Paper reviews terrestrial biodiversity responses to intensive forest management

Forests provide numerous ecosystem functions and services such as wood products, clean water, and support for biodiversity. Many forests in the US are managed and, in
some locations, forest management has become more intensive over time. This trend has led to questions about the extent to which intensively managed forests contribute to support of biological diversity.

Recently, a paper in Forest Ecology and Management reviewed and summarized the scientific literature describing contributions of intensively managed forests to vertebrate biodiversity. The paper emphasizes research in the US and Canada that has emerged in the past two decades.

Key findings from the review are that intensive forest management affects terrestrial vertebrates primarily by modifying habitat; effects are species-specific and linked to intensity and extent of habitat modification; landscape context and stand configuration have implications for vertebrate diversity; negative impacts on vertebrate diversity can often be ameliorated via management practices; and intensively managed forest landscapes contribute to conservation of biological diversity.

The paper was authored by Drs. Stephen Demarais of Mississippi State University, Jacob P. Verschuyl of NCASI, Gary J. Roloff of Michigan State University, Darren A. Miller of Weyerhaeuser Company, and T. Bently Wigley of NCASI. The abstract for the paper follows.

“In the United States, intensively managed forests (IMFs) comprise approximately 9% (27.9 million ha) of total forest area. These forests are primarily in highly productive areas and are managed primarily for wood and fiber production. Intensively managed forests provide both opportunities and constraints for conservation of vertebrate biodiversity. A comprehensive review of these opportunities and limitations within the U.S. is lacking, so we reviewed effects of typical silvicultural management regimes within IMFs on terrestrial vertebrate species. The typical silvicultural regime in IMFs includes practices associated with establishing forest management units (stands), weed control, intermediate thinning, and final harvest. Effects of intensive forest management on vertebrate diversity are mostly indirect through habitat modification. Terrestrial vertebrate responses to intensive forest management are species-specific and directly linked to intensity and extent of habitat modification. Shorter crop tree rotations compress successional stages and limit development and recruitment of mature forest structures (e.g., snags, den/roost trees, coarse woody debris). During stand establishment, increased intensification of site preparation and weed control tends to result in lower vertebrate diversity. Generally, vertebrate diversity of intensively managed stands is progressively reduced after stand establishment as canopy closure occurs and sunlight to the forest floor is restricted, reducing vegetation structural complexity. However, intermediate management practices like thinning, which re-opens the forest canopy, generally have positive or neutral effects on most vertebrate taxa. Final tree harvest removes the overstory and, predictably, vertebrate taxa depending on older or undisturbed forest conditions decline and early seral species increase. To ameliorate negative effects of final harvest on terrestrial vertebrate diversity, land managers have instituted various practices, including retaining habitat elements, protecting riparian zones and sensitive ecological areas, and limiting final harvest unit size as well as how soon an adjacent forest patch can be harvested. Juxtaposition and interspersion of forest stands of varying ages are important determinants of terrestrial vertebrate responses to intensively managed landscapes. A typical intensively managed landscape contains a variety of stand ages, forest types, and other features (e.g., streams, mature forest stands, set-aside areas) that provide habitat for a diversity of terrestrial vertebrate species. Landscape context has direct ramifications for terrestrial vertebrate diversity in intensively managed landscapes, with negative effects more pronounced in forests imbedded in agriculture or anthropogenic landscapes. Most field studies have been of short duration (<5 years) and localized (e.g., multiple stands in an area), hence we call for a greater commitment to longer-term research and monitoring replicated across landscapes. Significant research gaps include how to improve functionality of retained structures, riparian zones, and unique ecological communities, whether vertebrates are evolving or adapting to the rapid changes in habitat conditions characteristic of IMFs, and how landscape context, including spatial distribution of varying stand ages, affects vital rates of terrestrial vertebrate species (hereafter wildlife).”

Reference 

Demarais, S., J.P. Verschuyl, G.J. Roloff, D.A. Miller, and T.B. Wigley. 2017. Tamm review: Terrestrial vertebrate biodiversity and intensive forest management in the U.S. Forest Ecology and Management 385:308–330. https://doi.org/10.1016/j.foreco.2016.10.006 

Forests provide numerous ecosystem functions and services such as wood products, clean water, and support for biodiversity. Many forests in the US are managed and, in
some locations, forest management has become more intensive over time. This trend has led to questions about the extent to which intensively managed forests contribute to support of biological diversity.

