All posts by Don

Well_Read_Robyn_12_30_2016

Compilation by Robyn Darbyshire, Regional Silviculturist

Baker, S. C., C. B. Halpern, et al. (2016). “A cross-continental comparison of plant and beetle responses to retention of forest patches during timber harvest.” Ecological Applications 26(8): 2493-2504.

Timber harvest can adversely affect forest biota. Recent research and application suggest that retention of mature forest elements (retention forestry), including unharvested patches (or aggregates) within larger harvested units, can benefit biodiversity compared to clearcutting. However, it is unclear whether these benefits can be generalized among the diverse taxa and biomes in which retention forestry is practiced. Lack of comparability in methods for sampling and analyzing responses to timber harvest and edge creation presents a challenge to synthesis. We used a consistent methodology (similarly spaced plots or traps along transects) to investigate responses of vascular plants and ground-active beetles to aggregated retention at replicate sites in each of four temperate and boreal forest types on three continents: Douglas-fir forests in Washington, USA; aspen forests in Minnesota, USA; spruce forests in Sweden; and wet eucalypt forests in Tasmania, Australia. We assessed (1) differences in local (plot-scale) species richness and composition between mature (intact) and regenerating (previously harvested) forest; (2) the lifeboating function of aggregates (capacity to retain species of unharvested forest); and whether intact forests and aggregates (3) are susceptible to edge effects and (4) influence the adjacent regenerating forest. Intact and harvested forests differed in composition but not richness of plants and beetles. The magnitude of this difference was generally similar among regions, but there was considerable heterogeneity of composition within and among replicate sites. Aggregates within harvest units were effective at lifeboating for both plant and beetle communities. Edge effects were uncommon even within the aggregates. In contrast, effects of forest influence on adjacent harvested areas were common and as strong for aggregates as for larger blocks of intact forest. Our results provide strong support for the widespread application of aggregated retention in boreal and temperate forests. The consistency of pattern in four very different regions of the world suggests that, for forest plants and beetles, responses to aggregated retention are likely to apply more widely. Our results suggest that through strategic placement of aggregates, it is possible to maintain the natural heterogeneity and biodiversity of mature forests managed for multiple objectives.

FULL TEXT LINK:  http://dx.doi.org/10.1002/eap.1406

 

Miller, M. E., W. J. Elliot, et al. (2016). “Rapid-response tools and datasets for post-fire remediation: linking remote sensing and process-based hydrological models.” International Journal of Wildland Fire 25(10): 1061-1073.

Post-wildfire flooding and erosion can threaten lives, property and natural resources. Increased peak flows and sediment delivery due to the loss of surface vegetation cover and fire-induced changes in soil properties are of great concern to public safety. Burn severity maps derived from remote sensing data reflect fire-induced changes in vegetative cover and soil properties. Slope, soils, land cover and climate are also important factors that require consideration. Many modelling tools and datasets have been developed to assist remediation teams, but process-based and spatially explicit models are currently underutilised compared with simpler, lumped models because they are difficult to set up and require properly formatted spatial inputs. To facilitate the use of models in conjunction with remote sensing observations, we developed an online spatial database that rapidly generates properly formatted modelling datasets modified by user-supplied soil burn severity maps. Although assembling spatial model inputs can be both challenging and time-consuming, the methods we developed to rapidly update these inputs in response to a natural disaster are both simple and repeatable. Automating the creation of model inputs facilitates the wider use of more accurate, process-based models for spatially explicit predictions of post-fire erosion and runoff.

FULL TEXT LINK:  http://www.publish.csiro.au/paper/WF15162

 

Lovett, G. M., M. Weiss, et al. (2016). “Nonnative forest insects and pathogens in the United States: Impacts and policy options.” Ecological Applications 26(5): 1437-1455.

