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Net Primary Production of Temperate Deciduous Forest Exhibits Threshold Response to Increasing Disturbance Severity
Published: January 01, 2015
Posted: November 25, 2015

The global carbon balance is vulnerable to disturbances that alter terrestrial carbon storage. Disturbances to forests occur along a continuum of severity, from low-intensity disturbance causing the mortality or defoliation of only a subset of trees to severe stand-replacing disturbance that kills all trees; yet, considerable uncertainty remains in how forest production changes across gradients of disturbance intensity. In a recent study, researchers used a gradient of tree mortality in an upper Great Lakes forest ecosystem to: (1) quantify how aboveground wood net primary production (ANPPw) responds to a range of disturbance severities and 2) identify mechanisms supporting ANPPw resistance or resilience following moderate disturbance. They found that ANPPw declined nonlinearly with rising disturbance severity, remaining stable until > 60 % of the total tree basal area senesced. As upper canopy openness increased from disturbance, greater light availability to the subcanopy enhanced the leaf-level photosynthesis and growth of this formerly light-limited canopy stratum, compensating for upper canopy production losses and a reduction in total leaf area index (LAI). As a result, whole-ecosystem production efficiency (ANPPw/LAI) increased with rising disturbance severity, except in plots beyond the disturbance threshold. These findings provide a mechanistic explanation for a nonlinear relationship between ANPPw and disturbance severity, in which the physiological and growth enhancement of undisturbed vegetation is proportional to the level of disturbance until a threshold is exceeded. These results have important ecological and management implications, demonstrating that in some ecosystems moderate disturbance levels minimally alter forest production.

Reference: Stuart-Haëntjens, E., P. S. Curtis, R. T. Fahey, C. S. Vogel, and C. M. Gough. 2015. “Net Primary Production of a Temperate Deciduous Forest Exhibits a Threshold Response to Increasing Disturbance Severity,” Ecology 96, 2478–87. (Reference link)

Contact: Jared DeForest, SC-23, (301) 903-3251, Daniel Stover, SC-23.1, (301) 903-0289
Topic Areas:

  • Research Area: Terrestrial Ecosystem Science
  • Research Area: Carbon Cycle, Nutrient Cycling

Division: SC-33.1 Earth and Environmental Sciences Division, BER

 

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