不同修复措施对黄河源退化高寒草甸植物群落与土壤养分的影响

为了揭示退化高寒草甸逆向转变的驱动因子,通过野外调查和室内分析相结合的方法探究了黄河源不同修复措施（施有机肥F、免耕补播N、施有机肥+免耕补播FN）处理高寒草甸植物群落特征、土壤理化性质和两者相关性的变化规律,阐明不同修复措施对黄河源退化高寒草甸植物群落与土壤养分的影响。结果表明：免耕补播显著增加草甸物种丰富度指数（P<0.05）;施有机肥+免耕补播显著增加草甸植物盖度、总生物量、Shannon Wiener多样性指数和Pielous均匀度指数（P<0.05）。不同人工修复后草甸植物功能群地上、地下生物量变化趋势基本一致（除豆科）。和对照相比,莎草科,杂类草地上和地下生物量含量在N、FN处理分别降低83.04%、73.86%、30.43%、92.37%和96.51%、84.09%、85.68%、95.36%;禾本科地上和地下生物量含量在F、N和FN处理分别增加7.29%、23.45%、17.93%和6.04%、4.03%、10.52%;豆科地上生物量含量基本保持不变,地下生物量含量在F、N和FN处理分别降低24.43%、82.19%和42.61%。F显著增加土壤有机碳含量（P=0.033）;N显著降低土壤NO₃^--N含量（P=0.009）;FN显著降低土壤pH和增加土壤速效磷含量（P=0.024）;F和FN显著增加土壤含水量（P=0.000）,N则显著降低土壤含水量（P=0.000）;F显著降低土壤容重（P=0.018）。相关性分析表明植物Shannon Wiener多样性和Pielous均匀度与土壤速效磷含量呈显著正相关（P=0.037;P=0.033）,土壤有机碳和含水量与总生物量呈显著正相关（P=0.027;P=0.032）,pH与盖度呈显著负相关（P=0.049）。冗余度分析结果表明土壤有机碳含量和含水量显著影响了植物群落结构特征,解释率分别为30.3%和19.7%。研究结果表明,因地制宜进行退化高寒草甸施有机肥+免耕补播修复措施,能够明显提高草地生产力,改善草甸植物群落及其土壤养分和水分环境。

Effects of different rehabilitation measures on plant community and soil nutrient of degraded alpine meadow in the Yellow River Source

In this study, the dynamic changes of plant community characteristics, soil physicochemical properties and their correlations in severely degraded alpine meadow by different restoration measures (fertilization i.e. F, no-tillage reseeding i.e. N, fertilization+no-tillage reseeding i.e. FN) in the Yellow River source, China were investigated by field investigation and laboratory studies. The aims were to elucidate the driving factors of the reverse transformation of the degraded alpine meadow. Results showed that the rehabilitation measure of no-tillage reseeding (N) significantly increased the richness index of the meadow (P<0.05), while fertilization+no-tillage reseeding (FN) significantly increased the coverage, total biomass, Shannon Wiener diversity index and Pielous evenness index of the alpine meadow (P<0.05). The change trend of aboveground and underground biomass of plant functional groups was the same after different artificial restorations (except Leguminosae). Compared with control treatment, the aboveground and underground biomasses of Cyperaceae and weeds under no-tillage reseeding (N)and fertilization+no-tillage reseeding (FN) decreased by 83.04%, 73.86%, 96.51%, 84.09% and 30.43%, 92.37%, 85.68%, 95.36%, respectively. The aboveground and underground biomasses of Gramineae under fertilization (F), no-tillage reseeding (N) and fertilization+no-tillage reseeding (FN) increased by 7.29%, 23.45%, 17.93%, and 6.04%, 4.03%, 10.52%, respectively. The aboveground biomass of Leguminosae remained basically unchanged, and the belowground biomass under fertilization (F), no-tillage reseeding (N) and fertilization+no-tillage reseeding (FN) decreased by 24.43%, 82.19% and 42.61%, respectively. Fertilization (F) significantly increased soil organic carbon content (P=0.033); No-tillage reseeding (N) significantly decreased soil nitrate nitrogen content (P=0.009); Fertilization+no-tillage reseeding (FN) significantly affected soil pH and available phosphorus content (P=0.024); Fertilization (F) and fertilization+no-tillage reseeding (FN) reseeded significantly increased soil water content (P=0.000), while no-tillage reseeding (N) significantly decreased soil water content (P=0.000); Fertilization (F) significantly inhibited soil bulk density (P=0.018). Correlation analysis showed that plant Shannon Wiener diversity index and Pielous evenness index were significantly positively correlated with soil available phosphorus content (P=0.037; P=0.033). Soil organic carbon and water content were significantly positively correlated with plant total biomass (P=0.027; P=0.032), and soil pH was significantly negatively correlated with plant coverage (P=0.049). Redundancy analysis showed that soil organic carbon content and water content were the most significant factors affecting vegetation characteristics, the interpretation rates were 30.3% and 19.7%, respectively. In conclusion, fertilization+no-tillage reseeding (FN) could significantly improve grassland productivity, plant community, soil nutrient and water environment of the severely degraded alpine meadow in the Yellow River source, China.