We review and synthesize information on invasions of nonnative forest insects and diseases in the United States, including their ecological and economic impacts, pathways of arrival, distribution within the United States, and policy options for reducing future invasions. Nonnative insects have accumulated in United States forests at a rate of ~2.5 per yr over the last 150 yr. Currently the two major pathways of introduction are importation of live plants and wood packing material such as pallets and crates. Introduced insects and diseases occur in forests and cities throughout the United States, and the problem is particularly severe in the Northeast and Upper Midwest. Nonnative forest pests are the only disturbance agent that has effectively eliminated entire tree species or genera from United States forests within decades. The resulting shift in forest structure and species composition alters ecosystem functions such as productivity, nutrient cycling, and wildlife habitat. In urban and suburban areas, loss of trees from streets, yards, and parks affects aesthetics, property values, shading, stormwater runoff, and human health. The economic damage from nonnative pests is not yet fully known, but is likely in the billions of dollars per year, with the majority of this economic burden borne by municipalities and residential property owners. Current policies for preventing introductions are having positive effects but are insufficient to reduce the influx of pests in the face of burgeoning global trade. Options are available to strengthen the defenses against pest arrival and establishment, including measures taken in the exporting country prior to shipment, measures to ensure clean shipments of plants and wood products, inspections at ports of entry, and post-entry measures such as quarantines, surveillance, and eradication programs. Improved data collection procedures for inspections, greater data accessibility, and better reporting would support better evaluation of policy effectiveness. Lack of additional action places the nation, local municipalities, and property owners at high risk of further damaging and costly invasions. Adopting stronger policies to reduce establishments of new forest insects and diseases would shift the major costs of control to the source and alleviate the economic burden now borne by homeowners and municipalities.

FULL TEXT LINK:  http://dx.doi.org/10.1890/15-1176

 

Hatten, J. R., T. R. Batt, et al. (2016). “Effects of Dam Removal on Tule Fall Chinook salmon Spawning Habitat in the White Salmon River, Washington.” River Research and Applications 32(7): 1481-1492.

Condit Dam is one of the largest hydroelectric dams ever removed in the USA. Breached in a single explosive event in October 2011, hundreds-of-thousands of cubic metres of sediment washed down the White Salmon River onto spawning grounds of a threatened species, Columbia River tule fall Chinook salmon Oncorhynchus tshawytscha. We investigated over a 3-year period (2010–2012) how dam breaching affected channel morphology, river hydraulics, sediment composition and tule fall Chinook salmon (hereafter ‘tule salmon’) spawning habitat in the lower 1.7 km of the White Salmon River (project area). As expected, dam breaching dramatically affected channel morphology and spawning habitat due to a large load of sediment released from Northwestern Lake. Forty-two per cent of the project area that was previously covered in water was converted into islands or new shoreline, while a large pool near the mouth filled with sediments and a delta formed at the mouth. A two-dimensional hydrodynamic model revealed that pool area decreased 68.7% in the project area, while glides and riffles increased 659% and 530%, respectively. A spatially explicit habitat model found the mean probability of spawning habitat increased 46.2% after dam breaching due to an increase in glides and riffles. Shifting channels and bank instability continue to negatively affect some spawning habitat as sediments continue to wash downstream from former Northwestern Lake, but 300 m of new spawning habitat (river kilometre 0.6 to 0.9) that formed immediately post-breach has persisted into 2015. Less than 10% of tule salmon have spawned upstream of the former dam site to date, but the run sizes appear healthy and stable. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

FULL TEXT LINK:  http://dx.doi.org/10.1002/rra.2982

 

Ren, X., Y. Lv, et al. (2017). “Evaluating differences in forest fragmentation and restoration between western natural forests and southeastern plantation forests in the United States.” Journal of Environmental Management 188: 268-277.

