. The Canadian field-naturalist. 1994 Parker, Kimball, and Dalzell: Bird Communities in Plantations For example, a total of 10 stems, all of which were conifer, in a specific height class would receive a rat- ing of 10 (10 x 1 - 10) whereas if five of the 10 stems were deciduous (ie., ), the rating would be 50 (10 x 5 = 50). This stem interspersion, or hetero- geneity, score was further weighted for value to breeding bird species by each stem height class (H). We introduced an increasing multiplier for increasing height class; , the same 10 stems have greater influence on richness, abun
. The Canadian field-naturalist. 1994 Parker, Kimball, and Dalzell: Bird Communities in Plantations For example, a total of 10 stems, all of which were conifer, in a specific height class would receive a rat- ing of 10 (10 x 1 - 10) whereas if five of the 10 stems were deciduous (ie., ), the rating would be 50 (10 x 5 = 50). This stem interspersion, or hetero- geneity, score was further weighted for value to breeding bird species by each stem height class (H). We introduced an increasing multiplier for increasing height class; , the same 10 stems have greater influence on richness, abundance and diversity of breeding bird populations (in general) between 3-5 m in height than between 1-2 m in height. We gave no consideration for stems 1 2 3 5 79m 1 2 4 8 16 32 The 10 stems with an interspersion value (I) of 50 would be further multiplied by 2 if in the 2-3 m height stratum and by 8 if in the 5-7 m stratum. The habitat diversity index (HDI) is the summa- tion of the two weighted measures for each stem height stratum (i) divided by 100. HDI= I ft ⢠Hi i=l 100 The HDI provides increasing values for habitats with high interspersion of conifer and deciduous stems in the upper height strata. A mature conifer forest stand with normal stocking rate but dense conifer/deciduous understory > 1 m would receive a higher HDI rating than a comparable aged site with the same stocking rate but minimal or no measurable understory. We measured the compatibility of habitat diversity and bird species diversity, density and richness among the 18 sample sites by Spearman's rank cor- relation (one-tailed test for positive correlation only). The numerical distribution of species (richness) among habitat types was tested for selection by the Chi-square test of goodness-of-fit. Results Plant Communities Total ground cover of brush and slash, raspberry (Rubiis spp.) and tree and shrub foliage < 2 m above ground declined during the years following cutting (Figure 1). The relation
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