2002-07-08_GENERAL DOCUMENTS - M2002004 (2)

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'FROM : HABITAT MANAGEMENT, INC. Diversity is a complex, frequently ambiguous concept. Imprecise if not erroneous use of the term is rampant, e_g., "lodgepoie really is quite diverse" (Barret 1995). Probably the best advice is to ask people what they mean by diversity, and how they would measure it (West 1993). More than a decade ago, DePuit (1984) identified some topsoiling strategies aimed at increasing vegetational diversity. In this paper, we consider concepts of diversity and how they are Treasured, identify factors that influence plant diversity, and suggest diversity strategies that can be incorporated into the reclamation processes_ Alpha Diversity PHCNE NO. : 303 _lye 4 ,' 1 r Jut. up eue v - LNTR.ODUCTION PART I: CONCEPTS AND MEASUREMENT OF DIVERSITY Scales of Diversity In considering diversity within the context of mineland reclamation, scale is the first consideration. The reclaimed field, assuming a relatively uniform soillsubstrate and seeding/planting regime, comprises a single habitat and plant c nu nimity. - Often sets of fields comprise similar sites with dosely allied plant communities. This is the scale of alpha diversity (Whittaker 1972), -also !mown as within - habitat diversity. Measures of within- habitat diversity include richness, species density, and heterogeneity_ Richness is most simply defined as the number of species observed in a macroplot or sample set of constant size. A species area curve that indicates adequate floristic sampling might be a better means of comparing ridhness than the same number of samples. We follow Peet and others (1983) in referring to the average number of species per small sample as species density. Since species counts vary temporally and are virtually unobtainable for large areas or numerous t n ununities, richness and density measurements as discussed in this paper are sample-based. Richness ignores species abundance. The concept of heterogeneity compounds richness with evenness (Peet 1974). Examples are the Simpson Index (descriptively titled "dominance ") and the Shannon Index, probably the most popular proportional - abundance index. The Simpson Index and the Shannon. Index are closely related (Pielou 1977, p_ 311), which has also been shown empirically for numerous prairie types in Montana (Prodgers 1978, pp. 64 -65). • Whereas richness is influenced by the particulars of sampling, the Shannon Index can be calculated from species composition summaries. Sampling irethods may differ as long as sampling is accevate and adequate. The formula follows: H' (Shannon Index) _ -Z p, log pi Where: p. is the relative cover expressed as a decimal. While log and log sometimes are used, there is a growing trend toward natural logs (ln or log e ) Results can be trans for comparisons. Bonham and others (1980) suggested comparing revegetation with reference areas or technical standards based on the relative contribution of each species to the total Shannon value. They suggest that a weighted average of H could be detenn fined from the If of each applicable reference area, but this sort of arithmetic is inappropriate. 142