Changes in forest ecosystem structure and functions are considered some of the research issues in landscape ecology. In this study, advancing Forman’s theory, we considered five spatially explicit processes associated with fragmentation, including perforation, dissection, subdivision, shrinkage, and attrition, and two processes associated with restoration, i.e., increment and expansion processes. Following this theory, a forest fragmentation and restoration process model that can detect the spatially explicit processes and ecological consequences of forest landscape change was developed and tested in the current analysis. Using the National Land Cover Databases (2001, 2006 and 2011), the forest fragmentation and restoration process model was applied to US western natural forests and southeastern plantation forests to quantify and classify forest patch losses into one of the four fragmentation processes (the dissection process was merged into the subdivision process) and to classify the newly gained forest patches based on the two restoration processes. At the same time, the spatio-temporal differences in fragmentation and restoration patterns and trends between natural forests and plantations were further compared. Then, through overlaying the forest fragmentation/restoration processes maps with targeting year land cover data and land ownership vectors, the results from forest fragmentation and the contributors to forest restoration in federal and nonfederal lands were identified. Results showed that, in natural forests, the forest change patches concentrated around the urban/forest, cultivated/forest, and shrubland/forest interfaces, while the patterns of plantation change patches were scattered sparsely and irregularly. The shrinkage process was the most common type in forest fragmentation, and the average size was the smallest. Expansion, the most common restoration process, was observed in both natural forests and plantations and often occurred around the previous expansion or covered the previous subdivision or shrinkage processes. The overall temporal fragmentation pattern of natural forests had a “perforation-subdivision/shrinkage-attrition” pathway, which corresponded to Forman’s landscape fragmentation rule, while the plantation forests did not follow the rule strictly. The main land cover types resulted from forest fragmentation in natural forests and plantation forests were shrubland and herbaceous, mainly through subdivision and shrinkages process. The processes and effects of restoration of plantation forests were more diverse and efficient, compared to the natural forest, which were simpler with a lower regrowth rate. The fragmentation mostly occurred in nonfederal lands. In natural forests, forest fragmentation pattern differed in different land tenures, yet plantations remained the same in federal and nonfederal lands.

FULL TEXT LINK:  http://www.sciencedirect.com/science/article/pii/S0301479716309604

 

Well_Read_Robyn_12_16_2016

Compilation by Robyn Darbyshire

Ricotta, C., F. de Bello, et al. (2016). “Measuring the functional redundancy of biological communities: a quantitative guide.” Methods in Ecology and Evolution 7(11): 1386-1395.

* The preservation of ecosystem processes under ongoing biotic erosion requires that some species within affected communities perform similar functions, a property that is usually defined as functional redundancy. Although functional redundancy has recently become a relevant part of ecological research, so far there is no agreement on its measurement. * The scope of this work is thus to propose a consistent framework based on functional dissimilarities among species for summarizing different facets of functional redundancy. The behaviour of the proposed measures is illustrated with one small artificial data set, together with actual examples on the species functional turnover along successional gradients. * We believe this new framework provides an important contribution for the clarification and quantification of key metrics of community redundancy and vulnerability. The method, for which we provide a simple r function called ‘uniqueness’, further allows summarizing the functional contribution of single species to the overall redundancy of any type of biological community.

FULL TEXT LINK:  http://dx.doi.org/10.1111/2041-210X.12604

 

Healey, S. P., C. L. Raymond, et al. (2016). “Root disease can rival fire and harvest in reducing forest carbon storage.” Ecosphere 7(11).

Root diseases are known to suppress forest regeneration and reduce growth rates, and they may become more common as susceptible tree species become maladapted in parts of their historic ranges due to climate change. However, current ecosystem models do not track the effects of root disease on net productivity, and there has been little research on how the dynamics of root disease affect carbon (C) storage and productivity across infected landscapes. We compared the effects of root disease against the effects of other types of forest disturbance across six national forest landscapes, 1990–2011. This was enabled by a monitoring tool called the Forest Carbon Management Framework (ForCaMF), which makes use of ground inventory data, an empirical growth model, and time series of Landsat satellite imagery. Despite several large fires that burned across these landscapes during the study period, retrospective ForCaMF analysis showed that fire and root disease had approximately equal impacts on C storage. Relative to C accumulation that would have occurred in their absence, fires from 1990 to 2011 were estimated to reduce regionwide C storage by 215.3 ± 19.1 g/m2 C, while disease in the same period was estimated to reduce storage by 211.4 ± 59.9 g/m2 C. Harvest (75.5 ± 13.5 g/m2 C) and bark beetle activity (14.8 ± 12.5 g/m2 C) were less important. While long-term disturbance processes such as root disease have generally been ignored by tools informing management of forest C storage, the recent history of several national forests suggests that such disturbances can be just as important to the C cycle as more conspicuous events like wildfires.

