Problem 3.  Impacts of Biotic Invasion, Other Stresses, and Their Interactions

Although individual impacts of some stresses on forests are well known, many important stresses have received less attention. Furthermore, combinations of multiple stresses interact in complex ways, often defying efforts to experimentally measure cumulative effects. Further understanding can be gained by investigating important new stresses on forest ecosystems and by developing and demonstrating models that integrate effects of multiple stresses. 

Problem 3a.  Invasive species are progressively—and sometimes radically—altering the species composition and dynamics of forests; knowledge of species invasiveness and habitat invasibility as well as development of user-friendly predictive tools for early warning/prevention/spread and effective control methods are critically lacking. 

Problem 3b.  Losses of forest cover through land-use conversion and changes in forest ownership have far-reaching influences on the susceptibility of forests to other threats and on management capacity to respond. 

Problem 3c.  Wildland fire is both a social and ecological issue that currently demands inordinate management attention, yet conflicts continue to escalate. 

Problem 3d. Airborne pollutants such as nitrates, sulfates, and ozone interact with each other and other stressors, in ways that are poorly understood, to exacerbate effects on forests and forest resources.