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Athens, GA, United States

Harrington T.C.,Iowa State University | Fraedrich S.W.,Southern Research Station
Phytopathology | Year: 2010

The laurel wilt pathogen, Raffaelea lauricola, is a fungal symbiont of the redbay ambrosia beetle, Xyleborus glabratus, which is native to Asia and was believed to have brought R. lauricola with it to the southeastern United States. Individual X. glabratus beetles from six populations in South Carolina and Georgia were individually macerated in glass tissue grinders and serially diluted to quantify the CFU of fungal symbionts. Six species of Raffaelea were isolated, with up to four species from an individual adult beetle. The Raffaelea spp. were apparently within the protected, paired, mandibular mycangia because they were as numerous in heads as in whole beetles, and surface-sterilized heads or whole bodies yielded as many or more CFU as did nonsterilized heads or whole beetles. R. lauricola was isolated from 40 of the 41 beetles sampled, and it was isolated in the highest numbers, up to 30,000 CFU/beetle. Depending on the population sampled, R. subalba or R. ellipticospora was the next most frequently isolated species. R. arxii, R. fusca, and R. subfusca were only occasionally isolated. The laurel wilt pathogen apparently grows in a yeast phase within the mycangia in competition with other Raffaelea spp. Source

Wickham J.D.,National Exposure Research Laboratory NERL | Wade T.G.,National Exposure Research Laboratory NERL | Riitters K.H.,Southern Research Station
Global Ecology and Biogeography | Year: 2013

Because of the low albedo of forests and other biophysical factors, most scenario-based climate modelling studies indicate that removal of temperate forest will promote cooling, indicating that temperate forests are a source of heat relative to other classes of land cover. Our objective was to test the hypothesis that US temperate forests reduce surface temperatures. Location: The continental United States. Methods: Ordinary least squares regression was used to develop relationships between forest extent and surface temperature. Forest extent was derived from the 900m2 2001 National Land Cover Database (NLCD 2001) and surface temperature data were from the MODIS 1 km2 8-day composite (MYD11A2). Forest-surface temperature relationships were developed for winter, spring, summer, autumn and annually using 5 years of MODIS land surface temperature data (2007-11) across six spatial scales (1, 4, 9, 16, 25 and 36 km2). Regression models controlled for the effects of elevation, aspect and latitude (by constraining the regressions within a 1° range). Results: We did not find any significant positive slopes in regressions of average annual surface temperatures versus the proportion of forest, indicating that forests are not a source of heat relative to other types of land cover. We found that surface temperatures declined as the proportion of forest increased for spring, summer, autumn and annually. The forest-surface temperature relationship was also scale dependent in that spatially extensive forests produced cooler surface temperatures than forests that were dominant only locally. Main conclusions: Our results are not consistent with most scenario-based climate modelling studies. Because of their warming potential, the value of temperate afforestation as a potential climate change mitigation strategy is unclear. Our results indicate that temperate afforestation is a climate change mitigation strategy that should be implemented to promote spatially extensive forests. Copyright © 2013 Blackwell Publishing. Source

Sutton W.B.,Alabama A&M University | Wang Y.,Alabama A&M University | Schweitzer C.J.,Southern Research Station
Forest Ecology and Management | Year: 2013

