Conserving biological diversity in a changing climate poses major challenges for land managers and society. Effective adaptive strategies for dealing with climate change require a socioecological systems perspective. We highlight some of the projected ecological responses to climate change in the Pacific Northwest, U.S.A and identify possible adaptive actions that federal forest managers could take. The forest landscape, ownership patterns and recent shift toward ecologically based forest management provide a good starting place for conserving biological diversity under climate change. Nevertheless, undesirable changes in species and ecosystems will occur and a number of adaptive actions could be undertaken to lessen the effects of climate change on forest ecosystems. These include: manipulation of stand and landscape structure to increase ecological resistance and resilience; movement of species and genotypes; and engaging in regional, multi-ownership planning to make adaptive actions more effective. Although the language and goals of environmental laws and policies were developed under the assumption of stable climate and disturbance regimes, they appear to be flexible enough to accommodate many adaptive actions. It is less certain, however, if sufficient social license and economic capacity exist to undertake these actions. Given the history of contentious and litigious debate about federal forest management in this region, it is likely that some of these actions will be seen as double-edge swords, spurring social resistance, especially where actions involve cutting trees. Given uncertainties and complexity, collaborative efforts that promote learning (e.g., adaptive management groups) must be rejuvenated and expanded.
We monitored populations of snowshoe hares (Lepus americanus, Erxleben) in interior Alaska for 10 years from 1999 to 2008. During this period, fall densities of hares fluctuated approximately 14-fold. High population growth rates over summer were followed by large population declines over winter. Young-of-the-year hares tended to gain mass over winter, while adult hares tended to loose body mass. The average mass of adult hares was significantly lower during the low phase of the cycle compared with when hares were abundant. Overwinter survival of juveniles relative to adults decreased strongly as a function of the frequency of snowfall events. However, effects of temperature and precipitation on hare demography were season dependent and appear to act as modifiers of the primary controls over population dynamics (predation and food) rather than as direct sources of mortality. The rapid changes in green-up and snow-up in interior Alaska may affect forage conditions as well as the timing of molt in snowshoe hares. The strength of these interactions may increase in importance if the asynchrony of environmental seasonality and life history traits of snowshoe hares becomes more pronounced as the climate continues to change.
Large-scale government efforts to develop resources for societal benefit have often experienced cycles of growth and decline that leave behind difficult social and ecological legacies. To understand the origins and outcomes of these failures of resource governance, scholars have applied the framework of the adaptive cycle. In this study, we used the adaptive cycle as a diagnostic approach to trace the drivers and dynamics of forest governance surrounding a boom–bust sequence of industrial forest management in one of the largest-scale resource systems in U.S. history: the Tongass National Forest in southeastern Alaska. Our application of the adaptive cycle combined a historical narrative tracing dynamics in political, institutional, and economic subsystems and a longitudinal analysis of an indicator of overall system behavior (timber harvests). We found that federal policies in concert with global market changes drove transformative change in both forest governance (policy making) and forest management (practices), through creation and dissolution of subsidized long-term lease contracts. Evidence of the systemic resilience provided by these leases was found in the analysis of industry responses to market volatility before and after Tongass-specific federal reforms. Although the lease contracts stabilized the Tongass system for a period of time, they fostered a growing degree of rigidity that contributed to a severe industrial collapse and the subsequent emergence of complex social traps. Broader lessons from the Tongass suggest that large-scale changes occurred only when the nested economic and policy cycles were in coherence, and a systemic effort to minimize social and ecological variability ultimately resulted in catastrophic collapse of governance. This collapse resulted in a pervasive and challenging legacy that prevents Tongass reorganization and limits the adaptive capacity of the larger social–ecological system of southeastern Alaska. Although this legacy has inhibited system renewal for two decades, recent trends indicate the emergence of new opportunities for progress toward sustainable governance of the Tongass National Forest.
Field Guide to Owls of California and the West. Written primarily for nonprofessionals,this little field guide is a treasure trove of published and unpublished information on the natural history and distribution of owls in the western United States. It covers just about everything you could want to know about owls, from why they take dust baths, to facultative zygodactyly.
In severely burned plantations, dynamics of (1) shrub, herbaceous, and cryptogam richness; (2) cover; (3) topographic, overstory, and site influences were characterized on two contrasting aspects 2 to 4 years following fire. Analysis of variance was used to examine change in structural layer richness and cover over time. Non-metric multidimensional scaling, multi-response permutation procedure, and indicator species analysis were used to evaluate changes in community composition over time. Vegetation established rapidly following wildfire in burned plantations, following an initial floristics model of succession among structural layers. Succession within structural layers followed a combination of initial and relay floristic models. Succession occurred simultaneously within and among structural layers following wildfire, but at different rates and with different drivers. Stochastic (fire severity and site history) and deterministic (species life history traits, topography, and predisturbance plant community) factors determined starting points of succession. Multiple successional trajectories were evident in early succession.
In spite of numerous habitat restoration programs in fresh waters with an aggregate annual funding of millions of dollars, many populations of Pacific salmon remain significantly imperiled. Habitat restoration strategies that address limited environmental attributes and partial salmon life-history requirements or approaches that attempt to force aquatic habitat to conform to idealized but ecologically unsustainable conditions may partly explain this lack of response. Natural watershed processes generate highly variable environmental conditions and population responses, i.e., multiple life histories, which are often not considered in restoration. Examples from several locations underscore the importance of natural variability to the resilience of Pacific salmon. The implication is that habitat restoration efforts will be more likely to foster salmon resilience if they consider processes that generate and maintain natural variability in fresh water. We identify three specific criteria for management based on natural variability: the capacity of aquatic habitat to recover from disturbance, a range of habitats distributed across stream networks through time sufficient to fulfill the requirements of diverse salmon life histories, and ecological connectivity. In light of these considerations, we discuss current threats to habitat resilience and describe how regulatory and restoration approaches can be modified to better incorporate natural variability.
