Managing Moose from Home: Determining Landscape Carrying Capacity for Alces alces Using Remote Sensing

Abstract

In temperate forests of the northeastern U.S., moose (Alces alces) populations are adapted for mixed-age heterogeneous landscapes that provide abundant herbaceous forage in warm months and coniferous forage during winter. Heterogeneity of forest stands is driven by management activities or natural disturbance, resulting in a multi-age forest at a landscape scale. Here, we present a method to estimate landscape carrying capacity of moose by combining remote sensing classification of forest cover class with literature or field-based estimates of class-specific forage abundance. We used Landsat imagery from 1991 to 2013 for the Allegheny National Forest and 2013–2018 for the Adirondack Park, and associated training polygons, to predict based on NDVI and SWI whether a forested landscape fit into one of three cover classes: mature forest, intermediate timber removal, or overstory timber removal. Our three-classes yielded a mean land cover prediction accuracy of 94.3% (Khat = 0.91) and 86.9% (Khat = 0.76) for ANFR and AP, respectively. In the AP, we applied previously calculated summer crude protein values to our predicted cover types, resulting in an estimated average carrying capacity of 760 moose (SD ± 428) across all sampling years, similar in magnitude to a density estimate of 716 moose (95% CI = 566–906) calculated during the same time. Our approach was able to accurately identify forest timber treatments across landscapes at differing spatial and temporal scales and provide an alternative method to estimate landscape-level ungulate carrying capacity. The ability to accurately identify areas of potential conflict from overbrowsing, or to highlight areas in need of land cover treatments can increase the toolset for ungulate management in managed forest landscapes.

Challenges and opportunities for estimating abundance of a low‐density moose population

“…We identified land cover types such as agriculture, developed, forest, shrub, wetland, and water using United States Geological Survey National Land Cover Data (United States Geological Survey 2016). We obtained a map of the location and type of timber cuts from the New York State Department of Environmental Conservation that combined both intermediate and overstory removal classes into a single layer (Kramer et al 2022). We acquired elevation data from a 30‐m digital elevation model (U.S. Geological Survey 2016).…”

“…Forever wild forests are composed largely of second‐growth forest with remnants of original old growth (McGee et al 1999, Keeton et al 2007). The remaining areas of the Park are privately owned and mostly designated for resource management yielding a patchwork of partially cut, uneven‐aged forests (McGee et al 1999, Kramer et al 2022). Although timber harvest played a large role in maintaining early seral stages across the Park, the restrictive use of public lands and long rotation age of northern hardwood forests has ensured the dominance of older and thick canopy cover (Lorimer and White 2003, McGee et al 2007).…”

A model-based estimate of winter distribution and abundance of white-tailed deer in the Adirondack Park

“…Predominant canopy cover for northern hardwood stands consisted of sugar maple ( Acer saccharum ), red maple ( Acer rubrum ), yellow birch ( Betula alleghaniensis ), white birch ( Betula paperyfera ), and American beech ( Fagus grandifolia ). Boreal stands of red spruce ( Picea rubens ), black spruce ( Picea mariana ), balsam fir ( Abies balsamea ), and eastern hemlock ( Tsuga canadensis ) dominated poorly drained lowland areas, riparian bottomlands, and subalpine forests at elevations above 760 m. More detail of the study area can be found in Kramer et al [ 24 ].…”

“…In the Park, publicly owned lands (~48% of the Park) consist of mostly second-growth forest with remnants of original growth because the New York State constitution has protected those areas as “forever wild forest lands” since 1892 [ 24 ]. Privately owned lands comprised the remaining areas of the park and were a patchwork of partially cut, uneven-aged forests resulting from timber management [ 24 ].…”

“…In the Park, publicly owned lands (~48% of the Park) consist of mostly second-growth forest with remnants of original growth because the New York State constitution has protected those areas as "forever wild forest lands" since 1892 [24]. Privately owned lands comprised the remaining areas of the park and were a patchwork of partially cut, uneven-aged forests resulting from timber management [24]. Although timber harvest played a large role in maintaining early seral stages across the Park, the restrictive use of public lands and long rotation age of northern hardwood forests has ensured the dominance of older and thick canopy cover [24][25][26].…”