Grass litter responses to warming and N addition: temporal variation in the contributions of litter quality and environmental effects to decomposition

Abstract

Aims We explored how climate warming and increased atmospheric nitrogen (N) deposition may influence grass litter decomposition over time, how litter quality versus environmental effects contribute to these responses, and the importance of these responses over winter. Methods We used litter bags to examine decomposition over 2 years in a warming and N addition field experiment, and examined the contributions of litter quality and environment to these responses by transferring litter reciprocally between the treatment plots and a common garden. Results Warming increased mass loss over the first year for Bromus inermis litter, which was consistent with the litter quality response, but by the second year there was no overall warming effect, and this change coincided with a negative environmental effect of warming. N addition increased mass loss and was more influential than warming in the early stages of Poa pratensis litter decomposition; the N effect appeared to be driven primarily by litter quality. Winter decomposition was not a substantial component of the treatment responses. ConclusionsOur results indicate that litter quality and environmental effects play different roles at different time scales in the decomposition responses of grass litter to warming and N addition, and these responses can be species specific.

Mass loss and nutrient dynamics during litter decomposition in response to warming and nitrogen addition in a desert steppe

“…In contrast to our findings, warming was found to decrease litter decomposition in low moisture treatment in a microcosm experiment [5] or have no significant effect on mass loss when moisture limitation occurred in a field experiment [26] . We suspect the differences between the results of that field study [26] and ours can be partly explained by the fact that long-term mean annual precipitation is much lower in our grassland (280 mm) than in that mesic old field (818 mm). When water availability becomes limited, the relatively wet ecosystem would be more sensitive than our arid grassland.…”

“…With respect to N addition, litter mass loss increased with the added N during the 2-year decomposition, which is consistent with previous studies [11,13,26] . However, N addition was found to have no significant effect on decomposition [15] or even reduce litter mass loss [14,30] .…”

“…The effect of increased temperature on litter decomposition has been extensively studied [23][24][25][26] . However, consistent results have not been obtained.…”

Effects of trees and nitrogen supply on macronutrient cycling in integrated crop–livestock systems

“…(2013), observed a t 1/2 of 50 d for the black oat residual biomass at the grazed areas. Differences in environmental conditions and nutrient supply, such as N fertilization via litter quality and decomposer effect, can explain the differences in the results between these sites (Aerts, 2006; Henry & Moise, 2014; Knorr et al., 2005).…”

“…Increasing N availability can stimulate decomposition by increasing the litter quality (Costa et al., 2014); however, this response can be species specific (Henry & Moise, 2014). High quality (low lignin) litter responds more to N, that is, litter decomposition is stimulated by N addition (Knorr, Frey, & Curtis, 2005).…”