Meadows are natural dynamic features of forested mountain landscapes of the Pacific Northwest. Proportions of meadows and forests change with environmental conditions and disturbance history. We investigated the belowground microbial communities associated with these two vegetation types and how they change across the meadow-forest transition at two sites in Oregon. Soils were sampled along replicate transects extending from meadow into forest. We quantified total bacterial and fungal biomass using direct microscopy and described the composition of bacterial and fungal communities using a DNA-based fingerprinting technique. Bacterial biomass was similar in meadow and forest soils, but fungal biomass was significantly higher in forest soil. Meadow and forest soils had distinct communities of bacteria and fungi. Bacterial communities near the meadow-forest boundary reflected current vegetation, but fungal communities under meadow vegetation near the forest edge were intermediate in composition between those found in meadow and forest soils. The more gradual transition observed with fungal communities may reflect the influence of tree roots and their associated ectomycorrhizal fungi or possibly colonization by saprotrophic fungi associated with tree litter accumulating near the forest edge. Invasion of forest-associated fungi into the meadow soils may presage subsequent expansion of forest vegetation into meadows.
We describe methodologies currently in use or those under development containing features for estimating fire occurrence risk assessment. We describe two major categories of fire risk assessment tools: those that predict fire under current conditions, assuming that vegetation, climate, and the interactions between them and fire remain relatively similar to their condition during recent history, and those that anticipate changes in fire risk as climate and vegetation communities change through time. Three types of models have proven useful for predicting fire under current conditions: (1) biophysical models that predict fire from vegetation type, fuel load, and climate; (2) statistical models; and (3) fire behavior models. Programs such as LANDFIRE have great promise for using biophysical properties to estimate risk. Statistical models that use historical data to predict fire probabilities if landscape-fire relationships continue to remain relatively unchanged, are gaining interest as more data become available. Fire behavior models are producing accurate predictions of the ways individual fires will move across the landscape. For longer periods, fire risk needs to be evaluated by models that predict the ways vegetation communities will change over time because these changes will alter fire probabilities. We identified models capable of being used to track changes in vegetation and the resulting effect on changes in fire frequency. Risk systems need to be designed to track changes in fire susceptibility as the climate changes, using models such as MAPSS. Prediction of fire occurrence is just the first part of a complete analysis of risks associated with fire. Fire occurrence risk needs to be combined with models that determine the risk of the effects of fire. Models that predict mortality, fuel consumption, smoke production, and soil heating caused by prescribed fire or wildfire should be used, as well as those capable of evaluating second order effects, such as changes in site productivity, animal use, insects, and disease. Fire must be looked at in the context of other stresses, such as invasive insects and pathogens, encroaching urbanization, and loss of critical habitat. There are interactions among stresses that play a role in affecting the frequency and intensity of fire, and fire, in turn, can affect the probability of those stresses. Consequently, risk evaluation systems need to be created that can simultaneously estimate the probability of other major stresses influencing ecosystem development.
Florida’s Wildland Fire Risk Assessment (FRA), which was completed in 2002, is a statewide effort to develop a comprehensive suite of standardized spatial data layers developed to support implementation of a statewide fuels management strategy. By maintaining focus on fire and fuel dynamics for use with scientifically credible local to statewide applications, the FRA builds on a statewide surface fuels map, fire history data from many agencies, and weather data collected over a period of 20 years. Change detection is currently being utilized to update the statewide surface fuels layer. The process used in the FRA builds on a process first applied in the Lake Tahoe Basin Land Management Unit. Subsequently, the methods used in the FRA have recently been applied to 13 Southern States in the Southern Wildfire Risk Assessment.
High-resolution macroscopic charcoal and pollen analysis were used to reconstruct an 11 000-year-long record of fire and vegetation history from Beaver Lake, Oregon, the first complete Holocene paleoecological record from the floor of the Willamette Valley. In the early Holocene (ca 11 000-7500 calendar years before present [cal yr BP]), warmer, drier summers than at present led to the establishment of xeric woodland of Quercus, Corylus, and Pseudotsuga near the site. Disturbances (i.e., floods, fires) were common at this time and as a result Alnus rubra grew nearby. High fire frequency occurred in the early Holocene from ca 11 200-9300 cal yr BP. Riparian forest and wet prairie developed in the middle Holocene (ca 7500 cal yr BP), likely the result of a decrease in the frequency of flooding and a shift to effectively cooler, wetter conditions than before. The vegetation at Beaver Lake remained generally unchanged into the late Holocene (from 4000 cal yr BP to present), with the exception of land clearance associated with Euro-American settlement of the valley (ca 160 cal yr BP). Middle-to-late Holocene increases in fire frequency, coupled with abrupt shifts in fire-episode magnitude and charcoal composition, likely indicate the influence of anthropogenic burning near the site. The paleoecological record from Beaver Lake, and in particular the general increase in fire frequency over the last 8500 years, differs significantly from other low-elevation sites in the Pacific Northwest, which suggests that local controls (e.g., shifts in vegetation structure, intensification of human land-use), rather than regional climatic controls, more strongly influenced its environmental history.