 

Recently, a paper in Forest Ecology and Management reviewed and summarized the scientific literature describing contributions of intensively managed forests to vertebrate biodiversity. The paper emphasizes research in the US and Canada that has emerged in the past two decades.

Key findings from the review are that intensive forest management affects terrestrial vertebrates primarily by modifying habitat; effects are species-specific and linked to intensity and extent of habitat modification; landscape context and stand configuration have implications for vertebrate diversity; negative impacts on vertebrate diversity can often be ameliorated via management practices; and intensively managed forest landscapes contribute to conservation of biological diversity.

The paper was authored by Drs. Stephen Demarais of Mississippi State University, Jacob P. Verschuyl of NCASI, Gary J. Roloff of Michigan State University, Darren A. Miller of Weyerhaeuser Company, and T. Bently Wigley of NCASI. The abstract for the paper follows.

“In the United States, intensively managed forests (IMFs) comprise approximately 9% (27.9 million ha) of total forest area. These forests are primarily in highly productive areas and are managed primarily for wood and fiber production. Intensively managed forests provide both opportunities and constraints for conservation of vertebrate biodiversity. A comprehensive review of these opportunities and limitations within the U.S. is lacking, so we reviewed effects of typical silvicultural management regimes within IMFs on terrestrial vertebrate species. The typical silvicultural regime in IMFs includes practices associated with establishing forest management units (stands), weed control, intermediate thinning, and final harvest. Effects of intensive forest management on vertebrate diversity are mostly indirect through habitat modification. Terrestrial vertebrate responses to intensive forest management are species-specific and directly linked to intensity and extent of habitat modification. Shorter crop tree rotations compress successional stages and limit development and recruitment of mature forest structures (e.g., snags, den/roost trees, coarse woody debris). During stand establishment, increased intensification of site preparation and weed control tends to result in lower vertebrate diversity. Generally, vertebrate diversity of intensively managed stands is progressively reduced after stand establishment as canopy closure occurs and sunlight to the forest floor is restricted, reducing vegetation structural complexity. However, intermediate management practices like thinning, which re-opens the forest canopy, generally have positive or neutral effects on most vertebrate taxa. Final tree harvest removes the overstory and, predictably, vertebrate taxa depending on older or undisturbed forest conditions decline and early seral species increase. To ameliorate negative effects of final harvest on terrestrial vertebrate diversity, land managers have instituted various practices, including retaining habitat elements, protecting riparian zones and sensitive ecological areas, and limiting final harvest unit size as well as how soon an adjacent forest patch can be harvested. Juxtaposition and interspersion of forest stands of varying ages are important determinants of terrestrial vertebrate responses to intensively managed landscapes. A typical intensively managed landscape contains a variety of stand ages, forest types, and other features (e.g., streams, mature forest stands, set-aside areas) that provide habitat for a diversity of terrestrial vertebrate species. Landscape context has direct ramifications for terrestrial vertebrate diversity in intensively managed landscapes, with negative effects more pronounced in forests imbedded in agriculture or anthropogenic landscapes. Most field studies have been of short duration (<5 years) and localized (e.g., multiple stands in an area), hence we call for a greater commitment to longer-term research and monitoring replicated across landscapes. Significant research gaps include how to improve functionality of retained structures, riparian zones, and unique ecological communities, whether vertebrates are evolving or adapting to the rapid changes in habitat conditions characteristic of IMFs, and how landscape context, including spatial distribution of varying stand ages, affects vital rates of terrestrial vertebrate species (hereafter wildlife).”

Reference 

Demarais, S., J.P. Verschuyl, G.J. Roloff, D.A. Miller, and T.B. Wigley. 2017. Tamm review: Terrestrial vertebrate biodiversity and intensive forest management in the U.S. Forest Ecology and Management 385:308–330. https://doi.org/10.1016/j.foreco.2016.10.006