Local spatial variation in species distributions is driven by a mix of abiotic and biotic factors, and understanding such hierarchical variation is important for conservation of biodiversity across larger scales. We sought to understand how variation in species composition of understory vascular plants, spiders, and carabid beetles is associated with concomitant spatial variation in forest structure on a 1-ha permanent plot in a never-cut mixedwood forest in central Alberta (Canada). Using correlations among dendrograms produced by cluster analysis we associated data about mapped distribution of all living and dead stems > 1 cm diameter at breast height with distributions of the three focal taxa sampled from regular grids across the plot. Variation in each of these species assemblages were significantly associated with several forest structure variables at various spatial scales, but the scale of the associations varied among assemblages. Variation in species richness and abundance was explained mostly by changes in basal area of trees across the plot; however, other variables (e.g., snag density and tree density) were also important, depending on assemblage. We conclude that fine-scale habitat variation is important in structuring spatial distribution of the species of the forest floor, even within a relatively homogeneous natural forest. Thus, assessments that ignore within-stand heterogeneity and management that ignores its maintenance will have limited utility as conservation measures for these taxa, which are major elements of forest biodiversity.
Usage Notes:
Biodiversity and Forest Structure at George Lake PSP
Data from a permanent sampling plot (PSP) in central Alberta (Canada). All live and dead stems with DBH > 1.0 cm were identified and mapped within a 1 Ha (100m x 100m) plot. The plot was subdivided into 25 non-overlapping subplots (20m x 20m) and stem data summarized at this level. In addition, from each of these 25 subplots, biodiversity data (ground-dwelling spiders and carabid beetles, foliage-dwelling spiders, and understory vascular plants) were collected. The data consists of six spreadsheets. The first sheet contains univariate summaries of forest structure for each subplot (live and dead stem density and basal area, and in three DBH classes: DBH1: 1.0-4.9 cm; DBH2: 5-20 cm; DBH3: > 20 cm). The second sheed contains multivariate summaries of forest structure for each subplot (live and dead stem density and basal area by species). The remaining sheets contain raw abundances (ground-dwelling spiders and carabid beetles, and foliage-dwelling spiders) or percent cover (understory vascular plants) for species collected and/or observed in each of the 25 subplots.
Pinzon et al_DOI_10.1111ecog.03379.xlsx