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Compilation by Robyn Darbyshire
Harmon, M. E. and R. J. Pabst (2015). “Testing predictions of forest succession using long-term measurements: 100 yrs of observations in the Oregon Cascades.” Journal of Vegetation Science 26(4): 722-732.
Question Many predictions about forest succession have been based on chronosequences. Are these predictions – at the population, community and ecosystem level – consistent with long-term measurements in permanent plots? Location Pseudotsuga menziesii (Mirb.) Franco dominated forest in western Oregon, US. Methods Over a 100-yr period, measurements every 5–10 yrs of the growth, mortality and regeneration of individually tagged trees in three 0.4-ha forest plots dominated by P. menziesii were used to test predictions derived from chronosequence studies. Results Population- and community-level predictions generally matched observations: the initial cohort of pioneer species declined exponentially, with the shorter-lived Prunus emarginata (Douglas ex Hook.) Eaton and Arbutus menziesii Pursh disappearing altogether, and long-lived species such as P. menziesii persisting; tree size distribution shifted from a log-normal to a normal distribution, although the establishment of mid- to late-seral species created a bimodal distribution that may represent a transitional phase not usually elaborated in prior work; and mortality shifted from largely density-dependent to increasing amounts of density-independent causes. The observed biomass composition of these forests, even after 154 yrs, was still largely dominated by P. menziesii, which was consistent with the prediction from chronosequence studies. The slowing of biomass accumulation as stands aged predicted from ecosystem theory was not consistent with the observation that live biomass accumulated at a relatively constant rate for the 100-yr period. Conclusion Predictions from chronosequences at the population and community level were consistent with long-term observations in permanent plots, whereas those at the ecosystem level were not. At the spatial scale (<2 ha) examined with these plots, the high heterogeneity of tree mortality may lead to a multi-modal pattern of net live biomass accumulation with long periods of constant gain interrupted by sudden losses of live biomass.
FULL TEXT LINK: http://dx.doi.org/10.1111/jvs.12273
Dymond, C. C., S. Tedder, et al. (2014). “Diversifying managed forests to increase resilience.” Canadian Journal of Forest Research 44(10): 1196-1205.
In British Columbia, Canada, a recent epidemic of mountain pine beetle (Dendroctonus ponderosae Hopkins, 1902) caused widespread forest mortality. This epidemic was due in part to the changing climate, and damage from pests and diseases is expected to increase in the future. Therefore, we used a historical retrospective approach as a proxy to evaluate management options on reducing the forest health damage that may occur under a future changing climate. We assessed two landscape-scale strategies, intended to increase tree species diversity, for the response in ecosystem resilience and compared the results with the business-as-usual strategy. The assessment was based on simulation modelling of the Merritt Timber Supply Area for 1980–2060. We applied a strategy to increase the harvest of the most dominant tree species, plant more diverse species, and increase natural regeneration. This strategy resulted in greater ecological resilience (higher diversity and growing stocks), higher harvest rates, and higher, more consistent net revenue over time than the business-as-usual strategy or the strategy that only employed a diversity of planting. A sensitivity analysis indicated a high level of robustness in the results. Our study showed that it may not be necessary to compromise economic viability to reduce forest health risks and consequently improve socio-ecological resilience.
FULL TEXT LINK: http://dx.doi.org/10.1139/cjfr-2014-0146
Stavros, E. N., J. Abatzoglou, et al. (2014). “Regional projections of the likelihood of very large wildland fires under a changing climate in the contiguous Western United States.” Climatic Change 126(3-4): 455-468.
Seasonal changes in the climatic potential for very large wildfires (VLWF ≥ 50,000 ac ~ 20,234 ha) across the western contiguous United States are projected over the 21st century using generalized linear models and downscaled climate projections for two representative concentration pathways (RCPs). Significant (p ≤ 0.05) increases in VLWF probability for climate of the mid-21st century (2031–2060) relative to contemporary climate are found, for both RCP 4.5 and 8.5. The largest differences are in the Eastern Great Basin, Northern Rockies, Pacific Northwest, Rocky Mountains, and Southwest. Changes in seasonality and frequency of VLWFs depend on changes in the future climate space. For example, flammability-limited areas such as the Pacific Northwest show that (with high model agreement) the frequency of weeks with VLWFs in a given year is 2–2.7 more likely. However, frequency of weeks with at least one VLWF in fuel-limited systems like the Western Great Basin is 1.3 times more likely (with low model agreement). Thus, areas where fire is directly associated with hot and dry climate, as opposed to experiencing lagged effects from previous years, experience more change in the likelihood of VLWF in future projections. The results provide a quantitative foundation for management to mitigate the effects of VLWFs.
FULL TEXT LINK: http://dx.doi.org/10.1007/s10584-014-1229-6
Griffiths, A. D. and B. W. Brook (2014). “Effect of fire on small mammals: a systematic review.” International Journal of Wildland Fire 23(7): 1034-1043.
Fire is a natural disturbance that exerts an important influence on global ecosystems, affecting vegetation distribution and structure, the carbon cycle and climate. However, human-induced changes to fire regimes may affect at-risk species groups such as small mammals. We examine the effect of fire on small mammals and evaluate the relative sensitivity to fire among different groups using a systematic review methodology that included critiquing the literature with respect to survey design and statistical analysis. Overall, small mammal abundance is slightly higher, and demographic parameters more favourable, in unburnt sites compared to burnt sites. This was more pronounced in species with body size range of 101–1000 g and with habitat requirements that are sensitive to fire (e.g. dense ground cover): in 66.6 and 69.7% of pairwise comparisons, abundance or a demographic parameter were higher in unburnt than burnt sites. This systematic review demonstrates that there remains a continued focus on simple shifts in abundance with regards to effect of fire and small mammals, which limits understanding of mechanisms responsible for change. Body size and habitat preference were most important in explaining variation in small mammal species’ responses to fire.
