A Quantitative Assessment of the Conservation Benefits of the Wetlands Reserve Program to Amphibians

Abstract

The Mississippi Alluvial Valley (MAV) originally consisted of nearly contiguous bottomland hardwood (BLH) forest encompassing approximately 10 million hectares. Currently, only 20–25% of the historical BLH forests remain in small patches fragmented by agricultural lands. The Wetlands Reserve Program (WRP) was established to restore and protect the functions and values of wetlands in agricultural landscapes. To assess the potential benefit of WRP restoration to amphibians, we surveyed 30 randomly selected WRP sites and 20 nearby agricultural sites in the Mississippi Delta. We made repeat visits to each site from May to August 2008 and performed both visual encounter and vocalization surveys. We analyzed the encounter history data for 11 anuran species using a Bayesian hierarchical occupancy model that estimated detection probability and probability of occurrence simultaneously for each species. Nine of the 11 species had higher probabilities of occurrence at WRP sites compared to agriculture. Derived estimates of species richness were also higher for WRP sites. Five anuran species were significantly more likely to occur in WRP than in agriculture, four of which were among the most aquatic species. It appears that the restoration of a more permanent hydrology at the WRP sites may be the primary reason for this result. Although amphibians represent only one group of wildlife species, they are useful for evaluating restoration benefits for wildlife because of their intermediate trophic position. The methods used in this study to evaluate the benefit of restoration could be used in other locations and with other groups of indicator species.

Wetland Reserve Program Enhances Site Occupancy and Species Richness in Assemblages of Anuran Amphibians in the Mississippi Alluvial Valley, USA

“…Our results correspond with known habitat associations of these species (Table 1; Lichtenberg et al 2006) and indicate that patches undergoing restoration after cultivation may be an important transitional habitat for anuran species frequently associated with natural, forested wetlands. Although the relatively short term nature of our study may limit the scope of our inference somewhat, our results support the conclusion of other studies that conservation practices such as restoring wetlands under the WRP are successful in reducing the impact of cultivation-induced habitat loss on amphibian populations (Balas et al 2012;Waddle et al 2013). …”

“…Using amphibians as indicators of restoration success, Balas et al (2012) and Waddle et al (2013) demonstrated the effectiveness of conservation practices implemented under the WRP, and the results of the present study support their findings. Amphibian populations are declining at an alarming rate on public lands in the USA (Adams et al 2013), but the status of amphibians is currently unknown on the nearly 60 % of land in the United States that is privately owned (Nickerson et al 2011;Meyer et al 2012).…”

“…The higher occurrence of these four species in WRP sites may be a function of their affinities for several features of restored wetlands, including longer hydroperiods due to the presence of water control structures (Venne et al 2012;Waddle et al 2013); higher densities of herbaceous (as opposed to woody) plant cover around wetland margins, along with the presence of herbaceous leaf litter; and a lack of forest canopy (Guerry and Hunter 2002;Lichtenberg et al 2006; Table 1). The extent of canopy cover over breeding ponds and the amount and composition of leaf litter in pond basins are factors that play a strong role in the distribution and abundance of some species of amphibians.…”

“…Amphibians are useful bioindicators of habitat quality and restoration success (Waddle 2006;Dixon et al 2011;Guzy et al 2012;Waddle et al 2013). Worldwide, amphibians are experiencing the most severe population declines of all the vertebrate groups, primarily because of loss and modification of suitable habitat (Collins and Storfer 2003;Stuart et al 2004Stuart et al , 2008Becker et al 2007;Gallant et al 2007;Becker et al 2010;Collins 2010).…”

“…Wetland restoration and creation are beneficial for many aquatic-breeding amphibians (e.g. Korfel et al 2010;Lesbarrères et al 2010;Shulse et al 2010;Brown et al 2012;Shulse et al 2012), but few studies have directly addressed the responses of amphibians to restoration associated with conservation programs (Faulkner et al 2011;Balas et al 2012;Waddle et al 2013).…”