Multi Species Wildlife Habitat Model

     Timber harvesting impacts habitat for protected fauna in ways that could violate environmetal laws.  The Federal Endangered Species Act (ESA) considers as potential take, “significant habitat modification or degradation…impairing behavioral patterns such as breeding, feeding, or sheltering.”  Making environmental protection a mandatory part of the permitting process, the California Environmental Quality Act (CEQA) encourages the development of threshold guidelines to be used to determine the significance of environmental effects.
     Unfortunately, environmetal permitting places demands that existing methods for evaluating wildlife-habitat cannot deliver.  For not only must habitat encroachments be analyzed against existing baseline conditions, strategic planning also requires forecasting suitability in time and space.

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    Before habitat can be modeled, it must first be mapped and classified. Wildlife-habitat relationships models based on the assumption that habitat suitability can be evaluated from knowledge of a small number of key habitat variables may be uniquely suited for timber management. The California Wildlife Habitat-Relationships (CWHR) program was fashioned after a nascent wildlife habitat-relationships model for the Blue Mountains of Oregon.   

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     Useful in describing floristic forest habitat types; however, with a suggested minimum polygon size of 40 acres, CWHR lacks the granularity required to assess managed forests.  Furthermore, categorizing forest structure simply in terms of quadratic mean tree diameter and total canopy intrinsically misclassifies younger forest types with older tree components.

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                        “In forests subject to stand-replacing disturbances,   
             conventional models of succession typically overlook early-
            seral stages as a simple re-organization/establishment period.
            These models treat structural development in essentially ‘relay
            floristic’ terms, with structural complexity (three-dimensional
            heterogeneity) developing primarily in old-growth stages, only
            after a closed canopy ‘self-thinning’ phase and subsequent
            canopy gap formation. However, is it possible that early-
            successional forests can sometimes exhibit spatial complexity
            similar to that in old-growth forests...?”   (Donato et al. 2012).              
    

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      Because it fails to address important stand attributes associated with NSO habitat, the U.S. Fish and Wildlife Service (USFWS) have issued the California Department of Forestry and Fire Protection (Cal Fire) with a more appropriate classifications scheme.  Thus, for the last thirty years, every timber-harvesting plan (THP) within the range of the NSO has required habitat assessment. Hundreds of thousands of acres, painstakingly mapped by way of aerial photo-interpretation.

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       Unfortunately, of the significant proportion of private timberlands mapped for NSO habitat, little has been transferred to GIS. Not only do species-specific habitat evaluation schemes correlate poorly to other sensitive species; less than consistent, NSO habitat typing is still ad hoc.

     Whereas CWHR is today hardly ever used for forest management, as shown below, CWHR nomenclature may with a few modifications be employed to model three-dimensional heterogeneity as a continuum. Suggesting how stand structure can mapped with innovative color shading schemes; below slideshows illustrate how forest vegetation can be classified in terms of NSO habitat, and quantified according to functional suitability. Making it is possible to use this method for both THP analysis and strategic management.

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