Regional analysis of litter quality in the central grassland region of North America

Abstract

Abstract. The central grassland region of North America is characterized by large gradients of temperature and precipitation. These climatic variables are important determinants of the distribution of plant species, and strongly influence plant morphology and tissue chemistry. We analysed regional patterns of plant litter quality as they vary with climate in grassland ecosystems throughout central North America including tall‐grass prairie, mixed grass prairie, shortgrass steppe, and hot desert grasslands. An extensive database from the International Biological Program and the Long‐Term Ecological Research Program allowed us to isolate the effects of climate from those of plant functional types on litter quality. Our analysis of grass species confirms a previously recognized positive correlation between C/N ratios and precipitation. Precipitation exhibited a similar positive relationship with lignin/N and percent lignin. Although there was no significant correlation between temperature and C/N, there was a significant positive relationship between temperature and both percent lignin and lignin/N. Among functional types, C3 grasses had a slightly lower C/N ratio than C4 grasses. Tall grass species exhibited higher C/N, lignin/N, and percent lignin than short grass species. This understanding of the regional patterns of litter quality and the factors controlling them provides us with a greater knowledge of the effect that global change and the accompanying feedbacks may have on ecosystem processes.

Conservation of nitrogen increases with precipitation across a major grassland gradient in the Central Great Plains of North America

“…While the majority of the data collected in this study agrees with previously reported values for the region (Burke et al 1989;Clark 1977;Epstein et al 1997;Johnson and Matchett 2001;Murphy et al 2002), the fact that we report litter decomposition rates to be fastest and slowest in the mixed grass prairie sites is somewhat unique. However, our litter decomposition results support those of recent studies utilizing Long-Term Inter-site Decomposition Experiment data that show litter chemistry is a primary determinant of aboveground decomposition rates (Bontti et al 2008;Parton et al 2007).…”

“…However, the trends in litter quality across sites were parallel during the two collection periods and reflect previously reported regional trends in litter quality of senescent plant material (Murphy et al 2002). Therefore, while decomposition rates reported here may be somewhat higher than would be measured on senescent material from each site, we think the regional patterns we observed are robust.…”

“…However, N use efficiency (NUE), C:N ratios, and %lignin of the vegetation have been shown to increase in a similar fashion across this bio-climatic gradient (Murphy et al 2002). Thus, the dominant controls on N mineralization rates (climate and substrate quantity and quality) are arrayed in contrasting patterns across this grassland region.…”

Intrinsic effects of species on leaf litter and root decomposition: a comparison of temperate grasses from North and South America

“…Finally, the environment can indirectly influence decomposition through its effect on litter quality (Coû teaux et al 1995;Aerts 1997). This interaction between the climate and litter quality has been reported for single species along a precipitation gradient (e.g., Austin and Vitousek 1998;Murphy et al 2002) and also as a global trend across latitude (McGroddy et al 2004). As a result, the interactions between environmental conditions and their effect on litter chemistry make it difficult to disentangle the relative importance of intrinsic effects of species on litter decomposition from the indirect effects of environmental characteristics on litter quality parameters.…”

Responses of a desert nematode community to changes in water availability

“…Plants, especially in arid ecosystems, have strategies that conserve moisture, which enable them to withstand periods of drought longer than bacteria or fungi. When altered levels of water availability persist over longer timescales, changes in plant growth and resource allocation lead to changes in litter quantity, and changes in plant species composition result in altered litter quality (Murphy et al 2002, Cleland et al 2013. These litter changes in turn are expected to affect the structure of nematode communities through changes in abiotic factors and microbial communities (Sanaullah et al 2011).…”