Root disease and other unforeseen variables that confound restoration efforts
Unanticipated disease problems thwarting restoration efforts can emerge in forest ecosystems. An example is the longleaf pine (Pinus palustris Mill.) ecosystem. This species once occupied nearly 30 million ha but now its range is reduced to approximately 1.5 million ha. Restoring longleaf pine to many sites in its former range is an important goal involving several natural resource organizations. Longleaf pine has evolved with frequent fires and is dependent upon fire for successful regeneration and for maintenance of stand health. However, increased mortality associated with prescribed fire has been observed in certain 30-40 year-old longleaf pine stands. Preliminary studies show several species of root infecting fungi (Leptographium species, Heterobasidion annosum) and certain root colonizing insects are associated with mortality, although longleaf pine is considered highly tolerant to these pathogens. We hypothesize many sites no longer possess specific edaphic and environmental conditions under which the species evolved because of altered fire regimes, changes in soil conditions, or other factors that render trees susceptible to root pathogens.