Effects of belowground litter addition, increased precipitation and clipping on soil carbon and nitrogen mineralization in a temperate steppe

Abstract

Abstract. Soil carbon (C) and nitrogen (N) cycling are sensitive to changes in environmental factors and play critical roles in the responses of terrestrial ecosystems to natural and anthropogenic perturbations. This study was conducted to quantify the effects of belowground particulate litter (BPL) addition, increased precipitation and their interactions on soil C and N mineralization in two adjacent sites where belowground photosynthate allocation was manipulated through vegetation clipping in a temperate steppe of northeastern China from 2010 to 2011. The results show that BPL addition significantly increase soil C mineralization rate (CMR) and net N mineralization rate (NMR). Although increased precipitation-induced enhancement of soil CMR essentially ceased after the first year, stimulation of soil NMR and net nitrification rate continued into the second year. Clipping only marginally decreased soil CMR and NMR during the two years. There were significant synergistic interactions between BPL addition (and increased precipitation) and clipping on soil CMR and NMR, likely to reflect shifts in soil microbial community structure and a decrease in arbuscular mycorrhizal fungi biomass due to the reduction of belowground photosynthate allocation. These results highlight the importance of plants in mediating the responses of soil C and N mineralization to potentially increased BPL and precipitation by controlling belowground photosynthate allocation in the temperate steppe.

Carbon and nitrogen dynamics of native <i>Leymus chinensis</i> grasslands along a 1000 km longitudinal precipitation gradient in northeastern China

“…Such lack of response of the root biomass to precipitation variability was likely because nutrients limit root growth along the gradient. Although we cannot prove this point, manipulating N and water experiments demonstrated that N addition accelerated plant growth, especially root growth, whereas there was no effect of water addition on root biomass in this study region (Lü et al, 2010;Ma et al, 2012Ma et al, , 2013Xiao et al, 2007).…”

“…Higher mineralization processes typically indicate instability of soil organic matter (Trumbore, 1997). There is plenty of evidence to demonstrate that soil respiration and net N mineralization increased with precipitation and water availability in water-limited regions (Sierra, 1997;Barrett et al, 2002;Paul et al, 2003;McCulley et al, 2005;Ma et al, 2013). According to Stanford and Epstein (1974), the maximum net N mineralization rate occurs when soil moisture is close to field capacity.…”

Litter chemical structure is more important than species richness in affecting soil carbon and nitrogen dynamics including gas emissions from an alpine soil

“…Similar results were found in other ecosystems (Huang et al 2004;Mungai and Motavalli 2006;Jiang et al 2013;Begum et al 2014). The enhanced emissions may be due to the supply of energy during litter decomposition, which can stimulate significantly microbial activity (Ma et al 2013). Alpine steppe soil was the Bsink^of CH 4 , and litter treatments either decreased or had no effect.…”

“…Plant litter is the greatest source of soil organic matter (SOM), and its decomposition can form humus substances and organic layers in most natural ecosystems (Berg and Laskowski 2005). However, some studies claimed that litter inputs did not necessarily translate into increased SOM sequestration in nutrition-limited ecosystems, because microbial activity may be stimulated to such a degree that most or all of the added litter is decomposed rapidly (Rinnan et al 2008;Ma et al 2013). In our study, litter treatments (single and mixed litter) generally enhanced SOC, TN, WSOC, and WSON compared to the initial soil (Tables 3 and 4), and thus, it is reasonable to conclude that, in the cold and semiarid alpine steppe, litter decomposition is still able to cause SOM sequestration due to relatively low microbial activity (Table 4).…”

Soil moisture and land use are major determinants of soil microbial community composition and biomass at a regional scale in northeastern China

“…It has been shown that land use changes lead to great variation in soil microbial community composition in diverse ecosystems (Drenovsky et al, 2010), though their impacts depend on many factors, including the original vegetation that is being replaced and associated land management practices such as tillage and fallow periods, as well as related water and nutrient applications such as irrigation and fertilization (Scanlon et al, 2007;Ma et al, 2013;Yang et al, 2013;Chen et al, 2014). In one study, Drenovsky et al (2010) reported that distinct microbial communities were associated with land use types and disturbance at the regional scale in California.…”