Temporal stability of surface soil moisture of different vegetation types in the Loess Plateau of China

Abstract

The temporal stability of soil moisture (TSSM) was widely applied to optimize the soil moisture sampling scheme on a catchment or even larger spatial scale over wet and dry observational periods. However, the integration of the TSSM feature with specific hydrological response at a small plot scale has not been sufficiently researched. This study analyzed the temporal stability of surface soil moisture (0-10 cm) characteristics and corresponding influencing factors of different vegetation types under two typical soil moisture changing processes including wet-to-dry (WTD) and dry-to-wet (DTW), and determined the representative points. A total of 16 microplots (60 × 60 cm each) that were composed of three vegetation types containing Andropogon, Artemisia scoparia and Spiraea pubescens and bare land cover were selected. And the soil moisture in the central point (CP) and four ambient points (APs) of each microplot were measured during the WTD and DTW processes. The results showed that, 1) from DTW to WTD processes, the distribution of the soil water content in different vegetation types indicated a significant difference. Compared with the soil moisture in the AP or CP area of other vegetation types, the soil water content in tall shrub types (S. pubescens) was the lowest. 2) The autocorrelation coefficient indicated that both in the AP and CP areas, the soil moisture of the low shrub types (A. scoparia) had a higher temporal stability than that of other vegetation types. However, the soil water content in bare land had the highest temporal fluctuation from the DTW to WTD processes. Additionally, in the CP area, the TSSM of all the vegetation types tended to decrease during the WTD process. 3) Based on the TSSM analysis system that was derived from the principle of probability and statistics, the soil moisture in the low shrub types (A. scoparia) most likely provides the best representativeness of the spatial average soil water content of heterogeneous vegetation types. The determination of the representative soil moisture point via the hydrological-trait sampling method could be supplementary and significant for a TSSM study of the available soil water resources in an arid and semi-arid ecosystem.

Linking the soil moisture distribution pattern to dynamic processes along slope transects in the Loess Plateau, China

“…However, multiple land cover combinations disturbed this trend along the slope, and different combinations resulted in fluctuations in the soil moisture content from the lower to upper portion of the slope. Different land use or cover types increase the variability of soil moisture in space and time, but the type of stability of the soil moisture results in a pattern of stability that is often called temporal stability (Zhou et al 2015). It is necessary to measure the temporal stability of the soil moisture content to identify representative locations in this revegetated, typically hilly-gully Loess Plateau catchment.…”

Soil moisture temporal stability analysis for typical hilly and gully re-vegetated catchment in the Loess Plateau, China

“…Loessial soil, one kind of Calcic Cambisols in the study area is representative of the Loess Plateau. Its specific properties are a uniform texture, high porosity, and high erosivity (Zhou et al 2015). The distribution range of vegetation in the study site was classified as a forest-steppe vegetation area.…”

“…Implications for typical re-vegetated hilly and gully loess areas Soil moisture acts as a crucial factor in vegetation production in the Loess Plateau and has garnered a great deal of attentions in recent decades Wang et al 2012Wang et al , 2013Zhou et al 2015). However, manual sampling is difficult and time consuming, making it ill suited for large scale studies.…”

Spatio-Temporal Variability of Soil Water Content under Different Crop Covers in Irrigation Districts of Northwest China

“…The factors that determine SWC depend on the environment of the area of study and the presence or absence of vegetative canopy [14] and the spatio-temporal variability of SWC affect vegetation coverage and density [15]. Investigations on agricultural watersheds have shown that topography, rainfall, and soil texture have mixed effects on SWC at the watershed and regional scales, and that land cover influences runoff, interception and evapotranspiration processes, and in turn, the soil water dynamics [5,[16][17][18][19]. The spatial-temporal pattern of SWC can be obtained from measurements carried out in different experimental plots [3,4].…”

“…For investigating the spatio-temporal variability of SWC, both statistical and geostatistical methods have been applied using ground-based and remote sensing data [17,19,24,26]. A few studies have applied the entropy theory to investigate the spatio-temporal variability of SWC and dominant factors [30].…”