荒漠区湿地植物群落分类排序及其与土壤环境因子的关系

Classification and ordination of a plant community in a desert wetland and its relationship with soil environmental factors

湿地存亡可以作为荒漠地区植被恢复可持续性的指示器,明晰其生态系统内部植物群落空间分布特征及其与土壤环境因子关系,可为制定与生境高度相适应的多样化植被恢复模式提供科学依据。本研究以宁夏哈巴湖湿地汇水范围为研究对象,在12 km×12 km范围内,设置分辨率为1 km×1 km的152个调查样点的植被和土壤数据,采用多元回归树和冗余分析,探讨不同植物群落类型的空间分布特征及其对土壤理化因子的响应规律。结果表明:1)研究区植物群落可划分为短花针茅(Stipa breviflora)+牛枝子(Lespedeza bicolor)、冰草(Agropyron mongolicum)+赖草(Leymus secalinus)+草木樨状黄芪(Astragalus melilotoides)、苦豆子(Sophora alopecuroide)+猪毛蒿(Artemisia scoparia)、芨芨草(Splendid achnatherum)+盐爪爪(Slenderbranch Kalidium) 4种植物群落类型。2)土壤粘粉粒含量、生境海拔高度、土壤pH和盐分含量是4种植物群落空间分布的主要控制因素。3)随着土壤粘粉粒或细沙粒含量降低所表征的土壤粗质化程度增加,植物群落由短花针茅+牛枝子转变为冰草+赖草+草木樨状黄芪;随着海拔降低和土壤全盐增加,植物群落由短花针茅+牛枝子转变为芨芨草+盐爪爪。综上可知,荒漠湿地由分水岭高梁地到低滩湿地的景观植被系统,首先是土壤质地决定的旱生地带性植物群落空间分异,其次是海拔和盐分驱动的地带性向隐域性植物群落的二次分异。

The existence and disappearance of desert wetlands can be considered as the indicators of sustainability in vegetation recovery. The spatial distribution characteristics of plant communities and their relationship with soil environmental factors were described in the desert wetland ecosystem. This can provide a scientific basis for establishing a diversified vegetation restoration model based on the characteristics of different habitats. In this study, the Haba Lake wetland ecosystem in Ningxia was selected as the research object. Based on vegetation and soil data from 152 survey sites with 1 km × 1 km resolution, multiple regression tree and redundant analysis were used to explore the spatial distribution characteristics of different plant community types and their response to soil factors in a 12 km^(2) area. The results were as follows: 1) the plant community was divided into four types: Stipa breviflora + Lespedeza bicolor, Agropyron mongolicum +Leymus secalinus + Astragalus melilotoides, Sophora alopecuroide + Artemisia scoparia, and Splendid achnatherum +Slenderbranch Kalidium. 2) The main factors affecting the spatial distribution of these four plant communities included soil clay and fine sand contents, altitude, soil salt content, and pH. 3) With the decrease in soil clay content, the degree of soil coarsening increased, and the plant community changed from Stipa breviflora + Lespedeza bicolor to Agropyron mongolicum +Leymus secalinus + Astragalus melilotoides;owing to the decrease in altitude, the plant community changed from Stipa breviflora + Lespedeza bicolor to Splendid achnatherum + Slenderbranch kalidium. Conclusion: Across the watershed land to the low beach wetland, the spatial variations in the landscape vegetation system in the desert wetland can be described as follows: spatial differentiation of xerophytic zonal plant communities depends on soil texture, whereas secondary differentiation of zonal to crypzonal plant communities is based on altitude and salinity.