Litter quality and nutrient cycling affected by grazing‐induced species replacements along a precipitation gradient

By M. Semmartín, M. Aguiar, R. Distel, A. Moretto, C. Ghersa. 2004

127 citations recorded by the source corpus.

One of the potential mechanisms for the impact of herbivores on nutrient cycling is the effect of selective grazing on litter quality through changes in species composition. However, the scarce evidence collected on this mechanism is controversial and seemingly influenced by site-specific variables In this paper, we explored the consequences of grazing-induced changes in species composition on litter quality and nitrogen cycling with a regional perspective. Along a 900-mm of mean annual rainfall gradient, we selected species promoted and diminished by grazing from three natural rangelands of Argentina, analyzed their litter quality, and determined their decomposition and nutrient release kinetics under common greenhouse conditions. Litter quality and decomposition rates were strongly associated with plant response to grazing. However, the magnitude and direction of these differences depended on the ecosystem considered. In the wettest site, the species promoted by grazing (forbs) had higher nitrogen and phosphorus contents, faster decomposition rates, and higher release of nitrogen to the soil than species diminished by grazing (C 3 and C 4 grasses). In the intermediate and dry sites, species promoted by grazing had lower nitrogen and phosphorus contents, and slower decomposition rates than those diminished by grazing (C 3 grasses in both cases). Decomposition of the entire group of species was not correlated with mean annual rainfall, but when litter of the species diminished by grazing was analyzed, it was negatively correlated with precipitation. Nitrogen was immobilized more often than mineralized, even after one year of incubation. Immobilization was negatively correlated with precipitation. All these results indicate that grazing may significantly alter nutrient cycling by affecting litter quality through changes in species composition. These effects seem to be larger when species replacements induced by grazing either involve functional groups, as it was the case in our wettest site, or change root to shoot ratios. Therefore, the functional groups involved in the replacement of species as well as shifts between belowground and aboveground allocation should play a key role in grazing-induced changes on nitrogen cycling.

Subfields: Ecology, Nature and Landscape Conservation, Soil Science

View Paper: https://www.semanticscholar.org/paper/b0a3d89ec414ae6ab8db0df38dc38b3ba470d53f

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Ecology

1. M. Sternberg
2. Carly Golodets
3. J. Kigel
4. E. Chaneton

In Nature and Landscape Conservation

1. M. Sternberg
2. J. Kigel
3. L. Garibaldi
4. Carly Golodets
5. E. Chaneton

In Soil Science

1. M. Sternberg
2. Carly Golodets
3. J. Kigel

Citations in the corpus

• Recovery of plant species composition and ecosystem function after cessation of grazing in a Mediterranean grassland (2010, background): “We asked whether relationships observed in grasslands dominated by perennials (Altesor et al. 2005; Semmartin et al. 2004) are similar to grasslands dominated by annuals, such as Mediterranean grasslands which have been barely studied in this context.”
• Grazing history effects on above- and below-ground litter decomposition and nutrient cycling in two co-occurring grasses (2008, background): “The limited evidence on this topic suggests that idiosyncratic, intraspecific changes in litter decomposition as a function of prior grazing may be the norm (Ruess and McNaughton 1987; Jaramillo and Detling 1988; Polley and Detling 1988; Holland et al. 1992; Smith 1998; Semmartin et al. 2004).”