Climatic and anthropogenic controls of topsoil features in the semi‐arid East Asian steppe

Abstract

Topsoil characteristics and their determinants in the steppe on the central Inner Mongolian Plateau were investigated. Percentages of different grain size fractions of topsoil samples from 236 plots and corresponding standardized data of four environmental/human‐activity factors, namely mean annual temperature (MAT), mean annual precipitation (MAP), human disturbance index (HDI) and land use/land cover (LULC) types were used to perform canonical correspondence analysis (CCA). The roles of both human land uses and climatic factors on topsoil grain size distribution are highlighted. Climatic factors seem to have played a significant role in determining the coarse sand (0.2–1 mm in size) percentages in the steppe and meadow by affecting the vegetation cover, while human disturbance indicated by species composition appears to have significantly influenced the percentages of clay (<0.002 mm in size) and fine‐medium silt (0.002–0.016 mm in size) in the typical steppe (P < 0.01). Soil Organic Carbon (SOC) content is negatively correlated with coarse sand percentages (P < 0.01), implying that reduction of soil fertility is linked to soil coarsening. Percentages of fine‐medium silts (0.002–0.016 mm in size) are still more abundant in the area where artificial vegetation are planted and remains as the major source of dust storms. This study implies that afforestation in the steppe region has not improved soil conditions and thus reduced dust storms as earlier expected.

Carbon and nitrogen contents in particle–size fractions of topsoil along a 3000 km aridity gradient in grasslands of northern China

“…In arid and semi-arid ecosystems experiencing increasing aridity, soils become more vulnerable to wind erosion because vegetation coverage declines (Zhang and Liu, 2010). Similar to our results, Liu et al (2008) found that sand fractions in soils of steppe and meadow were negatively correlated with MAP and positively correlated with MAT due to drought-driven vegetation cover decline in the semi-arid East Asian steppe.…”

Anthropogenic and climatic impacts on surface pollen assemblages along a precipitation gradient in north‐eastern China

“…MAT, MAP and a human disturbance index (HDI) were selected as environmental variables. The calculation of HDI was based on plant species composition in each plot (Liu et al. , 2006, 2008a, b).…”

“…First, an importance value (IV) was calculated for each species in each sample based on the sum of its relative abundance, relative coverage and relative height. Second, all species were divided into three groups, and weighted based on the different degree of vegetation degradation and human disturbance as 1/3 (Group I), 2/3 (group II) and 1 (Group III), respectively (Liu et al. , 2006, 2008a, b).…”

“…where IV1, IV2 and IV3 represent the IVs of species in the three classes, respectively (Liu et al. , 2006, 2008a, b).…”

Global semi-arid climate change over last 60 years

“…Most human effects on semi-arid climates are related to agricultural exploitation of lands. Introduction of agriculture into such areas, whose natural condition is already agriculturally marginal, might be motivated by a number of economic or social factors (Liu et al 2008). These factors include the need to provide food for a larger population, the decreasing productivity of existing agricultural land, and the profit motive.…”