FULL TEXT LINK: http://www.publish.csiro.au/paper/WF14026
Wohl, E., B. P. Bledsoe, et al. (2015). “The Natural Sediment Regime in Rivers: Broadening the Foundation for Ecosystem Management.” BioScience 65(4): 358-371.
Water and sediment inputs are fundamental drivers of river ecosystems, but river management tends to emphasize flow regime at the expense of sediment regime. In an effort to frame a more inclusive paradigm for river management, we discuss sediment inputs, transport, and storage within river systems; interactions among water, sediment, and valley context; and the need to broaden the natural flow regime concept. Explicitly incorporating sediment is challenging, because sediment is supplied, transported, and stored by nonlinear and episodic processes operating at different temporal and spatial scales than water and because sediment regimes have been highly altered by humans. Nevertheless, managing for a desired balance between sediment supply and transport capacity is not only tractable, given current geomorphic process knowledge, but also essential because of the importance of sediment regimes to aquatic and riparian ecosystems, the physical template of which depends on sediment-driven river structure and function.
FULL TEXT LINK: http://bioscience.oxfordjournals.org/content/65/4/358.abstract
Compilation by Robyn Darbyshire
Pausas, J. G. (2015). “Evolutionary fire ecology: lessons learned from pines.” Trends in Plant Science 20(5): 318-324.
Macroevolutionary studies of the genus Pinus provide the oldest current evidence of fire as an evolutionary pressure on plants and date back to ca. 125 million years ago (Ma). Microevolutionary studies show that fire traits are variable within and among populations, especially among those subject to different fire regimes. In addition, there is increasing evidence of an inherited genetic basis to variability in fire traits. Added together, pines provide compelling evidence that fire can exert an evolutionary pressure on plants and, thus, shape biodiversity. In addition, evolutionary fire ecology is providing insights to improve the management of pine forests under changing conditions. The lessons learned from pines may guide research on the evolutionary ecology of other taxa.
Harpold, A. A., N. P. Molotch, et al. (2015). “Soil moisture response to snowmelt timing in mixed-conifer subalpine forests.” Hydrological Processes 29(12): 2782-2798.
Western US forest ecosystems and downstream water supplies are reliant on seasonal snowmelt. Complex feedbacks govern forest–snow interactions in which forests influence the distribution of snow and the timing of snowmelt but are also sensitive to snow water availability. Notwithstanding, few studies have investigated the influence of forest structure on snow distribution, snowmelt and soil moisture response. Using a multi-year record from co-located observations of snow depth and soil moisture, we evaluated the influence of forest-canopy position on snow accumulation and snow depth depletion, and associated controls on the timing of soil moisture response at Boulder Creek, Colorado, Jemez River Basin, New Mexico, and the Wolverton Basin, California. Forest-canopy controls on snow accumulation led to 12–42 cm greater peak snow depths in open versus under-canopy positions. Differences in accumulation and melt across sites resulted in earlier snow disappearance in open positions at Jemez and earlier snow disappearance in under-canopy positions at Boulder and Wolverton sites. Irrespective of net snow accumulation, we found that peak annual soil moisture was nearly synchronous with the date of snow disappearance at all sites with an average deviation of 12, 3 and 22 days at Jemez, Boulder and Wolverton sites, respectively. Interestingly, sites in the Sierra Nevada showed peak soil moisture prior to snow disappearance at both our intensive study site and the nearby snow telemetry stations. Our results imply that the duration of soil water stress may increase as regional warming or forest disturbance lead to earlier snow disappearance and soil moisture recession in subalpine forests.
FULL TEXT LINK: http://dx.doi.org/10.1002/hyp.10400
Homyack, J. and A. Kroll (2014). “Slow Lives in the Fast Landscape: Conservation and Management of Plethodontid Salamanders in Production Forests of the United States.” Forests 5(11): 2750-2772.
Intensively-managed forest (IMF) ecosystems support environmental processes, retain biodiversity and reduce pressure to extract wood products from other forests, but may affect species, such as plethodontid salamanders, that are associated with closed canopies and possess limited vagility. We describe: (1) critical aspects of IMF ecosystems; (2) effectiveness of plethodontid salamanders as barometers of forest change; (3) two case studies of relationships between salamanders and coarse woody debris (CWD); and (4) research needs for effective management of salamanders in IMF ecosystems. Although plethodontid salamanders are sensitive to microclimate changes, their role as ecological indicators rarely have been evaluated quantitatively. Our case studies of CWD and salamanders in western and eastern forests demonstrated effects of species, region and spatial scale on the existence and strength of relationships between plethodontid species and a “critical” microhabitat variable. Oregon slender salamanders (Batrachoseps wrighti) were more strongly associated with abundance of CWD in managed second growth forests than ensatina salamanders (Ensatina eschscholtzii). Similarly, CWD was not an important predictor of abundance of Appalachian salamanders in managed hardwood forest. Gaining knowledge of salamanders in IMF ecosystems is critical to reconciling ecological and economic objectives of intensive forest management, but faces challenges in design and implementation.
FULL TEXT LINK: http://www.mdpi.com/1999-4907/5/11/2750
Donovan, S. B., M. Penelope, et al. (2014). “Is proportion burned severely related to daily area burned?” Environmental Research Letters 9(6): 064011.
The ecological effects of forest fires burning with high severity are long-lived and have the greatest impact on vegetation successional trajectories, as compared to low-to-moderate severity fires. The primary drivers of high severity fire are unclear, but it has been hypothesized that wind-driven, large fire-growth days play a significant role, particularly on large fires in forested ecosystems. Here, we examined the relative proportion of classified burn severity for individual daily areas burned that occurred during 42 large forest fires in central Idaho and western Montana from 2005 to 2007 and 2011. Using infrared perimeter data for wildfires with five or more consecutive days of mapped perimeters, we delineated 2697 individual daily areas burned from which we calculated the proportions of each of three burn severity classes (high, moderate, and low) using the differenced normalized burn ratio as mapped for large fires by the Monitoring Trends in Burn Severity project. We found that the proportion of high burn severity was weakly correlated (Kendall τ = 0.299) with size of daily area burned (DAB). Burn severity was highly variable, even for the largest (95th percentile) in DAB, suggesting that other variables than fire extent influence the ecological effects of fires. We suggest that these results do not support the prioritization of large runs during fire rehabilitation efforts, since the underlying assumption in this prioritization is a positive relationship between severity and area burned in a day.
