Relationships between vegetation and soil and topography in a dry warm river valley, SW China

Abstract

Understanding of the relationships between vegetation and soil and topography would be very important for ecosystem restoration and management efforts in the dry valleys of Himalayan region but how to clarify the complicated relationships and figure out key factors for practical purpose is a challenge. The main objective of this research was to propose a four-staged procedure by combining several multivariate statistical techniques to detect the relationships between vegetation and soil and topography, and thereby identify the key factors for the degraded ecosystem restoration and management. Forty-three plots (5 m × 5 m) were selected for the field survey of the vegetation, soil and topography variables in the dry warm river valley of the upper Minjiang River, Sichuan Province, China. Cluster analysis (CA) demonstrated that high plant diversity, cover and height were associated with good soil quality and favorable topographic positions with lower solar incident radiation, runoff and soil erosion potential. Correlation analysis (simple correlation analysis and canonical correlation analysis) and multiple linear stepwise regression analysis affirmed that plant diversity was mainly correlated with soil water content, and soil water content was mainly determined by soil texture (clay content). Soil clay content alone could explain about 70% of the total variance. Identifying the favorable topographic position and the distribution pattern of soil texture and its controlling mechanisms is thus very important for restoration practices. In the process of ecosystem restoration, we should promote the co-evolution of vegetation and soil, and follow the natural succession sequence. Some relevant conservation polices are also needed to reduce human disturbance on ecosystem.

Elevational trends in leaf size of Campylotropis polyantha in the arid Minjiang River valley, SW China

“…The arid valley is a unique feature of geographic units in the Hengduan Mountain ranges (Xu et al, 2008b). As in many other mountains of the world (Barry, 2008;Fu, 1983), there is a general altitudinal trend that is the reduction of air temperature with elevation in the arid valley (Table 2).…”

“…Arid valleys are peculiar geographic units widely distributed (range from 1200 m to 3600 m elevation) in the Hengduan Mountain ranges, which is a unique feature of the Himalayan ranges (Xu et al, 2008b). These arid valleys offer varied vegetation distribution and environmental gradients across short spatial distances (Bao et al, 2012;He, 2002;Xu et al, 2008a), providing natural ecological study sites.…”

“…These arid valleys offer varied vegetation distribution and environmental gradients across short spatial distances (Bao et al, 2012;He, 2002;Xu et al, 2008a), providing natural ecological study sites. The arid Minjiang River valley of the northern part in this area mainly distributed in the elevation range from 1200 m to 2200 m with the length of about 161 km and the area of about 170 km 2 (Xu et al, 2008b). The strong Foehn effects lead to specific local dryness and high temperature condition at valley bottom as well as specific patterns of moisture availability along elevational gradients (Bao et al, 2012;Xu et al, 2008b), hence were very different from other mountain regions worldwide (Barry, 2008;Gieger and Leuschner, 2004;Körner, 2007;Qiang et al, 2003).…”

“…The arid Minjiang River valley of the northern part in this area mainly distributed in the elevation range from 1200 m to 2200 m with the length of about 161 km and the area of about 170 km 2 (Xu et al, 2008b). The strong Foehn effects lead to specific local dryness and high temperature condition at valley bottom as well as specific patterns of moisture availability along elevational gradients (Bao et al, 2012;Xu et al, 2008b), hence were very different from other mountain regions worldwide (Barry, 2008;Gieger and Leuschner, 2004;Körner, 2007;Qiang et al, 2003). Previous studies suggest remarkable variations in species composition and soil seed bank exist in the communities thriving across the elevational and latitudinal gradients here (Li et al, 2011b) and a relationship exists between plant morphological traits and soil erosion in this area (Xu et al, 2008a,b).…”

Soil Water Storage Changes within Deep Profiles under Introduced Shrubs during the Growing Season: Evidence from Semiarid Loess Plateau, China

“…In the further implementation of the GGP, the selection of drought-resistant shrubs (e.g., HR) should be prioritized, and then zonal species can be introduced once the environment has been sufficiently modified by pioneer and early successional species [67]. In the GGP process, suitable engineering measures, such as microtopography, should be taken into consideration.…”