field data from 171 sites sampled across a range of environmental settings in two subregions: the eastern Cascades and the Ochoco Mountains. We identified four forest types in the eastern Cascades and four analogous types with lower densities in the Ochoco Mountains. All types historically contained ponderosa pine, but differed in the historical and modern proportions of shade-tolerant vs. shade-intolerant tree species. The Persistent Ponderosa Pine and Recent Douglas-fir types occupied relatively hot-dry environments compared to Recent Grand Fir and Persistent Shade Tolerant sites, which occupied warm-moist and cold-wet environments, respectively. Twentieth-century selective harvesting halved the density of large trees, with some variation among forest types. In contrast, the density of small trees doubled or tripled early in the 20th century, probably due to land-use change and a relatively cool, wet climate. Contrary to the common perception that dry ponderosa pine forests are the most highly departed from historical conditions, we found a greater departure in the modern composition of small trees in warm-moist environments than in either hot-dry or cold-wet environments. Furthermore, shade-tolerant trees began infilling earlier in cold-wet than in hot-dry environments and also in topographically shaded sites in the Ochoco Mountains. Our new classification could be used to prioritize management that seeks to restore structure and composition or create resilience in mixed-conifer forests of the region.

FULL TEXT LINK: http://dx.doi.org/10.1890/13-1585.1

 

McManamay, R. A. and E. A. Frimpong (2014). “Hydrologic filtering of fish life history strategies across the United States: implications for stream flow alteration.” Ecological Applications 25(1): 243-263.

Lotic fish have developed life history strategies adapted to the natural variation in stream flow regimes. The natural timing, duration, and magnitude of flow events has contributed to the diversity, production, and composition of fish assemblages over time. Studies evaluating the role of hydrology in structuring fish assemblages have been more common at the local or regional scale with very few studies conducted at the continental scale. Furthermore, quantitative linkages between natural hydrologic patterns and fish assemblages are rarely used to make predictions of ecological consequences of hydrologic alterations. We ask two questions: (1) what is the relative role of hydrology in structuring fish assemblages at large scales? and (2) can relationships between fish assemblages and natural hydrology be utilized to predict fish assemblage responses to hydrologic disturbance? We developed models to relate fish life histories and reproductive strategies to landscape and hydrologic variables separately and then combined. Models were then used to predict the ecological consequences of altered hydrology due to dam regulation. Although hydrology plays a considerable role in structuring fish assemblages, the performance of models using only hydrologic variables was lower than that of models constructed using landscape variables. Isolating the relative importance of hydrology in structuring fish assemblages at the continental scale is difficult since hydrology is interrelated to many landscape factors. By applying models to dam-regulated hydrologic data, we observed some consistent predicted responses in fish life history strategies and modes of reproduction. In agreement with existing literature, equilibrium strategists are predicted to increase following dam regulation, whereas opportunistic and periodic species are predicted to decrease. In addition, dam regulation favors the selection of reproductive strategies with extended spawning seasons and preference for stable conditions.

FULL TEXT LINK: http://dx.doi.org/10.1890/14-0247.1

 

Root, H. T., L. H. Geiser, et al. (2015). “Epiphytic macrolichen indication of air quality and climate in interior forested mountains of the Pacific Northwest, USA.” Ecological Indicators 53(0): 95-105.

Biomonitoring can provide cost-effective and practical information about the distribution of nitrogen (N) deposition, particularly in regions with complex topography and sparse instrumented monitoring sites. Because of their unique biology, lichens are very sensitive bioindicators of air quality. Lichens lack a cuticle to control absorption or leaching of nutrients and they dynamically concentrate nutrients roughly in proportion to the abundance in the atmosphere. As N deposition increases, nitrogen-loving eutrophic lichens become dominant over oligotrophic lichens that thrive in nutrient-poor habitats. We capitalize on these characteristics to develop two lichen-based indicators of air-borne and depositional N for interior forested mountain ecosystems of the Pacific Northwest and calibrate them with N concentration measured in PM2.5 at 12 IMPROVE air quality monitoring sites in the study area. The two lichen indices and peak frequencies of individual species exhibited continuous relationships with inorganic N pollution throughout the range of N in ambient PM2.5, suggesting that the designation of a critical level or critical load is somewhat arbitrary because at any level above background, some species are likely to experience adverse impacts. The concentration of N in PM2.5 near the city of Spokane, Washington was the lowest measured at an instrumented monitoring site near known N pollution sources. This level, 0.37 μg/m3/year, served as a critical level, corresponding to a concentration of 1.02% N in the lichen Letharia vulpina, which is similar to the upper end of background lichen N concentrations measured elsewhere in the western United States. Based on this level, we estimate critical loads to be 1.54 and 2.51 kg/ha/year of through-fall dissolved inorganic N deposition for lichen communities and lichen N concentration, respectively. We map estimated fine-particulate (PM2.5) N in ambient air based on lichen community and lichen N concentration indices to identify hotspots in the region. We also develop and map an independent lichen community-based bioclimatic index, which is strongly related to gradients in moisture availability and temperature variability. Lichen communities in the driest climates were more eutrophic than those in wetter climates at the same levels of N air pollution.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S1470160X15000539

 

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Compilation by Robyn Darbyshire

Colgan, C., M. Hunter, et al. (2014). “Managing the middle ground: forests in the transition zone between cities and remote areas.” Landscape Ecology 29(7): 1133-1143.

