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Results for “Climate Change Responses”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 991 records · Page 55Linked to original sources
USGS1998

Influence of subglacial geology on the onset of a West Antarctic ice stream from aerogeophysical observations

Marine ice-sheet collapse can contribute to rapid sea-level rise . Today, the West Antarctic Ice Sheet contains an amount of ice equivalent to approximately six metres of sea-level rise, but most of the ice is in the slowly moving interior reservoir. A relatively small fraction of the ice sheet comprises several rapidly flowing ice streams which drain the ice to the sea. The evolution of this drainage system almost certainly governs the process of ice-sheet collapse . The thick and slow-moving interior ice reservoir is generally fixed to the underlying bedrock while the ice streams glide over lubricated beds at velocities of up to several hundred metres per year. The source of the basal lubricant — a water-saturated till overlain by a water system — may be linked to the underlying geology. The West Antarctic Ice Sheet rests over a geologically complex region characterized by thin crust, high heat flows, active volcanism and sedimentary basins . Here we use aerogeophysical measurements to constrain the geological setting of the onset of an active West Antarctic ice stream. The onset coincides with a sediment-filled basin incised by a steep-sided valley. This observation supports the suggestion that ice-stream dynamics — and therefore the response of the West Antarctice Ice Sheet to changes in climate — are strongly modulated by the underlying geology.

Nature↗
USGS2025

Land cover, elevation, and precipitation predict distribution and hotspots of three bird species of concern in boreal Alaska

The boreal forest biome is an important breeding area for migratory birds and is undergoing rapid changes, including drying of wetlands, changes to vegetation composition, and human development. Many boreal bird populations are declining, but information is often lacking on how these species associate with habitat characteristics and thus how they may respond to changing conditions. We used a large point-count dataset to describe habitat associations and hotspots for three boreal species of concern in Alaska, USA: Tringa flavipes (Lesser Yellowlegs), Contopus cooperi (Olive-sided Flycatcher), and Euphagus carolinus (Rusty Blackbird). We used an N-mixture model to evaluate covariates of abundance and two components of detection (availability and perceptibility). We then used the estimated relationships with covariates to predict density of each species across the Northwestern Interior Forest (Bird Conservation Region 4) in Alaska, including identifying hotspots where density was predicted to be in the top 10% of all locations. T. flavipes and E. carolinus were associated with wetlands and mean values of June precipitation; T. flavipes were also associated with low elevation and recent fire; and C. cooperi was associated with needleleaf forest and moderate elevation. Hotspots for T. flavipes and E. carolinus usually overlapped, while hotspots for C. cooperi almost never overlapped with those of the other two species. Following ground-truthing, these predicted distributions could be used to indicate areas of high importance for species of conservation concern and thus inform management decisions and mitigation measures. Our results could also help identify areas that are likely to be important for these species in the future, given the rapid changes now occurring across the boreal biome in response to climate warming and drying.

Alaska↗
USGS2017

Semi-quantitative assessment of disease risks at the human, livestock, wildlife interface for the Republic of Korea using a nationwide survey of experts: A model for other countries

Wildlife-associated diseases and pathogens have increased in importance; however, management of a large number of diseases and diversity of hosts is prohibitively expensive. Thus, the determination of priority wildlife pathogens and risk factors for disease emergence is warranted. We used an online questionnaire survey to assess release and exposure risks, and consequences of wildlife-associated diseases and pathogens in the Republic of Korea (ROK). We also surveyed opinions on pathways for disease exposure, and risk factors for disease emergence and spread. For the assessment of risk, we employed a two-tiered, statistical K -means clustering algorithm to group diseases into three levels (high, medium and low) of perceived risk based on release and exposure risks, societal consequences and the level of uncertainty of the experts’ opinions. To examine the experts’ perceived risk of routes of introduction of pathogens and disease amplification and spread, we used a Bayesian, multivariate normal order-statistics model. Six diseases or pathogens, including four livestock and two wildlife diseases, were identified as having high risk with low uncertainty. Similarly, 13 diseases were characterized as having high risk with medium uncertainty with three of these attributed to livestock, six associated with human disease, and the remainder having the potential to affect human, livestock and wildlife (i.e., One Health). Lastly, four diseases were described as high risk with high certainty, and were associated solely with fish diseases. Experts identified migration of wildlife, international human movement and illegal importation of wildlife as the three routes posing the greatest risk of pathogen introduction into ROK. Proximity of humans, livestock and wildlife was the most significant risk factor for promoting the spread of wildlife-associated diseases and pathogens, followed by high density of livestock populations, habitat loss and environmental degradation, and climate change. This study provides useful information to decision makers responsible for allocating resources to address disease risks. This approach provided a rapid, cost-effective method of risk assessment of wildlife-associated diseases and pathogens for which the published literature is sparse.

