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

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r [Nui s • nno l ink I inp v r rrLW1 1 VV. • JtJJ ( v 1 The application of Whittaker's beta diversity to reclaimed areas is problematic for two reasons. In coal reclamation, environmental differences between fields are minor and random. Samples on a 100 - meter grid exhibit spatial independence with respect to soil parameters (Keck and others 1993), a situation better described as a complex than a geographic gradation. However, trend analysis did reveal some larger -scale correlation in the depth of topsoil application. Blending or burying 'unsuitable' soils homogenizes soils while destroying structure; at the Same time, disparate topsoils and subsoils often are combined in unnatural profiles. In short, habitat factors in reclamation are both more homogeneous and less connected than in many natural landscapes. Even if a unifying habitat gradient existed, the recentness of plantings would overshadow any gradient manifestations in vegetation composition. It is entirely possible to fill the same habitat with two dissimilar plant communities_ Thanks to the power of initial floristics and vegetational inertia, significant changes in composition due to succession and niche differentiation may not be evident during the career of the plant ecologist who initially inventoried the revegetated communities. Our opinion is that determining beta diversity floristically is inappropriate in revegetation. hi a reclamation setting, discrete "habitats" can be distinguished directly, then associated biotic elements may be inventoried if desired. Gamma and Landscape Diversity Whittake? s (1972) gamma diversity refers to species diversity for a range of habitats. Whereas beta diversity is measured in ratios or differences, gamma diversity shares the units of alpha diversity. Gamma diversity is the outcome of both alpha and beta diversity, but in a practical application to revegetation, one could inventory units of any size larger than fields using richness, heterogeneity, etc. Whether alpha or gamma diversity is being measured, and the distinction may not be clear, the parameters are the same. Distinct from gamma diversity, regional landscape diversity refers to kilometers -wide areas in which visually distinctive plant communities or stands form mosaics or complexes. Our wester 's rangelands exhibit both monotonous basins and plains and areas of breathtaking diversity. The latter are found in areas with highly varied topography and abrupt soil/substrate change, sometimes with an altitudinal or moisture gradient. The former often is modeled in reclamation in the form of broad expanses of uniform habitat and closely allied plant communities. Visually similar plant communities, no matter how dissimilar in species composition, do not contribute to landscape diversity. Community structure (physiognomy) and color are key factors in diversity at this scale_ Whether landscape diversity is an issue depends on the size and shape of the mine and differences between premine and postrnine vegetation at the physiognomic level. From a regional landscape perspective, the 5,000 or so reclaimed acres at Western Energ)'s Rosebud Mine in southeastern Montana provide a unique patch of very productive cool - season grasslands against a background of alluvial valleys and sandswne(scoria or gumbo ridges. Since the plant communities associated with such landforms are common, perhaps we should rethink the need to re establish them in reclaimed areas. This is a hornet's nest because it inevitably involves considering off -mine land use and vegetational patterns. Where reclamation occupies several sections in a blocky pattern, local landscape diversity may well be a concern. The physiognomy of plant communities rather than their composition is there the appropriate focus. 144 Jul. G.J GtJ J e; ,iirm