In many parts of the world there are extensive landscapes where forests and people strongly intermingle, notably in the suburbs and exurbs of cities. This landscape of transitional forest generally receives limited attention from policy makers and researchers who tend to be rooted in traditions centered on either urban planning or management of natural resources in rural areas. The transitional forest is on the periphery of both perspectives, but it is a large area that provides numerous important values (biodiversity, ecosystem function, forest products, and amenities) to the people that live in them and their neighboring cities. Here we argue for increased attention to transitional forests, identify major challenges, and suggest changes to planning and management practices needed to ensure that the values of these forests are sustained.

FULL TEXT LINK: http://dx.doi.org/10.1007/s10980-014-0054-7

 

Humphries, P., H. Keckeis, et al. (2014). “The River Wave Concept: Integrating River Ecosystem Models.” BioScience 64(10): 870-882.

We introduce the river wave concept: a simple, holistic model that unifies river ecosystem concepts. The river wave concept proposes that river flow can be conceptualized as a series of waves varying in shape, amplitude, wavelength, and frequency, traveling longitudinally and laterally; the position on the wave determines the source of organic production or inputs and the storage, transformation, and transport of material and energy; and existing concepts explain ecosystem phenomena at different positions on the river wave. The river wave concept hypothesizes that, at the troughs of waves, local autochthonous and allochthonous inputs predominate; on the ascending or descending limbs of waves, upstream allochthonous inputs and longitudinal transport of material and energy predominate; and as waves rise to crests, allochthonous inputs of material and energy and autochthonous production from the floodplain increase. We describe how river waves interact with their environment and the relevance for biota.

FULL TEXT LINK: http://bioscience.oxfordjournals.org/content/64/10/870.abstract

 

Kuglerová, L., A. Ågren, et al. (2014). “Towards optimizing riparian buffer zones: Ecological and biogeochemical implications for forest management.” Forest Ecology and Management 334: 74-84.

Riparian forests (RFs) along streams and rivers in forested landscapes provide many ecosystem functions that are important for the biodiversity and biogeochemistry of both terrestrial and aquatic ecosystems. In riverine landscapes, many of these ecological and biogeochemical functions have been found to be maximized in riparian areas with discharge of upland-originating groundwater (GW). This ecological significance, and the fact that riparian areas with GW discharge are important sources of many chemical elements in streams and rivers, makes these places important hotspots in the landscape. The natural functioning of RFs is however threatened by poorly designed management practices, with forestry being one of the most important examples in timber producing regions. Logging operations in riparian, but also in adjoining upland forests, threaten to alter many riparian functions. This effect is accelerated in GW discharge hotspots because of their sensitive soils and the high connectivity with uphill areas. We thus argue that forestry practices should give higher consideration to riparian GW discharge areas, and we demonstrate how improved riparian buffer zone management can be incorporated into every-day forestry planning. We offer a practical tool for more optimized site-specific riparian buffer design by using model-derived high resolution maps with detailed information about wetness and soil–water flow paths within RFs. We describe how such site-specific riparian buffer management differs from fixed-width buffers, which are generally applied in today’s forestry, and address some risks connected to fixed-width buffer management. We conclude that site-specific riparian management, allowing wider buffers at GW discharge areas and more narrow buffers on sites of lower ecological significance (i.e. riparian sites without GW flow paths), would benefit a variety of ecosystem services, mitigate negative effects caused by forestry and create more variable and heterogeneous riparian corridors. Finally, we show examples of how the new forestry planning can be applied.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714005222

 

Keenan, R. (2015). “Climate change impacts and adaptation in forest management: a review.” Annals of Forest Science 72(2): 145-167.

Adaptation of forest management to climate change requires an understanding of the effects of climate on forests, industries and communities; prediction of how these effects might change over time; and incorporation of this knowledge into management decisions. This requires multiple forms of knowledge and new approaches to forest management decisions. Partnerships that integrate researchers from multiple disciplines with forest managers and local actors can build a shared understanding of future challenges and facilitate improved decision making in the face of climate change.

Climate change presents significant potential risks to forests and challenges for forest managers. Adaptation to climate change involves monitoring and anticipating change and undertaking actions to avoid the negative consequences and to take advantage of potential benefits of those changes.