FULL TEXT LINK: http://stacks.iop.org/1748-9326/9/i=6/a=064011
Robichaud, P. R., H. Rhee, et al. (2014). “A synthesis of post-fire Burned Area Reports from 1972 to 2009 for western US Forest Service lands: trends in wildfire characteristics and post-fire stabilisation treatments and expenditures.” International Journal of Wildland Fire 23(7): 929-944.
Over 1200 post-fire assessment and treatment implementation reports from four decades (1970s–2000s) of western US forest fires have been examined to identify decadal patterns in fire characteristics and the justifications and expenditures for the post-fire treatments. The main trends found were: (1) the area burned by wildfire increased over time and the rate of increase accelerated after 1990; (2) the proportions of burned area assessed as low, moderate and high burn severity likely have remained fairly constant over time, but the use of satellite imagery that began c. 2000 increased the resolution of burn severity assessments leading to an apparent decreased proportion of high burn severity during the 2000s; (3) treatment justifications reflected regional concerns (e.g. soil productivity in areas of timber harvest) and generally reflected increased human encroachment in the wildland–urban interface; (4) modifications to roads were the most frequently recommended post-fire treatment type; (5) seeding was the most frequently used land treatment, but declined in use over time; (6) use of post-fire agricultural straw mulch has steadily increased because of proven success; and (7) the greatest post-fire expenditures have been for land treatments applied over large areas to protect important resources (e.g. municipal water sources).
FULL TEXT LINK: http://www.publish.csiro.au/paper/WF13192
Compilation by Robyn Darbyshire
Hautier, Y., D. Tilman, et al. (2015). “Anthropogenic environmental changes affect ecosystem stability via biodiversity.” Science 348(6232): 336-340.
Human-driven environmental changes may simultaneously affect the biodiversity, productivity, and stability of Earth’s ecosystems, but there is no consensus on the causal relationships linking these variables. Data from 12 multiyear experiments that manipulate important anthropogenic drivers, including plant diversity, nitrogen, carbon dioxide, fire, herbivory, and water, show that each driver influences ecosystem productivity. However, the stability of ecosystem productivity is only changed by those drivers that alter biodiversity, with a given decrease in plant species numbers leading to a quantitatively similar decrease in ecosystem stability regardless of which driver caused the biodiversity loss. These results suggest that changes in biodiversity caused by drivers of environmental change may be a major factor determining how global environmental changes affect ecosystem stability.
FULL TEXT LINK: http://www.sciencemag.org/content/348/6232/336.abstract
Marton, J. M., I. F. Creed, et al. (2015). “Geographically Isolated Wetlands are Important Biogeochemical Reactors on the Landscape.” BioScience 65(4): 408-418.
Wetlands provide many ecosystem services, including sediment and carbon retention, nutrient transformation, and water quality improvement. Although all wetlands are biogeochemical hotspots, geographically isolated wetlands (GIWs) receive fewer legal protections compared with other types of wetlands because of their apparent isolation from jurisdictional waters. Here, we consider controls on biogeochemical functions that influence water quality, and estimate changes in ecosystem service delivery that would occur if these landscape features were lost following recent US Supreme Court decisions (i.e., Rapanos, SWANCC). We conclude that, despite their lack of persistent surfacewater connectivity or adjacency to jurisdictional waters, GIWs are integral to biogeochemical processing on the landscape and therefore maintaining the integrity of US waters. Given the likelihood that any GIW contributes to downstream water quality, we suggest that the burden of proof could be shifted to assuming that all GIWs are critical for protecting aquatic systems until proven otherwise.
FULL TEXT LINK: http://bioscience.oxfordjournals.org/content/65/4/408.abstract
Collins, B. M., A. J. Das, et al. (2014). “Beyond reducing fire hazard: fuel treatment impacts on overstory tree survival.” Ecological Applications 24(8): 1879-1886.
Fuel treatment implementation in dry forest types throughout the western United States is likely to increase in pace and scale in response to increasing incidence of large wildfires. While it is clear that properly implemented fuel treatments are effective at reducing hazardous fire potential, there are ancillary ecological effects that can impact forest resilience either positively or negatively depending on the specific elements examined, as well as treatment type, timing, and intensity. In this study, we use overstory tree growth responses, measured seven years after the most common fuel treatments, to estimate forest health. Across the five species analyzed, observed mortality and future vulnerability were consistently low in the mechanical-only treatment. Fire-only was similar to the control for all species except Douglas-fir, while mechanical-plus-fire had high observed mortality and future vulnerability for white fir and sugar pine. Given that overstory trees largely dictate the function of forests and services they provide (e.g., wildlife habitat, carbon sequestration, soil stability) these results have implications for understanding longer-term impacts of common fuel treatments on forest resilience.
FULL TEXT LINK: http://www.esajournals.org/doi/pdf/10.1890/14-0971.1
Standish, R. J., R. J. Hobbs, et al. (2014). “Resilience in ecology: Abstraction, distraction, or where the action is?” Biological Conservation 177: 43-51.
