若尔盖湿地土壤特性空间变化研究

Study on the spatial variation of soil characteristics in Zoige wetland

若尔盖湿地是青藏高原高寒湿地生态系统的典型代表,近年来湿地急剧萎缩和退化。根据若尔盖湿地分布特点,采用野外调查和室内试验分析相结合的方式,对在6个样区采取的349个土壤样品进行测试分析,研究若尔盖湿地土壤质地、土壤水分、养分空间特性变化,探讨湿地生态系统演化对土壤状况的影响。研究结果表明:若尔盖湿地土壤质地变化在空间和垂向上差异较小,花湖地区主要为壤土,纳若桥、达水曲、排水沟、哈丘湖为砂壤土,喜马拉也地区则为壤砂土。土壤pH值的变异系数最小,空间变异性相对较弱,有机质的变异系数相对较大,其次为速效磷和速效钾;有机质从表层到80 cm处呈降低趋势,有机质含量花湖>纳若桥>排水沟>哈丘湖>达水曲>喜马拉也。不同区域的土壤水分特征曲线Van Genuchten模型参数差异显著,喜马拉也和达水曲区域的A和n值明显高于其余区域,土壤水分持水性能较弱。研究结合不同区域的土壤性质、水分及养分特性变化,对若尔盖未来湿地保护和管理的重点方向和区域进行指导和建议。

As a typical representative of the Qinghai-Tibet Plateau Alpine wetland ecosystem,Zoige wetland has undergone sharp contraction and degradation in recent years. Based on the characteristics of Zoige wetland,in order to understand the changes of soil texture,soil moisture,and nutrient of the wetland,349 soil samples were taken and analyzed from six sample areas by combining field investigation and laboratory analysis to explore the impact of wetland ecosystem evolution on soil conditions. Results showed that the differences of soil texture change in space and vertical were small. The soil texture is loam for Huahu,sandy loam for Naruoqiao,Dashuiqu,Drainage area and Haqiuhu area,but loamy sand for Ximalaye area. The variation coefficient of pH value was the smallest,and the spatial variability was relatively weak. The coefficient of variation of organic matter was relatively large,followed by available phosphorus and available potassium. The organic matter decreased from the surface to 80 cm,and the organic matter content for the six areas follows the order as Huahu > Naruoqiao > Drainage area > Haqiuhu> Dashuiqu > Ximalaye. The parameters of the soil water characteristic curve of different regions were significantly different in the Van Genuchten model. Parameter A and n in the Ximalaye and Dashuiqu area,where the soil water retention was lower,were significantly higher than the other areas. In this paper,based on the changes in soil properties,water and nutrient characteristics in different regions,some suggestions on Zoige wetland protection and management in different areas were also proposed to control soil desertification and improve the capacity of retaining water of wetland.