This paper aimed to review recent research on climate change impacts and management options for adaptation to climate change and to identify key themes for researchers and for forest managers.

The study is based on a review of literature on climate change impacts on forests and adaptation options for forest management identified in the Web of Science database, focusing on papers and reports published between 1945 and 2013.

One thousand one hundred seventy-two papers were identified in the search, with the vast majority of papers published from 1986 to 2013. Seventy-six percent of papers involved assessment of climate change impacts or the sensitivity or vulnerability of forests to climate change and 11 % (130) considered adaptation. Important themes from the analysis included (i) predicting species and ecosystem responses to future climate, (ii) adaptation actions in forest management, (iii) new approaches and tools for decision making under uncertainty and stronger partnerships between researchers and practitioners and (iv) policy arrangements for adaptation in forest management.

Research to support adaptation to climate change is still heavily focused on assessing impacts and vulnerability. However, more refined impact assessments are not necessarily leading to better management decisions. Multi-disciplinary research approaches are emerging that integrate traditional forest ecosystem sciences with social, economic and behavioural sciences to improve decision making. Implementing adaptation options is best achieved by building a shared understanding of future challenges among different institutions, agencies, forest owners and stakeholders. Research-policy-practice partnerships that recognise local management needs and indigenous knowledge and integrate these with climate and ecosystem science can facilitate improved decision making.

NO FULL TEXT LINK: full text available from FS Library Services http://fsweb.wo.fs.fed.us/library/document-delivery.htm (or email rdarbyshire@fs.fed.us)

 

Rex, J. F., E. L. Petticrew, et al. (2014). “The influence of Pacific salmon decay products on near-field streambed sediment and organic matter dynamics: a flume simulation.” Earth Surface Processes and Landforms 39(10): 1378-1385.

Pacific salmon are biogeomorphic agents shown to induce positive feedbacks on their natal watersheds. However, the literature documenting their ecological effects on in-stream natal environments is more divisive. The disturbance salmon create during redd construction has the potential to reduce stream productivity. The pulse of salmon organic matter (SOM) and marine derived nutrients (MDNs) released during carcass decay has been reported as either stimulating in-stream productivity or having no local effect. To evaluate the ecological costs and benefits of salmon spawning events, MDN delivery and storage processes need to be identified and quantified. A simulation was conducted in three flow-through flumes (2 m × 2 m × 30 m) over a 33-day period (consisting of 15 baseline, four MDN exposure, and 14 post-exposure days) to assess near-field sediment and organic matter dynamics during active and post-spawn simulations. The objective of the study was to measure changes in the amounts and particle sizes of suspended and gravel-stored fine sediment, in order to elucidate the process and significance of SOM recruitment to the gravel bed via sedimentation. Gravel beds in all flumes were enriched with SOM following treatments but the response was highest in the active spawn simulation. The more effective delivery in the active spawn simulation was attributed to its higher inorganic sediment concentration, which is known to enhance floc formation. Although the active spawn simulation delivered more SOM to the gravel bed, the post-spawn phase may be equally important to natural streams because its decay phase is longer than the active spawn and consequently can provide SOM to the streambed as long as carcasses remain in-stream. The delivery, and potential retention, of SOM to spawning streambeds and the intergravel environment may be particularly important for interior streams, which experience low flow conditions during the spawning phase and accordingly have the potential for hyporheic nutrient recruitment and storage.

FULL TEXT LINK: http://dx.doi.org/10.1002/esp.3591

 

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Compilation by Robyn Darbyshire

Archer, S. R. and K. I. Predick (2014). “An ecosystem services perspective on brush management: research priorities for competing land-use objectives.” Journal of Ecology 102(6): 1394-1407.

* The vegetation of semi-arid and arid landscapes is often comprised of mixtures of herbaceous and woody vegetation. Since the early 1900s, shifts from herbaceous to woody plant dominance, termed woody plant encroachment and widely regarded as a state change, have occurred world-wide. This shift presents challenges to the conservation of grassland and savanna ecosystems and to animal production in commercial ranching systems and pastoral societies. * Dryland management focused on cattle and sheep grazing has historically attempted to reduce the abundance of encroaching woody vegetation (hereafter, ‘brush management’) with the intent of reversing declines in forage production, stream flow or groundwater recharge. Here, we assess the known and potential consequences of brush management actions, both positive and negative, on a broader suite of ecosystem services, the scientific challenges to quantifying these services and the trade-offs among them. * Our synthesis suggests that despite considerable investments accompanying the application of brush management practices, the recovery of key ecosystem services may be short-lived or absent. However, in the absence of such interventions, those and other ecosystem services may be compromised, and the persistence of grassland and savanna ecosystem types and their endemic plants and animals threatened. * Addressing the challenges posed by woody plant encroachment will require integrated management systems using diverse theoretical principles to design the type, timing and spatial arrangement of initial management actions and follow-up treatments. These management activities will need to balance cultural traditions and preferences, socio-economic constraints and potentially competing land-use objectives. * Synthesis. Our ability to predict ecosystem responses to management aimed at recovering ecosystem services where grasslands and savannas have been invaded by native or exotic woody plants is limited for many attributes (e.g. primary production, land surface–atmosphere interactions, biodiversity conservation) and inconsistent for others (e.g. forage production, herbaceous diversity, water quality/quantity, soil erosion, carbon sequestration). The ecological community is challenged with generating robust information about the response of ecosystem services and their interactions if we are to position land managers and policymakers to make objective, science-based decisions regarding the many trade-offs and competing objectives for the conservation and dynamic management of grasslands and savannas.

