Organic Matter and Water Addition Enhance Soil Respiration in an Arid Region

Abstract

Climate change is generally predicted to increase net primary production, which could lead to additional C input to soil. In arid central Asia, precipitation has increased and is predicted to increase further. To assess the combined effects of these changes on soil CO2 efflux in arid land, a two factorial manipulation experiment in the shrubland of an arid region in northwest China was conducted. The experiment used a nested design with fresh organic matter and water as the two controlled parameters. It was found that both fresh organic matter and water enhanced soil respiration, and there was a synergistic effect of these two treatments on soil respiration increase. Water addition not only enhanced soil C emission, but also regulated soil C sequestration by fresh organic matter addition. The results indicated that the soil CO2 flux of the shrubland is likely to increase with climate change, and precipitation played a dominant role in regulating soil C balance in the shrubland of an arid region.

Precipitation alters plastic film mulching impacts on soil respiration in an arid area of Northwest China

“…Therefore, the barrier of the plastic mulch would contain the CO2 141 underneath, which would restrain CO2 production and emission. Berger et al (2013) 142 found extraordinarily low N2O fluxes from the plastic mulch and that N2O emission and semiarid regions (Lai et al, 2013). Discrete precipitation pulses are important 174 triggers for the activity of plants and microbes and these factors combine to influence 175 the carbon balance (Huxman et al, 2004).…”

Landscape Position Influences Microbial Composition and Function via Redistribution of Soil Water across a Watershed

“…Fluxes of carbonaceous gases, such as carbon dioxide (CO 2 ) and methane (CH 4 ), significantly affect the size of the carbon sink, with soil respiration accounting for the largest terrestrial CO 2 flux to the atmosphere (2). CO 2 in soil pore spaces is derived primarily from autotrophic (root) and heterotrophic (microbe) respiration, which is mediated by environmental factors such as temperature, soil water content (SWC), O 2 availability, and organic matter (3)(4)(5). The direction and intensity of CH 4 flux depends on the local balance of the CH 4 consumption by methanotrophs and CH 4 production by methanogens, both of which also are subject to such environmental influences.…”

“…CO 2 in soil pore spaces is derived primarily from autotrophic (root) and heterotrophic (microbe) respiration, which is mediated by environmental factors such as temperature, soil water content (SWC), O 2 availability, and organic matter (3)(4)(5). The direction and intensity of CH 4 flux depends on the local balance of the CH 4 consumption by methanotrophs and CH 4 production by methanogens, both of which also are subject to such environmental influences. Because diffusive gas transport through soils is reduced with increasing SWC, hydrologic variations can strongly affect soil O 2 levels, which in turn influence the relative rates of (anaerobic) methanogenesis and (aerobic) methanotrophy.…”

“…Because diffusive gas transport through soils is reduced with increasing SWC, hydrologic variations can strongly affect soil O 2 levels, which in turn influence the relative rates of (anaerobic) methanogenesis and (aerobic) methanotrophy. Although saturated soils (e.g., wetlands) are major terrestrial sources of CH 4 emissions (6), emission may at times occur from unsaturated soils, depending on the finescale heterogeneity of soil redox status (7); in some cases, CH 4 source/sink switching behavior is observed with seasonal flooding or drydown (8)(9)(10)(11)(12).…”

“…Little is known about how soil microbial community structure is influenced by both historical and contemporary environmental conditions of subalpine forested soils (13) and how microbial community structure might correlate with soil fluxes of CO 2 and CH 4 . Landscape factors that may influence the occurrence and abundance of microorganisms include geographic location (14), topographic features such as drainages (15), and soil characteristics across spatial scales (16).…”