FULL TEXT LINK:  http://dx.doi.org/10.1002/ecs2.1569

 

Tsen, E. W. J., T. Sitzia, et al. (2016). “To core, or not to core: the impact of coring on tree health and a best-practice framework for collecting dendrochronological information from living trees.” Biological Reviews 91(4): 899-924.

Trees are natural repositories of valuable environmental information that is preserved in the growth and structure of their stems, branches and roots. Dendrochronological analyses, based on the counting, crossdating and characterisation of incrementally formed wood rings, offer powerful insights for diverse fields including ecology, climatology and archaeology. The application of this toolset is likely to increase in popularity over coming decades due to advances in the field and a reduction in the cost of analyses. In research settings where the continued value of living trees subject to dendrochronological investigation is important, the use of an increment bore corer to extract trunk tissue is considered the best option to minimise negative impacts on tree health (e.g. stress and fitness). A small and fragmented body of literature, however, reports significant after-effects, and in some cases fatal outcomes, from this sampling technique. As it stands, the literature documenting increment bore coring (IBC) impacts lacks experimental consistency and is poorly replicated, making it difficult for prospective users of the method to assess likely tree responses to coring. This paucity of information has the potential to lead to destructive misuse of the method and also limits its safe implementation in circumstances where the risk of impacts may be appropriate. If IBC is to fulfil its potential as a method of choice across research fields, then we must first address our limited understanding of IBC impacts and provide a framework for its appropriate future use. Firstly, we review the historical context of studies examining the impacts of IBC on trees to identify known patterns, focal issues and biases in existing knowledge. IBC wound responses, particularly those that impact on lumber quality, have been the primary focus of prior studies. No universal treatment was identified that conclusively improved wound healing and few studies have linked wound responses to tree health impacts. Secondly, we build on literature insights using a theoretical approach to identify the most important factors to guide future research involving implementation of IBC, including innate tree characteristics and environmental factors. Thirdly, we synthesise and interrogate the quantitative data available through meta-analysis to identify risk factors for wound reactions. Although poor reporting standards, restricted scopes and a bias towards temperate ecosystems limited quantitative insight, we found that complete cambial wound closure could still harbour high rates of internal trunk decay, and that conditions favouring faster growth generally correlated with reduced indices of internal and external damage in broadleaved taxa. Finally, we propose a framework for guiding best-practice application of IBC to address knowledge gaps and maximise the utility of this method, including standardised reporting indices for identifying and minimising negative impacts on tree health. While IBC is an underutilised tool of ecological enquiry with broad applicability, the method will always incur some risk of negative impacts on the cored tree. We caution that the decision to core, or not to core, must be given careful consideration on a case-by-case basis. In time, we are confident that this choice will be better informed by evidence-based insight.

FULL TEXT LINK:  http://dx.doi.org/10.1111/brv.12200

 

Magnússon, R. Í., A. Tietema, et al. (2016). “Sequestration of carbon from coarse woody debris in forest soils.” Forest Ecology and Management 377: 1-15.