Increasingly, the success of management interventions aimed at biodiversity conservation are viewed as being dependent on the ‘resilience’ of the system. Although the term ‘resilience’ is increasingly used by policy makers and environmental managers, the concept of ‘resilience’ remains vague, varied and difficult to quantify. Here we clarify what this concept means from an ecological perspective, and how it can be measured and applied to ecosystem management. We argue that thresholds of disturbance are central to measuring resilience. Thresholds are important because they offer a means to quantify how much disturbance an ecosystem can absorb before switching to another state, and so indicate whether intervention might be necessary to promote the recovery of the pre-disturbance state. We distinguish between helpful resilience, where resilience helps recovery, and unhelpful resilience where it does not, signalling the presence of a threshold and the need for intervention. Data to determine thresholds are not always available and so we consider the potential for indices of functional diversity to act as proxy measures of resilience. We also consider the contributions of connectivity and scale to resilience and how to incorporate these factors into management. We argue that linking thresholds to functional diversity indices may improve our ability to predict the resilience of ecosystems to future, potentially novel, disturbances according to their spatial and temporal scales of influence. Throughout, we provide guidance for the application of the resilience concept to ecosystem management. In doing so, we confirm its usefulness for improving biodiversity conservation in our rapidly changing world.
Sovern, S. G., E. D. Forsman, et al. (2015). “Roosting habitat use and selection by northern spotted owls during natal dispersal.” The Journal of Wildlife Management 79(2): 254-262.
We studied habitat selection by northern spotted owls (Strix occidentalis caurina) during natal dispersal in Washington State, USA, at both the roost site and landscape scales. We used logistic regression to obtain parameters for an exponential resource selection function based on vegetation attributes in roost and random plots in 76 forest stands that were used for roosting. We used a similar analysis to evaluate selection of landscape habitat attributes based on 301 radio-telemetry relocations and random points within our study area. We found no evidence of within-stand selection for any of the variables examined, but 78% of roosts were in stands with at least some large (>50 cm dbh) trees. At the landscape scale, owls selected for stands with high canopy cover (>70%). Dispersing owls selected vegetation types that were more similar to habitat selected by adult owls than habitat that would result from following guidelines previously proposed to maintain dispersal habitat. Our analysis indicates that juvenile owls select stands for roosting that have greater canopy cover than is recommended in current agency guidelines.
FULL TEXT LINK: http://dx.doi.org/10.1002/jwmg.834
Compilation by Robyn Darbyshire
Carvalho-Santos, C., J. P. Honrado, et al. (2014). “Hydrological services and the role of forests: Conceptualization and indicator-based analysis with an illustration at a regional scale.” Ecological Complexity 20(0): 69-80.
Forests are among the most important ecosystems for the provision of hydrological services. These include water supply and water damage mitigation, in the dimensions of quantity, timing and quality. Although the hydrological role of forests is well documented in the literature, a conceptual framework integrating these three dimensions is still missing. In this study, a comprehensive conceptual framework to improve the assessment of hydrological services provided by forests was developed. In addition, the framework was tested by an illustration for northern Portugal, a region with both Mediterranean and Atlantic climatic influences. The TEEB (The Economics of Ecosystems and Biodiversity) framework of ecosystem services was adapted to the relation between forests and water. Then, this new framework was complemented with a set of spatially-explicit indicators that quantify the supply and demand of hydrological services. In addition, the implications of the framework were discussed in the context of the social-ecological systems, using the DPSIR (Drivers, Pressures, State, Impacts, and Responses) model. Finally, the framework and the indicators were illustrated for northern Portugal using the water supply (quantity) and soil erosion control as examples. Results show that the proposed conceptual framework is a useful tool to support land planning and forest management, adapting the provision of hydrological services to the regional biophysical and social conditions. The test of the framework across a heterogeneous region suggests that a spatially explicit combination of system property, function, service and benefit indicators can be an effective way of analysing and managing the supply and demand of the hydrological services.
Moody, J. A. and B. A. Ebel (2014). “Infiltration and runoff generation processes in fire-affected soils.” Hydrological Processes 28(9): 3432-3453.
Post-wildfire runoff was investigated by combining field measurements and modelling of infiltration into fire-affected soils to predict time-to-start of runoff and peak runoff rate at the plot scale (1 m2). Time series of soil-water content, rainfall and runoff were measured on a hillslope burned by the 2010 Fourmile Canyon Fire west of Boulder, Colorado during cyclonic and convective rainstorms in the spring and summer of 2011. Some of the field measurements and measured soil physical properties were used to calibrate a one-dimensional post-wildfire numerical model, which was then used as a ‘virtual instrument’ to provide estimates of the saturated hydraulic conductivity and high-resolution (1 mm) estimates of the soil-water profile and water fluxes within the unsaturated zone. Field and model estimates of the wetting-front depth indicated that post-wildfire infiltration was on average confined to shallow depths less than 30 mm. Model estimates of the effective saturated hydraulic conductivity, Ks, near the soil surface ranged from 0.1 to 5.2 mm h−1. Because of the relatively small values of Ks, the time-to-start of runoff (measured from the start of rainfall), tp, was found to depend only on the initial soil-water saturation deficit (predicted by the model) and a measured characteristic of the rainfall profile (referred to as the average rainfall acceleration, equal to the initial rate of change in rainfall intensity). An analytical model was developed from the combined results and explained 92–97% of the variance of tp, and the numerical infiltration model explained 74–91% of the variance of the peak runoff rates. These results are from one burned site, but they strongly suggest that tp in fire-affected soils (which often have low values of Ks) is probably controlled more by the storm profile and the initial soil-water saturation deficit than by soil hydraulic properties.
FULL TEXT LINK: http://dx.doi.org/10.1002/hyp.9857
Podolak, C. J. P. (2014). “A visual framework for displaying, communicating and coordinating a river restoration monitoring project.” River Research and Applications 30(4): 527-535.
A visual framework to display complex river restoration monitoring plans is proposed. The framework provides for four dimensions of information—spatial coverage, and the frequency, density and type of measurement to be evaluated—in a concise and transparent fashion. It is not only useful as a display and communication tool but also facilitates identification of overlaps, gaps and inefficiencies. The visual framework is particularly useful for coordinating multiple monitoring efforts and for communicating or negotiating modifications. An example application of the framework is presented using the multi-year monitoring effort surrounding the removal of the Marmot Dam from the Sandy River, OR.