Transboundary and Emerging Diseases↗
USGS2020

The effects of tissue fixation on sequencing and transcript abundance of nucleic acids from microdissected liver samples of smallmouth bass (Micropterus dolomieu)

There is an increasing emphasis on effects-based monitoring to document responses associated with exposure to complex mixtures of chemicals, climate change, pathogens, parasites and other environmental stressors in fish populations. For decades aquatic monitoring programs have included the collection of tissues preserved for microscopic pathology. Consequently, formalin-fixed, paraffin-embedded (FFPE) tissue can be an important reservoir of nucleic acids as technologies emerge that utilize molecular endpoints. Despite the cross-linking effects of formalin, its impact on nucleic acid quality and concentration, amplification, and sequencing are not well described. While fresh-frozen tissue is optimal for working with nucleic acids, FFPE samples have been shown to be conducive for molecular studies. Laser capture microdissection (LCM) is one technology which allows for collection of specific regions or cell populations from fresh or preserved specimens with pathological alterations, pathogens, or parasites. In this study, smallmouth bass (Micropterus dolomieu) liver was preserved in three different fixatives, including 10% neutral buffered formalin (NBF), Z-Fix® (ZF), and PAXgene® (PG) for four time periods (24 hr, 48 hr, seven days, and 14 days). Controls consisted of pieces of liver preserved in RNALater® or 95% ethanol. Smallmouth bass were chosen as they are an economically important sportfish and have been utilized as indicators of exposure to endocrine disruptors and other environmental stressors. Small liver sections were cut out with laser microdissection and DNA and RNA were purified and analyzed for nucleic acid concentration and quality. Sanger sequencing and the NanoString nCounter® technology were used to assess the suitability of these samples in downstream molecular techniques. The results revealed that of the formalin fixatives, NBF samples fixed for 24 and 48 hr were superior to ZF samples for both Sanger sequencing and the Nanostring nCounter®. The non-formalin PAXgene® samples were equally successful and they showed greater stability in nucleic acid quality and concentration over longer fixation times. This study demonstrated that small quantities of preserved tissue from smallmouth bass can be utilized in downstream molecular techniques; however, future studies will need to optimize the methods presented here for different tissue types, fish species, and pathological conditions.

PLoS ONE↗
USGS2013

An alternative to soil taxonomy for describing key soil characteristics

We are pleased to see the letter by Schimel and Chadwick (Front Ecol Environ 2013; 11[8]: 405–06), highlighting the importance of soil characterization in ecological and biogeochemical research and explaining the value of soil taxonomy, and we agree with the authors that reporting soil taxonomic classification would greatly increase the interpretive value of many studies. However, in our extensive work with land managers and scientists, we have found that taxonomic classifications are not particularly useful because they are poorly understood. For those unfamiliar with soil taxonomy, deconstructing the meaning of a classification is not a simple task. Furthermore, because the US system of soil taxonomy is not applied universally, its utility as a means for effectively describing soil characteristics to readers in other countries is limited. Finally, and most importantly, even at the finest level of soil classification there are often large within-taxa variations in critical properties that can determine ecosystem responses to drivers such as climate and land-use change.

Frontiers in Ecology and the Environment↗
USGS2016

Topobathymetric elevation model development using a new methodology: Coastal National Elevation Database

During the coming decades, coastlines will respond to widely predicted sea-level rise, storm surge, and coastalinundation flooding from disastrous events. Because physical processes in coastal environments are controlled by the geomorphology of over-the-land topography and underwater bathymetry, many applications of geospatial data in coastal environments require detailed knowledge of the near-shore topography and bathymetry. In this paper, an updated methodology used by the U.S. Geological Survey Coastal National Elevation Database (CoNED) Applications Project is presented for developing coastal topobathymetric elevation models (TBDEMs) from multiple topographic data sources with adjacent intertidal topobathymetric and offshore bathymetric sources to generate seamlessly integrated TBDEMs. This repeatable, updatable, and logically consistent methodology assimilates topographic data (land elevation) and bathymetry (water depth) into a seamless coastal elevation model. Within the overarching framework, vertical datum transformations are standardized in a workflow that interweaves spatially consistent interpolation (gridding) techniques with a land/water boundary mask delineation approach. Output gridded raster TBDEMs are stacked into a file storage system of mosaic datasets within an Esri ArcGIS geodatabase for efficient updating while maintaining current and updated spatially referenced metadata. Topobathymetric data provide a required seamless elevation product for several science application studies, such as shoreline delineation, coastal inundation mapping, sediment-transport, sea-level rise, storm surge models, and tsunami impact assessment. These detailed coastal elevation data are critical to depict regions prone to climate change impacts and are essential to planners and managers responsible for mitigating the associated risks and costs to both human communities and ecosystems. The CoNED methodology approach has been used to construct integrated TBDEM models in Mobile Bay, the northern Gulf of Mexico, San Francisco Bay, the Hurricane Sandy region, and southern California.

