Landscape analysis of plant diversity

Studies to identify gaps in the protection of habitat for species of concern have been inconclusive and hampered by single-scale or poor multi-scale sampling methods, large minimum mapping units (MMU's of 2 ha to 100 ha), limited and subjectively selected field observations, and poor mathematical and ecological models. We overcome these obstacles with improved multi-scale sampling techniques, smaller MMU's (< 0.02 ha), an unbiased sampling design based on double sampling, improved mathematical models including species-area curves corrected for habitat heterogeneity and geographic information system-based ecological models. We apply this landscape analysis approach to address resource issues in Rocky Mountain National Park, Colorado. Specifically, we quantify the effects of elk grazing on plant diversity, identify areas of high or unique plant diversity needing increased protection, and evaluate the patterns of non-native plant species on the landscape. Double sampling techniques use satellite imagery, aerial photography, and field data to stratify homogeneous and heterogeneous units and ''keystone ecosystems'' (ecosystems that contain or support a high number of species or have distinctive species compositions). We show how a multi-scale vegetation sampling design, species-area curves, analyses of within-and between-vegetation type species overlap, and geographic information system (GIS) models can be used to quantify landscape-scale patterns of vascular plant diversity in the Park. The new multi-scale vegetation plot techniques quickly differentiated plant species differences in paired study sites, Three plots in the Ouzel Burn area (burned in 1978) contained 75 plant species, while only 17 plant species were found in paired plots outside the burn. Riparian areas contained 109 plant species, compared to just 55 species in paired plots in adjacent forests. However, plant species richness patterns inside and outside elk exclosures were more complex, One elk exclosure contained more species than its adjacent open range (52 species inside and 48 species outside). Two elk exclosures contained fewer species inside than outside (105 and 41 species inside and 112 and 74 species outside, respectively). However, there was only 26% to 48% overlap (using Jaccard's Coefficient) of plant species composition inside and outside the exclosures. One elk exclosure had 13% cover of non-indigenous species inside the exclosure compared to 4% outside, but non-indigenous species cover varied by location. We compared plant diversity patterns from vegetation maps made with 100 ha, 50 ha, 2 ha, and 0.02 ha MMU's in the 754 ha Beaver Meadows study area using four 0.025 ha and twenty-one 0.1 ha multi-scale vegetation plots. Preliminary data suggested that the 2 ha MMU provided an accurate estimate of the number of plant species (-14%) for a study area, but the number of habitats (polygons) was reduced by 67%, and aspen, a unique and important habitat type, was missed entirely, We describe a hypothesis-driven approach to the design and implementation of geospatial databases for local resource monitoring and ecosystem management.