FULL TEXT LINK: http://dx.doi.org/10.1002/rra.2651
Kane, V. R., J. A. Lutz, et al. (2015). “Water balance and topography predict fire and forest structure patterns.” Forest Ecology and Management 338: 1-13.
Mountainous topography creates fine-scale environmental mosaics that vary in precipitation, temperature, insolation, and slope position. This mosaic in turn influences fuel accumulation and moisture and forest structure. We studied these the effects of varying environmental conditions across a 27,104 ha landscape within Yosemite National Park, California, USA, on the number of fires and burn severity (measured from Landsat data for 1984–2010) and on canopy cover at two heights (>2 m and 2–8 m) and dominant tree height (measured with airborne LiDAR data). We used site water balance (actual evapotranspiration and climatic water deficit) and topography (slope position, slope, and insolation) as environmental predictors. Random forest modeling showed that environmental conditions predicted substantial portions of the variations in fire and forest structure: e.g., 85–93% of the variation in whether a location did not burn, burned once, or burned twice; 64% of the variation in the burn severity; and 72% of the variation in canopy cover >2 m for unburned forests, 64% for once-burned forests, and 59% for twice-burned forests. Environmental conditions also predicted a substantial portion of forest structure following one and two fires, even though the post-fire forest structures were substantially different than pre-fire structures. This suggests a feedback mechanism in which local fire regimes and pre-fire forest structures are related to local environments, and their interaction produces post-fire structures also related to local environments. Among environmental predictors, water balance had the greatest explanatory power, followed by slope position, and then by slope and insolation. Managers could use our methods to help select reference areas that match environmental conditions, identify areas at risk for fires that endanger critical habitat or other resources, and identify climate analog areas to help anticipate and plan for climate change.
Martinuzzi, S., V. C. Radeloff, et al. (2015). “Scenarios of future land use change around United States’ protected areas.” Biological Conservation 184: 446-455.
Land use change around protected areas can diminish their conservation value, making it important to predict future land use changes nearby. Our goal was to evaluate future land use changes around protected areas of different types in the United States under different socioeconomic scenarios. We analyzed econometric-based projections of future land use change to capture changes around 1260 protected areas, including National Forests, Parks, Refuges, and Wilderness Areas, from 2001 to 2051, under different land use policies and crop prices. Our results showed that urban expansion around protected areas will continue to be a major threat, and expand by 67% under business-as-usual conditions. Concomitantly, a substantial number of protected areas will lose natural vegetation in their surroundings. National land-use policies or changes in crop prices are not likely to affect the overall pattern of land use, but can have effects in certain regions. Discouraging urbanization through zoning, for example, can reduce future urban pressures around National Forests and Refuges in the East, while the implementation of an afforestation policy can increase the amount of natural vegetation around some Refuges throughout the U.S. On the other hand, increases in crop prices can increase crop/pasture cover around some protected areas, and limit the potential recovery of natural vegetation. Overall, our results highlight that future land-use change around protected areas is likely to be substantial but variable among regions and protected area types. Safeguarding the conservation value of protected areas may require serious consideration of threats and opportunities arising from future land use.
Compilation by Robyn Darbyshire
Hulshof, C. M., N. G. Swenson, et al. (2015). “Tree height–diameter allometry across the United States.” Ecology and Evolution 5(6): 1193-1204.
The relationship between tree height and diameter is fundamental in determining community and ecosystem structure as well as estimates of biomass and carbon storage. Yet our understanding of how tree allometry relates to climate and whole organismal function is limited. We used the Forest Inventory and Analysis National Program database to determine height–diameter allometries of 2,976,937 individuals of 293 tree species across the United States. The shape of the allometric relationship was determined by comparing linear and nonlinear functional forms. Mixed-effects models were used to test for allometric differences due to climate and floristic (between angiosperms and gymnosperms) and functional groups (leaf habit and shade tolerance). Tree allometry significantly differed across the United States largely because of climate. Temperature, and to some extent precipitation, in part explained tree allometric variation. The magnitude of allometric variation due to climate, however, had a phylogenetic signal. Specifically, angiosperm allometry was more sensitive to differences in temperature compared to gymnosperms. Most notably, angiosperm height was more negatively influenced by increasing temperature variability, whereas gymnosperm height was negatively influenced by decreasing precipitation and increasing altitude. There was little evidence to suggest that shade tolerance influenced tree allometry except for very shade-intolerant trees which were taller for any given diameter. Tree allometry is plastic rather than fixed and scaling parameters vary around predicted central tendencies. This allometric variation provides insight into life-history strategies, phylogenetic history, and environmental limitations at biogeographical scales.
FULL TEXT LINK: http://dx.doi.org/10.1002/ece3.1328
Prera, A., K. Grimsrud, et al. (2014). “Using Canonical Correlation Analysis to Identify Environmental Attitude Groups: Considerations for National Forest Planning in the Southwestern U.S.” Environmental Management 54(4): 756-767.
As public land management agencies pursue region-specific resource management plans, with meaningful consideration of public attitudes and values, there is a need to characterize the complex mix of environmental attitudes in a diverse population. The contribution of this investigation is to make use of a unique household, mail/internet survey data set collected in 2007 in the Southwestern United States (Region 3 of the U.S. Forest Service). With over 5,800 survey responses to a set of 25 Public Land Value statements, canonical correlation analysis is able to identify 7 statistically distinct environmental attitudinal groups. We also examine the effect of expected changes in regional demographics on overall environmental attitudes, which may help guide in the development of socially acceptable long-term forest management policies. Results show significant support for conservationist management policies and passive environmental values, as well as a greater role for stakeholder groups in generating consensus for current and future forest management policies.
FULL TEXT LINK: http://dx.doi.org/10.1007/s00267-014-0349-0
Thompson, M. P. (2014). “Social, Institutional, and Psychological Factors Affecting Wildfire Incident Decision Making.” Society & Natural Resources 27(6): 636-644.