Journal of Coastal Research↗
USGS2008

Opening the Landsat Archive

The USGS Landsat archive holds an unequaled 36-year record of the Earth's surface that is invaluable to climate change studies, forest and resource management activities, and emergency response operations. An aggressive effort is taking place to provide all Landsat imagery [scenes currently held in the USGS Earth Resources Observation and Science (EROS) Center archive, as well as newly acquired scenes daily] free of charge to users with electronic access via the Web by the end of December 2008. The entire Landsat 7 Enhanced Thematic Mapper Plus (ETM+) archive acquired since 1999 and any newly acquired Landsat 7 ETM+ images that have less than 40 percent cloud cover are currently available for download. When this endeavor is complete all Landsat 1-5 data will also be available for download. This includes Landsat 1-5 Multispectral Scanner (MSS) scenes, as well as Landsat 4 and 5 Thematic Mapper (TM) scenes.

Fact Sheet↗
USGS2014

Natural regeneration processes in big sagebrush ( Artemisia tridentata )

Big sagebrush, Artemisia tridentata Nuttall (Asteraceae), is the dominant plant species of large portions of semiarid western North America. However, much of historical big sagebrush vegetation has been removed or modified. Thus, regeneration is recognized as an important component for land management. Limited knowledge about key regeneration processes, however, represents an obstacle to identifying successful management practices and to gaining greater insight into the consequences of increasing disturbance frequency and global change. Therefore, our objective is to synthesize knowledge about natural big sagebrush regeneration. We identified and characterized the controls of big sagebrush seed production, germination, and establishment. The largest knowledge gaps and associated research needs include quiescence and dormancy of embryos and seedlings; variation in seed production and germination percentages; wet-thermal time model of germination; responses to frost events (including freezing/thawing of soils), CO 2 concentration, and nutrients in combination with water availability; suitability of microsite vs. site conditions; competitive ability as well as seedling growth responses; and differences among subspecies and ecoregions. Potential impacts of climate change on big sagebrush regeneration could include that temperature increases may not have a large direct influence on regeneration due to the broad temperature optimum for regeneration, whereas indirect effects could include selection for populations with less stringent seed dormancy. Drier conditions will have direct negative effects on germination and seedling survival and could also lead to lighter seeds, which lowers germination success further. The short seed dispersal distance of big sagebrush may limit its tracking of suitable climate; whereas, the low competitive ability of big sagebrush seedlings may limit successful competition with species that track climate. An improved understanding of the ecology of big sagebrush regeneration should benefit resource management activities and increase the ability of land managers to anticipate global change impacts.

Rangeland Ecology and Management↗
USGS1999

A first-order analysis of the potential role of CO2 fertilization to affect the global carbon budget: A comparison of four terrestrial biosphere models

