黄土丘陵区白羊草群落光谱特征对氮磷添加的响应

为利用草地群落光谱参数来评价氮磷施肥效应,本研究以安塞纸坊沟流域内白羊草(Bothriochloa ischae-mum)群落为研究对象,测定计算不同氮磷添加[N处理:0(N0),25(N25),50(N50)和100(N100)kg N·hm-2·a-1;P处理(以P2O5计):0(P0),20(P20),40(P4...

Spectral Characteristics of Bothriochloa ischaemum Community in Response to Nitrogen and Phosphorus Addition at Loess Hilly-gully Region

Analyzing the spectral characteristics of Bothriochloa ischaemum community in response to nitrogen (N) and phosphorus (P) addition can provide scientific basis for evaluating fertilization effect on grassland. Four N addition treatments [0(N₀),25(N₂₅),50(N₅₀) and 100(N₁₀₀) kg N·hm^-2·a^-1] and four P addition treatments [0(P₀),20(P₂₀),40(P₄₀) and 80(P₈₀) kg P₂O₅·hm^-2·a^-1] were conducted in Zhifanggou watershed at Ansai District of Yan’an City,Shaanxi Province. Spectral characteristics of grassland community were obtained and calculated. The aboveground biomass production (AGB),community coverage (Cov) and community diversity index were also measured and analyzed. Results showed that AGB and Cov increased significantly after N addition,and Cov increased significantly under P addition,while diversity index showed no responses to N and/or P addition. The spectral reflectance of "blue-valley","green-peak" and "red-valley" decreased significantly after N and P addition,and the red edge-slope and red edge-area values increased significantly with P addition,while red edge-positon values had no response to N addition. Four vegetation indices increased significantly in response to N or P addition,and the increase of phosphorus addition was greater than that of nitrogen addition treatment. In summary,N or P addition differently influenced the aboveground biomass and canopy coverage of B. ischaemum community. P addition would efficiently improve community coverage and photosynthetic capacity of B. ischaemum,and the community photosynthetic capacity was the highest under 50 kg N·hm^-2·a^-1 and 40 kg P₂O₅·hm^-2·a^-1 combined application treatment.