Managing wildland fire incidents can be fraught with complexity and uncertainty. Myriad human factors can exert significant influence on incident decision making, and can contribute additional uncertainty regarding programmatic evaluations of wildfire management and attainment of policy goals. This article develops a framework within which human sources of uncertainty in wildfire management can be classified and managed, specifically identifying social, institutional, and psychological factors that can affect wildland fire incident decision making. These factors are reviewed in the context of wildland fire incident management and the literature regarding fire manager decision making. I then provide specific recommendations for addressing these issues, with a focus on improving incident decision processes. Extending this framework to consider a broader set of human factors and to consider how human factors affect the broader wildfire management spectrum could lead to improved fire management outcomes.
FULL TEXT LINK: http://dx.doi.org/10.1080/08941920.2014.901460
Munoz, N. J., A. P. Farrell, et al. (2015). “Adaptive potential of a Pacific salmon challenged by climate change.” Nature Clim. Change 5(2): 163-166.
Pacific salmon provide critical sustenance for millions of people worldwide and have far-reaching impacts on the productivity of ecosystems. Rising temperatures now threaten the persistence of these important fishes, yet it remains unknown whether populations can adapt. Here, we provide the first evidence that a Pacific salmon has both physiological and genetic capacities to increase its thermal tolerance in response to rising temperatures. In juvenile chinook salmon (Oncorhynchus tshawytscha), a 4 °C increase in developmental temperature was associated with a 2 °C increase in key measures of the thermal performance of cardiac function. Moreover, additive genetic effects significantly influenced several measures of cardiac capacity, indicative of heritable variation on which selection can act. However, a lack of both plasticity and genetic variation was found for the arrhythmic temperature of the heart, constraining this upper thermal limit to a maximum of 24.5 ± 2.2 °C. Linking this constraint on thermal tolerance with present-day river temperatures and projected warming scenarios, we predict a 17% chance of catastrophic loss in the population by 2100 based on the average warming projection, with this chance increasing to 98% in the maximum warming scenario. Climate change mitigation is thus necessary to ensure the future viability of Pacific salmon populations.
FULL TEXT LINK: http://dx.doi.org/10.1038/nclimate2473
Alfaro, R. I., B. Fady, et al. (2014). “The role of forest genetic resources in responding to biotic and abiotic factors in the context of anthropogenic climate change.” Forest Ecology and Management 333: 76-87.
The current distribution of forest genetic resources on Earth is the result of a combination of natural processes and human actions. Over time, tree populations have become adapted to their habitats including the local ecological disturbances they face. As the planet enters a phase of human-induced climate change of unprecedented speed and magnitude, however, previously locally-adapted populations are rendered less suitable for new conditions, and ‘natural’ biotic and abiotic disturbances are taken outside their historic distribution, frequency and intensity ranges. Tree populations rely on phenotypic plasticity to survive in extant locations, on genetic adaptation to modify their local phenotypic optimum or on migration to new suitable environmental conditions. The rate of required change, however, may outpace the ability to respond, and tree species and populations may become locally extinct after specific, but as yet unknown and unquantified, tipping points are reached. Here, we review the importance of forest genetic resources as a source of evolutionary potential for adaptation to changes in climate and other ecological factors. We particularly consider climate-related responses in the context of linkages to disturbances such as pests, diseases and fire, and associated feedback loops. The importance of management strategies to conserve evolutionary potential is emphasised and recommendations for policy-makers are provided.
Compilation by Robyn Darbyshire
Egan, D., M. Stoddard, et al. (2015). “Ecological and social implications of employing diameter caps at a collaborative forest restoration project near Flagstaff, Arizona, USA.” Forest Policy and Economics 52: 39-45.
The issue of implementing diameter caps as a means of preserving old-growth trees on forest restoration projects continues to permeate collaborative land management discussions and treatment decisions on public lands in the Southwest and, indeed, throughout the western United States. We examine the ecological and social results of the collaborative Fort Valley Ecosystem Restoration Project on U.S. Forest Service lands near Flagstaff, Arizona. Since this experiment had areas treated with and without a diameter cap, we sought to determine: 1) the ecological consequences of implementing a 16-inch diameter cap, 2) whether the fears and concerns of the environmental groups who proposed the diameter cap were, in fact, warranted, and 3) how the local collaborative responded to implementing the diameter cap. The ecological data revealed that a site’s management history played a major role in how a diameter cap would affect the restoration of stand structure in terms of tree density and tree size. The data suggest that, if implemented, diameter caps are best applied in a manner that takes into account both site conditions and stand management history. In general, we found the concerns about the loss of old-growth trees due to thinning treatments were not realized at Fort Valley. Finally, stakeholder surveys indicate that while the discussion of diameter caps caused tension within the collaborative group, the overall goal of forest restoration was not compromised.
Yetemen, O., E. Istanbulluoglu, et al. (2015). “Ecohydrologic role of solar radiation on landscape evolution.” Water Resources Research 51(2): 1127-1157.
Solar radiation has a clear signature on the spatial organization of ecohydrologic fluxes, vegetation patterns and dynamics, and landscape morphology in semiarid ecosystems. Existing landscape evolution models (LEMs) do not explicitly consider spatially explicit solar radiation as model forcing. Here, we improve an existing LEM to represent coupled processes of energy, water, and sediment balance for semiarid fluvial catchments. To ground model predictions, a study site is selected in central New Mexico where hillslope aspect has a marked influence on vegetation patterns and landscape morphology. Model predictions are corroborated using limited field observations in central NM and other locations with similar conditions. We design a set of comparative LEM simulations to investigate the role of spatially explicit solar radiation on landscape ecohydro-geomorphic development under different uplift scenarios. Aspect-control and network-control are identified as the two main drivers of soil moisture and vegetation organization on the landscape. Landscape-scale and long-term implications of these short-term ecohdrologic patterns emerged in modeled landscapes. As north facing slopes (NFS) get steeper by continuing uplift they support erosion-resistant denser vegetation cover which leads to further slope steepening until erosion and uplift attains a dynamic equilibrium. Conversely, on south facing slopes (SFS), as slopes grow with uplift, increased solar radiation exposure with slope supports sparser biomass and shallower slopes. At the landscape scale, these differential erosion processes lead to asymmetric development of catchment forms, consistent with regional observations. Understanding of ecohydrogeomorphic evolution will improve to assess the impacts of past and future climates on landscape response and morphology.
