Effects of Nitrogen Application and Clipping Height on Vegetation Productivity and Plant Community Composition of Haying Meadow Steppe

作者 Wang Kaili; Yang Helong; Xiao Hong; Sun Wei; Rong Yuping

期刊 Scientia Agricultura Sinica , 2020,13:53

摘要 【Objective】The aim of this study was to improve soil nutrients in haying steppe, to increase grassland productivity, and to maintain sustainable utilize of grassland.【Method】Five nitrogen application levels (0, 10, 20, 30, and 40 g N·m~(-2)·a~(-1)) and two mowing heights (4 and 8 cm) were set in the haying field of Hulunbuir Grassland Agro-ecosystem Experiment Station with spit-plot design, which was carried out in mid-June and mid-August from 2016 to 2019, respectively, and the responses of nitrogen application and clipping height to community and plant functional group''s species richness and aboveground biomass, crucial species'' important value, dominant species'' functional traits, and soil properties were investigated.【Result】The results showed that nitrogen application and mowing height had no significant effect on community and plant functional group''s species richness (P>0.05). Nitrogen application significantly increased the aboveground biomass of grasses and community by 69.2%-115.3% and 36.5%-84.8%, respectively (P<0.05), but there was no significant difference within 10-40 g·m~(-2)·a~(-1). Lower cutting height significantly reduced the aboveground biomass of grasses by 18.3% (P<0.05). Nitrogen application significantly increased and reduced the important value of Leymus chinensis and Bromus inermis, respectively (P<0.05). Lower mowing height significantly reduced the important value of Leymus chinensis, which increased the value of Bromus inermis; nitrogen application increased the important value of Leymus chinensis, which reduced the important value of Bromus inermis(P<0.05). Lower cutting height significantly increased the important value of Potentilla bifurca and Potentilla acaulis and reduced the important value of Cleistogenes squarrosa (P<0.05). Nitrogen addition significantly increased the plant height, leaf area and shoot nitrogen content of Bromus inermis and Leymus chinensis (P<0.05), but there was no significant difference within 20-40 g·m~(-2)·a~(-1). The soil pH and soil water content decreased significantly along with the increase of nitrogen application rate, while NH4+-N, NO3--N and inorganic nitrogen (ION) in soil increased (P<0.05). The species richness of community, grasses and nongraminous forbs was positively correlated with soil water content, while the aboveground biomass of community and grasses was negatively correlated with soil water content (P<0.05). 【Conclusion】Short-term nitrogen application and suitable clipping height were beneficial to improve vegetation productivity and maintain community composition, and the effects of nitrogen addition were strongly dependent on water availability. It was suggested that the suitable mowing height of grassland in Hulunber haying meadow steppe was 8 cm, and the comfortable nitrogen application rate was 10-20 g·m~(-2)·a~(-1).

涉及物种 二裂委陵菜 Potentilla bifurca