FULL TEXT LINK: http://dx.doi.org/10.1111/1365-2745.12314

 

Ratnam, W., O. P. Rajora, et al. (2014). “Genetic effects of forest management practices: Global synthesis and perspectives.” Forest Ecology and Management 333: 52-65.

Understanding the genetic impacts of forest management practices is crucial for conservation and management of forest genetic resources. Forest management practices based on selective and clear cut systems followed by natural or artificial regeneration can impact population structure and mating patterns, thus gene flow and genetic diversity. Survival and productivity of both tree and non-tree species can be compromised or, possibly, enhanced. The extent of genetic impacts depend on the management system applied, stand structure as well as species’ distribution, demography, biological attributes and ecology. The impact of management practices is reviewed and synthesized for temperate, boreal and tropical forests based on experimental and simulation studies. In addition, the effects of genetically improved planting materials and establishment of large scale plantations on natural forests are examined. Recommendations are made for genetically sustainable forest management practices.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714003697

 

Hagmann, R. K., J. F. Franklin, et al. (2014). “Historical conditions in mixed-conifer forests on the eastern slopes of the northern Oregon Cascade Range, USA.” Forest Ecology and Management 330: 158-170.

Historical forest conditions in frequent-fire forests may be increasingly useful in guiding contemporary forest management given (1) projections for increased drought stress associated with climate change and (2) increases in vertical and horizontal fuel connectivity related to changes in land use over the past 150 years. Records from a 1922–25 timber inventory reveal historical variability at the landscape-level on mixed-conifer habitats on the eastern slopes of the Cascade Range in northern Oregon. Live conifers > 15 cm dbh (diameter at breast height) were tallied by species and diameter class in a 20% sample of over 50,000 hectares (ha). Forests were predominantly low density (66 tph, standard deviation = 32, range = 0–289) relative to current conditions (312 ± 245, 0–1643 tph). Historical basal area averaged 14 ± 7 (0–70) m2 ha−1. Total stand density, large tree (> 53 cm dbh) density, and ponderosa pine density were relatively stable across a wide moisture gradient (42–187 cm annual precipitation). Large trees dominated total basal area (73 ± 16%) and comprised 42 ± 17% of total trees per hectare (tph). Ponderosa pine contributed 62 ± 27% of basal area. Together, ponderosa pine and Douglas-fir constituted 91 ± 15% of basal area. Large ponderosa pine and Douglas-fir were nearly ubiquitous across the landscape in this historical data set, occurring on 94% and 83% of transects respectively. Large grand fir occurred on 20% of transects but contributed only 2 ± 6% to large tree basal area. Higher-density values (> 120 tph), although rare, were distributed throughout the mixed-conifer habitat while large (> 1.6 ha) treeless (no conifers > 15 cm dbh) areas were almost entirely restricted to higher elevation, colder, wetter habitat types. Currently ponderosa pine no longer dominates large tree basal area, large trees no longer dominate total basal area, and Douglas-fir is now the dominant species across the landscape. Current mean tree densities are more than four times greater than values recorded in the historical cruise, and current basal area is approximately two times greater. Currently, large trees dominate basal area on only 29% of area inventoried compared to 91% in 1922–25. This systematic sample of a large landscape provides information about variability in species composition, densities, and structures at multiple spatial scales, which are highly relevant to management activities to restore and conserve desired ecosystem functions. Forest conditions comparable to those in this historical record have demonstrated resilience and resistance to fire and drought-related stressors in other frequent-fire forests.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714004253

 

Acker, S. A., J. R. Boetsch, et al. (2015). “Recent tree mortality and recruitment in mature and old-growth forests in western Washington.” Forest Ecology and Management 336: 109-118.

