Background
Southern pine beetles are arguably the greatest source of natural disturbance in forest ecosystems of the southeastern United States.
Compared to hurricanes, another agent of large scale disturbance in the region, the spatial scale of individual beetle infestations tends
to be less, but the frequency and average return time is much higher, so the total forest area that is impacted or recovering from
southern pine beetle infestations at any given time in the last century has probably been at least as high as hurricanes, fires, or any
other natural disturbance. Geographic analyses of the frequency and intensity of southern pine beetle outbreaks shows that the
economic impacts of the southern pine beetle varies dramatically across regions within the southeastern United States. Spatial
analyses of southern pine beetle outbreaks at a somewhat finer scale suggests that the probability of outbreaks also varies strongly
among sites within regions (e.g., among forest management units within National Forest districts).
General Objectives
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Develop a foundation for short-term predictions of population tendencies in the southern pine beetle to guide strategies of pest
control and forest management.
- Develop long-term projections of population tendencies in the southern pine beetle under different scenarios of climate and land-use.
Specific Objectives
- Predict regional constraints on southern pine beetle outbreaks based upon climate-based patterns in the potential population growth
rate and overwintering survival of southern pine beetles.
- Evaluate spatial variation in the resin flow of loblolly pine to (1) test whether spatial variation in tree defenses is sufficiently large
to influence the reproductive success and population dynamics of bark beetles; (2) test whether spatial patterns can be predicted
from previous studies of temporal variation in water availability, nutrient availability, and thinning history; and (3) test for easily
measured tree attributes that allow prediction of suitability for bark beetles.
- Develop statistical models that test for effects of spatial variation in (1) the probability of winter mortality in southern pine beetles,
(2) the number of southern pine beetle generations per year, and (3) the physiology of loblolly pine on average infestation levels of
southern pine beetles.
- Develop statistical models that test for effects of spatial variation in (1) the probability of winter mortality in southern pine beetles,
(2) the number of southern pine beetle generations per year, and (3) the physiology of loblolly pine on the annual probability of
transition in bark beetle infestation status (i.e., from infested to uninfested or uninfested to infested).
- Use time-series data to test for differences in the population dynamics of SPB in different regions (e.g., GA, NC, and TX). Test for
differences in (1) strength of endogenous dynamics, (2) period and amplitude of endogenous cycles if they are indicated, and (3)
strength and form of exogenous effects.
- Develop a regional model predicting the timing and duration of earlywood growth in loblolly pine as a function of regional
differences in the initiation of tree growth, precipitation, and evapotranspiration.
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