不同植被恢复模式下三峡库区万州段消落带土壤养分及其空间分布特征

消落带植被状况与水位消涨是影响土壤养分及其分布的重要因子。本文以三峡库区万州段消落带为研究地点,通过对人工和自然恢复样地沿海拔梯度对土壤进行取样和分析,揭示了不同恢复模式下消落带土壤养分及其空间分布特征。研究结果表明,植被恢复模式对土壤养分有显著影响,人工恢复样地消落带主要土壤养分含量总体高于自然恢复样地,显示人工恢复能有效促进土壤养分在植物群落中的积累;在库区反季节水位消涨的作用下,人工恢复地消落带土壤养分沿海拔梯度呈先增加后减少的空间分布格局,土壤养分含量在消落带中部(海拔165 m)达到最高值,而自然恢复地土壤有机质和全氮的空间分布则随海拔梯度增加而增加,以消落带上部(海拔175 m)的值最高。土壤养分的空间分布格局源自于不同海拔梯度的消落带受水位消涨扰动程度以及植被恢复状况的差异,植被恢复模式对土壤养分的空间分布仍有一定影响。今后应在消落带上部进一步引种适宜的乔灌木物种,不断提高消落带植被对土壤养分的固持能力。

Characteristics of Soil Nutrient and Spatial Distribution on Riparian Zone Restored by Different Vegetation Restoration Methods at Wanzhou Section in the Three Gorges Reservoir Area,China

Riparian vegetation and water-level fluctuation are critical factors influencing soil nutrients and their spatial distribution. Taking Wanzhou section as a case study, the characteristics of soil nutrient and spatial distribution in riparian vegetation restored by different methods in the Three Gorges Reservoir area were uncovered by field investigation and chemical analysis of soil samples collected from the artificial and natural restoration plots, respectively. Results showed that restoration method had significant effect on soil nutrients. The content of soil nutrients in the artificial restoration plot was generally higher than that in the natural recovery plot indicating that artificial restoration promoted accumulation of soil nutrients in vegetation. Under the influence of the reverse seasonal water-level fluctuation, a special spatial distribution pattern that the riparian soil nutrients increased and then decreased with the increasing latitude appeared on the artificial restoration plot. The maximum content of soil nutrients occurred at the middle riparian part(altitude 165 m). However, soil organic matter and total nitrogen increased with the increasing of altitude gradient on the natural restoration plot, and reached the maximum at the upper riparian part(altitude 175 m). The spatial distribution pattern of soil nutrients resulted from the differentiation of water-level fluctuation disturbance and vegetation among altitude gradients. Restoration methods also affected the spatial distribution of soil nutrients as it influenced vegetation restoration. Appropriate tree and shrub species adapting to the disturbance of the reverse seasonal water-level fluctuation should be further introduced to the upper riparian part to promote the vegetation capacity of holding soil nutrients.