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Individual Highlight

Contrasting Effects of Invasive Insects and Fire on Forest Carbon Dynamics

Photo of A prescribed fire burning in the New Jersey Pinelands.  Recovery following prescribed fires is rapid, and over a ten-year period burned stands sequestered twice the amount of carbon compared to stands defoliated by invasive insects. Michael Gallagher, USDA Forest ServiceA prescribed fire burning in the New Jersey Pinelands. Recovery following prescribed fires is rapid, and over a ten-year period burned stands sequestered twice the amount of carbon compared to stands defoliated by invasive insects. Michael Gallagher, USDA Forest ServiceSnapshot : Forest Service scientists quantified rates of carbon sequestration and water use by forests before and after invasive insect defoliation and prescribed burns in the Pinelands of New Jersey. Ecosystem Water Use Efficiency (WUEe), a measure of the amount of water used to sequester carbon by forests, was reduced in oak-dominated and mixed stands during defoliation, whereas, prescribed fire had little effect on WUEe. Long-term data indicated that even when consumption losses from fires are considered, insect-defoliated stands were only half as productive compared to burned stands, while water use was less affected.

Principal Investigators(s) :
Clark, Ken 
Research Location : New Jersey
Research Station : Northern Research Station (NRS)
Year : 2014
Highlight ID : 647

Summary

Forest Service scientists quantified changes in forest structure and measured water use and net carbon dioxide (CO2) exchange from towers in forest stands that were burned in prescribed fires or defoliated by invasive insects. Prescribed burns resulted in little change to nitrogen in foliage during the following growing season, while insect defoliation and subsequent tree mortality reduced canopy nitrogen pools. Ecosystem Water Use Efficiency (WUEe) was reduced to 60 percent and 46 percent of pre-disturbance values in oak-dominated and mixed stands during defoliation; prescribed fire had little effect. Over a decade, carbon sequestration by an intensively studied defoliated stand totaled about 5.4 tons of carbon per hectare (1 hectare equals nearly 2.5 acres), while a burned stand sequestered 10.6 tons of carbon per hectare. These results indicate that forest carbon dynamics, and especially rates of net carbon dioxide exchange, are more sensitive to disturbance than hydrologic fluxes, and disturbances that result in large nitrogen transfers within stands may have long-term effects on rates of carbon sequestration. This work improves scientists' ability to predict interactions between carbon and water cycles under climate change scenarios that result in a greater likelihood of insect invasions, wildfire, or other disturbances.

Forest Service Partners

External Partners

  • Nicholas Skowronski and Michael Gallagher
  • New Jersey Forest Fire Service
  • Rutgers University, Newark and New Brunswick