Effects of Simulated Nitrogen Deposition on Soil Ciliates Community in Alpine Meadow of Northwest China
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: CK<T20<T5<T10, i.e., ciliate abundance was highest at T10and the lowest at the control (CK), indicating that there was a threshold effect of N addition. N treatment had a significant effect (P<0.05) on soil pH with lower pH being recorded at higher N application. Redundancy analysis and Pearson correlation analysis showed that soil water content and pH were the dominant environmental factors affecting the ciliate community composition. In conclusion, high N treatment is not conducive to the growth and reproduction of ciliates in this field experiments. In order to maintain a stable and good ecosystem function, the application rate of 5~10 g·m-2·a-1N fertilizer can be used as reference for the optimal fertilization level of alpine meadow value.
国家科技期刊平台
NSTL
万方数据
维普