Worldwide, forests have absorbed around 30% of global anthropogenic emissions of carbon dioxide (CO2) annually, thereby acting as important carbon (C) sinks. It is proposed that leaving large fragments of dead wood, coarse woody debris (CWD), in forest ecosystems may contribute to the forest C sink strength. CWD may take years to centuries to degrade completely, and non-respired C from CWD may enter the forest soil directly or in the form of dissolved organic C. Although aboveground decomposition of CWD has been studied frequently, little is known about the relative size, composition and fate of different C fluxes from CWD to soils under various substrate-specific and environmental conditions. Thus, the exact contribution of C from CWD to C sequestration within forest soils is poorly understood and quantified, although understanding CWD degradation and stabilization processes is essential for effective forest C sink management. This review aims at providing insight into these processes on the interface of forest ecology and soil science, and identifies knowledge gaps that are critical to our understanding of the effects of CWD on the forest soil C sink. It may be seen as a “call-to-action” crossing disciplinary boundaries, which proposes the use of compound-specific analytical studies and manipulation studies to elucidate C fluxes from CWD. Carbon fluxes from decaying CWD can vary considerably due to interspecific and intraspecific differences in composition and different environmental conditions. These variations in C fluxes need to be studied in detail and related to recent advances in soil C sequestration research. Outcomes of this review show that the presence of CWD may enhance the abundance and diversity of the microbial community and constitute additional fluxes of C into the mineral soil by augmented leaching of dissolved organic carbon (DOC). Leached DOC and residues from organic matter (OM) from later decay stages have been shown to be relatively enriched in complex and microbial-derived compounds, which may also be true for CWD-derived OM. Emerging knowledge on soil C stabilization indicates that such complex compounds may be sorbed preferentially to the mineral soil. Moreover, increased abundance and diversity of decomposer organisms may increase the amount of substrate C being diverted into microbial biomass, which may contribute to stable C pools in the forest soil.

FULL TEXT LINK:  http://www.sciencedirect.com/science/article/pii/S0378112716303309

 

Marion, J. L. (2016). “A Review and Synthesis of Recreation Ecology Research Supporting Carrying Capacity and Visitor Use Management Decisionmaking.” Journal of Forestry 114(3): 339-351.

Resource and experiential impacts associated with visitation to wilderness and other similar backcountry settings have long been addressed by land managers under the context of ‘carrying capacity’ decisionmaking. Determining a maximum level of allowable use, below which high-quality resource and experiential conditions would be sustained, was an early focus in the 1960s and 1970s. However, decades of recreation ecology research have shown that the severity and areal extent of visitor impact problems are influenced by an interrelated array of use-related, environmental, and managerial factors. This complexity, with similar findings from social science research, prompted scientists and managers to develop more comprehensive carrying capacity frameworks, including a new Visitor Use Management framework. These frameworks rely on a diverse array of management strategies and actions, often termed a ‘management toolbox’ for resolving visitor impact problems. This article reviews the most recent and relevant recreation ecology studies that have been applied in wildland settings to avoid or minimize resource impacts. The key findings and their management implications are highlighted to support the professional management of common trail, recreation site, and wildlife impact problems. These studies illustrate the need to select from a more diverse array of impact management strategies and actions based on an evaluation of problems to identify the most influential factors that can be manipulated.

Management and Policy Implications:  Wildland managers struggle to balance their resource protection and recreation provision objectives. Over the course of six decades, the recreation carrying capacity concept has been repeatedly applied and revised as a management tool, evolving from a simplistic focus on fixed visitation limits to comprehensive decisionmaking frameworks focused on sustaining high-quality recreational opportunities. Recreation ecology studies investigating relationships between amount of visitor use and the magnitude of resource impacts consistently find that use and impact are strongly related only at initial and low levels of visitation, with weak correlations at higher use levels. However, unacceptable resource impacts often occur on well-established and heavily used trails and recreation sites: reducing use to improve their condition is generally an ineffective practice. An increasing number of recreation ecology studies describe the efficacy of alternative management interventions, including the siting, design, construction, and maintenance of more sustainable trails and recreation sites, the spatial and temporal redistribution of visitor use, and persuasive communication or regulations that encourage visitors to apply low-impact practices.

FULL TEXT LINK:  http://www.ingentaconnect.com/content/saf/jof/2016/00000114/00000003/art00012

 

Well_Read_Robyn_10_28_16

Compilation by Robyn Darbyshire

Martínez-Vilalta, J. and F. Lloret (2016). “Drought-induced vegetation shifts in terrestrial ecosystems: The key role of regeneration dynamics.” Global and Planetary Change 144: 94-108.

