Western Academic Research

Pages

There’s snow(show) place like home: integrating field measurements and remotely sensed data to assess and model snowshoe hare habitat.
The Southern Rocky Mountains are at the southern range of snowshoe hares (Lepus americanus) and their iconic predator, the Canada lynx (Lynx canadensis). In this region recreational uses, backcountry roads and trails, and other human developments have been identified as risk factors affecting lynx productivity through altering the snowshoe hare prey base. Beginning in 2013, Crested Butte Mountain Resort in western Colorado began proposals, and was conditionally approved in 2019 to construct ski trails and infrastructure in an undeveloped section of the Gunnison National Forest that currently supports snowshoe hare. In continuation of a 2016 pilot study, we carried out fecal pellet counts in the summer-fall of 2020 to assess whether this area contains adequate hare density (~0.5 hares/hectare) to support the imperiled Canada lynx. Pellet counts were significantly higher at a site dominated by old-growth spruce-fir forest, which has been cited as an important determinant of snowshoe hare and Canada lynx presence. Mean and median pellets counted varied by year; nonetheless, in neither year nor study site did values reach the threshold of 0.5 hares/hectare. We also estimated dense horizontal cover, considered an important component of winter hare habitat, as a rough assessment of habitat quality. Alongside this data, we utilized forest structural variables derived from satellite and LiDAR imagery to develop candidate models for predicting snowshoe hare population density. Our aim was to determine whether remotely sensed data could serve as a supplement or alternative to the traditional, resource-intensive field methods for assessing snowshoe hare population density and habitat quality for lynx management purposes. We conclude that open-access, remotely sensed data is valuable for land managers, but may not yet be collected at the scales suitable to assess habitat for species that rely on both stand-level variables (i.e., forest type) and fine-scale forest structural variables including dense horizontal cover.
Using the past and the present to understand fire ecology in sagebrush habitats of the Gunnison Sage-grouse
The historical role of fire in shaping sagebrush ecosystems remains poorly understood, yet is important for informing the management and conservation of sagebrush landscapes and obligate species such as the threatened Gunnison sage-grouse (GUSG; Centrocercus minimus). To gain insight into the historical role of fire in sagebrush landscapes of the Upper Gunnison Basin (UGB), we reconstructed the historical (1424-2001) frequency of low-severity fire from tree-ring fire-scars at sagebrush-forest ecotones (10 sites, 111 trees), and conducted surveys of plant composition and structure at 100 sagebrush sites with and without recent (2001-2020) fire. Tree-ring fire-scars revealed a history of repeated (mean fire return interval of 18.2 to 79.7 years) low-severity fire at sagebrush-forest ecotones until ca. 1900, followed by over a century that was fire-free. Fires occurred synchronously at two or more sites on average every 23.6 years. Recent burns exhibited strong reductions in sagebrush (from an average of 36.5% to 5.7% cover) and concomitant increases in herbaceous cover (from 40.1% to 55.1%) relative to unburned sites. These shifts diminished with time since fire, but persisted for at least two decades. Together, these results indicate that portions of the sagebrush landscape of the UGB, including occupied GUSG habitat, were historically characterized by repeated fire and vegetation mosaics including patches dominated by grasses and forbs. These findings suggest that prescribed fire could be used to maintain and restore the important ecological process of fire, but also highlight the need for additional research on how such conditions might affect GUSG populations in the context of contemporary conditions.

Pages