We evaluated the response of amphibians and reptiles to two levels of prescribed burning and three levels of thinning using a field experiment consisting of a before-after, control-impact, and factorial complete block design over a 4 year period in the William B. Bankhead National Forest located in northwestern Alabama. We captured 2643 individuals representing 47 species (20 amphibians and 27 reptiles) during 3132 trap nights. Pre-treatment captures varied widely for both amphibians and reptiles among the stands designated for management, which was likely due to forest structural changes caused by tree mortality resulting from Southern Pine Beetle (Dendroctonus frontalis) infestations. Within each amphibian and reptile species assemblage, we observed species-specific associations with specific treatments and environmental characteristics. In regards to individual species responses, Eastern Fence Lizards (Sceloporus undulatus) increased in thin-with-burn treatments and Green Anoles (Anolis carolinensis) tended to increase in all thinned stands. North American Racers (Coluber constrictor) increased in thin-only plots primarily during the second post-treatment year. Mississippi Slimy Salamander (Plethodon mississippi) captures tended to decrease in all treatment stands throughout the study period, which may been due to either drier environmental conditions during post-treatment sampling or natural population cycling. Pool-breeding amphibian captures were more likely related to the hydroperiod of aquatic breeding environments within 290. m of survey locations rather than forest treatments. Our results illustrate that forest restoration through tree thinning can positively influence certain reptile species with limited impacts on amphibians in upland, pine-dominated forests of northern Alabama. However, as our forest stands are scheduled to be burned every 3-5. years, continued monitoring is necessary to understand the impacts of repeated disturbances. © 2013 Elsevier B.V. Source

Davis J.C.,Florida Fish And Wildlife Conservation Commission | Castleberry S.B.,University of Georgia | Kilgo J.C.,Southern Research Station
Journal of Mammalogy | Year: 2010

Shrew abundance has been linked to the presence of coarse woody debris (CWD), especially downed logs, in many regions in the United States. We investigated the importance of CWD to shrew communities in managed upland pine stands in the southeastern United States Coastal Plain. Using a randomized complete block design, 1 of the following treatments was assigned to twelve 9.3-ha plots: removal (n 3; all downed CWD ≥10 cm in diameter and ≥60 cm long removed), downed (n 3; 5-fold increase in volume of downed CWD), snag (n 3; 10-fold increase in volume of standing dead CWD), and control (n 3; unmanipulated). Shrews (Blarina carolinensis, Sorex longirostris, and Cryptotis parva) were captured over 7 seasons from January 2007 to August 2008 using drift-fence pitfall trapping arrays within treatment plots. Topographic variables were measured and included as treatment covariates. More captures of B. carolinensis were made in the downed treatment compared to removal, and captures of S. longirostris were greater in downed and snag compared to removal. Captures of C. parva did not differ among treatments. Captures of S. longirostris were positively correlated with slope. Our results suggest that abundance of 2 of the 3 common shrew species of the southeastern Coastal Plain examined in our study is influenced by the presence of CWD. © 2010 American Society of Mammalogists. Source

Ulyshen M.D.,Southern Research Station
PLoS ONE | Year: 2014

Saproxylic arthropods are thought to play an important role in wood decomposition but very few efforts have been made to quantify their contributions to the process and the factors controlling their activities are not well understood. In the current study, mesh exclusion bags were used to quantify how arthropods affect loblolly pine (Pinus taeda L.) decomposition rates in both seasonally flooded and unflooded forests over a 31-month period in the southeastern United States. Wood specific gravity (based on initial wood volume) was significantly lower in bolts placed in unflooded forests and for those unprotected from insects. Approximately 20.5% and 13.7% of specific gravity loss after 31 months was attributable to insect activity in flooded and unflooded forests, respectively. Importantly, minimal between-treatment differences in water content and the results from a novel test carried out separately suggest the mesh bags had no significant impact on wood mass loss beyond the exclusion of insects. Subterranean termites (Isoptera: Rhinotermitidae: Reticulitermes spp.) were 5-6 times more active below-ground in unflooded forests compared to flooded forests based on wooden monitoring stakes. They were also slightly more active above-ground in unflooded forests but these differences were not statistically significant. Similarly, seasonal flooding had no detectable effect on above-ground beetle (Coleoptera) richness or abundance. Although seasonal flooding strongly reduced Reticulitermes activity below-ground, it can be concluded from an insignificant interaction between forest type and exclusion treatment that reduced above-ground decomposition rates in seasonally flooded forests were due largely to suppressed microbial activity at those locations. The findings from this study indicate that southeastern U.S. arthropod communities accelerate above-ground wood decomposition significantly and to a similar extent in both flooded and unflooded forests. Seasonal flooding has the potential to substantially reduce the contributions of these organisms to wood decomposition below-ground, however. Source

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