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Zhou D.-Y.,Nanjing Forestry University | Bu D.-R.,Nanjing Forestry University | Ge Z.-W.,Nanjing Forestry University | Yan J.,Chinese Academy of Sciences | And 3 more authors.
Chinese Journal of Ecology | Year: 2015

Increased atmospheric nitrogen (N) deposition is a serious threat to the structure and function of ecosystems globally. Soil fauna is sensitive to environmental changes, and increased nitrogen deposition may profoundly influence soil faunal communities. We conducted a field experiment with different N addition treatments (0, 5, 10, 15 and 30 g N · m2 · a-1, respectively) to examine the effects of N deposition on the structure of soil faunal communities in poplar (Populus deltoides cv. I-35) plantations with different ages (7, 11, 18 years old) in a coastal area of eastern China in May 2012. Our results showed that the individual density of soil fauna increased significantly with increasing the stand age, but 11 years old poplar plantations had the greatest number of soil fauna group. The individual density of soil fauna decreased after an initial increase with the increasing N level, and it was the highest at the addition of 15 g N · m2 · a-1. Furthermore, the diversity of soil fauna was significantly correlated with soil TOC and TN. Significant effect of N addition on the diversity of soil fauna community was found only in 11 years old poplar plantation. Shannon diversity index and Pielou index showed a decreasing trend with the increasing N concentration, but Simpson index was completely opposite. In conclusion, N addition may cause great effects on the structure of soil fauna community through altering soil nutrition condition. Moderate N addition had a promoting effect on soil fauna community, but high N addition had a negative effect. © 2015, Editorial Board of Chinese Journal of Ecology. All rights reserved. Source


Xie T.,Nanjing Forestry University | Wang M.-h.,Nanjing Forestry University | Zheng A.-b.,Nanjing Forestry University | Xu C.-b.,State Forest Farm of Dongtai City | And 3 more authors.
Chinese Journal of Ecology | Year: 2012

To understand the characteristics of soil labile organic carbon and its correlations with soil physical and chemical properties in the poplar (Populus euramericana cv. San Martino) plantations of different ages in coastal area of North Jiangsu, five poplar plantations of 4-, 8-, 12-, 15-, and 20 years old were selected, with the total organic carbon (TOC), water-soluble organic carbon (WSOC), microbial biomass carbon (MBC), and physical and chemical properties in 0-10, 10-25, and 25-40 cm soil layers analyzed. In the five plantations, the contents of soil TOC, WSOC, and MBC all decreased with soil depth, and the soil TOC content had a trend of decreased after an initial increase with increasing plantation age, being the maximum in the 15 years old plantation and the minimum in the 4 years old plantation. Overall, the contents of soil WSOC and MBC had the same variation trend as soil TOC content, and the soil WSOC/ TOC and MBC/ TOC ratios increased with increasing plantation age. There was a significant correlation between soil WSOC and MBC, and the soil WSOC and MBC were significantly correlated with soil TOC, TN, C/ N, pH, and bulk density but not correlated with soil total S and soil moisture. This study indicated that with the increasing age of the poplar plantations in the coastal area of North Jiangsu, soil labile organic carbon content had no definite variation pattern, which affected the plantations acting as a carbon sink to a certain extent. Source


Zhao C.,Nanjing Forestry University | Zhang W.-W.,Nanjing Forestry University | Ruan H.-H.,Nanjing Forestry University | Xu C.-B.,State Forest Farm of Dongtai City | Cao G.-H.,State Forest Farm of Dongtai City
Chinese Journal of Ecology | Year: 2015

Soil microbial communities may respond to anthropogenic increases in ecosystem nitro­gen (N) availability, and the microbial response may ultimately feed back on ecosystem carbon and N dynamics. We examined the effects of nitrogen deposition on soil microbial community structure composition in a Chinese poplar plantation subject to simulated nitrogen deposition for two years at Dongtai Forest Farm of Jiangsu Province, China. Nitrogen loadings were designed at 5 levels as N0 (control) , low-N (50 kg • hm-2 • a-2 ), mdeium-N (100 kg • hm-2 • a-1), high-N (150 kg • hm-2 a-1), ultra high-N (300 kg • hm-2 a-1) , respectively. Nitrogen addi­tion was carried out within the forest monthly during May and August in 2012-2013. Soil samples were collected at 0-10 cm depths in October 200. Soil microbial community structure composi­tion was measured using phospholipid fatty acid (PLFA) analysis. Nitrogen additions did not change the total content of PLFAs but increased the amount of bacterial and gram-positive bacte­rial PLFAs. The content of fungal PLFAs did not change significantly, except under the medium level N addition. Nitrogen additions of medium, high, ultrahigh levels decreased the amount of arbuscular mycorrhizal fungal and protistic PLFAs. Principal component analysis (PCA) of microbial PLFA data showed that microbial community structure were changed in all N-added plots except the low-N trreatment. Our findings indicated that soil community structure can be influenced by short-term N additions in the poplar plantation. © 2015, editorial Board of Chinese Journal of Ecology. All rights reserved. Source


Xu K.,Nanjing Forestry University | Xu Y.,Nanjing Forestry University | Zhang M.-S.,Nanjing Forestry University | Xu C.-B.,State Forest Farm of Dongtai City | And 3 more authors.
Chinese Journal of Ecology | Year: 2014

The impacts of nitrogen deposition on soil labile carbon at different age poplar plantations were examined in this study. Beginning in May 2012, we conducted a field experiment to simulate nitrogen deposition with five treatments at Dongtai Forest Farm in Jiangsu Province. In June 2013, the soil samples were taken to analyze the variations of soil labile organic carbon. The results indicated that soil microbial biomass carbon decreased after an initial increase with the increasing nitrogen level in the 5 and 9 years old poplar plantations, and increased with the increased nitrogen level in the 15 years old poplar plantation. Increasing the level of nitrogen enhanced the content of soil dissolved organic carbon in all poplar plantations. There was a significant correlation between the soil MBC and DOC. Furthermore, the soil MBC and DOC were significantly correlated with the soil TN, MBN, DON, NH4+ -N, NO3--N. Our results imply that nitrogen deposition might enhance the content of soil labile organic carbon, and thus affect the dynamics of soil organic carbon in the poplar plantations. © 2014, Editorial Board of Chinese Journal of Ecology. All rights reserved. Source


Chen S.-X.,Nanjing Forestry University | Wang G.-B.,Nanjing Forestry University | Ruan H.-H.,Nanjing Forestry University | Yue Z.,Nanjing Forestry University | And 2 more authors.
Chinese Journal of Ecology | Year: 2014

The variations of soil mineral N under four different land use types (i. e. poplar plantation, crop-poplar integrated system, grassland, and cropland) in a coastal area of northern Jiangsu were investigated by a close-top incubation method. The net N mineralization rate under each of the four land use types was higher in spring than in autumn, winter and summer. The net N mineralization rate decreased in order of poplar plantation, crop-poplar integrated system, cropland and grassland. Ammonium N and nitrate N showed obvious seasonal variations under the four land use types. The concentrations of ammonium N and nitrate N were generally higher in spring than in other three seasons. The soil mineral N decreased with increasing soil depth. In 10-25 cm soil layer, the soil mineral N concentration was significantly different between poplar plantation and crop-poplar integrated system. In poplar plantation and grassland, the soil mineral N concentration was significantly different between 25-40 and 0-10, 10-25 cm soil layers. The concentration of soil mineral N was significantly higher in poplar plantation than in cropland and grassland in 0-10 cm soil layer. Source

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