Tree mortality is a fundamental driver of forest ecosystems and occurs both in catastrophic events and as a chronic process. Persistent changes in the rate of chronic or background mortality can dramatically alter the structure and composition of forests stands. Tree recruitment is the complement to tree mortality, combining with mortality to determine changes in tree density and species composition. The purpose of this study is to ascertain trends of mortality and recruitment in mature and old-growth forests in western Washington state, U.S.A. We used a set of permanent plots established in units of the National Park System spanning the environmental gradient of forests in these parks (from near sea-level to 1800 m elevation). Duration of observation was five years for most plots and two or three years for a small number of plots. Principal tree species on the plots were Picea sitchensis, Tsuga heterophylla, Pseudotsuga menziesii, Thuja plicata, Abies lasiocarpa, and Abies amabilis. Tree mortality was evaluated annually; recruitment was recorded at the end of the study. For small (dbh 12.7–76.1 cm) and large (dbh >76.1 cm) trees, annual mortality pooled across all elevations, parks, plots, and years was <1% (mean and upper 95% confidence intervals). For saplings (dbh 2.5–12.6 cm), mean mortality was < 1% though the upper limit of the confidence interval was slightly greater than 1%. Recruitment outweighed mortality (and growth into the small-tree class) for saplings. Recruitment and losses of stems balanced one another for small trees; both processes were negligible for large trees. Recruitment of saplings increased representation of shade-tolerant species (e.g., T. heterophylla, and A. amabilis). Biotic factors predominated as the proximate cause of death for all size-classes of trees (i.e., trees died standing), though particular agents of mortality were not identified in most cases. Our results contrasted with a recent report of annual tree mortality >1% for unmanipulated, old-growth forests in the Pacific Northwest.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714005908

 

Bardgett, R. D. and W. H. van der Putten (2014). “Belowground biodiversity and ecosystem functioning.” Nature 515(7528): 505-511.

Evidence is mounting that the immense diversity of microorganisms and animals that live belowground contributes significantly to shaping aboveground biodiversity and the functioning of terrestrial ecosystems. Our understanding of how this belowground biodiversity is distributed, and how it regulates the structure and functioning of terrestrial ecosystems, is rapidly growing. Evidence also points to soil biodiversity as having a key role in determining the ecological and evolutionary responses of terrestrial ecosystems to current and future environmental change. Here we review recent progress and propose avenues for further research in this field.

FULL TEXT LINK: http://dx.doi.org/10.1038/nature13855

Well_Read_Robyn_2_27_15

Compilation by Robyn Darbyshire

McCune, J., M. Vellend, et al. (2015). “Combining phytolith analysis with historical ecology to reveal the long-term, local-scale dynamics within a savannah-forest landscape mosaic.” Biodiversity and Conservation 24(3): 609-626.

An understanding of the historical range of variability of an ecosystem can improve management and restoration activities, but this variability depends on the spatial and temporal scale at which it is measured. We examined the extent of local-scale variation in vegetation prior to European settlement across a savannah-forest landscape mosaic on southeastern Vancouver Island, British Columbia, Canada. We used phytoliths extracted from soil surface samples to calibrate an index that differentiates open savannahs from closed canopy Douglas-fir forests and then examined shifts in this index with soil depth at seven local sites. We tested whether changes with depth aligned with known vegetation changes based on land survey records from the mid-1800s, and then inferred vegetation change prior to European settlement. The log ratio of astrosclereids (phytolith specific to Douglas-fir) and rondels (phytolith specific to grasses) in soil surface samples accurately distinguished between current vegetation types, and shifts in this ratio with depth were sensitive to known historical changes in most of the cores. Some sites have supported open savannah vegetation for at least 2,000 years, while others that were formerly open have been filled in by Douglas-fir forest. However, this infilling appears to have begun at different times for different sites. Our findings demonstrate that the degree and timing of historical variation in vegetation can differ between local sites within a broader regional landscape that appears relatively stable.

FULL TEXT LINK: http://dx.doi.org/10.1007/s10531-014-0840-1

 

Lorimer, C. G. and C. R. Halpin (2014). “Classification and dynamics of developmental stages in late-successional temperate forests.” Forest Ecology and Management 334: 344-357.

