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Soil productivity is a primary determinant of vegetation restoration and land resources utilization in debris flow deposits. However, little is known on the soil productivity change process of debris flow deposits behind check dams during rehabilitation. To investigate the change process of soil productivity at debris flow deposits behind check dams, soil physicochemical properties were measured in different time of rehabilitation (0, 2, 4, 5, 16, 23, 28, 33, 39, 45 years) in Hunshui gully (HSG). Modified Productivity Index (MPI) model was used to evaluate soil productivity. The results showed that soil organic matter (OM), total nitrogen, total phosphorus, available potassium and clay increased with rehabilitation time, while total potassium, pH and bulk density decreased. OM and MPI exponentially increased with the increase of rehabilitation time from 0.1% to 1.7% and 0.0006 to 0.1423, respectively. The rehabilitation time of 23 years was most likely a threshold time for the restoration of soil productivity at debris flow deposits. The trend of MPI indicated that soil productivity increased slowly in the early stage of ecosystem restoration, followed by a rapid with the increase of vegetation and OM. Our results can provide scientific bases for the effective utilization and restoration of debris flow deposits. [ABSTRACT FROM AUTHOR]

Development of sustainable mountain agriculture will require an increased understanding of the effects of climatic and environmental factors on grain yield. The objective of this study was to explore the drivers on variations of grain meteorological yield (MY) in Yunnan province, a typical high mountainous region. We used biological logistic regression model to simulate the trend yield to eliminate technological and management improvements effect. MY was calculated based on the data of actual grain yield (AGY) and trend yield. Our findings showed that during 1985–2012, MY showed an irregular fluctuation over time. Extreme temperature indices exerted a relatively greater impact on MY compared to extreme precipitation indices and annual precipitation. Spatially, topographic factors had higher direct effect on spatial variation of MY than that of extreme climate index, multi-year average temperature and precipitation, and soil properties. Redundancy analysis revealed that extreme temperature index (SU30) significantly affected inter-annual variation of MY, while spatial variation of MY was strongly influenced by slope, which can explain 44.62%. Our results illustrated the drivers on temporal-spatial variations of grain meteorological yield were inconsistent and topography effect should be considered when assessing the climatic change on crop yield in mountainous region. [ABSTRACT FROM AUTHOR]

Soil erodibility is a key parameter to measure soil susceptibility to water erosion and thus to soil erosion modelling, introduced as K factor in the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE). However, subject to soil spatial heterogeneity and data availability, large-scale K value acquisition has not been properly addressed. In this study, authors aimed to construct a new large-scale soil erodibility mapping technique to provide methodological support for regional soil erosion surveys. Taking the mountainous Yunnan province as a case, 743 soil samples from 252 typical soil series were collected. A 'GIS-based pedological method' was developed to construct a large-scale soil erodibility database by linking a soil map with soil properties. K value in Yunnan varied between 0.0004 and 0.0169 t ha h ha−1 MJ−1 mm−1, with an average of 0.0065 t ha h ha−1 MJ−1 mm−1. Significantly different K values were found among different types of soils and land use (p < 0.05). Redundancy analysis indicated that annual average temperature and latitude were the dominant control factors. The study showed that regional K value estimated by 'GIS-based pedological method' manifested an improvement compared to the traditional spatial interpolation method. [ABSTRACT FROM AUTHOR]

Soil microbial diversity is influenced by many factors, which are rarely studied together. To determine the dominant control on soil bacterial diversity in a typical dry-hot valley (DHV) of southwestern China, we collected soil samples in farmland, garden land and forestland along four elevation gradients of < 600, 600–700, 700–800, and > 800 m. Soil bacterial community abundance and composition was determined by high-throughput sequencing of 16S rDNA. The results showed that the dominant phyla in all soil samples were Proteobacteria, Actinobacteria, Firmicutes, chloroflexi and Acidobacteria. Soil bacterial absolute abundance in farmland was the greatest, followed by forestland and garden land. Differences in soil bacterial composition among three land uses were significant (p < 0.05) at elevations < 600 and 600–700 m. Four α-diversity indices (Shannon, Simpson, ACE and chao1) of soil bacteria in forestland and farmland showed insignificant differences among elevation gradients. Redundancy analysis indicated that land use was the dominant control on soil bacteria diversity, implying that shifts in land use could impact soil microbial diversity. [ABSTRACT FROM AUTHOR]