Relationship between Vegetation and Environment in an Arid-Hot Valley in Southwestern China

Jun Pei,Xiaoxiao Li,Yujun Yi,Yangpeng Cai,Wei Yang

doi:10.3390/su10124774

Abstract

The sparse and fragile vegetation in the arid-hot valley is an important indicator of ecosystem health. Understanding the correlation between this vegetation and its environment is vital to the plant restoration. We investigated the differences of soil moisture and fertility in typical vegetation (Dodonaea viscosa and Pinus yunnanensis) under a range of elevations, slopes, and aspects in an arid-hot valley of China’s Jinsha River through field monitoring and multivariate statistical analysis. The soil moisture differed significantly between the dry and rainy seasons, and it was higher at high elevation (>1640 m) and on shade slopes at the end of the dry season. Soil fertility showed little or no variation among the elevations, but was highest at 1380 m. Dodonaea viscosa biomass increased, then decreased, with increasing elevation on the shade slopes, but decreased with increasing elevation on the sunny slopes. On the shade slopes, Pinus yunnanensis biomass was higher at low elevations (1640 m) than it was on sunny slopes, but lower at high elevation (1940 m) on the sunny slopes. We found both elevation and soil moisture were significantly positively correlated with P. yunnanensis biomass and negatively correlated with D. viscosa biomass. Thus, changes in soil moisture as a function of elevation control vegetation restoration in the arid-hot valley. Both species are adaptable indigenous plants with good social and ecological benefits, so these results will allow managers to restore the vegetation more effectively.

Highlights

The high temperature and low humidity in the arid-hot valley results from a combination of local climatic conditions with strong sunlight and valley wind and evapotranspiration
Our results suggest that soil moisture was relatively adequate during the rainy season, but that only D. viscosa survived on sunny slopes at lower elevations (≤1520 m) near the end of the dry season because of the low average soil moisture
The lack of large differences in soil fertility among the elevations suggest that soil fertility would have a relatively small influence on vegetation restoration

Summary

Introduction

The high temperature and low humidity in the arid-hot valley results from a combination of local climatic conditions with strong sunlight and valley wind ( winds caused by convection during a forest fire) and evapotranspiration. A deficiency of soil moisture results in sparse vegetation and decreased restoration effectiveness in the arid-hot valley and, especially at the end of the drought season, the values of soil moisture may be lower than the plant-wilting coefficient [6,7]. Topography plays an important role in vegetation growth and distribution [8], since it affects many aspects of the plant’s environment; higher solar radiation and less available water on the sunny slopes of semi-arid valleys would exacerbate drought stress, resulting in the survival of fewer species, a lower plant density, and lower growth rates of the surviving plants [9]. To improve ecological restoration efficiency, it is necessary to deeply understand the relationships between the targeted native vegetation and the local environment (e.g., topography, soil, other habitat conditions), and to identify the key factors that affect the growth, survival, and distribution of vegetation in the arid-hot valley [13,14]

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Conclusion