Abiotic Stressors

The capacity of southern forests to provide extensive and diverse resource values is seriously compromised by unhealthy forest conditions. Poor health jeopardizes the underlying ecosystems that support timber, wildlife, fisheries, water, and scenic resources. A variety of insects, diseases, and other stressors have had pervasive impacts on the structure and composition of the forests and threaten forest health in this region. The forest health section of the encyclopedia highlights many of the important factors which influence the health of our forests.

There are several types of biotic forest stressors highlighted in the South-wide encyclopedia including insects, diseases, and exotic and invasive plant species. There also exists a host of abiotic, or nonliving, stressors which can cause harmful effects to living organisms.

Environmental factors such as temperature, precipitation, atmospheric carbon dioxide (CO₂) and ozone (O₃) concentrations, and acid deposition affect forest processes such as carbon, water, and nutrient fluxes. These processes are the foundation of forest ecosystems, and abnormally large variability in their size, timing, or location may influence forest sustainability. From an ecosystem perspective, therefore, changes in forest processes may be indicators of long-term forest function and health. (SOFRA-Moore)

Forest carbon sequestration, the ability of forests to store and release carbon, is currently an important issue debated in the policy arena. Carbon stored in forests affects the amount of carbon contributing to the increasing atmospheric CO₂ concentration. Reductions in carbon emissions have been proposed as a mitigation strategy for rising atmospheric CO₂, which may be causing global warming. Rising atmospheric CO₂ levels could also be mitigated by increasing carbon sequestration through forestry and other land management activities. Terrestrial ecosystems have enormous potential to capture CO₂ and store carbon. (SOFRA-Moore)

Climate change also could generate forest stress, and extreme weather events cause disturbances that shape forest systems by influencing their composition, structure, and functional processes. (SOFRA-Moore)

In this section, climate change is recognized as an important abiotic concern, acknowledging some of the extreme weather witnessed in recent history as a threat. The role of carbon sequestration is also addressed. Air quality is a concern for southern forests, including primary and secondary pollutants, visibility issues, and acid deposition. The effects of forest fires on resource quality reduction are also focused on in terms their threat to air, water, and soil quality, as well as possible effects on plants, animals, and people.