Spatiotemporally variable management by grazing and burning increases marsh diversity and benefits amphibians: A field experiment

Abstract

Ecosystem management often aims to maintain a diversity of habitats to benefit a large number of species within a landscape. We studied the effects of wetland management by lowintensity cattle-grazing and late-summer burning on marsh vegetation and globally declining anuran amphibians (frogs and toads) in a previously homogeneous reedbed. Burning effectively removed old reed and increased the variability of reed cover and marsh vegetation by the next spring. However, reed grew back strong in areas burned 2 or 3 years before the study, indicating that fire rejuvenates reedbeds. In contrast, cattle-grazing kept reed cover homogeneously low and created open water surfaces. The number of amphibian species and individuals decreased with mean reed cover and old reed density, and increased with variability in reed cover. Correspondingly, amphibian richness and counts were greatest in newly burned areas the next spring. In contrast, a year later, richness and counts were greatest in grazed-only areas, with large decreases in newly burned and control areas. Our results suggest that combined management with grazing and burning can create different habitat patches, some of which will be optimal for amphibians in one year, whereas other patches may become suitable in a subsequent year when successional changes alter previously optimal patches. To maximize optimal habitats, mosaic management should repeat burning once every 2 or 3 years in a rotational manner, and also maintain low-intensity cattle-grazing, which controls reeds and benefits amphibians more sustainably. Our study supports spatiotemporally varied management to facilitate habitat heterogeneity and complexity in dynamic landscapes.

Amphibian responses to livestock use of wetlands: new empirical data and a global review

“…Because rangeland ecosystems tend to be more compatible with wildlife use than other more intensive forms of agriculture, they may be able to contribute to an "off-reserve" system designed to reduce global biodiversity losses (Delaney and Linda 1994, Morrison and Humphrey 2001, Babbitt et al 2009). The results of our literature review and empirical data set support the notion that for at least some amphibian species, particularly ones with an evolutionary history tied to open-canopy habitats, a well-managed rangeland is compatible with maintaining amphibian species richness and may act either as a compliment to protected areas or in special cases serve as a stand-alone reservoir of viable populations (Homyack and Giuliano 2002, Burton et al 2009, Verga et al 2012, Mester et al 2015. In peninsular Florida, the high number of seasonally inundated wetlands Tanner 2000, Baber et al 2002) and intact woodlands present on many ranches provide enough habitat to maintain high amphibian diversity while simultaneously being used for commercial cattle production (Babbitt et al 2006(Babbitt et al , 2009.…”

“…, Mester et al. ). In peninsular Florida, the high number of seasonally inundated wetlands (Babbitt and Tanner , Baber et al.…”

Freshwater biodiversity conservation through source water protection: Quantifying the potential and addressing the challenges

“…The relationship between animal grazing and freshwater ecosystems is complicated. Because grasslands can require natural disturbance or active management to prevent succession to forest, grazing at certain levels and times of the year may be an appropriate and necessary activity in some systems, and can contribute to maintaining native freshwater biodiversity (Bloom, Howerter, Emery, & Armstrong, 2013;Marty, 2015;Mester, Szalai, Mero, Puky, & Lengyel, 2015); however, overgrazing can have impacts on sediment and nutrient delivery, as well as on hydrology. Furthermore, livestock congregating in riparian zones and entering streams in order to cross or gain access to water can have direct impacts on stream banks and can introduce bacterial and nutrient contaminants into the water, as well as increase sediments (Fitch & Adams, 1998).…”

Long-term effects of rotational wetland mowing on breeding birds: evidence from a 30-year experiment

“…The impact of grazing on the soil is also more heterogeneous, which can, under some circumstances, favour the establishment of shrubs. To prevent this, grazing is often used in combination with burning, with promising results (Middleton et al 2006;Little et al 2015;Mér} o et al 2015;Mester et al 2015). Preliminary tests of grazing are ongoing in the Grande Cariçaie reserves and will give insights onto how widely applicable this technique is.…”