Amphibians are essential components of many natural ecosystems. They are indicators of ecosystem health (Freda and Dunson 1986; Hager 1998) and have important functions in natural food webs (Cortwright 1988; Fauth and Resetarits 1991; Holomuzki et al. 1994). Amphibian populations have declined in the US Midwest (Lannoo et al. 1994; Christiansen 1998; Thurow 1999) and on a global scale (Houlahan et al. 2000; Stuart et al. 2004). Habitat loss, degradation and fragmentation are major threats to amphibian conservation (Knutson et al. 1999; McCollough 1999; Dodd and Smith 2003). For example, the sand prairie-savanna-wetland mosaic of the Grand Kankakee Marsh, Beaver Lake and wet-mesic sand prairie ecosystems in northwest Indiana south of the Kankakee River was drained, cleared, and converted to agriculture in the late 19th and early 20th century (Smallwood and Osterholz 1990). Remaining habitats suitable for use as amphibian breeding sites are now highly fragmented and degraded. Habitat alteration is estimated to have reduced amphibian populations 90-95% in northwest Indiana (Brodman and Kilmurry 1998; Brodman et al. 2002). Remaining populations are often restricted to small uncultivated patches and three state-owned natural areas (Brodman and Kilmurry 1998). Corridors and connectivity of remaining patches of habitat have a positive affect on animal movement and diversity (Debinski and Holt 2000). Because aquatic amphibian eggs and larvae are vulnerable to predation by fish, the primary management objective for conserving amphibians is to preserve complexes of small ephemeral and large semi-permanent wetlands adjacent to terrestrial habitat favorable for adult survival (McWilliams and Bachmann 1988; Semlitsch and Bodie 1998). Terrestrial buffer zones should extend at least 200 m beyond the wetland margin (Semlitsch 1998). A substantial amount (3000 ha) of farmland at Kankakee Sands in Newton County, Indiana, USA, is being restored to sand prairie (especially wet-mesic sand prairie), sand oak savanna and marsh habitats by The Nature Conservancy (Fig. 1). The intent of the restoration at Kankakee Sands is to form 8500 ha of contiguous habitat by connecting three disjunct stateowned natural areas: Willow Slough Fish & Wildlife Area, Beaver Lake Prairie, and Conrad Savanna Nature Preserves.
These habitats are dominated by sandy ecosystems that are distinct, and ecologically diverse (Meyer 1936, Smith and Minton 1957; Schneider 1966; Post 1997). The Indiana Natural Heritage Data Center (INHDC) considers these sandy habitats to feature significant high quality natural communities and less than 0.5% of these remain in Indiana. The INHDC has ranked natural communities at the state level. State data on natural communities has been synthesized by NatureServe into global ranks. Sand prairie is considered globally rare and state imperiled in Indiana, while sand oak savanna is globally and state imperiled. The most globally significant native community in the area is wet-mesic sand prairie which is considered to be globally critically imperiled and has been almost eliminated from Indiana (INHDC). Habitat restoration is required to conserve the unique amphibian community that is associated with these sandy, now fragmented, ecosystems (Smith and Minton 1957; Brodman 1998a).
Wetland habitat restoration has been shown to facilitate repatriation of a few focal amphibian species (Cortwright 1998; Sexton et al. 1998; Merovich and Howard 2000; Pechmann et al. 2001); however, little is known about the long-term colonization of amphibian populations at the ecosystem or landscape level. The large-scale habitat restoration at Kankakee Sands provides an opportunity to study colonization and recovery of amphibian biodiversity in a fragmented landscape and to assess landscapelevel ecosystem restoration as a tool for biodiversity conservation.
sandy ecosystems that are distinct, and ecologically diverse (Meyer 1936, Smith and Minton 1957; Schneider 1966; Post 1997). The Indiana Natural Heritage Data Center (INHDC) considers these sandy habitats to feature significant high quality natural communities and less than 0.5% of these remain in Indiana. The INHDC has ranked natural communities at the state level. State data on natural communities has been synthesized by NatureServe into global ranks. Sand prairie is considered globally rare and state imperiled in Indiana, while sand oak savanna is globally and state imperiled. The most globally significant native community in the area is wet-mesic sand prairie which is considered to be globally critically imperiled and has been almost eliminated from Indiana (INHDC). Habitat restoration is required to conserve the unique amphibian community that is associated with these sandy, now fragmented, ecosystems (Smith and Minton 1957; Brodman 1998a).
Wetland habitat restoration has been shown to facilitate repatriation of a few focal amphibian species (Cortwright 1998; Sexton et al. 1998; Merovich and Howard 2000; Pechmann et al. 2001); however, little is known about the long-term colonization of amphibian populations at the ecosystem or landscape level. The large-scale habitat restoration at Kankakee Sands provides an opportunity to study colonization and recovery of amphibian biodiversity in a fragmented landscape and to assess landscapelevel ecosystem restoration as a tool for biodiversity conservation. We collected data on amphibian populations for five years during a six year period to assess the effect of ecosystem restoration on amphibian biodiversity. For the purpose of this study, an amphibian population is defined by each species that is detected breeding at a wetland or found in adjacent uplands. For example if a site has four species of amphibians breeding in a wetland and using adjacent upland habitat, then that site would have four amphibian populations. Amphibian populations are considered distinct if breeding sites are separated by > 200 m. Therefore, a species found at two water bodies separated by
Our objectives were to: 1) Determine the number of amphibian breeding sites, the number of amphibian populations at each breeding site, the abundance of each population at each site, and the number of species (species richness) of amphibians at Kankakee Sands prior to restoration and in restored habitats; 2) Test the following predictions of colonization: a) colonization will be faster in the southwestern habitats of Kankakee Sands that are adjacent to species rich Willow Slough (Brodman et al, 2002) and recovery of amphibian diversity will generally move from southwest to northeast, b) species that can dig into the cultivated soil during dry periods, such as toads (genus Bufo) and Tiger Salamanders (Ambystoma tigrinum), and those species that survive well in mesic and wet prairies, such as Northern Leopard Frogs (Rana pipiens) and Western Chorus Frogs (Pseudacris triseriata), will colonize wetlands before other species.
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