We compared the simulated responses of net primary production, heterotrophic respiration, net ecosystem production and carbon storage in natural terrestrial ecosystems to historical (1765 to 1990) and projected (1990 to 2300) changes of atmospheric CO2 concentration of four terrestrial biosphere models: the Bern model, the Frankfurt Biosphere Model (FBM), the High-Resolution Biosphere Model (HRBM) and the Terrestrial Ecosystem Model (TEM). The results of the model intercomparison suggest that CO2 fertilization of natural terrestrial vegetation has the potential to account for a large fraction of the so-called 'missing carbon sink' of 2.0 Pg C in 1990. Estimates of this potential are reduced when the models incorporate the concept that CO2 fertilization can be limited by nutrient availability. Although the model estimates differ on the potential size (126 to 461 Pg C) of the future terrestrial sink caused by CO2 fertilization, the results of the four models suggest that natural terrestrial ecosystems will have a limited capacity to act as a sink of atmospheric CO2 in the future as a result of physiological constraints and nutrient constraints on NPP. All the spatially explicit models estimate a carbon sink in both tropical and northern temperate regions, but the strength of these sinks varies over time. Differences in the simulated response of terrestrial ecosystems to CO2 fertilization among the models in this intercomparison study reflect the fact that the models have highlighted different aspects of the effect of CO2 fertilization on carbon dynamics of natural terrestrial ecosystems including feedback mechanisms. As interactions with nitrogen fertilization, climate change and forest regrowth may play an important role in simulating the response of terrestrial ecosystems to CO2 fertilization, these factors should be included in future analyses. Improvements in spatially explicit data sets, whole-ecosystems experiments and the availability of net carbon exchange measurements across the globe will also help to improve future evaluations of the role of CO2 fertilization on terrestrial carbon storage.

Tellus, Series B: Chemical and Physical Meteorolog↗
USGS2013

Final report for sea-level rise response modeling for San Francisco Bay estuary tidal marshes

The International Panel on Climate Change has identified coastal ecosystems as areas that will be disproportionally affected by climate change. Current sea-level rise projections range widely with 0.57 to 1.9 meters increase in mea sea level by 2100. The expected accelerated rate of sea-level rise through the 21 st century will put many coastal ecosystems at risk, especially those in topographically low-gradient areas. We assessed marsh accretion and plant community state changes through 2100 at 12 tidal salt marshes around San Francisco Bay estuary with a sea-level rise response model. Detailed ground elevation, vegetation, and water level data were collected at all sites between 2008 and 2011 and used as model inputs. Sediment cores (taken by Callaway and others, 2012) at four sites around San Francisco Bay estuary were used to estimate accretion rates. A modification of the Callaway and others (1996) model, the Wetland Accretion Rate Model for Ecosystem Resilience (WARMER), was utilized to run sea-level rise response models for all sites. With a mean sea level rise of 1.24 m by 2100, WARMER projected that the vast majority, 95.8 percent (1,942 hectares), of marsh area in our study will lose marsh plant communities by 2100 and to transition to a relative elevation range consistent with mudflat habitat. Three marshes were projected to maintain marsh vegetation to 2100, but they only composed 4.2 percent (85 hectares) of the total marsh area surveyed.

California↗
USGS2021

Response of forage plants to alteration of temperature and spring thaw date: Implications for geese in a warming Arctic

Changes in summer temperatures in Arctic Alaska have led to longer and warmer growing seasons over the last three decades. Corresponding with these changes in climate, the abundance and distributions of geese have increased and expanded over the same period. We used an experimental approach to assess the response of goose forage plants to simulated environmental change. We subjected Carex subspathacea , a preferred goose forage growing on the Arctic Coastal Plain (ACP) of Alaska, to manipulations of temperature and timing of spring thaw to measure potential effects in terms of plant nitrogen concentration, aboveground biomass, and total nitrogen availability. Carex subspathacea responded to warming in a dynamic fashion. Increases in temperature led to decreases in leaf nitrogen concentration but increases in aboveground biomass. The increase in biomass was stronger than the decline in nitrogen concentration such that total nitrogen availability was increased with temperature for the first 35–40 d of the season. Grazing removal accounted for only minimal offtake of biomass, and we found no indication that grazing maintained elevated levels of nitrogen concentration longer in the season as reported in other studies. Based on demonstrated relationships in the literature between forage nitrogen concentrations and gosling growth rates, we conclude that there is currently abundant high-quality forage available across the ACP. This finding fits with recent evidence of high gosling growth rates and increasing trends in goose abundance on the ACP. Our results suggest that with climate warming of a few degrees, nitrogen concentration of forage may decrease, but forage biomass and total nitrogen availability will increase. Our data suggest that nitrogen concentration will not fall below the minimum threshold required by geese in the near future. As such, we suggest that there is currently no bottom-up limitation to goose numbers on the ACP.

Alaska↗
USGS2017

Cross-scale phenological data integration to benefit resource management and monitoring

Climate change is presenting new challenges for natural resource managers charged with maintaining sustainable ecosystems and landscapes. Phenology, a branch of science dealing with seasonal natural phenomena (bird migration or plant flowering in response to weather changes, for example), bridges the gap between the biosphere and the climate system. Phenological processes operate across scales that span orders of magnitude—from leaf to globe and from days to seasons—making phenology ideally suited to multiscale, multiplatform data integration and delivery of information at spatial and temporal scales suitable to inform resource management decisions. A workshop report: Workshop held June 2016 to investigate opportunities and challenges facing multi-scale, multi-platform integration of phenological data to support natural resource management decision-making.

