Restoration of shortleaf pine (Pinus echinata)-hardwood ecosystems severely impacted by the southern pine beetle (Dendroctonus frontalis)

by | May 24, 2022 | 2011-2020 Publications, Southern Pine Beetle

Abstract

In the Southern Appalachian Mountains of eastern USA, pine-hardwood ecosystems have been severely impacted by the interactions of past land use, fire exclusion, drought, and southern pine beetle (SPB, Dendroctonus frontalis). We examined the effects of restoration treatments: burn only (BURN); cut + burn on dry sites (DC + B); cut + burn on sub-mesic sites (MC + B); and reference sites (REF; no cutting or burning) on shortleaf pine-hardwood forests. We also evaluated the effectiveness of seeding native bluestem grasses. Structural (down wood, live and dead standing trees, shrubs, herbaceous layer) and functional (forest floor mass, C, and N; soil C, N, P, and cations; and soil solution N and P) attributes were measured before and the first and second growing seasons after treatment. We used path analysis to test our conceptual model that restoration treatments will have direct and indirect effects on these ecosystems. Total aboveground mass loss ranged from 24.33 Mg ha-1 on the BURN to 74.44 Mg ha-1 on the DC + B treatment; whereas, REF gained 13.68 Mg ha-1 between pre-burn and post-burn. Only DC + B sites had increased soil NO3–N, NH4–N Ca, Mg, and PO4–P and soil solution NO3–N, NH4–N, O–PO4 for several months.
We found a significant increase in the density of oak species (Quercus alba, Q. coccinea, Q. montana, Q. rubra, and Q. velutina) on all burn treatments. However, oaks accounted for a smaller proportion of the total stem density than red maple, other tree species, and shrubs. The high densities of woody species other than oaks, coupled with the fast growth rates of some of these species, suggests that oaks will continue to be at a competitive disadvantage in these pine-hardwood communities through time, without further intervention. Pine regeneration was not improved on any of our burned sites with little to no recruitment of pines into the understory after two years and the pine saplings that were present before the burns were killed by fire on all sites. We found an increase in herbaceous layer cover and richness on all fire treatments. DC + B had higher bluestem grass cover than the other treatments, and it was the only treatment with increased bluestem grass cover between the first (2.96%, SE = 0.29) and second (6.88%, SE = 0.70) growing seasons. Our path model showed that fire severity explained a large proportion of the variation in overstory response; and fire severity and overstory response partially explained soil NO3–N. These variables, directly and indirectly, explained 64% of the variation in soil solution NO3–N at 30 cm soil depth (within the rooting zone for most plants). We found a good-fit path model for herbaceous layer response in the second growing season, where fire severity had direct effects on overstory and herbaceous layer responses and indirect effects on herbaceous layer response mediated through overstory response. Our path model explained 46% and 42% of the variation in herbaceous layer cover and species richness, respectively.

Keywords

Prescribed burning, Fuel reduction, Structural equation modeling, Path analysis, Fire severity

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Elliott, Katherine J., James M. Vose, Jennifer D. Knoepp, and Barton D. Clinton. 2012. “Restoration of Shortleaf Pine (Pinus Echinata)-Hardwood Ecosystems Severely Impacted by the Southern Pine Beetle (Dendroctonus Frontalis).” Forest Ecology and Management 274 (June): 181–200. https://doi.org/10.1016/j.foreco.2012.02.034.

Southern pine beetle regional outbreaks modeled on landscape, climate and infestation history

by | May 24, 2022 | 2011-2020 Publications, Southern Pine Beetle

Abstract

The southern pine beetle (Dendroctonus frontalis, SPB) is the major insect pest of pine species in the southeastern United States. It attains outbreak population levels sufficient to mass attack host pines across the landscape at scales ranging from a single forest stand to interstate epidemics. This county level analysis selected and examined the best climatic and landscape variables for predicting infestations at regional scales. The analysis showed that, for a given county, the most important factor in predicting outbreaks was that the county was classified as in outbreak status in the previous year. Other important factors included minimum winter temperature and the greatest difference between the average of daily minimums and a subsequent low temperature point, precipitation history either seasonally in the previous year or difference from average over the previous 2 years, the synchronizing effect of seasonal temperatures on beetle populations and the relative percentage of total forest area composed of host species. The statistical models showed that climatic variables are stronger indicators of outbreak likelihood than landscape structure and cover variables. Average climatic conditions were more likely to lead to outbreaks than extreme conditions, supporting the notion of coupling between a native insect and its native host. Still, some extreme events (i.e., periods of very low temperature or very high precipitation) did precede beetle infestation. This analysis suggested that there are predisposing and inciting factors at the large scale but the driving factors leading to individual infestations operate at smaller scales.

