GIS Forest Inventory and Evaluation in the Wake of Climate Change

Because climate and vegetation are so strongly associated, it is assumed that the forecast rapid changes in climate will affect plant distributions and alter the makeup of forest communities. For example, climate change could cause regional wind patterns to shift, which would be accompanied by an increase in wind speed intensity. Such shifts could impact existing rain shadow effects in some regions causing more precipitation on the windward side of mountain ranges while creating even drier conditions on the leeward sides. Fire patterns are likely to be altered as well, which could affect a variety of plant species, even those that are fire resistant or require the presence of fire to regenerate. History has shown that most species respond individually to climatic change and not as communities. Those individuals that have the ability to migrate likely will do so, resulting in a number of new associations. In addition to differences in migration rates, community types will be altered and new associations will be created due to changes in disturbance regimes and competition.

Unique species such as the bristlecone pine (Pinus longaeva) and the giant sequoia (Sequoiadendron giganteum), have maintained their present locations for thousands of years despite substantial climatic change, indicating that some species have a high degree of physiological tolerance to climatic fluctuations. In some cases, stress-tolerant species could benefit from extreme climates if competitors are locally depleted or eliminated. However, for many species of vegetation, climatic changes resulting in a temperature difference of a few degrees or a slight variation in rainfall pattern may determine whether a particular species survives or becomes extinct.

To inventory, evaluate, and mitigate the damage to forest communities as a result of climate change, researchers require the use of spatial analysis tools such as Geographic Information Systems (GIS). The first modern GIS, the Canadian Geographic Information System, was developed in the early 1960s to inventory Canada's natural resources by classifying land according to its capability for forestry, agriculture, recreation, and wildlife. The Canadians understood that in order for GIS to be an effective environmental tool, accurate and relevant data must be incorporated into the system. Foremost among these are the spatial data required to generate an accurate forecast. Longitudinal data are necessary to establish past and future long-term patterns and trends. Yet, appropriately extensive climate records might not be available for a given location, which is one of the problems associated with trying to resolve the effect of global warming on forests.

This research examines several case studies of GIS applications related to forests and climate change. For example, a GIS was developed to assess the response of alpine plant species distribution to various climatic and land-use scenarios and found that alpine plant species with restricted habitat availability above the tree line will experience severe fragmentation and habitat loss. A GIS analysis of vegetation structure with forest functions and value in Chicago, Illinois, revealed that local urban forests remove 5575 metric tons of air pollutants and sequester approximately 315,800 metric tons of carbon annually. In Chattanooga, Tennessee, a practical GIS was created to map tree locations, and track the type and size of every tree along city streets and in downtown parks in order to maintain a database of tree size and health conditions. To examine detailed spatial environmental data, satellite imagery was integrated with a GIS for a region in northern Wisconsin, which allows an assessment of changes in the forest landscape over time. And in a unique approach to GIS-based modeling discussed in the paper, researchers found that the future threat to the forests of Europe due to climate change is predicted to increase in Scandinavia and Eastern Europe.

Although GIS is a proven instrument for assessing environmental impacts on forests and woodlands, numerous challenges remain. For instance, when developing GIS models urban forests tend to be treated as isolated elements, which can lead to miscalculations in predicting landscape changes. And while there has been substantial improvement in simulating disturbances within landscapes, it is presently difficult to model global vegetation change at the landscape scale. Despite these and other shortcomings, the results of this research suggest that a well-designed GIS can serve as a frontline defense against environmental impacts associated with climate change.