Ongoing climate change is modifying climatic conditions worldwide, with a trend towards drier conditions in most regions. Vegetation will respond to these changes, eventually adjusting to the new climate. It is unclear, however, how close different ecosystems are to climate-related tipping points and, thus, how dramatic these vegetation changes will be in the short- to mid-term, given the existence of strong stabilizing processes. Here, we review the published evidence for recent drought-induced vegetation shifts worldwide, addressing the following questions: (i) what are the necessary conditions for vegetation shifts to occur? (ii) How much evidence of drought-induced vegetation shifts do we have at present and where are they occurring? (iii) What are the main processes that favor/oppose the occurrence of shifts at different ecological scales? (iv) What are the complications in detecting and attributing drought-induced vegetation shifts? (v) What ecological factors can interact with drought to promote shifts or stability? We propose a demographic framework to classify the likely outcome of instances of drought-induced mortality, based upon the survival of adults of potential replacement species and the regeneration of both formerly dominant affected species and potential replacement species. Out of 35 selected case studies only eight were clearly consistent with the occurrence of a vegetation shift (species or biome shift), whereas three corresponded to self-replacements in which the affected, formerly dominant species was able to regenerate after suffering drought-induced mortality. The other 24 cases were classified as uncertain, either due to lack of information or, more commonly, because the initially affected and potential replacement species all showed similar levels of regeneration after the mortality event. Overall, potential vegetation transitions were consistent with more drought-resistant species replacing less resistant ones. However, almost half (44%) of the vegetation trajectories associated to the 35 case studies implied no change in the functional type of vegetation. Of those cases implying a functional type change, the most common one was a transition from tree- to shrub-dominated communities. Overall, evidence for drought-induced vegetation shifts is still limited. In this context, we stress the need for improved, long-term monitoring programs with sufficient temporal resolution. We also highlight the critical importance of regeneration in determining the outcome of drought-induced mortality events, and the crucial role of co-drivers, particularly management. Finally, we illustrate how placing vegetation shifts in a biogeographical and successional context may support progress in our understanding of the underlying processes and the ecosystem-level implications.

FULL TEXT LINK:  http://www.sciencedirect.com/science/article/pii/S0921818115301405

 

Cooper, M.G., Nolin, A.W., et al. (2016). “Testing the recent snow drought as an analog for climate warming sensitivity of Cascades snowpacks.” Environmental Research Letters 11(8): 084009.

Record low snowpack conditions were observed at Snow Telemetry stations in the Cascades Mountains, USA during the winters of 2014 and 2015. We tested the hypothesis that these winters are analogs for the temperature sensitivity of Cascades snowpacks. In the Oregon Cascades, the 2014 and 2015 winter air temperature anomalies were approximately +2 °C and +4 °C above the climatological mean. We used a spatially distributed snowpack energy balance model to simulate the sensitivity of multiple snowpack metrics to a +2 °C and +4 °C warming and compared our modeled sensitivities to observed values during 2014 and 2015. We found that for each +1 °C warming, modeled basin-mean peak snow water equivalent (SWE) declined by 22%–30%, the date of peak SWE (DPS) advanced by 13 days, the duration of snow cover (DSC) shortened by 31–34 days, and the snow disappearance date (SDD) advanced by 22–25 days. Our hypothesis was not borne out by the observations except in the case of peak SWE; other snow metrics did not resemble predicted values based on modeled sensitivities and thus are not effective analogs of future temperature sensitivities. Rather than just temperature, it appears that the magnitude and phasing of winter precipitation events, such as large, late spring snowfall, controlled the DPS, SDD, and DSC.

FULL TEXT LINK:  http://stacks.iop.org/1748-9326/11/i=8/a=084009

 

Hough-Snee, N., A. Kasprak, et al. (2016). “Hydrogeomorphic and Biotic Drivers of Instream Wood Differ Across Sub-basins of the Columbia River Basin, USA.” River Research and Applications 32(6): 1302-1315.

