@article{9db275acb509453b91be494c1a29ec09,
title = "Evidence for widespread changes in the structure, composition, and fire regimes of western North American forests",
abstract = "Implementation of wildfire- and climate-adaptation strategies in seasonally dry forests of western North America is impeded by numerous constraints and uncertainties. After more than a century of resource and land use change, some question the need for proactive management, particularly given novel social, ecological, and climatic conditions. To address this question, we first provide a framework for assessing changes in landscape conditions and fire regimes. Using this framework, we then evaluate evidence of change in contemporary conditions relative to those maintained by active fire regimes, i.e., those uninterrupted by a century or more of human-induced fire exclusion. The cumulative results of more than a century of research document a persistent and substantial fire deficit and widespread alterations to ecological structures and functions. These changes are not necessarily apparent at all spatial scales or in all dimensions of fire regimes and forest and nonforest conditions. Nonetheless, loss of the once abundant influence of low- and moderate-severity fires suggests that even the least fire-prone ecosystems may be affected by alteration of the surrounding landscape and, consequently, ecosystem functions. Vegetation spatial patterns in fire-excluded forested landscapes no longer reflect the heterogeneity maintained by interacting fires of active fire regimes. Live and dead vegetation (surface and canopy fuels) is generally more abundant and continuous than before European colonization. As a result, current conditions are more vulnerable to the direct and indirect effects of seasonal and episodic increases in drought and fire, especially under a rapidly warming climate. Long-term fire exclusion and contemporaneous social-ecological influences continue to extensively modify seasonally dry forested landscapes. Management that realigns or adapts fire-excluded conditions to seasonal and episodic increases in drought and fire can moderate ecosystem transitions as forests and human communities adapt to changing climatic and disturbance regimes. As adaptation strategies are developed, evaluated, and implemented, objective scientific evaluation of ongoing research and monitoring can aid differentiation of warranted and unwarranted uncertainties.",
keywords = "Climate Change and Western Wildfires, climate adaptation, ecosystem management, fire exclusion, forested landscapes, frequent fire, high-severity fire, landscape restoration, multi-dimensional fire regimes, multi-scale spatial patterns, reference conditions, wildfire adaptation",
author = "Hagmann, {R. K.} and Hessburg, {P. F.} and Prichard, {S. J.} and Povak, {N. A.} and Brown, {P. M.} and Ful{\'e}, {P. Z.} and Keane, {R. E.} and Knapp, {E. E.} and Lydersen, {J. M.} and Metlen, {K. L.} and Reilly, {M. J.} and {S{\'a}nchez Meador}, {A. J.} and Stephens, {S. L.} and Stevens, {J. T.} and Taylor, {A. H.} and Yocom, {L. L.} and Battaglia, {M. A.} and Churchill, {D. J.} and Daniels, {L. D.} and Falk, {D. A.} and P. Henson and Johnston, {J. D.} and Krawchuk, {M. A.} and Levine, {C. R.} and Meigs, {G. W.} and Merschel, {A. G.} and North, {M. P.} and Safford, {H. D.} and Swetnam, {T. W.} and Waltz, {A. E.M.}",
note = "Funding Information: We are grateful for funding from California Department of Forestry and Fire Protection; Ecological Restoration Institute; Washington State Department of Natural Resources; The Wilderness Society; The Nature Conservancy of Oregon; Conservation Northwest; USDA-FS, Pacific Northwest and Pacific Southwest Research Stations; and USDI-FWS Oregon Fish and Wildlife Office. Constructive reviews from K. Norman Johnson, Cameron E. Naficy, James Rosen, Frank K. Lake, Collin Haffey, and two anonymous reviewers substantially improved our manuscript. This paper was written and prepared by U.S. Government employees on official time, and therefore it is in the public domain and not subject to copyright. The findings and conclusions in this article are those of the author(s) and do not necessarily represent the views of the U.S. Fish and Wildlife Service or the USDA Forest Service. Funding Information: We are grateful for funding from California Department of Forestry and Fire Protection; Ecological Restoration Institute; Washington State Department of Natural Resources; The Wilderness Society; The Nature Conservancy of Oregon; Conservation Northwest; USDA‐FS, Pacific Northwest and Pacific Southwest Research Stations; and USDI‐FWS Oregon Fish and Wildlife Office. Constructive reviews from K. Norman Johnson, Cameron E. Naficy, James Rosen, Frank K. Lake, Collin Haffey, and two anonymous reviewers substantially improved our manuscript. This paper was written and prepared by U.S. Government employees on official time, and therefore it is in the public domain and not subject to copyright. Publisher Copyright: {\textcopyright} 2021 The Authors. Ecological Applications published by Wiley Periodicals LLC on behalf of Ecological Society of America. This article has been contributed to by US Government employees and their work is in the public domain in the USA",
year = "2021",
month = dec,
doi = "10.1002/eap.2431",
language = "English (US)",
volume = "31",
journal = "Ecological Applications",
issn = "1051-0761",
publisher = "Ecological Society of America",
number = "8",
}