Forest Health and Disturbance
Dating red
oak borer holes from callus tissue on oaks is one example of using tree-rings to assess a forest health and
disturbance issue. By determining the number of borer injuries
over a long time period we can assess the historic abundance of the
insect in a particular region. Oak
mortality in Arkansas and parts of Missouri is becoming widespread, and red oak
borer activity is reportedly the highest recorded to date. The red
oak borer epidemic is likely the result of the intense drought that has
gripped that part of the country. Information about the scale,
frequency, and legacy of disturbance regimes and their relation to the
distribution of forest species is sparse. Knowledge of these relationships is valuable for understanding
present-day forest ecosystem species composition and structure and for
predicting how forests will respond to management. We generate correlation matrixes of
diverse variables to evaluate the hypothesis that plant and animal species
abundances at are closely linked to historic disturbance regimes documented
by dated fire scars and tree-ring growth patterns. Landscape level distribution of plants
and animals are affected by the long-term interactions between fire, human
population density, and topographic roughness. Abrupt ring-width reductions in shortleaf
pine, fire frequency, and historical data are used to determine the
frequency of disturbance events. Disturbance variables are correlated with topographic roughness,
forest bird territory density, lizard and skink captures, blueberry fruit
abundance, Armillaria abundance, and three indices of forest
succession derived from over-story tree species, oak over-story species,
and tree species ground flora. Disturbance history, species distributions, and tree species
diversity support the argument that long-term disturbance regimes and successional sequences are major factors affecting species and
structure in Ozarks forests.
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