Biophysical and potential vegetation growth surfaces for a small watershedin northern Cape Breton Island, Nova Scotia, Canada

Surfaces of potential vegetation growth in this paper represent the spatial distribution of growing conditions (habitat) for six deciduous tree specie s native to the Clyburn River valley watershed of northeastern Cape Breton Island, Nova Scotia. Development of potential growth surfaces is based on i ntegrating point calculations of (i) net potential solar radiation, (ii) ne t long-wave radiation, (iii) growing season degree-day accumulation, and (i v) mean summer soil water content with species-specific evaluations of long -term species environmental response. Functions describing potential specie s response to available environmental resources are based on generalised ma thematical functions that scale species response values between 0 and 1, wh ere 0 represents unsuitable growing conditions and 1, optimal growing condi tions. Limitation effects of resource deficits on potential growth are addr essed as a multiplication of individual environmental responses. Derived sp ecies distributions of potential growth are compared with aerial photo-inte rpreted distributions of forest vegetation found within the Clyburn River v alley watershed. Modelled and photo-interpreted valley distributions demons trate nearly similar geographic ranges. Actual percent cover for shade-tole rant species displays a positive correlation with modelled potential growth (r(2) = 0.5). This is not the case for shade-intolerant species considered , whereby r(2) approximate to 0.