Keywords

Classification and Regression Tree, Insect infestation, Logistic regression, Dendroctonus frontalis, Pinus taeda

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Duehl, Adrian J., Frank H. Koch, and Fred P. Hain. 2011. “Southern Pine Beetle Regional Outbreaks Modeled on Landscape, Climate and Infestation History.” Forest Ecology and Management 261 (3): 473–79. https://doi.org/10.1016/j.foreco.2010.10.032.

Predicting County-Level Southern Pine Beetle Outbreaks From Neighborhood Patterns

by | May 10, 2022 | 2011-2020 Publications, Southern Pine Beetle

Abstract

The southern pine beetle (Dendroctonus frontalis Zimmermann, Coleoptera: Curculionidae) is the most destructive insect in southern forests. States have kept county-level records on the locations of beetle outbreaks for the past 50 yr. This study determined how accurately patterns of county-level infestations in preceding years could predict infestation occurrence in the current year and if there were emergent patterns that correlated strongly with beetle outbreaks. A variety of methods were tested as infestation predictors, including quantification of either the exact locations of infested grid cells during one or two preceding years, or the neighborhood infestation intensity (number of infested cells in a neighborhood) in these years. The methods had similar predictive abilities, but the simpler methods performed somewhat better than the more complex ones. The factors most correlated with infestations in future years were infestation in the current year and the number of surrounding counties that were infested. Infestation history helped to predict the probability of future infestations in a region, but county-level patterns alone left much of the year-to-year variability unexplained.

Keywords

southern pine beetle, cellular automata, county pattern, forest damage

To read the full article please visit the link below:

Duehl, Adrian J., Frank H. Koch, and Fred P. Hain. 2011. “Southern Pine Beetle Regional Outbreaks Modeled on Landscape, Climate and Infestation History.” Forest Ecology and Management 261 (3): 473–79. https://doi.org/10.1016/j.foreco.2010.10.032.

Expansion of Southern Pine Beetle into Northeastern Forests: Management and Impact of a Primary Bark Beetle in a New Region

by | May 5, 2022 | 2011-2020 Publications, Southern Pine Beetle

Abstract

After more than a decade of damage in pitch pine forests of New Jersey, an unprecedented range expansion of southern pine beetle (SPB), Dendroctonus frontalis, has recently occurred with populations established or detected in parts of the northeastern United States. Widespread tree mortality in pitch pine stands has occurred on Long Island, New York, an area previously free of SPB. Tree mortality has also been documented in several small pine stands in Connecticut. Trapping surveys have detected SPB farther north than it had previously been known to exist, with positive trap catches in Connecticut, Massachusetts, and Rhode Island. Integrated pest management plans that consist of preventative silvicultural treatments, landscape prioritization, detection and monitoring, and direct control provide the best opportunity to reduce the effects of SPB in northeastern US pine ecosystems. Most hard pine species present in the region are at risk to SPB, but less is known about white pine susceptibility. Unmanaged pine barrens are a particular concern, as they provide stand conditions conducive to SPB outbreaks. Infestation suppression implementing cut-and-leave tactics has been used in some areas of Long Island and will continue to be the primary management tool to limit damage from SPB.

Keywords

Dendroctonus, climate, pine barrens, integrated pest management, tree mortality

To read the full article please visit the link below:

Dodds, Kevin J., Carissa F. Aoki, Adriana Arango-Velez, Jessica Cancelliere, Anthony W. D’Amato, Marc F. DiGirolomo, and Robert J. Rabaglia. 2018. “Expansion of Southern Pine Beetle into Northeastern Forests: Management and Impact of a Primary Bark Beetle in a New Region.” Journal of Forestry116 (2): 178–91. https://doi.org/10.1093/jofore/fvx009.