Assessing the Conservation Value of a Complementary System of Habitat Reserves Relative to Butterfly Species at Risk and Divergent Populations
Shuey, John A., The American Midland Naturalist
Indiana's system of natural area reserves is evaluated to assess the system's conservation value for imperiled butterflies. This system of nature reserves was designed to conserve representative examples of all terrestrial community types present in the state. It is one of the more long-lived attempts to develop a representative conservation system in the United States. The system of complementary reserves appears to be conserving most of the state-imperiled butterfly fauna. Of the 38 species evaluated, 32 are known to occur on sites that are either part of the reserve system or on sites that have been identified as priority additions to the system of reserves. There are 187 known populations of state-imperiled butterflies within the nature reserve system and on other public lands. Species with specialized habitat requirements such as fen, prairie, glade and oak savanna are well represented in the system. The system fares less well at conserving species at the extreme periphery of their range. These species, which have few known populations in the state, are sparingly represented or are missed entirely by the system. A few rare, but widespread, species of forested habitats are also poorly represented in the system.
Four butterflies with discernable phenotypic variation are also evaluated to determine if the reserve system adequately captures phenotypic variability across the state. Divergent populations of all four species were captured within the system.
Including specific conservation goals and concepts for conserving butterflies and other insects in the context of broader conservation strategies is a relatively new trend. Most butterfly conservation efforts are focused at the level of species (Pyle, 1976, 1995; Pyle et al., 1981; Samways, 1997) or umbrella species which may serve as surrogates for other lesser known entities (Main, 1996; New, 1997). For example, New (1997) describes 22 Lepidoptera conservation case studies, all of which revolve around species-specific conservation targets. The conservation goal of such species-centric efforts has generally been limited to conserving only the rarest and most imperiled butterflies and populations. However, conservation of butterflies as an array requires that they be treated as a fauna, and goals should be developed at the faunal level. Ultimate success will require an effort that identifies and conserves all species at all levels of biological organization including genetic divergence at the population level.
The general conservation community, both academic and applied, has invested deeply in developing targeting systems for programs that maximize conservation impact while simplifying planning per se. Efforts to identify biological hot spots (Predergast, 1993; Dobson et al., 1997), indicator taxa (Lawton et al., 1998; Ricketts et al., 1999; Chaplin et al., 2000) and systems of complementary sites (Howard et al., 1998; Gaston et al., 2001; Groves, 2003) are intended to maximize conservation efficiency. These approaches all share the common thread of using surrogate systems/targets to identify sites for conserving broad arrays of communities, species and populations. These strategies represent compromises that balance available conservation resources and the need to act quickly against the potential negatives associated with the broad ecological generalizations and unknowns that pervade the practice of conserving biodiversity.
Indiana represents the extremes of conservation opportunity and implementation. The obstacles and constraints to conservation in the State are almost overwhelming. Located at the heart of North America's agricultural corn belt, vast tracts of the state are dominated by traditional row-crop agriculture. Less that 20% of the state's land is in natural cover, and even this is often degraded low-quality habitat. Public lands account for approximately 3% of the state (Jackson, 1997), one of the lowest percentages in the United States. …