Abstract
Expected changes in precipitation over large regions of the world under global climate change will have profound effects on terrestrial ecosystems in arid and semiarid regions. To explore how changes in the amount of precipitation in the growing season would affect soil nitrogen (N) availability in a semiarid ecosystem, we established rainout shelters and irrigation systems by simulating 30% reduced (DRY) and 30% increased precipitation (WET) relative to natural precipitation (Control) to measure some key soil process properties for two growing seasons in a nutrient-poor Mongolian pine (P. sylvestris var. mongolica) plantation. Both WET and DRY treatments significantly affected monthly soil inorganic nitrogen concentrations, which showed a higher inorganic N under DRY than Control in each month and lower in WET than Control. Monthly soil microbial biomass N content was reduced by DRY and raised by WET treatments. The results indicated the asynchrony of the availability of soil moisture and soil nutrients in Mongolian pine plantations at the Horqin Sandy Lands in Northeast China. Water limited plant growth in Mongolian pine plantations when precipitation decreased, and nitrogen limitation became increasingly important when precipitation increased. Accumulation of N in microbial biomass is an important mechanism for N cycling in this ecosystem. To effectively manage Mongolian pine plantations, it is advised that evapotranspiration is minimized when precipitation decreases and that there is an increase in soil N availability by protecting litterfall when precipitation increases.
Highlights
Global climate change is expected to alter precipitation regimes over large regions of the world [1,2,3,4]
The changes in microenvironment caused by precipitation manipulation were small
The average high daily PAR was reduced by 8.5%–16.3% under the rainout shelters compared to CK
Summary
Global climate change is expected to alter precipitation regimes over large regions of the world [1,2,3,4]. A great deal of research has focused on the effects of precipitation on biomass production [5,6,7], with fewer studies examining the effects of precipitation change in the soil properties of arid and semiarid ecosystems [8,9,10,11,12]. Weltzin et al [13] proposed that changes in precipitation regimes will have greater effects on ecological processes in arid and semiarid regions than global warming and increasing levels of CO2 due to the central role that water plays in determining the. Precipitation is a key driver in determining chemical and biological processes; previous studies on the relationships between water and N availability have yielded mixed results, with N availability increasing with decreasing water content [8,9,15]. Further experiments were needed to determine the details of altered N availability following changes in precipitation
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