Instream wood promotes habitat heterogeneity through its influence on flow hydraulics and channel geomorphology. Within the Columbia River Basin, USA, wood is vital for the creation and maintenance of habitat for threatened salmonids. However, our understanding of the relative roles of the climatic, geomorphic, and ecological processes that source wood to streams is limited, making it difficult to identify baseline predictions of instream wood and create targets for stream restoration. Here, we investigate how instream wood frequency and volume differ between seven sub-basins of the interior Columbia River Basin and what processes shape these differences within these sub-basins. We collected data on wood volume and frequency, discharge and stream power, and riparian and watershed forest structure for use in modelling wood volume and frequency. Using random forest models, we found that mean annual precipitation, riparian tree cover, and the individual watershed were the most important predictors of wood volume and frequency. Within sub-basins, we used linear models, finding that some basins had unique predictors of wood. Discharge, watershed area, or precipitation often combined with forest cover, riparian conifer, and/or large tree cover in models of instream large wood volume and frequency. In many sub-basins, models showed at least one hydrologic variable, indicative of transport competence and one ecological variable, indicative of the reach or upstream watershed’s capability to grow measurable instream wood. We conclude that basin-specific models yield important insights into the hydrologic and ecological processes that influence wood loads, creating tractable hypotheses for building predictive models of instream wood.

FULL TEXT LINK:  http://dx.doi.org/10.1002/rra.2968

 

Latif, Q. S., J. S. Sanderlin, et al. (2016). “Avian relationships with wildfire at two dry forest locations with different historical fire regimes.” Ecosphere 7(5).

Wildfire is a key factor influencing bird community composition in western North American forests. We need to understand species and community responses to wildfire and how responses vary regionally to effectively manage dry conifer forests for maintaining biodiversity. We compared avian relationships with wildfire burn severity between two dry forest locations of Arizona and Idaho. We predicted different responses to wildfire between locations due to regional differences in historical fire regime. We conducted point count surveys for 3 yr following wildfire (Arizona: 1997–1999; Idaho: 2008–2010) and used multispecies hierarchical models to analyze relationships of bird occupancy with burn severity. Consistent with our prediction for mixed-severity fire regimes characterizing the Idaho location, we observed proportionately more positive species occupancy relationships and, consequently, a positive species richness relationship with burn severity in Idaho. We also observed the opposite pattern in Arizona, which was congruent with our prediction for the low-severity fire regime characterizing that location. Cavity nesters and aerial insectivores occupied more severely burned sites following wildfire, corresponding with predicted increases in nesting substrate and foraging opportunities for these species. In contrast, canopy-nesting foliage gleaners and pine seed consumers exhibited negative relationships with burn severity. Our results were consistent with predictions based on species life histories and with patterns from the literature, suggesting generality of observed relationships and locational difference in relationships with wildfire. We therefore suggest that optimal management strategies for maintaining avian diversity could differ regionally. Specifically, intensive fuels management may be ecologically less appropriate for promoting biodiversity in areas such as the Idaho location where mixed-severity wildfires and dense forest stands were historically more common.

FULL TEXT LINK:  http://dx.doi.org/10.1002/ecs2.1346

 

Giunta, A., M. Jenkins, et al. (2016). “Disturbance Agents and Their Associated Effects on the Health of Interior Douglas-Fir Forests in the Central Rocky Mountains.” Forests 7(4): 80.

Interior Douglas-fir is a prevalent forest type throughout the central Rocky Mountains. Past management actions, specifically fire suppression, have led to an expansion of this forest type. Although Douglas-fir forests cover a broad geographic range, few studies have described the interactive effects of various disturbance agents on forest health conditions. In this paper, we review pertinent literature describing the roles, linkages, and mechanisms by which disturbances, including insect outbreaks, pathogens, fire, and other abiotic factors, affect the development, structure, and distribution of interior montane forests primarily comprised of Douglas-fir. We also discuss how these effects may influence important resource values such as water, biodiversity, wildlife habitat, timber, and recreation. Finally, we identify gaps where further research may increase our understanding of these disturbance agents, their interacting roles, and how they influence long-term forest health.

FULL TEXT LINK:  http://www.mdpi.com/1999-4907/7/4/80