黑土滩草地群落及土壤化学计量特征对重建年限的响应

Response of community and soil stoichiometric char⁃ acteristics of black soil land grassland to reconstruction years

摘要:

研究三江源人工草地植物群落和土壤化学计量特征，有助于评价退化草地修复效果。本试验以黑土滩作为对照，与建植 12，19 年的人工草地及天然草地的植物群落和土壤化学计量特征进行比较，分析了环境因子对植物群落组成的影响。结果表明：(1)植被重建改变了黑土滩退化草地的群落组成，优良牧草比例增加，人工草地的优势种是垂穗披碱草、矮生嵩草和高山嵩草，黑土滩的优势种是臭蒿、细叶亚菊和黄帚橐吾；植被丰富度、多样性指数和均匀度指数均为天然草地＞黑土滩＞人工草地。 (2)土壤有机碳、全氮和全磷含量变化趋势呈现为天然草地＞人工草地＞黑土滩，土壤有机碳、全氮和全磷间显著相关(P＜0. 05)，C∶N 和 C∶P 两者间显著相关(P=0. 001 5)。(3)冗余分析表明，土壤 pH、 土壤含水量、全氮和全磷是影响植物种类分布变异的主要因子，其中土壤 pH 解释了植物群落组成 29% 的变异(P=0. 002)，土壤含水量解释了植物群落组成 21% 的变异(P=0. 016)，土壤全氮解释了植物群落组成解释 19% 的变异(P=0. 002)，土壤全磷解释了植物群落组成解释 13% 的变异(P= 0. 004)。结合植被群落特征和碳氮磷生态化学计量特征，建植 19 年的人工草地植物群落相对稳定，但还未恢复为天然草地，应加强人工草地的氮素添加和土壤改良。

Abstract:

The study on the plant community and soil stoichiometric characteristics of artificial grassland is help- ful for us to evaluate the restoration effect of degraded grassland in the three -river-source region. In this experiment， black soil land was used as control，and the plant community and soil stoichiometric characteristics were compared with native grassland and artificial grassland for 12 and 19 years. The effects of environmental factors on the species composition of the community were also analyzed. The results show that：(1)Vegetation reconstruction changed the community composition of degraded grassland on black soil land，and the proportion of excellent forage increased. The dominant species of artificial grassland were Elymus nutans，Kobresia humilis and Kobresia pygmaea，but the dominant species of black soil land were Artemisia hedinii，Ajania tenuifolia and Ligularia virgaurea. The vegetation richness，diversity index and evenness index displayed a definite trend： native grassland ＞ black soil land ＞ artificial grassland.(2) The trends of soil organic carbon，total nitrogen and total phosphorus content was as follows： native grassland ＞ artificial grassland ＞ black soil land. There were significantly correlations among soil organic carbon，to- tal nitrogen and total phosphorus(P＜0. 05). Likewise，there was a significantly correlation between Soil C∶N and C∶ P(P=0. 0015).(3) The results of redundancy analysis(RDA)showed that soil pH，soil moisture，total nitrogen and total phosphorus were the main factors affecting plant species distribution. Soil pH explained 29% (P=0. 002)，soil water content explained 21% (P=0. 016)，and soil total nitrogen explained 16% (P=0. 002) of the variance of plant community composition. Soil total phosphorus explained 13% of the variance of plant community composition (P= 0. 004). Combined with the characteristics of vegetation community and ecological stoichiometry of carbon，nitrogen and phosphorus，the plant community of artificial grassland established for 19 years was relatively stable，but it was not completely recovered to the state of native grassland. Therefore，the nitrogen addition and soil improvement of ar- tificial grassland should be strengthened in the future.