宁夏东部杨柴生态修复区短期水氮添加对草本植物群落的影响OA北大核心CSTPCD

In order to study the effects of short-term water and nitrogen addition on the quantitative characteristics and the diversity of herbaceous plant communities in ecological restoration area of Corethrodendron fruticosum var.mongolicum,a water and nitrogen addition experiment was conducted in ecological restoration area of Corethrodendron fruticosum var.mongolicum in Baijitan National Nature Reserve in Ningxia,and a random block design experiment was adopted in the present study.Sixteen coupled water and nitrogen addition treatments which were 16 pairs of random combinations of one water addition gradient and one nitrogen addition gradient from 4 water addition gradients(W0:no water added;W1:adding 33%of the annual average precipitation;W2:adding 66%of the annual average precipitation;W3:adding 100%of the annual average precipitation)and 4 nitrogen addition gradients(N0:no nitrogen added,N1:5 g N·m-2·a-1;N2:10 g N·m-2·a-1;N3:20 g N·m-2·a-1)were set in each block.Four blocks in total were carried out in the present study.It was found that Water and nitrogen addition caused significant changes in plant community structure.Compared with the control(W0N0),the importance value of the dominant species of Setaria viridis in the herbaceous plant layer reached the maximum value under the treatments of moderate nitrogen without water addition(W0N2),low water coupling with high nitrogen(W1N3),moderate water without nitrogen application(W2N0)and moderate water coupling with moderate nitrogen(W2N2),and the peak value was 0.46.The aggregated distribution of Setaria viridis indicated that the community aggregation effect was obvious under the moderate level of single water or nitrogen,or the moderate level of water and nitrogen coupling measures.Under all the treatments of water and nitrogen addition,from no nitrogen application(N0)to high nitrogen level(N3),the species richness,Shannon-Wiener index,Simpson index and Pielou index of herbaceous plant community all increased first and then decreased with the increase of nitrogen level,and all of them had the maximum value under the treatment of moderate water coupling with low nitrogen(W2N1).Nitrogen addition had significant effects on plant species richness,Simpson index and Shannon-Wiener index(P<0.05).Collectively,appropriate amount of water and nitrogen addition was more conductive to vegetation restoration in ecological restoration areas.The treatment of W2N1 could best improve the species diversity of herbaceous plant community in the ecological restoration area of Corethrodendron fruticosum var.mongolicum,thus effectively promoted the process of desertification reversal.