| Soil fauna are considered as an important participant of terrestrial ecosystems in the litterdecomposition and N mineralization process. However, the influences of soil macro-andmeso-fauna on litter decomposition and N mineralization, and the soil fauna communitycharacteristics in coastal regions of northern Jiangsu Province were not well-recognized.Litterbags are often used to determine the impact of soil animals on litter decomposition ratesthrough the use of varied mesh sizes that exclude soil animals on the basis of body size, so weused the different mesh sizes (5mm,1mm,0.01mm) litterbags under different land use patterns(i.e. Poplar-farmland compound plantation, poplar plantation, cropland and grassland) inDongtai state-owned forest farm of Jiangsu province. We conducted the investigation of soilfauna and researched its influence on litter decomposition; Meanwhile,we used Close-Top TubeIncubations to conduct the research of N mineralization in different soil fauna control methods(fauna, no fauna, no nematode) under4land types.(1) The abundance and diversity of the fauna were quantified at the levels of order andclass; in total,25715individuals of soil meso-and macro-fauna were obtained through4samplings from2012to2013, which belonged to3phyla,13classes and35orders. Of that,Acarina, Collembola and Scolopendrida were dominant groups in litterbags of four sites, andOmnivores soil fauna always existed in the whole decomposition process. Comparing with thepoplar plantation, Poplar-farmland compound plantation increased the number of soilmicrofauna.(2) The litter decomposition rates of three mesh-sizes litterbags at different land usepatterns were significantly different (P<0.01), suggesting that the land use types may be one ofthe important factors affecting the litter decomposition. The mass remaining in the sites was inorder of small mesh（72.22%）>coarse mesh (48.03%)> medium mesh (44.70%). Most of thediversity comparisons between sites differed significantly. Pielou biodiversity index wasnegative correlation with litter mass loss in coarse mesh litterbags (P<0.05), while therelationship between Shannon-Wiener diversity index and litter mass loss in different meshsizes was not significant difference. The relationship of Simpson index between grass and theother sites was also significant difference. The average contribution ratio of soil meso-andmicro-fauna (24.89%) was much bigger than that in the coarse mesh litterbags (0.698%). Thecontributions of soil macrofauna and mesofauna to litter decomposition indicated thatcontributions to grassland and cropland were the maximum and minimum, respectively. Landuse changes alter the community structure of soil fauna, and then influence litter decomposition (3)in coastal regions of northern Jiangsu Province.(3) In4different land types of ecosystem, the existence of soil nematodes significantlyimproved the content of soil NH4+-N and NO3--N, and in the same land use of the same soillayer under different soil fauna control, soil NO3--N content had a significant difference（p<0.01）, which indicated that the soil animals and nematodes can significantly increased thecontent of NO3--N.(4) We suggested that in different control methods and fauna removed research,soil netnitrogen mineralization rates showed obvious seasonal dynamic. soil net nitrogenmineralization rate maximum in P, GS sample plots (respectively,0.1997mg/kg,0.1974mg/kg/d) appeared in the spring, but in PF, F sample plots, soil net nitrogen mineralization rateof the maximum value (respectively,0.4742mg/kg,0.1719mg/kg/d) appeared in the summer.(5) The contribution rates of soil fauna on net N mineralization in the four land use typesare different, and the difference is significant. In addition, the contribution rate of soil fauna inGS on net N mineralization is higher in four lands. |
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