Late-successional forests often have complex disturbance histories that can result in stands with widely varying structure, ranging from young pole stands to uneven-aged old growth. Arranging stands in chronosequences, however, is problematic because ‘stand age’ is not a meaningful concept for multi-aged stands and ‘time since last stand-replacing disturbance’ often cannot be determined from tree-ring evidence. In this paper, we describe a systematic approach for classifying developmental stages in late-successional forests using structural metrics known to be correlated with key ecological properties such as total biomass, carbon storage, stand production rates, and wildlife habitat. While conceptually based on the amount of aggregate crown area occupied by different size classes of trees, the computations in this study, for ease of use, are based entirely on absolute and relative basal area of four size classes (saplings, poles, mature, and large trees). Eight forest structural stages are recognized, including four stages of old growth (early-, mid-, late-transition, and steady state). The method was used to classify developmental stages of 70 primary northern hardwood stands (Acer–Betula–Tsuga) in large landscape reserves in upper Michigan, USA. The degree to which the developmental stages mimic underlying temporal trends in stand dynamics was investigated with the aid of 30-year permanent plot records in primary forests and multi-century simulations using the CANOPY forest dynamics model. Results indicated good correspondence between the postulated developmental sequence in the 70 field stands compared with CANOPY simulations of structural changes over time and changes observed on the permanent plots. Results support the Bormann–Likens hypothesis that the number of large trees reaches a maximum toward the end of the lifespan of an even-aged cohort and subsequently declines in the steady state. While most of the field plots were uneven-aged, both simulations and field data suggest that developmental pathways of even-aged and multi-aged stands after disturbance are very similar and are difficult to distinguish based on the form of the size distributions. In the study area landscapes, 78% of the stands were classified as old growth, with 39% in early or mid-transition and 39% in late transition or steady state. The method should be useful, with appropriate site-specific modifications, in evaluating the degree to which stands meet structural goals under ecological forestry methods, in monitoring responses to environmental change, and in examining biotic changes along a gradient of structural development following disturbance.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714005258

 

Seidl, R., W. Rammer, et al. (2014). “Disturbance legacies increase the resilience of forest ecosystem structure, composition, and functioning.” Ecological Applications 24(8): 2063-2077.

Disturbances are key drivers of forest ecosystem dynamics, and forests are well adapted to their natural disturbance regimes. However, as a result of climate change, disturbance frequency is expected to increase in the future in many regions. It is not yet clear how such changes might affect forest ecosystems, and which mechanisms contribute to (current and future) disturbance resilience. We studied a 6364-ha landscape in the western Cascades of Oregon, USA, to investigate how patches of remnant old-growth trees (as one important class of biological legacies) affect the resilience of forest ecosystems to disturbance. Using the spatially explicit, individual-based, forest landscape model iLand, we analyzed the effect of three different levels of remnant patches (0%, 12%, and 24% of the landscape) on 500-year recovery trajectories after a large, high-severity wildfire. In addition, we evaluated how three different levels of fire frequency modulate the effects of initial legacies. We found that remnant live trees enhanced the recovery of total ecosystem carbon (TEC) stocks after disturbance, increased structural complexity of forest canopies, and facilitated the recolonization of late-seral species (LSS). Legacy effects were most persistent for indicators of species composition (still significant 500 years after disturbance), while TEC (i.e., a measure of ecosystem functioning) was least affected, with no significant differences among legacy scenarios after 236 years. Compounding disturbances were found to dampen legacy effects on all indicators, and higher initial legacy levels resulted in elevated fire severity in the second half of the study period. Overall, disturbance frequency had a stronger effect on ecosystem properties than the initial level of remnant old-growth trees. A doubling of the historically observed fire frequency to a mean fire return interval of 131 years reduced TEC by 10.5% and lowered the presence of LSS on the landscape by 18.1% on average, demonstrating that an increase in disturbance frequency (a potential climate change effect) may considerably alter the structure, composition, and functioning of forest landscapes. Our results indicate that live tree legacies are an important component of disturbance resilience, underlining the potential of retention forestry to address challenges in ecosystem management.

FULL TEXT LINK:

 

Ruzicka, K. J., K. J. Puettmann, et al. (2014). “Management of Riparian Buffers: Upslope Thinning with Downslope Impacts.” Forest Science 60(5): 881-892.

We examined the potential of using upslope density management to influence growth and drought tolerance of trees in untreated downslope riparian forests. Increment cores from Douglas-fir trees in three mature stands in western Oregon, USA, were collected and measured. Trees responded to an apparent edge effect up to 15 m downslope of thinned areas but not downslope of gaps. Growth responses in riparian trees were not affected by slope or potential solar radiation (as a function of location and topography). In addition, in a retrospective analysis of tree growth and allocation patterns (represented by the ratio of earlywood to latewood) and climate after treatment over a 12-year period, trees in our study area did not appear to be water limited and did not show a strong correlation with regional drought metrics. We hypothesize that vegetation layers in these riparian forest stands responded differentially to additional resources becoming available as a result of thinning, with overstory trees in riparian areas responding downslope of thinned uplands and subdominant canopy layers responding downslope of gaps. Our study demonstrates that managers can affect riparian forests with upland treatments to a limited spatial extent, which may be the only option in areas where direct riparian management is restricted due to concerns for other ecosystem services.

FULL TEXT LINK: http://www.ingentaconnect.com/content/saf/fs/2014/00000060/00000005/art00008

 

Wan, H. Y., A. C. Olson, et al. (2014). “Legacy effects of fire size and severity on forest regeneration, recruitment, and wildlife activity in aspen forests.” Forest Ecology and Management 329: 59-68.

