Beargrass (Xerophyllum tenax (Pursh) Nutt.) is a source of food, habitat, and raw material for animals, pollinating insects, and people across its range in the Western United States. The plant has long been used by Native Americans, who harvest the leaves for basketry and other crafts. More recently, beargrass has become an important component of international trade for the commercial floral greens industry. Changes in natural and anthropogenic disturbances are occurring within the range of beargrass, including fire frequency and severity, plant harvest intensity, and land use. This report documents how changes in disturbance patterns might affect beargrass and its associated ecosystem diversity, identifies gaps in knowledge or potential conflicts in human use, and records quantitative and qualitative information on the natural and cultural history of beargrass. We list and discuss some key sociocultural, environmental, and economic issues that relate to managing beargrass and the forested ecosystems in which it grows. These include a lack of information on the main factors affecting beargrass reproduction and persistence, including the importance of pollinators and light environment on plant fitness; differences in desired leaf properties sought by traditional and commercial harvesters; and inconsistent documentation on the volume and properties of harvested beargrass in total and by harvester group. Future research needs include advancing knowledge of the effects of human and natural disturbances on the plant and its habitat, including silvicultural practices, leaf harvest practices, and fire (both prescribed and wild).
Current evidence from temperate studies suggests that ectomycorrhizal (ECM) fungi require overland routes for migration because of their obligate symbiotic associations with woody plants. Despite their key roles in arctic ecosystems, the phylogenetic diversity and phylogeography of arctic ECM fungi remains little known. Here we assess the phylogenetic diversity of ECM communities in an isolated, formerly glaciated, high arctic archipelago, and provide explanations for their phylogeographic origins. Our results indicate numerous recent colonization events and suggest that long-distance, transoceanic dispersal is widespread in arctic ECM fungi, which differs markedly from the currently prevailing view on the dispersal capabilities of ECM fungi. Our molecular evidence indicates that long-distance dispersal has probably played a major role in the phylogeographic history of some ECM fungi in the Northern Hemisphere. Our results may have implications for studies on the biodiversity, ecology and conservation of arctic fungi in general.
Lidar is currently the most accurate method for remote estimation of forest structure, but it has limited spatial and temporal coverage. Conversely, Landsat data are more widely available, but exhibit a weaker relationship with structure under medium to high leaf area conditions. One potentially valuable means of enhancing the relationship between Landsat reflectance and forest structure is to incorporate Landsat spectral trends prior to a date of interest. Because the condition of a forest stand at any point in time is linked to the stand's disturbance history, an approach that directly leverages the temporal information of Landsat time series should improve estimates of forest structure. The main objective of this study was to test and demonstrate the utility of disturbance and recovery metrics derived from spectral profiles of annual Landsat time series (LTS) to predict current forest structure attributes (as compared to more traditional approaches, including airborne, discrete return lidar and single-date Landsat). We estimated aboveground live biomass (AGBlive), dead woody biomass (AGBdead), basal area (live and dead), and Lorey's mean stand height for a mixed-conifer forest in eastern Oregon, USA, and compared the results with estimates from lidar and single, current-date Landsat imagery. Annual time-series stacks for the entire Landsat record ( 1972-201 0) were obtained to characterize all long-term (insect, growth) and short-term (fire, harvest) vegetation changes that occurred during that period. This required the additional objective of integrating Landsat data from MSS and TM/ETM +sensors, and we describe here our approach. To extract spectral trajectories and change metrics associated with forest disturbances and recovery we applied a temporal segmentation to the calibrated time series.
Disturbance processes of various types substantially modify ecosystem carbon dynamics both temporally and spatially, and constitute a fundamental part of larger landscape-level dynamics. Forests typically lose carbon for several years to several decades following severe disturbance, but our understanding of the duration and dynamics of post-disturbance forest carbon fluxes remains limited. Here we capitalize on a recent North American Carbon Program disturbance synthesis to discuss techniques and future work needed to better understand carbon dynamics after forest disturbance. Specifically, this paper addresses three topics: (1) the history, spatial distribution, and characteristics of different types of disturbance (in particular fire, insects, and harvest) in North America; (2) the integrated measurements and experimental designs required to quantify forest carbon dynamics in the years and decades after disturbance, as presented in a series of case studies; and (3) a synthesis of the greatest uncertainties spanning these studies, as well as the utility of multiple types of observations (independent but mutually constraining data) in understanding their dynamics. The case studies—in the southeast U.S., central boreal Canada, U.S. Rocky Mountains, and Pacific Northwest—explore how different measurements can be used to constrain and understand carbon dynamics in regrowing forests, with the most important measurements summarized for each disturbance type. We identify disturbance severity and history as key but highly uncertain factors driving post-disturbance carbon source-sink dynamics across all disturbance types. We suggest that imaginative, integrative analyses using multiple lines of evidence, increased measurement capabilities, shared models and online data sets, and innovative numerical algorithms hold promise for improved understanding and prediction of carbon dynamics in disturbance-prone forests.