FULL TEXT LINK: http://dx.doi.org/10.1002/2014WR016169
Franklin, J. and K. Norman Johnson (2014). “Lessons in policy implementation from experiences with the Northwest Forest Plan, USA.” Biodiversity and Conservation 23(14): 3607-3613.
Approximately 20 years ago, the preeminent goal for management of the federal forests of the Pacific Northwest shifted suddenly and permanently from sustained timber harvest to conservation of biodiversity and ecological processes, following a series of court cases over protection of species in decline that were associated with old forests. While old growth harvest has largely ceased, some key species are still in decline and forest management has been restricted more than intended. Creation of openings, even those based on disturbance processes, has been especially difficult. Some lessons from this experience include the difficulty of adaptive management, the importance of ecological foundations for management, and the need for stakeholder collaboration. In addition, it is essential to provide society with a vision of ecologically-based forestry, including field demonstrations, and to communicate this approach and its scientific foundation in the popular media.
FULL TEXT LINK: http://dx.doi.org/10.1007/s10531-014-0789-0
Yospin, G. I., S. D. Bridgham, et al. (2014). “A new model to simulate climate-change impacts on forest succession for local land management.” Ecological Applications 25(1): 226-242.
We developed a new climate-sensitive vegetation state-and-transition simulation model (CV-STSM) to simulate future vegetation at a fine spatial grain commensurate with the scales of human land-use decisions, and under the joint influences of changing climate, site productivity, and disturbance. CV-STSM integrates outputs from four different modeling systems. Successional changes in tree species composition and stand structure were represented as transition probabilities and organized into a state-and-transition simulation model. States were characterized based on assessments of both current vegetation and of projected future vegetation from a dynamic global vegetation model (DGVM). State definitions included sufficient detail to support the integration of CV-STSM with an agent-based model of land-use decisions and a mechanistic model of fire behavior and spread. Transition probabilities were parameterized using output from a stand biometric model run across a wide range of site productivities. Biogeographic and biogeochemical projections from the DGVM were used to adjust the transition probabilities to account for the impacts of climate change on site productivity and potential vegetation type. We conducted experimental simulations in the Willamette Valley, Oregon, USA. Our simulation landscape incorporated detailed new assessments of critically imperiled Oregon white oak (Quercus garryana) savanna and prairie habitats among the suite of existing and future vegetation types. The experimental design fully crossed four future climate scenarios with three disturbance scenarios. CV-STSM showed strong interactions between climate and disturbance scenarios. All disturbance scenarios increased the abundance of oak savanna habitat, but an interaction between the most intense disturbance and climate-change scenarios also increased the abundance of subtropical tree species. Even so, subtropical tree species were far less abundant at the end of simulations in CV-STSM than in the dynamic global vegetation model simulations. Our results indicate that dynamic global vegetation models may overestimate future rates of vegetation change, especially in the absence of stand-replacing disturbances. Modeling tools such as CV-STSM that simulate rates and direction of vegetation change affected by interactions and feedbacks between climate and land-use change can help policy makers, land managers, and society as a whole develop effective plans to adapt to rapidly changing climate.
FULL TEXT LINK: http://dx.doi.org/10.1890/13-0906.1
Lookingbill, T. R., E. S. Minor, et al. (2014). “Incorporating Risk of Reinvasion to Prioritize Sites for Invasive Species Management.” Natural Areas Journal 34(3): 268-281.
The relationship between landscape pattern and the distribution and spread of exotic species is an important determinant of where and when management actions are best applied. We have developed an interdisciplinary approach for prioritizing treatment of harmful, nonnative, invasive plants in National Park landscapes of the Mid-Atlantic USA. The approach relies upon a detailed model of reinvasion risk that combines information on: (1) global factors representing park-level infestation from seed and sprout, (2) landscape factors including disturbance-based spread vectors and neighborhood seed density, and (3) local factors determining establishment probability based on habitat suitability. Global seed rain estimates are derived empirically from park inventory data and modified by information on species reproductive strategies. Landscape-level propagule pressure is modeled spatially using species life history characteristics including dispersal attributes, connectivity to nearby plant populations, and increased propagule pressure through disturbance. The local-scale habitat suitability model uses a Mahalanobis distance approach, parameterized from plant inventory plot data and GIS-based data on plot wetness, land cover, slope, radiation, and soil characteristics. We illustrate the model for Ailanthus altissima (tree-of-heaven) in Antietam National Battlefield Park. The results of the A. altissima modeling highlight regions of the park where eradication would be most prudent and feasible based on current infestation patterns and landscape heterogeneity. Although the success of different treatment modalities is often considered in invasive species management, a spatially explicit assessment of likely treatment success is rarely undertaken. Our approach provides a valuable tool to assist natural resource practitioners to prioritize management options in confronting biological invasions.
FULL TEXT LINK: http://dx.doi.org/10.3375/043.034.0303
Compilation by Robyn Darbyshire
Bar-Massada, A., V. C. Radeloff, et al. (2014). “Biotic and Abiotic Effects of Human Settlements in the Wildland–Urban Interface.” BioScience 64(5): 429-437.
The wildland–urban interface (WUI) is the area in which human settlements adjoin or intermix with ecosystems. Although research on the WUI has been focused on wildfire risk to settlements, we argue here that there is a need to quantify the extent of areas in which human settlements interact with adjoining ecosystems, regardless of their ability to support fire spread. Besides wildfires, human settlements affect neighboring ecosystems through biotic processes, including exotic species introduction, wildlife subsidization, disease transfer, landcover conversion, fragmentation, and habitat loss. The effects of WUI settlements on ecosystems are two tiered, starting with habitat modification and fragmentation and progressing to various diffusion processes in which direct and indirect effects of anthropogenic activities spread into neighboring ecosystems at varying scales. New scientific, management, and policy tools are needed in order to better understand the WUI as a unique social–ecological zone and to mitigate negative consequences of its continued growth.