Human activities and climate change are increasing the size and severity of wildfires globally, creating a need for research that links changes in fire regimes with community-level responses. The objective of this study was to understand how variability in fire regimes influences forest regeneration and recruitment patterns and wildlife activity at large temporal and spatial scales. Across 25 fires in five National Forests (Uinta-Wasatch-Cache NF, Ashley NF, Fishlake NF, Dixie NF, and Manti-La Sal NF) in the state of Utah, we examined aspen regeneration and recruitment levels, and wildlife and livestock fecal group counts along belt transects that spanned gradients of fire size and severity. Forest cover change was assessed by comparing pre-fire and post-fire satellite images. The fires dated from 1992 to 2002 and were at least 10 years old when this study was conducted. Fire size and severity were positively related to aspen regeneration (density of saplings) and recruitment (saplings >2 m in height). There was a significant fire size and severity interaction effect on aspen regeneration, such that the positive influence of fire size increased with greater fire severity (R2 = 0.40, P < 0.001). Change in the extent of aspen cover was not correlated with fire size. Deer and cattle became more dispersed with increasing fire size and severity, but elk activity showed no difference. Deer preferred low severity burn patches in smaller fires, but appeared to avoid low severity patches as fires became larger. Our results suggest that fire size and severity are important ecological filters that can interact to affect forest development and the distribution and abundance of large herbivores. Effective management of forest systems in response to altered fire regimes will require an understanding of the legacy effects of fire size and severity at the landscape scale.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0378112714003673

 

Well-Read-Robyn_2_20_15

Compilation by Robyn Darbyshire

Beechie, T. and H. Imaki (2014). “Predicting natural channel patterns based on landscape and geomorphic controls in the Columbia River basin, USA.” Water Resources Research 50(1): 39-57.
Based on known relationships of slope, discharge, valley confinement, sediment supply, and sediment caliber in controlling channel patterns, we developed multivariate models to predict natural channel patterns across the 674,500 km2 Columbia River basin, USA. We used readily available geospatial data sets to calculate reach slopes, 2 year flood discharge, and valley confinement, as well as to develop hypothesized landscape-level surrogates for sediment load and caliber (relative slope, percent of drainage area in alpine terrain, and percent of drainage area in erosive fine-grained lithologies). Using a support vector machine (SVM) classifier, we found that the four channel patterns were best distinguished by a model including all variables except valley confinement (82% overall accuracy). We then used that model to predict channel pattern for the entire basin and found that the spatial distribution of straight, meandering, anabranching, and braided patterns were consistent with regional topography and geology. A simple slope-discharge model distinguished meandering channels from all other channel patterns, but did not clearly distinguish braided from straight channels (68% overall accuracy). Addition of one or more of the hypothesized sediment supply surrogates improved prediction accuracy by 4–14% over slope and discharge alone. Braided and straight channels were most clearly distinguished on an axis of relative slope, whereas braided and anabranching channels were most clearly distinguished by adding percent alpine area to the model. The relatively high prediction accuracies indicate that it is feasible to develop models to predict channel pattern across a geologically and climatically diverse landscape based on simple physical and landscape variables, and that such predictions can be used in conservation planning for river ecosystems.

FULL TEXT LINK: http://dx.doi.org/10.1002/2013WR013629

Benda, L. and P. Bigelow (2014). “On the patterns and processes of wood in northern California streams.” Geomorphology 209: 79-97.
Forest management and stream habitat can be improved by clarifying the primary riparian and geomorphic controls on streams. To this end, we evaluated the recruitment, storage, transport, and the function of wood in 95 km of streams (most drainage areas < 30 km2) in northern California, crossing four coastal to inland regions with different histories of forest management (managed, less-managed, unmanaged). The dominant source of variability in stream wood storage and recruitment is driven by local variation in rates of bank erosion, forest mortality, and mass wasting. These processes are controlled by changes in watershed structure, including the location of canyons, floodplains and tributary confluences; types of geology and topography; and forest types and management history. Average wood storage volumes in coastal streams are 5 to 20 times greater than inland sites primarily from higher riparian forest biomass and growth rates (productivity), with some influence by longer residence time of wood in streams and more wood from landsliding and logging sources. Wood recruitment by mortality (windthrow, disease, senescence) was substantial across all sites (mean 50%) followed by bank erosion (43%) and more locally by mass wasting (7%). The distances to sources of stream wood are controlled by recruitment process and tree height. Ninety percent of wood recruitment occurs within 10 to 35 m of channels in managed and less-managed forests and upward of 50 m in unmanaged Sequoia and coast redwood forests. Local landsliding extends the source distance. The recruitment of large wood pieces that create jams (mean diameter 0.7 m) is primarily by bank erosion in managed forests and by mortality in unmanaged forests. Formation of pools by wood is more frequent in streams with low stream power, indicating the further relevance of environmental context and watershed structure. Forest management influences stream wood dynamics, where smaller trees in managed forests often generate shorter distances to sources of stream wood, lower stream wood storage, and smaller diameter stream wood. These findings can be used to improve riparian protection and inform spatially explicit riparian management.