The Five USDA Biomass Research Centers were created to facilitate coordinated research to enhance the establishment of a sustainable feedstock production for bio-based renewable energy in the United States. Scientists and staff of the Agricultural Research Service (ARS) and Forest Service (FS) within USDA collaborate with other federal agencies, universities and private partners to design, implement, and disseminate findings from research that has high impact on the bioenergy industry. The centers draw upon expertise in diverse disciplines and a history of long term research conducted at multiple locations within each region. Feedstocks development and production aspects are region specific. However, soil, water, and air quality as well as methods to minimize the adverse affects of bioenergy on existing agricultural markets are central to all production systems and regions.
Firesheds are geographic units used by the Forest Service to delineate areas with similar fire regimes, fire history, and wildland fire risk issues. Fireshed assessment is a collaborative process where specialists design fuel treatments to mitigate wildfire risk. Fireshed assessments are an iterative process where fuel treatments are proposed for specific stands based on potential fire behavior, and the resulting matrix of treatments is evaluated in terms of reducing landscape scale fire spread. The Fireshed process uses an array of fire behavior models and GIS operations making it difficult to analyze large numbers of scenarios in timely fashion. We automated Fireshed analysis with Visual Basic macros and ArcObjects. The macros are implemented on custom toolbars in ArcMap and link vegetation and wildfire behavior models with ArcGIS desktop office software and Forest Service vegetation databases.
Alterations in variance of riverine thermal regimes have been observed and are predicted with climate change and human development. We tested whether changes in daily or seasonal thermal variability, aside from changes in mean temperature, could have biological consequences by exposing Chinook salmon (Oncorhynchus tshawytscha) eggs to eight experimental thermal regimes. Thermal variance impacted both emergence timing and development at emergence. Further, genetics influenced the magnitude of that response. Ecological implications include: (1) changes in thermal variability, independent of warming, have the potential to alter the timing of life history processes, (2) the commonly-used degree day accumulation model is not sufficient to predict how organisms respond to altered temperature regimes, and (3) there are likely to be genetic differences in how individuals and populations respond to future water temperature regimes.
The history of forest change processes is written into forest age and distribution and affects earth systems at many scales. No one data set has been able to capture the full forest disturbance and land use record through time, so in this study, we combined multiple lines of evidence to examine trends, for six US regions, in forest area affected by harvest, fire, wind, insects, and forest conversion to urban/suburban use. We built an integrated geodatabase for the contiguous U.S. (CONUS) with data spanning the nation and decades, from remote sensing observations of forest canopy dynamics, geospatial data sets on disturbance and conversion, and statistical inventories, to evaluate relationships between canopy change observations and casual processes at multiple scales. Results show the variability of major change processes through regions across decades. Harvest affected more forest area than any other major change processes in the North East, North Central, Southeast, and South central regions. In the Pacific Coast and Intermountain West, more forest area was affected by harvest than forest fires. Canopy change rates at regional scales confounded the trends of individual forest change processes, showing the importance of landscape scale data. Local spikes in observed canopy change rates were attributed to wind and fire events, as well as volatile harvest regimes. This study improves the geographic model of forest change processes by updating regional trends for major disturbance and conversion processes and combining data on the dynamics of fire, wind, insects, harvest, and conversion into one integrated geodatabase for the CONUS.
We may expect butterflies as ectotherms to have particularly active lifehistory stages that occur in the warmest and lightest times of the year; however, there are temperate species that are active when climatic conditions seem unfavourable and photoperiod short, such as the Taylor’s checkerspot (Euphydryas editha taylori). For such species, studies suggest that even subtle changes to microclimate can potentially impact populations. Thus, understanding how in situ variations in microclimate influence the Taylor’s checkerspot butterfly could provide much needed insights into more effective management. We conducted a series of surveys that explored (i) adult habitat use, (ii) final instar larval distribution and (iii) adult movement up to and across site boundaries at two sites in Oregon, USA, in 2010 and 2011. We found that in situ habitat use by the Taylor’s checkerspot butterfly was strongly influenced by microclimate. Both adult activities and final instar larvae distribution were clustered within the warmest areas of the sites. Moreover, adults did not use up to 59% and larva up to 90% of their sites, despite vegetation structure and composition being uniform. More specifically, butterfly habitat use increased with increasing ground temperatures, and we found that areas with the highest ground temperatures were more exposed to direct sunlight. Similarly, we found that butterflies tended to only move through sunlit site boundaries. We conclude that the Taylor’s checkerspot is sensitive to changes in its thermal environment at fine spatial scales. Our results highlight the importance of microclimate as an indicator of habitat quality, and establishing the thermal criteria in which species of concern exists may provide valuable insights into the implications of climate change.
For a century, US Forest Service experimental forests and ranges (EFRs) have been a resource for scientists conducting long-term research relating to forestry and range management social science research has been limited, despite the history of occupation and current use of these sites for activities ranging from resource extraction and recreation to public education. This article encourages researchers to take advantage of the rich, though largely untapped, potential EFRs offer for social science by describing their many human dimensions and providing an overview of potential research topics. These topics include human uses, economics, historical studies, population and land-use change, human values, and interdisciplinary social-ecological studies. Lack of awareness among social scientists, limited budgets and networking, and the predominance of biophysical scientists who administer and conduct research at EFRs appear to be inhibiting the development of social science research there. We suggest ways of overcoming these barriers.