Final Report: The Structure of Diversity: Implications for Reserve DesignEPA Grant Number: R826102
Title: The Structure of Diversity: Implications for Reserve Design
Investigators: Ellstrand, Norman C.
Institution: University of California - Riverside
EPA Project Officer: Hahn, Intaek
Project Period: November 1, 1997 through October 31, 2000
Project Amount: $272,495
RFA: Exploratory Research - Environmental Biology (1997) RFA Text | Recipients Lists
Research Category: Biology/Life Sciences , Ecosystems
The goal of the research was to assess the consequences of alternative reserve design strategies on the maintenance of different levels of diversity. The research system comprised five rare plant taxa endemic to limestone and dolomite soils in the San Bernardino Mountains of southern California (Astragalus albens, Erigeron parishii, Eriogonum ovalifolium var. vineum, Lesquerella kingii ssp. bernardina, and Oxytheca parishii var. goodmaniana) and their associated communities. The research set out to answer the following questions: (1) Do general reserve guidelines applied to a species distribution conserve genetic diversity (in terms of allozyme variation), maintain likelihood of species persistence, conserve general species diversity, or conserve community diversity? (2) Do general reserve guidelines applied at the ecosystem level conserve individual rare species in terms of genetic (allozyme) diversity, likelihood of species persistence, conservation of general species diversity, or conservation of community diversity? (3) Does a reserve designed for one species adequately protect other rare taxa in the same community? (4) Are multiple species more effectively conserved in terms of likelihood of persistence and genetic diversity by using a species-by-species or by using a community approach?
Results and Relationship to Goals of the Project
Patterns of biological diversity at three levelsvegetation community, species richness, and allozyme diversity within the endemic taxawere described and compared. Vegetation diversity was characterized using ordination and classification of shrub, overstory, and perennial bunchgrass taxa, and 15 environmental variables in 669 0.04 hectare plots. A total of 502 vascular plant taxa were identified with a mean of 23.5 taxa per plot. Eight widespread vegetation types were distributed along one gradient that was primarily related to elevation and a second gradient related to percent soil calcium and slope angle. Species richness was calculated for each plot.
Allozyme diversity was assessed for four of the endemic taxa collected from a subset of the vegetation plots if at least one of the taxa were present. The endemic Lesquerella proved to be intractable for genetic analysis of apparent polyploidy. For the taxa analyzed, allozyme diversity was above or comparable to values from other studies of endemic plant taxa.
Potential for conserving diversity by encompassing the geographical range of elements at each level and for simultaneously conserving multiple levels was assessed. Relationships between patterns of species richness, distribution of endemic species, and measures of allozyme diversity were compared within the ordination gradients. The pattern of diversity at any one of these three levels did not correspond to the pattern of diversity at either of the other two levels. Each endemic taxon occurred in small and mostly nonoverlapping portions of the gradients and thus did not represent the range of vegetation diversity. Plots occupied by at least one endemic taxon supported fewer total taxa than the same number of plots chosen at random. Species-rich plots did not support most occurrences of the endemic taxa. There was no relationship between measures of allozyme diversity within taxa and either species richness or community composition.
Significance to the Field and How the Research Adds to Our Understanding of Reserve Design for Protection of the Environment
If a single reserve based on protecting a single level of diversity results in preserving multiple levels of diversity, then the costs of conservation can be minimized. However, that reserve design depends on the assumption that different levels of diversity have similar spatial structure. This research examined that assumption. The data collected in this study, which to our knowledge is the first of its kind, demonstrate that a reserve structured to optimize diversity at one level would simultaneously fail to optimize diversity at the other levels measured. Therefore, in this system, and likely many others, a single measure of biotic diversity cannot be used as the sole biological criterion for reserve design.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
|Other project views:||All 5 publications||4 publications in selected types||All 4 journal articles|
||Neel MC, Ross-Ibarra J, Ellstrand NC. Implications of mating patterns for conservation of the endangered plant Eriogonum ovalifolium var. vineum (Polygonaceae). American Journal of Botany 2001;88(7):1214-1222.||
||Neel MC, Ellstrand NC. Patterns of allozyme diversity in the threatened plant Erigeron parishii (Asteraceae). American Journal of Botany 2001;88(5):810-818.||
||Neel MC, Cummings MP. Effectiveness of conservation targets in capturing genetic diversity. Conservation Biology 2003, Volume: 17, Number: 1 (FEB), Page: 219-229.||
||Neel MC, Cummings MP. Genetic consequences of ecological reserve design guidelines: An empirical investigation. Conservation Genetics 2003;4(4):427-439.||