Figure 5
From: Oak, Fire, and Global Change in the Eastern USA: What Might the Future Hold?
Ecosystem condition with (A) passive management and (B) active management (e.g., thinning, prescribed fire, or a combination of the two; see Agee 2002). Relationships between drought and forest condition are complex and driven by differences in site conditions, current stand structure and composition, and historical and current disturbance regimes. For example, within the continuum of site conditions that support oak forests, we hypothesize that ecosystem condition (based on metrics such growth rate, mortality) on mesic upland sites will be more resilient to low and moderate levels of precipitation deficit relative to xeric upland sites; however, at high precipitation deficits, ecosystem condition on mesic uplands will degrade in a “threshold response” due to high rates of tree mortality. Xeric upland oak sites will be inherently more resistant and resilient to drought at all levels due to a greater proportion of dry site oaks (e.g., white oak [Q. alba], scarlet oak [Q. coccinea]). Active management could be used to maintain a higher level of ecosystem condition and reduce the magnitude of response to drought.