Defined loosely here as ‘data-driven models and explicit analytical approaches to inform decisions about habitat management’, decision support tools (especially tools that have been well-vetted and undergone scientific peer review) can provide help and guidance to land
managers grappling with how to best balance competing objectives in the management of burned forests. Below we describe four currently available tools, particularly those based on data from California ecosystems; in recent years the U.S. Forest Service in California has relied most heavily on the first two. We encourage land managers to explore the use of additional or further refined tools as they become available.
1. The California Wildlife Habitat Relationships system (CWHR; Mayer and Laudenslayer 1988) is widely used by Sierra Nevada land managers to assess habitat suitability for species of conservation interest. Based on the information summarized above, we suggest that within recently burned forest, large snags indicative of preferred foraging habitat for Black-backed Woodpeckers correspond roughly to CWHR class 4M, 4D, 5M, or 5D (where size class 4 indicates dbh = 11–24”, size class 5 indicates dbh >24”, M indicates pre-fire canopy closure of 40–59%, and D indicates pre-fire canopy closure >59%). Medium- and smaller-diameter snags typical of nesting habitat roughly correspond to CWHR size class 4M or 4D, or occasionally 3M or 3D (where size class 3 indicates dbh = 6–11”). However, size class
selection for foraging and nesting is somewhat fluid; birds may also nest in class 5 stands, and forage in class 3 stands. Recognizing this fluidity, we suggest that land managers assessing habitat suitability of burned forests within the Black-backed Woodpecker’s range in
California should consider stands with the following pre-fire CWHR classifications to be at least potentially suitable Black-backed Woodpecker habitat after fire: 3M, 3D, 4M, 4D, 5M, or 5D.
2. Tingley et al. (2015, 2016) developed and validated a spatially explicit Black-backed Woodpecker Abundance (BWA) model (sometimes informally referred to as the ‘Tingley model’) for predicting the likely effects of spatially explicit harvest scenarios on local Black-backed Woodpecker populations. The model, which has been routinely used in recent years by U.S. Forest Service personnel designing and evaluating post-fire forest management plans,
utilizes widely available geospatial environmental data to make predictions, and can therefore be implemented just weeks to months after a fire has burned.
The model requires only widely available, remote-sensed environmental information as inputs, so targeted surveys for Black-backed Woodpeckers are not required to predict
abundance. The model takes fine-scale environmental variables covering the entire footprint of a fire and converts them to a predicted Black-backed Woodpecker abundance surface at an approximate resolution of 30x30-m. Our code (see section below) for the BWA model provides one of two output options. The model itself is the direct product of three component models. The first component, an occupancy model, estimates the probability of occupancy at a particular location, as a function of a variety of environmental covariates, and indicates the general suitability of a post-fire landscape for Black-backed Woodpecker occupancy. To estimate abundance, the occupancy component is multiplied by a second component, which predicts the density of Black-backed Woodpecker territories in occupied habitat. This second component of the model is derived from work examining the variation of home-range sizes of Black-backed Woodpeckers (Tingley et al. 2014b), which determined that home-range size scales exponentially with the basal area of snags within occupied territories. Black-backed Woodpeckers occupying territories with greater densities of snags have smaller home ranges.
The final component of the model predicts the snag basal area expected in each pixel based on remotely-sensed pre-fire and post-fire environmental conditions. This final component is necessary in order to implement the home-range size model, which requires snag basal area as an input.
3. Casas et al. (2016) provide a more nuanced spatially explicit approach for predicting which areas of a burned forest are likely to be most valuable for Black-backed Woodpeckers – a determination that could be used to select retention areas when post-fire logging is to occur.
The authors used Airborne Laser Scanning (ALS) to detect and characterize individual conifer snags across the footprint of the 2013 Rim Fire in the central Sierra Nevada, and then
estimated pixel-scale snag basal area, and then, based on conifer snag basal area across Black-backed Woodpecker home ranges studied by Tingley et al. (2014), mapped contiguous areas with potential (i.e., snag basal area > the lowest mean basal area observed across any Black-backed Woodpecker home range) or optimal (i.e., snag basal area > the 50th percentile of average basal area values observed across any Black-backed Woodpecker home range) habitat. Optimal and potential habitat for Black-backed Woodpecker comprised 53.7 km2 and 58.4 km2, respectively, representing 5.1 and 5.6% of the footprint of the Rim Fire. The resulting maps of potential and optimal habitat could then be used to help select individual stands for retention or harvest, based on their likely value to Black-backed Woodpeckers if retained.
4. Latif et al. (2013) developed ensemble habitat suitability models for Black-backed Woodpeckers in 20 recently burned (≤ 6 years) dry mixed conifer forest areas of Montana using nest locations from fires in Idaho, Oregon, and Washington and then later (Latif et al.
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2016) explored factors that constrain the transferability of woodpecker habitat suitability models between fires or regions. Latif et al. suggest models developed at any one wildfire location are unlikely to be generally applicable across the entire range of Black-backed Woodpeckers, and conclude that generally applicable models to inform post-fire forest management likely require integration of data from multiple wildfire locations.
Acknowledgments
We thank the Pacific Southwest Region of the USDA Forest Service for providing the funding to develop and, more recently, update this Conservation Strategy. We thank the many colleagues who provided helpful information, advice, or peer review for this or the previous version of the Black-backed Woodpecker Conservation Strategy: J. Alexander, D. Applebee, P. Bratcher, R.
Burnett, D. Graber, S. Gross, C. Hanson, J. Miller, H. Safford, J. Sherlock, C. Skinner, G. Smith, S. Smith, G. Tarbill, A. White, D. Yasuda, S. Yasuda, and six anonymous reviwers. This project was coordinated by The Institute for Bird Populations’ Sierra Nevada Bird Observatory, under the auspices of California Partners in Flight. This is Contribution No. 582 of The Institute for Bird Populations.
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