The effect of atmospheric nitrogen (N) deposition on soil ciliate communities, the evaluation of the impact of N deposition on the ecosystem and the scientific basis for fertilization was investigated in field experiments at an alpine meadow in Gannan Maqu County, China. Artificial N deposition conditions were established and maintained as follows: CK (without N application), T5(5 g·m-2·a-1), T10(10 g·m-2·a-1), and T20(20 g·m-2·a-1). Identification and quantification of ciliates were carried out by employing observation in vivo and"three-level ten-fold dilution"methods,to study the difference of soil ciliate community composition in four gradient treatment groups. Physical-chemical parameters of the soil were also measured for each treatment including water content, temperature, pH and available N. The results showed that a total of 121 ciliate species were identified, belonging to 9 classes, 16 orders, 28 families and 46 genera. With the increase of N application, ciliates community composition tended to be simplified, and the dominant species were in the succession from the higher Hypotrichia to the highly adaptable Colpoda. Therefore, high N treatment had a negative effect on the ciliates community composition. Ciliate species number and diversity both decreased significantly (P<0.05) with the increase of N treatment, i.e. CK>T5>T10>T20for both indices. In terms of ciliate abundance, the effect of N application was as follows: CKT5>T10>T20;氮沉降处理对纤毛虫密度的影响表现为CK展开▼
