Evaluating the impact of abrupt changes in forest policy and management practices on landscape dynamics: analysis of a Landsat image time series in the Atlantic Northern Forest

PLoS One. 2015 Jun 24;10(6):e0130428. doi: 10.1371/journal.pone.0130428. eCollection 2015.

Abstract

Sustainable forest management is based on functional relationships between management actions, landscape conditions, and forest values. Changes in management practices make it fundamentally more difficult to study these relationships because the impacts of current practices are difficult to disentangle from the persistent influences of past practices. Within the Atlantic Northern Forest of Maine, U.S.A., forest policy and management practices changed abruptly in the early 1990s. During the 1970s-1980s, a severe insect outbreak stimulated salvage clearcutting of large contiguous tracts of spruce-fir forest. Following clearcut regulation in 1991, management practices shifted abruptly to near complete dependence on partial harvesting. Using a time series of Landsat satellite imagery (1973-2010) we assessed cumulative landscape change caused by these very different management regimes. We modeled predominant temporal patterns of harvesting and segmented a large study area into groups of landscape units with similar harvest histories. Time series of landscape composition and configuration metrics averaged within groups revealed differences in landscape dynamics caused by differences in management history. In some groups (24% of landscape units), salvage caused rapid loss and subdivision of intact mature forest. Persistent landscape change was created by large salvage clearcuts (often averaging > 100 ha) and conversion of spruce-fir to deciduous and mixed forest. In groups that were little affected by salvage (56% of landscape units), contemporary partial harvesting caused loss and subdivision of intact mature forest at even greater rates. Patch shape complexity and edge density reached high levels even where cumulative harvest area was relatively low. Contemporary practices introduced more numerous and much smaller patches of stand-replacing disturbance (typically averaging <15 ha) and a correspondingly large amount of edge. Management regimes impacted different areas to different degrees, producing different trajectories of landscape change that should be recognized when studying the impact of policy and management practices on forest ecology.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Abies
  • Conservation of Natural Resources / legislation & jurisprudence*
  • Ecology*
  • Environmental Monitoring / methods
  • Forests*
  • Geography
  • Maine
  • Policy
  • Satellite Imagery
  • Spatio-Temporal Analysis
  • Trees
  • United States

Grants and funding

This work was partially funded by the USDA Forest Service, Agenda 20/20 Program (project entitled "Predicting responses of forest landscape change on wildlife umbrella species: Modeling future effects of alternative forest harvesting scenarios on vertebrate diversity across multiple spatial scales on commercial forestlands in Maine") and the Northeastern States Research Cooperative (NSRC http://nsrcforest.org; project entitled "Developing and testing a third party landscape forest sustainability and biodiversity monitoring system"). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.