Conference Paper↗
USGS2018

Climate, disturbance, and vulnerability to vegetation change in the Northwest Forest Plan Area

Climate change is expected to alter the composition, structure, and function of forested ecosystems in the United States (Vose et al. 2012). Increases in atmospheric concentrations of greenhouse gases (e.g., carbon dioxide [CO2]) and temperature, as well as altered precipitation and disturbance regimes (e.g., fire, insects, pathogens, and windstorms), are expected to have profound effects on biodiversity, socioeconomics, and the delivery of ecosystem services within the Northwest Forest Plan (NWFP, or Plan) area over the next century (Dale et al. 2001, Franklin et al. 1991). The ecological interactions and diversity of biophysical settings in the region are complex. The effects of climate change on ecological processes will occur through a variety of mechanisms at a range of spatial scales and levels of biological organization, ranging from the physiological responses of individual plants to the composition and structure of stands and landscapes (Peterson et al. 2014a). Understanding and incorporating how climate change projections and the potential ecological effects and uncertainties differ within the region (e.g., Deser et al. 2012) is essential for developing adaptation and mitigation strategies.

California, Oregon, Washington↗
USGS2014

Temperature effects induced by climate change on the growth and consumption by salmonines in Lakes Michigan and Huron

We used bioenergetics models to investigate temperature effects induced by climate change on the growth and consumption by Chinook salmon Oncorhynchus tshawytscha , lake trout Salvelinus namaycush , and steelhead O. mykiss in Lakes Michigan and Huron. We updated biological inputs to account for recent changes in the food webs and used temperature inputs in response to regional climate observed in the baseline period (1964–1993) and projected in the future period (2043–2070). Bioenergetics simulations were run across multiple age-classes and across all four seasons in different scenarios of prey availability. Due to the increased capacity of prey consumption, future growth and consumption by these salmonines were projected to increase substantially when prey availability was not limited. When prey consumption remained constant, future growth of these salmonines was projected to decrease in most cases but increase in some cases where the increase in metabolic cost can be compensated by the decrease in waste (egestion and excretion) loss. Consumption by these salmonines was projected to increase the most during spring and fall when prey energy densities are relatively high. Such seasonality benefits their future growth through increasing annual gross energy intake. Our results indicated that lake trout and steelhead would be better adapted to the warming climate than Chinook salmon. To maintain baseline growth into the future, an increase of 10 % in baseline prey consumption was required for Chinook salmon but considerably smaller increases, or no increases, in prey consumption were needed by lake trout and steelhead.

Lake Huron, Lake Michigan↗
USGS2026

Temperature and precipitation source variability and glacial dynamics in the southwestern United States at Fish Lake, Utah, since late MIS 4

An improved understanding of hydroclimate response to natural climate forcings is needed to evaluate impacts of changing seasonal circulation patterns on current and future drought in the southwestern United States (‘the Southwest’). However, few terrestrial records from the Southwest preserve changes in moisture availability continuously prior to the Last Glacial Maximum (LGM, ∼24.5 ka). Fish Lake, in the Upper Colorado River Basin, preserves a long (∼67 ka), continuous, high-resolution (∼3.3 cm/century) sedimentary record spanning from late Marine Isotope Stage (MIS) 4 to present. Here, we investigate the relative contributions of seasonal precipitation and moisture source using the hydrogen isotope value of the n -C 29 leaf wax alkane and changes in temperature using branched glycerol dialkyl glycerol tetraethers (brGDGTs). During the warm post glacial period (14 ka to present), a greater contribution of annual precipitation is sourced from the North American Monsoon (NAM) in response to declining winter insolation and rising greenhouse gases, weakening westerly storms and shifting them northward. MIS 3 (∼61 to 29 ka) is also influenced by NAM inputs, however, to a smaller magnitude than during the post glacial period when temperatures were warmer. However, stadial periods (MIS 2, 29 to 14.1 ka) show 2 H-enriched values, suggesting warm conditions and large contributions of NAM precipitation during the LGM, contradicting other proxies and regional records. The LGM is the only period in the record where glaciers are present in the catchment, thus we hypothesize glacial erosion reworked pre-LGM aged soil organic matter and biased the record during this time.

