Study on plant diversity and soil nutrient heterogeneity in typical grasslands of the Lhasa River Basin

This paper is the result of natural resources comprehensive survey engineering.

Objective Taking the temperate steppe, alpine meadow steppe and alpine meadow in Lhasa River Basin in Tibet as the research object, this paper explores the relationship between the landscape vegetation characteristics and the physical and chemical properties of the supporting soil of the plateau vertical zonal grassland formed under complex habitat conditions and controlled by terrain and climate.

Methods Based on the survey data of 76 sample plots and 228 sample points, including plant community characteristics and soil nutrient data, the single factor variance and Pearson correlation were used to analyze the vegetation community characteristics, soil nutrient characteristics and regulation mechanism.

Results There were no significant differences in height and coverage between alpine meadow and alpine meadow grassland due to the similarity of habitats, but significant differences in aboveground biomass among the three Grasslands (P<0.05). The evenness index showed a gradual upward trend from alpine meadow grassland temperate grassland, and the evenness index and Shannon Wiener index were significantly different among the three types of plots (P<0.05). Shannon Wiener index showed a trend of increasing first and then decreasing, and the trend was not obvious, but the difference was significant (P<0.05). Patrick index showed no significant difference between alpine meadow and alpine meadow grassland, but the temperate grassland index decreased significantly (P<0.05). Simpson diversity index showed no significant difference between alpine meadow and temperate grassland, but significant difference with alpine meadow grassland (P<0.05). The key indexes of soil nutrients of the three grassland types showed a downward trend from alpine meadow to alpine meadow grassland to temperate grassland, and passed the significance test.

Conclusions The dominant species of alpine meadow plants showed that the alpine meadow was dominated by Cyperaceae, and the alpine meadow steppe appeared the competitive relationship between Cyperaceae and Gramineae, and the temperate grassland was dominated by gramineous or miscellaneous grass. The key indicators of soil nutrients of the three grassland types showed a downward trend from alpine meadow grassland to alpine meadow grassland to temperate grassland, which had a significant relationship with altitude. The aboveground biomass AGB was significantly positively correlated with soil OM, TN, TP, NH₄⁺−N and SWC contents (P<0.01), and negatively correlated with pH content (P<0.01). The biomass of alpine meadow and alpine meadow steppe is regulated by SWC, TP, TN and OM due to the similarity of habitat and species, which has a significant positive correlation.