FULL TEXT LINK:
Carwardine, J., C. Hawkins, et al. (2015). “Spatial Priorities for Restoring Biodiverse Carbon Forests.” BioScience 65(4): 372-382.
A price on carbon is driving land-use changes globally, including the establishment of biodiverse carbon plantings to sequester carbon. The biodiversity benefits of these plantings depend on many factors, including their spatial locations. We provide an approach for assessing the opportunities and spatial priorities for carbon sequestration and biodiversity restoration through biodiverse carbon plantings. Using Australia as a case study, we show how carbon market conditions affect the potential for achieving biodiversity benefits through restoring heavily cleared vegetation types to 30% of their original extent. Using a midrange carbon price, AU$20 per ton, we discovered that the top 25% of priority areas for biodiverse carbon plantings could sequester 132 megatons of carbon dioxide equivalents annually—more than 5% of Australia’s emissions. Lower carbon prices limit biodiversity outcomes. Spatial priorities for sequestering carbon are different from those for restoring biodiversity; therefore, accounting for both factors maximizes efficiency and opportunities.
FULL TEXT LINK: http://bioscience.oxfordjournals.org/content/65/4/372.abstract
Sloat, M. R. and G. H. Reeves (2014). “Demographic and phenotypic responses of juvenile steelhead trout to spatial predictability of food resources.” Ecology 95(9): 2423-2433.
We manipulated food inputs among patches within experimental streams to determine how variation in foraging behavior influenced demographic and phenotypic responses of juvenile steelhead trout (Oncorhynchus mykiss) to the spatial predictability of food resources. Demographic responses included compensatory adjustments in fish abundance, mean fish size, and size inequality. These responses paralleled shifts in individual foraging behavior, which increased the strength of exploitative competition relative to interference competition in streams with lower spatial predictability of food resources. Variation in the spatial predictability of food resources also favored different physiological phenotypes, as inferred from selection on an index of standard metabolic rate (SMR) based on fish otolith size. We observed positive directional selection on SMR in streams with spatially predictable food resources, disruptive selection for SMR at intermediate levels of spatial predictability, and negative directional selection for SMR in streams with the lowest level of spatial predictability of food resources. Thus, variation in the spatial predictability of food resources resulted in changes in individual behavior and modes of population regulation, and produced physiologically divergent cohorts of stream salmonids.
FULL TEXT LINK: http://dx.doi.org/10.1890/13-1442.1
Balfour, V. N., S. H. Doerr, et al. (2014). “The temporal evolution of wildfire ash and implications for post-fire infiltration.” International Journal of Wildland Fire 23(5): 733-745.
Changes in the properties of an ash layer with time may affect the amount of post-fire runoff, particularly by the formation of ash surface crusts. The formation of depositional crusts by ash have been observed at the pore and plot scales, but the causes and temporal evolution of ash layers and associated crusts have not yet been thoroughly investigated. In the long term, ash crusting effects will decrease as the ash layer is removed by wind and water erosion, but in the short term ash crusting could contribute to the observed changes in post-fire runoff. This research addresses these topics by studying the evolution over time of highly combusted ash layers from two high-severity wildfires that occurred in Montana in 2011. More specifically, this research was designed to assess the potential for ash crusts to form and thereby contribute to the observed decreases in infiltration after forest fires. Results indicate that high-combustion ash can evolve due to post-fire rainfall. Plots that exhibited a visible ash crust also displayed a significant decrease in effective porosity and hydraulic conductivity. These decreases in ash layer characteristics were attributed to raindrop compaction and ash hydration resulting in the formation of carbonate crystals, which decreased effective porosity and flow within the ash layer. During this same time period, inorganic carbon content more than doubled from 11 to 26% and bulk density significantly increased from 0.22 to 0.39 g cm–3 on crusted plots. Although raindrop impact increased the robustness of the ash crust, mineralogical transformations must occur to produce a hydrologically relevant ash crust. These results indicate that post-fire rainfall is an important control on the properties of the ash layer after burning and on crust formation. The observed temporal changes indicate that the timing of ash sampling can alter the predictions as to whether the ash layer is effecting post-fire infiltration and runoff. Despite the reduction in infiltration capacity, the formation of post-fire ash crusts could prove beneficial to post-fire hazard mitigation by stabilising the ash layer, and reducing aeolian mixing and erosion.
FULL TEXT LINK: http://www.publish.csiro.au/paper/WF13159
Siegel, R. B., R. L. Wilkerson, et al. (2014). “Roost sites of the Black-backed Woodpecker in burned forest.” Western Birds 45(4): 296-303.
The Black-backed Woodpecker (Picoides arcticus) is strongly associated with recently burned forest, which makes it vulnerable to salvage logging or other post-fire forest management that removes snags. As part of a larger radio-telemetry study of the species’ resource use and habitat selection in a burned forest in California, we located radio-tagged Black-backed Woodpeckers at night to find and describe their roost sites. We found 14 unique roost locations during night-time searches for five individual birds. Description of the micro-site on the tree that the bird used was impossible at five roosts where we could not visually locate the bird in the dark. At the nine roosts confirmed visually, none of the birds roosted in excavated cavities. Rather, they roosted in sheltered spaces within burned-out hollows of trunks (5 instances), in the crook of a forked trunk (1 instance), wedged between adjacent trunks of two closely spaced trees (1 instance), in a deep, natural bark furrow (1 instance), and clinging to a trunk directly above a horizontal branch (1 instance). Eleven of the 14 roosts (79%) were in dead trees. Our results suggest that in burned forests the Black-backed Woodpecker may benefit if, during salvage logging, emphasis is placed on retaining snags with burned-out hollows, forked trunks, or other relatively unusual structures that may create crevices or other opportunities for shelter.
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