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Scientia Silvae Sinicae ›› 2015, Vol. 51 ›› Issue (1): 1-11.doi: 10.11707/j.1001-7488.20150101

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Effects of Soil Fauna to Nitrogen and Phosphorus Releases during Litter Decomposition at Different Phenological Stages in the Subtropical Evergreen Broad-Leaved Forest in Sichuan Basin

Wang Wenjun, Yang Wanqin, Tan Bo, Liu Ruilong, Wu Fuzhong   

  1. Provincial Key Laboratory of Ecological Forestry Engineering Institute of Ecology & Forestry, Sichuan Agricultural University Chengdu 611130
  • Received:2013-09-13 Revised:2014-12-09 Online:2015-01-25 Published:2015-01-23

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Abstract:

[Objective]The release of nitrogen and phosphorus from litters at different phenological stages can be directly supplied to plants to meet the demands for nutrients to a certain extent. Soil fauna can promote nutrients release from foliar litter, and also compete with plants for available soil nutrients and other resources, but the hydro-thermal conditions and litter quality at different phenological stages could have direct impacts on play activities of soil fauna and other decomposers. Therefore, understanding of the effects of soil fauna on nitrogen and phosphorus release from litters is one of the essential components in knowing the ecological linkages between litter decomposition and plant growth.[Method]Litters of four representative tree species including Pinus massoniana and Cryptomeria fortunei as plantation species and Cinnamomum camphora and Quercus acutissima as secondary forest species in subtropical evergreen broad-leaved forests in Sichuan Basin of southwestern China were selected for the study. Litterbags with different mesh sizes (0.04 and 3 mm) were used to exclude soil fauna. To simulate the natural decomposition in field from November 2011 to October 2012, litterbags were sampled at different stages of leaf development: defoliation, budding, expanding, maturing, peaking and declining, in order to analyze nitrogen and phosphorus contents, release rate and characteristics of the release during the litter decomposition process with and without soil fauna.[Result]Nitrogen content tended to increase with the progress of litter decomposition regardless of tree species. Soil fauna increased nitrogen content for P. massoniana and C. camphora during the leaf maturing stage, but decreased nitrogen content for C. fortunei and Q. acutissima. Litter phosphorus content peaked during leaf maturing and peaking stages. Soil fauna had a significant impact on litter phosphorus content for C. camphora at the leaf maturing stage, but not significant for the other three species. Moreover, soil fauna significantly affected the processes of nitrogen and phosphorus release during litter decomposition. When excluding soil fauna, litter nitrogen was released at the leaf expanding stage and followed by continual decrease for all the 4 species, but litter phosphorus exhibited release at leaf expanding and maturing stages, accumulation at the peaking stage and release again at the declining stage. However, with soil fauna exists, the litter nitrogen and phosphorus for P. massoniana and C. camphora showed obvious accumulation at the maturing stage but release at the peaking stage, while those for C. fortunei and Q. acutissima showed release at the leaf maturing stage but accumulation at the peaking stage. After one year decomposition of litters, soil fauna significantly promoted litter nitrogen release for C. fortunei and Q. acutissima and litter phosphorus release of P. massoniana, but limited litter nitrogen release for P. massoniana and C. camphora and litter phosphorus release for C. camphora, C. fortunei and Q. acutissima. Soil fauna limited litter nitrogen and phosphorus release for P. massoniana and C. camphora at the defoliation and budding stages compared with other stages. In contrast, soil fauna promoted litter nitrogen and phosphorus release for P. massoniana, C. camphora and C. fortunei at leaf expanding, maturing and peaking stages.[Conclusion]Soil fauna significantly influenced the nitrogen and phosphorus release during litter decomposition in the subtropical evergreen broad-leaved forests in Sichuan Basin. The impacts on litter nitrogen and phosphorus release were relatively small at defoliation, budding and expanding stages in which plants grow slowly, but more evident at the leaf maturing and peaking stages in which plants consume a lot of nutrients, to some extent indicating that the competitive relationships between flora and the soil fauna.

Key words: soil fauna, litter decomposition, nitrogen and phosphorus releasing, evergreen broad-leaved forest

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