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Xing‐Guo Han: Influence Statistics

Fine root production and turnover play important roles in regulating carbon (C) cycling in terrestrial ecosystems. In order to examine effects of climate change on root production and turnover, a field experiment with increased temperature and precipitation had been conducted in a semiarid temperate steppe in northern China since April 2005. Experimental warming decreased annual root production, mortality, and mean standing crop by 10.3%, 12.1%, 7.0%, respectively, while root turnover ...

Biodiversity generally promotes ecosystem stability. To assess whether the diversity-stability relationship observed under ambient nitrogen (N) conditions still holds under N enriched conditions, we designed a 6-year field experiment to test whether the magnitude and frequency of N enrichment affects ecosystem stability and its relationship with species diversity in a temperate grassland. Results of this experiment showed that the frequency of N addition had no effect on either the ...

Climate change involves modifications in both the mean and the variability of temperature and precipitation. According to global warming projections, both the magnitude and the frequency of extreme weather events are increasing, thereby increasing climate variability. The previous studies have reported that climate warming tends to decrease biodiversity and the temporal stability of community primary productivity (i.e., community stability), but the effects of the variability of ...

Soil chemistry and physical conditions are the key factors controlling litter decomposition. We studied the effects of increased soil nitrogen (N), phosphorus (P), and water on the decomposition rates and associated nutrient dynamics of two dominant grassland plant species (i.e. Allium bidentatum Fisch. ex Prokh. & Ikonn.-Gal. and Stipa krylovii Roshev.) with contrasting life forms and tissue chemistry in a typical steppe of Inner Mongolia, China. The treatments included addition of urea ...

Land-use change can lead to changes in soil carbon (C) and nitrogen (N) storage. This study aimed to determine the impact of long-term grazing exclusion (GE) on soil organic C and total N (TN) storage in the Leymus chinensis grasslands of northern China and to estimate the dynamics of recovery after GE. We investigated the aboveground biomass and soil organic C and TN storage in six contiguous plots along a GE chronosequence comprising free grazing, 3-yr GE, 8-yr GE, 20-yr GE, 24-yr GE, ...

BACKGROUND AND AIMS: Changes in supplies of resources will modify plant functional traits. However, few experimental studies have addressed the effects of nitrogen and water variations, either singly or in combination, on functional traits.

METHODS: A 2-year field experiment was conducted to test the effects of nitrogen and water addition on leaf longevity and other functional traits of the two dominant (Agropyron cristatum and Stipa krylovii) and three most common species (Cleistogenes ...

Soil properties (i.e. soil organic carbon, SOC; soil organic nitrogen, SON; and soil C/N ratio) and vegetation in a semiarid grassland of Inner Mongolia, northern China, were studied with the method of geostatistical analysis. We examined the spatial heterogeneity of soil and plants, and possible impacts of land use on their heterogeneity and on the relationship between soil resources and plant richness. Land use affected small scale spatial heterogeneity in plants and soil. SOC, SON and ...

The two dominant species, Leymus chinensis and Stipa grandis have different distribution area in the Xilin River Basin: relatively wet and fertile for L. chinensis and dryer and leaner for S. grandis. Different photosynthetic physiology traits and resource use efficiency might contribute to the distribution pattern of two species in heterogeneous habitats. In this study, the plant nitrogen (N) content, C/N ratio, δ13C values and photosynthetic characteristics of L. chinensis and S. ...

Global nitrogen (N) deposition and climate change have been identified as two of the most important causes of current plant diversity loss. However, temporal patterns of species turnover underlying diversity changes in response to changing precipitation regimes and atmospheric N deposition have received inadequate attention. We carried out a manipulation experiment in a steppe and an old-field in North China from 2005 to 2009, to test the hypothesis that water addition enhances plant ...

An increasing amount of grasslands in Inner Mongolia of Northern China has been converted to cropland. The conversions in this extensive semiarid region have produced adverse ecological consequences at local and regional scales (e.g., dust storms). An important research need is to understand the fundamental ecosystem processes, such as energy and material fluxes, associated with the land conversions. The carbon fluxes, including net ecosystem exchange (NEE), ecosystem respiration (RE), ...

Water is the most important factor controlling plant growth, primary production, and ecosystem stability in arid and semi-arid grasslands. Here we conducted a 2-year field study to explore the contribution of winter half-year (i.e. October through April) and summer precipitation (May through September) to the growth of coexisting plant species in typical steppe ecosystems of Inner Mongolia, China. Hydrogen stable isotope ratios of soil water and stem water of dominant plant species, soil ...

Soil management and climate change affect N2O emission significantly. The semi-arid grassland in northern China is under strong anthropogenic disturbance (fertilization and land use) and toward a 30% increase in precipitation in future. To investigate their impacts on N2O emission, N2O fluxes were measured monthly in the grassland and abandoned cropland under mineral fertilizer (urea and superphosphate) and increased precipitation during the growing season. During the measured period, ...

Nitrogen isotopes provide integrated information about nitrogen cycling in terrestrial ecosystems. This study explores the regional patterns of ecosystem 15N abundance along a 1200 km transect in Inner Mongolian grasslands and their relationships with climate. Results indicate that climatic variables control approximately 50% of the variation in ecosystem 15N abundance along the transect. Ecosystem 15N abundance decreases as both mean annual precipitation (MAP) and mean annual ...

Multiple co-occurring environmental changes are affecting soil nitrogen cycling processes, which are mainly mediated by microbes. While it is likely that various nitrogen-cycling functional groups will respond differently to such environmental changes, very little is known about their relative responsiveness. Here we conducted four long-term experiments in a steppe ecosystem by removing plant functional groups, mowing, adding nitrogen, adding phosphorus, watering, warming, and ...

Plant biomass allocation between below- and above-ground parts can actively adapt to the ambient growth conditions and is a key parameter for estimating terrestrial ecosystem carbon (C) stocks. To investigate how climatic variations affect patterns of plant biomass allocation, we sampled 548 plants belonging to four dominant genera (Stipa spp., Cleistogenes spp., Agropyron spp., and Leymus spp.) along a large-scale (2500 km) climatic gradient across the temperate grasslands from west to ...