Utah↗
USGS2008

Tree die-off in response to global change-type drought: Mortality insights from a decade of plant water potential measurements

Global climate change is projected to produce warmer, longer, and more frequent droughts, referred to here as “global change-type droughts”, which have the potential to trigger widespread tree die-off. However, drought-induced tree mortality cannot be predicted with confidence, because long-term field observations of plant water stress prior to, and culminating in, mortality are rare, precluding the development and testing of mechanisms. Here, we document plant water stress in two widely distributed, co-occurring species, piñon pine ( Pinus edulis ) and juniper ( Juniperus monosperma ), over more than a decade, leading up to regional-scale die-off of piñon pine trees in response to global change-related drought. Piñon leaf water potentials remained substantially below their zero carbon assimilation point for at least 10 months prior to dying, in contrast to those of juniper, which rarely dropped below their zero-assimilation point. These data suggest that piñon mortality was driven by protracted water stress, leading to carbon starvation and associated increases in susceptibility to other disturbances (eg bark beetles), a finding that should help to improve predictions of mortality during drought.

Frontiers in Ecology and the Environment↗
USGS2022

On the role of climate in monthly baseflow changes across the continental United States

Baseflow is the portion of streamflow that comes from groundwater and subsurface sources. Although baseflow is essential for sustaining streams during low flow and drought periods, we have little information about how and why it has changed over large regions of the continental United States. The objective of this study was to evaluate how changes in the climate system have affected observed monthly baseflow records at 3,283 USGS gauges over the last 30 years (1989–2019). We developed a statistical modeling framework to determine the relationship between monthly baseflow and monthly climate predictors (i.e., precipitation, temperature, and antecedent wetness). Overall, we found that baseflow trends and the factors influencing them vary by region and month. In the US Northeast, increases were detected earlier in the year (February and March) and in the summer (May and June), and were likely due to increasing precipitation, warmer temperature, and subsequent changes in snowmelt. Increasing baseflow in the US Pacific Northwest and Midwest were associated with increases in precipitation and antecedent wetness throughout the year. Decreasing trends were located in the US Southeast and Southwest. Baseflow trends in the US Southeast were only detected in March, possibly as a result of decreased precipitation during the spring. On the other hand, decreases in baseflow in the Central Southwestern United States occurred throughout the year. These trends were associated with a lack of precipitation and increases in temperature. Finally, we examined the relationship between monthly baseflow trends and changes in total water storage using monthly Gravity Recovery and Climate Experiment mascon products from the Jet Propulsion Laboratory. In this study, trends in total water storage were strongly associated with baseflow trends across the United States. The spatial and temporal variability in baseflow response to climate reported here can aid water managers in adapting to future climate change.

continental United States↗
USGS1998

Assessing simulated ecosystem processes for climate variability research at Glacier National Park, USA

Glacier National Park served as a test site for ecosystem analyses that involved a suite of integrated models embedded within a geographic information system. The goal of the exercise was to provide managers with maps that could illustrate probable shifts in vegetation, net primary production (NPP), and hydrologic responses associated with two selected climatic scenarios. The climatic scenarios were (a) a recent 12-yr record of weather data, and (b) a reconstituted set that sequentially introduced in repeated 3-yr intervals wetter–cooler, drier–warmer, and typical conditions. To extrapolate the implications of changes in ecosystem processes and resulting growth and distribution of vegetation and snowpack, the model incorporated geographic data. With underlying digital elevation maps, soil depth and texture, extrapolated climate, and current information on vegetation types and satellite-derived estimates of leaf area indices, simulations were extended to envision how the park might look after 120 yr. The predictions of change included underlying processes affecting the availability of water and nitrogen. Considerable field data were acquired to compare with model predictions under current climatic conditions. In general, the integrated landscape models of ecosystem processes had good agreement with measured NPP, snowpack, and streamflow, but the exercise revealed the difficulty and necessity of averaging point measurements across landscapes to achieve comparable results with modeled values. Under the extremely variable climate scenario significant changes in vegetation composition and growth as well as hydrologic responses were predicted across the park. In particular, a general rise in both the upper and lower limits of treeline was predicted. These shifts would probably occur along with a variety of disturbances (fire, insect, and disease outbreaks) as predictions of physiological stress (water, nutrients, light) altered competitive relations and hydrologic responses. The use of integrated landscape models applied in this exercise should provide managers with insights into the underlying processes important in maintaining community structure, and at the same time, locate where changes on the landscape are most likely to occur.

Montana↗