| NSF Org: |
DEB Division Of Environmental Biology |
| Recipient: |
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| Initial Amendment Date: | May 31, 2012 |
| Latest Amendment Date: | May 31, 2012 |
| Award Number: | 1242013 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Matthew Kane
mkane@nsf.gov (703)292-7186 DEB Division Of Environmental Biology BIO Directorate for Biological Sciences |
| Start Date: | June 1, 2012 |
| End Date: | May 31, 2013 (Estimated) |
| Total Intended Award Amount: | $164,060.00 |
| Total Awarded Amount to Date: | $164,060.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
310 E CAMPUS RD RM 409 ATHENS GA US 30602-1589 (706)542-5939 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
GA US 30602-5016 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | ECOSYSTEM STUDIES |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.074 |
ABSTRACT
This study uses a soil warming experimental facility in an oak-dominated forest to examine for the first time how insect outbreaks affect nutrient cycling and availability to trees under both current temperatures and warmer soils expected in the future. In the southeastern United States caterpillar outbreaks have inflicted high rates of damage to oak trees, including up to 100% defoliation of individual trees. Species involved in this outbreak, black-dotted brown (Cissusa spadix) and common oak moth (Phoberia atomaris), were never known to outbreak before (Cissusa) or only rarely (Phoberia). However, in May 2010 Cissusa broke out for the first time ever recorded in the southeastern U.S., and in May 2011 both caterpillars exhibited outbreak numbers and caused extensive defoliation. In April 2012 these caterpillars broke out again but a month earlier than previous years, likely due to the mild winter of 2011-2012. Such large numbers of leaf-eating insects in a few weeks produce large quantities of excrement (frass) and other soil nutrient additions that may impact nutrient biogeochemical dynamics over an entire year or more. This study will be the first to address how insect outbreaks and warmer soils affect the availability to trees of important nutrients.
Insect outbreaks have been occurring more frequently and are projected to increase in frequency as climate warms. Understanding how forest ecosystems respond to outbreaks of foliage-eating insects concerns forest managers, timber harvesters, hikers, campers, and local and regional property owners. This work will have relevance for understanding soil nutrient availability to trees under current and future warmer conditions and, therefore, for future ecosystem services important to society. These services include, but are not limited to, provisioning of timber, forest carbon sequestration, wildlife habitat, and watershed integrity. During several weeks of outbreak each year, falling frass abundant enough to sound like drizzle and nightly climbing of thousands of caterpillars (per tree) up tree trunks garners much public interest and generates extensive media coverage, providing an excellent opportunity for discourse with the public.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
We studied the responses of forest ecosystems to a massive outbreak of two caterpillar species in April 2012. Both of these caterpillars consume the leaves of oak trees and can inflict high rates of leaf damage – up to 100% defoliation of individual trees. The two moth caterpillar species involved in this outbreak, brown-spotted black (Cissusa spadix) and common oak caterpillar (Phoberia atomaris) were never known to outbreak before (Cissusa) or only rarely (Phoberia). However, in May 2010 Cissusa broke out for the first time ever recorded in the southeastern U.S., and in May 2011 both Cissusa and Phoberia exhibited outbreak numbers and accompanying extensive damage to oak trees and forests. In April 2012 these caterpillars broke out again but a month earlier than the previous years, likely due to the mild winter of 2011-2012. Such large numbers of leaf-eating insects in the period of only a few weeks produce large quantities of excrement (fraas) and nutrient additions to the soils of oak forests that may have nutrient biogeochemical cycling impacts that last the entire year or more. Further, in this study, we will made use of a soil warming experimental facility located in an oak-dominated forest to examine for the first time how outbreak-level additions of fraas and other insect nutrient inputs impacts nutrient cycling rates both under current control temperatures and under warmer soils expected in the future.
We found that nitrogen availability varied by month, and that the type of insect nutrient input (fraas, throughfall, or a combination) was also marginally important for nitrogen availability. However, soils warmed to different temperatures did not impact the amount of nitrogen, nor was there an interaction between the temperature of the soil and the type in insect nutrient input. This work showed that insects impacted soil fertility, and did so for at least 6-months following this unusual leaf-eating insect outbreak.
Last Modified: 01/22/2016
Modified by: Jacqueline Mohan
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