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Assessing the Ecological Impacts of Biomass Harvesting along a Disturbance Severity Gradient

Citation

Kurth, Valerie et al. (2019), Assessing the Ecological Impacts of Biomass Harvesting along a Disturbance Severity Gradient, Dryad, Dataset, https://doi.org/10.5061/dryad.kkwh70s1m

Abstract

Disturbance is a central driver of forest development and ecosystem processes with variable effects within and across ecosystems.  Despite the high levels of variation in disturbance severity often observed in forests following natural and anthropogenic disturbance, studies quantifying disturbance impacts often rely on categorical classifications, thus limiting opportunities to examine potential gradients in ecosystem response to a given disturbance or management regime.  Given the potential increases in disturbance severity associated with global change, as well as shifts in management regimes related to procurement of biofuel feedstocks, there is an increasing need to quantitatively describe disturbance severity and associated responses of forest development, soil processes, and structural conditions. This study took advantage of two replicated large-scale studies of forest biomass harvesting in Populus tremuloides and Pinus bansksiana forests, respectively, to develop and test the utility of a continuous, quantitative disturbance severity index (DSI) for describing post-harvest response of plant communities and nutrient pools to different levels of biomass removal and legacy retention (i.e., live trees and coarse woody material). There was a high-degree of variability in DSI within categorical treatments associated with different levels of legacy retention and regression models using DSI as a predictor explained a portion of the variation (>50%) for many of the ecosystem- and community-level responses to biomass harvesting examined. Nutrient losses associated with biomass harvesting were positively related to disturbance severity, particularly in P. tremuloides forests, with post-harvest nutrient availability generally declining along the gradient of impacts. Consistent with expectations from ecological theory, species richness and diversity of woody plant communities were greatest at intermediate disturbance severities and regeneration densities of dominant trees species were most abundant at highest levels of disturbance. Although categorical benchmarks will continue to be the primary way through which management guidelines are conveyed to practitioners, evaluation of their effectiveness at sustaining ecosystem functioning should be through continuous analyses, such as the DSI approach used in this study, to allow for the more precise identification of thresholds that ensure a range of desirable outcomes exist across managed landscapes.

Usage Notes

Please consult the "Metadata" table of each spreadsheet for variable descriptions, format, units of measurement, and factor codes (where applicable). All files are in open document spreadsheet (.ods) format.

Data are divided by dataset and response variable, organized slightly differently between aspen and jack pine experiments. Below are descriptions for each file:

  1. jack_pine_community.ods: plot-level species richness, Bray-Curtis distances, evenness, Shannon's H', and Simpson's D for teh jack pine experiment
  2. jack_pine_lost_nutrients.ods: plot-level aboveground nutrient losses (N, Ca, K, P, and C), as well as forest floor biomass change for the jack pine experiment. As these data focus on post-harvest changes, variables are not repeated across years.
  3. jack_pine_ seedlings.ods: plot-level seedling densities for the jack pine experiment.
  4. aspen_available_nutrients.ods: availble nutrients (total N, NO3, NH4, Ca, Mg,and P) for 2010 and 2011 for the aspen experiment.
  5. aspen_community.ods: species richness, evenness, Simpson's D, and Shannon's H for the 2009-2013 period for the aspen experiment
  6. aspen_bray_curtis_distances.ods: Shift of sample plots in species space (Bray-Curtis distances) between the preharvest and postharvest period for the aspen experiment. As these data represent change, they are not repeated across years.
  7. aspen_lost_nutrients.ods: plot-level aboveground nutrient losses (N, Ca, K, P, and C), as well as forest floor biomass change for the aspen experiment. As these data focus on post-harvest changes, variables are not repeated across years.
  8. aspen_litterfall.ods: Annual litterfall biomass for 2010 and 2011 at the aspen experiment. This file also includes pre-post treatment forest floor biomass change following treatment.
  9. aspen_seedling_densities.ods: seedling densities of all species and Populus tremuloides for 2009 and 2010.

 

Funding

Minnesota Forest Resources Council

U.S. Department of Agriculture/Department of Energy Biomass Research Development Initiative

USDA Forest Service Northern Research Station

Minnesota Environmental and Natural Resources Trust Fund

U.S. Department of the Interior

U.S. Department of the Interior Northeast Climate Adaptation Science Center