Treesearch

Projected changes in climate (temperature and precipitation means and extreme events), increased atmospheric carbon dioxide (CO2), and increased nitrogen deposition are likely to affect U.S. forests throughout this century. Effects will be both direct (e.g., effects of elevated CO2 on forest growth and water use) and indirect (e.g., altered disturbance regimes), and will differ temporally and spatially across the United States. Some of these effects may already be occurring. For example, large insect outbreaks and large wildfires during the past decade (Bentz et al. 2009, Turetsky et al....

Forest ecosystems in the United States in the year 2100 will differ from those of today as a result of a changing climate. Those differences will be superimposed on the human imprint of forest management and the legacies of other land use activities, stressors, and disturbances of the 19th and 20th centuries. Future changes in forest ecosystems will occur across both public and private lands and will challenge our ability to manage forests sustainably, especially as the human population continues to grow, demands for ecosystem services increase, and fossil fuel supplies decrease. We...

Quaking aspen (Populus tremuloides) is declining across the western United States. Aspen habitats are diverse plant communities in this region and loss of these habitats can cause shifts in biodiversity, productivity, and hydrology across spatial scales. Western aspen occurs on the majority of sites seral to conifer species, and long-term maintenance of these aspen woodlands requires periodic fire. We use field data, remotely sensed data, and fire atlas information to develop a spatially explicit landscape simulation model to assess the effects of current and historic wildfire regimes and...

The Integrated Landscape Assessment Project (ILAP) is a three-year effort that produces information, models, data, and tools to help land managers, policymakers, and others examine mid- to broad-scale (e.g., watersheds to states and larger areas) prioritization of land management actions, perform landscape assessments, and estimate potential effects of management actions for planning and other purposes. ILAP provides wall-to-wall, cross-ownership geospatial data and maps on existing, potential and future vegetation conditions, land ownership and management allocation classes, and other...

Many threats are jeopardizing the sagebrush steppe of the Columbia Basin, including the spread of invasive species such as cheatgrass (Bromus tectorum L.) and the expansion of western juniper (Juniperus occidentalis Hook.) into historic shrub steppe. Native sagebrush steppe provides productive grazing lands and important habitat for many wildlife species, and managers are in need of landscapescale tools to assess shrub steppe conversion risk and management options to maintain native shrub steppe. We used a state-and-transition modeling approach to project changes in sagebrush steppe...

This research explored the ecological consequences of rural residential development and different management regimes on a tract of former industrial timberland in central Oregon known as the Bull Springs. Forage quality and habitat suitability models for mule deer (Odocoileus hemionus) winter range were joined to the outputs of a spatially explicit vegetation dynamics model under two management scenarios. In one scenario, the tract was managed as a working forest excluding development, and in the other, development was allowed to occur at historical rates. Landscape pattern analysis was...

Wildlife conservation often is a central focus in planning for natural resource management. Evaluation of wildlife habitat involves balancing the desire for information about detailed habitat characteristics and the feasibility of completing analyses across large areas. Our objective is to describe tradeoffs made in assessments of wildlife habitat within a multiple-objective vegetation-based state-and-transition model (STM) framework. Species-habitat relationships derived from STM vegetation characteristics require careful interpretation for several reasons. First, the observational unit...

The Integrated Landscape Assessment Project (ILAP) uses spatial vegetation data and state and transition models (STM) to forecast future vegetation conditions and the interacting effects of natural disturbances and management activities. Results from ILAP will help land managers, planners, and policymakers evaluate management strategies that reduce fire risk, improve wildlife habitat, and benefit rural communities. This case study illustrates the methodology for modeling timber volume, biomass estimates, and the forest carbon over time with the output of STM simulations. It presents how...

Land managers commonly use FVS and VDDT as planning aids. Although complementary, the models differ in their approach to projection, spatial and temporal resolution, simulation units and required input. When both are used, comparison of the model projections helps to identify differences in the assumptions of the two models and hopefully will result in more consistent results across models. We used the transition probability matrix as the basis for comparing the two models, using side-by-side simulations with FVS and VDDT to project 250 mixed conifer stands. We designed and carried out a...

The Forest Vegetation Simulator (FVS) has been used to provide rates of natural growth transitions under endemic conditions for use in State and Transition Models (STMs). This process has previously been presented. This paper expands on that work by citing the methods used to capture resultant vegetation states following disturbance activities; be it of natural causes or human induced. Forest Inventory and Analysis (FIA) plots were stratified by representative Potential Natural Vegetation Types (PNVTs) of the southwestern United States. Structural states within the Vegetation Dynamics...