FULL TEXT LINK: http://www.sciencedirect.com/science/article/pii/S0169555X13006144

Kidd, K., W. M. Aust, et al. (2014). “Recreational Stream Crossing Effects on Sediment Delivery and Macroinvertebrates in Southwestern Virginia, USA.” Environmental Management 54(3): 505-516.
Trail-based recreation has increased over recent decades, raising the environmental management issue of soil erosion that originates from unsurfaced, recreational trail systems. Trail-based soil erosion that occurs near stream crossings represents a non-point source of pollution to streams. We modeled soil erosion rates along multiple-use (hiking, mountain biking, and horseback riding) recreational trails that approach culvert and ford stream crossings as potential sources of sediment input and evaluated whether recreational stream crossings were impacting water quality based on downstream changes in macroinvertebrate-based indices within the Poverty Creek Trail System of the George Washington and Jefferson National Forest in southwestern Virginia, USA. We found modeled soil erosion rates for non-motorized recreational approaches that were lower than published estimates for an off-road vehicle approach, bare horse trails, and bare forest operational skid trail and road approaches, but were 13 times greater than estimated rates for undisturbed forests and 2.4 times greater than a 2-year old clearcut in this region. Estimated soil erosion rates were similar to rates for skid trails and horse trails where best management practices (BMPs) had been implemented. Downstream changes in macroinvertebrate-based indices indicated water quality was lower downstream from crossings than in upstream reference reaches. Our modeled soil erosion rates illustrate recreational stream crossing approaches have the potential to deliver sediment into adjacent streams, particularly where BMPs are not being implemented or where approaches are not properly managed, and as a result can negatively impact water quality below stream crossings.

FULL TEXT LINK: http://dx.doi.org/10.1007/s00267-014-0328-5

Roy, B. A., H. M. Alexander, et al. (2014). “Increasing forest loss worldwide from invasive pests requires new trade regulations.” Frontiers in Ecology and the Environment 12(8): 457-465.
Loss of forests due to non-native invasive pests (including insects, nematodes, and pathogens) is a global phenomenon with profound population, community, ecosystem, and economic impacts. We review the magnitude of pest-associated forest loss worldwide and discuss the major ecological and evolutionary causes and consequences of these invasions. After compiling and analyzing a dataset of pest invasions from 21 countries, we show that the number of forest pest invasions recorded for a given country has a significant positive relationship with trade (as indicated by gross domestic product) and is not associated with the amount of forested land within that country. We recommend revisions to existing international protocols for preventing pest entry and proliferation, including prohibiting shipments of non-essential plants and plant products unless quarantined. Because invasions often originate from taxa that are scientifically described only after their introduction, current phytosanitary regulations – which target specific, already named organisms – are ineffective.

FULL TEXT LINK: http://dx.doi.org/10.1890/130240

Linhart, Y. B., X. Moreira, et al. (2014). “Variability in seed cone production and functional response of seed predators to seed cone availability: support for the predator satiation hypothesis.” Journal of Ecology 102(3): 576-583.
* Mast seeding is a reproductive strategy in some perennial plants defined as synchronous production of large seed crops at irregular intervals. One widely accepted theory to explain this behaviour is the predator satiation hypothesis, which states that the synchronous and variable production of seeds within a population will maximize the probability of seed survival through satiation of seed predators. * Although some short-term studies have documented the influence of variable and synchronized production of seeds on herbivore attack rate during one or few mast years, long-term data including multiple mast seeding years and patterns of cone production and herbivore attack on individual trees are needed to assess (i) how cone production, variability and synchrony affect individual plant fitness and (ii) the functional responses of seed predators to mast seeding events. * We tested these objectives, collecting long-term (29 years) data on female seed cone production and rates of seed predator attack from 217 individual contiguous trees within a Pinus ponderosa population. * Our results support the predator satiation hypothesis. First, we found high interannual synchrony and variability in seed cone production and a type II functional response of seed predators to available cones. Secondly, years with high cone production (mast years) had markedly lower rates of seed predator attack than years of low production (i.e. a population-level satiation effect). Thirdly, within mast years, individuals with high cone production had markedly lower rates of attack than individuals with low cone production (i.e. an individual-level satiation effect). Finally, individual trees with greater synchrony and more variable cone production suffered lower rates of attack. * Synthesis: Our long-term data on individual trees lend strong support to the hypothesis that mast seeding in Pinus ponderosa has evolved in response to natural selection from insect seed predators.

FULL TEXT LINK: http://dx.doi.org/10.1111/1365-2745.12231