Rights & User Restrictions
Rights & Restrictions: This object is either not yet digitized or not digitally available. To learn how to gain access, please contact the Sterling Morton Library at library@mortonarb.org or (630) 719-2429.
Copyright statement:

Copyright restrictions applying to use or reproduction of this image are available from the Sterling Morton Library, The Morton Arboretum. For more information, please visit our ABOUT section or complete and submit this form.

Stuart-Haëntjens, Ellen J.
Curtis, Peter S.
Fahey, Bob
Vogel, Christoph S.
Gough, Christopher M.

Net primary production of a temperate deciduous forest exhibits a threshold response to increasing disturbance severity

Date created
The global carbon (C) balance is vulnerable to disturbances that alter terrestrial C 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. We used a gradient of tree mortality in an upper Great Lakes forest ecosystem to: (1) quantify how aboveground wood net primary production (ANPP(w)) responds to a range of disturbance severities; and (2) identify mechanisms supporting ANPP(w) resistance or resilience following moderate disturbance. We found that ANPP(w) 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 (ANPP(w)/LAI) increased with rising disturbance severity, except in plots beyond the disturbance threshold. These findings provide a mechanistic explanation for a nonlinear relationship between ANPP(w) 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. Our results have important ecological and management implications, demonstrating that in some ecosystems moderate levels of disturbance minimally alter forest production.
Alternate Title

Volume, Issue, Page Number
96, 9, 2478-2487