The Decomposition Of Two Lawn Grass Litter And The Function Of Soil Fauna

It is main channel in the biological elements circulating and energy flowing in the ecosystem by the litter. Litter decomposition affect terrestrial ecosystem energy flowing and nutrient cycling significantly, which is an important form for nutrition return back to the soil. As one of the litter dis-integrator, soil fauna not only affect matter transferring, energy reserving and transferring, used for soil ecological toxicology diagnosing, instructed the environment ecological changing and ecological functions on global change and so on, but also play an important role on maintaining matter circulating and energy flowing in the urban land ecology system. It is a common belief that lawn grass which is significant for maintaining the balance of ecological environment, reducing psychological pressure, eliminating fatigue and restoring physical strength. Litter bag experiment was carried out to evaluate the different aperture(0.02mm, lmm,3mm) decomposition dynamics of Trifolium repens L.and Festuca arundinace litter mass loss, ecological features of soil fauna community, dominant species and character structure of functional community group, nutrition dynamic and so on. Then analyzed the character of diversity and functional groups of soil fauna. Conclusions were as follows:1. The process of different lawn grass litter substrates decompositionLitter mass loss rate of Trifolium repens L. was higher than Festuca arundinace and decomposition of litter leaf faster than litter root in the different grass substrates. Through five months decomposed, mass loss rate of Trifolium repens L. has reached 100%, mass loss rate of the litter root has reached 100% after six months, too. Whereas, mass loss rate of Festuca arundinace arrived at 100% through 9 months decomposed, but the maximum mass loss rate was 89.51% of litter root after 12 months. Analysis of ANOVA indicated that the mass loss rate in the process of decomposition with significant difference (P<0.05) in the different aperture, which is the aperture of 3mm significantly higher than that of 1mm and 0.02mm respectively in the whole decomposition stage.2. The community structure of soil fauna in the process of lawn grass litter decompositionA total of 8177 individuals were surveyed in the litter decomposition stage, which belonged to 3 phyla,3 orders,28 families. A total of 226 individuals were the soil macro-fauna, which belonged to 7 orders,17 families; A total of 2759 individuals were the meso-micro mikio soil fauna which belonged to 13 orders,41 families. Among them, there were 5192 individuals of the meso-micro wet soil fauna which belonged to 8 orders,17 families. The dominant species of the soil macro-fauna were Formicinae, Curculionidae and Cucujidae, which accounted for 18.14%,10.18% and 17.70% respectively;The meso-micro soil fauna taxa of Onychiuridae, Poduridae, Orchesellidae and Pygmephoridae were accounted for 12.47%,21.2%,10.69% and 12.47% respectively; The meso-micro wet soil fauna of Tylenchidae, Cyatholaimidae, Rhabditidae and Enchytraeidae which are accounted for 28.70%,10.11%,24.63% and 28.70% respectively.There are some difference between in the number of soil fauna individuals, taxa and different decomposition stage. Litter mass loss rate with different individuals and groups of soil fauna showed a significant positive correlation in the whole decomposition stage; Mass loss rate of lawn grass litter and diversity index of the soil fauna, which related with H, J, C, D were changed in differ, a total positive correlation greater than the negative correlation. It showed that the diversity of soil fauna which can adjust the litter decomposition and accelerate or decrease litter decomposition.3. Dynamic of soil fauna functional group in the process of decompositionDynamic of soil fauna functional group varied from Phytophage, Fungivore, Predators to Saprozoiein in the process of litter decomposition. Among them, Onychiuridae, Entomobryidae and Poduridae of Collembola, Formicinae of Hymenoptera and Cucujidae of Coleoptera were dominant groups; The Fungivore dominant groups were Anystidae of Prostigmata and Ladlapidae of Mesostigmata; The meso-micro wet soil fauna were Enchytraeidae and Naididae of Lumbridida; The dominant groups of soil macro-fauna predators were Curculionidae and Elateridae of Coleoptera; The meso-micro soil fauna in the predatory were common groups; The meso-micro wet soil fauna foucus on the saprozoie, in which dominant groups are Rhabditidae, Tylenchidae and Cyatholaimidae of Rhabditida; However, a few of meso-micro mikio soil fauna are saprozoie, such as Pygmephoridae of Prostigmata; The changing in the different diets showed that the selection by the different soil fauna in the process of litter decomposition.4. Dynamics of the lawn grass litter nutrition in the process of decompositionThere is a decreasing tendency on Trifolium repens L. Litter C, N, P, lignin and cellulose content and K released slowly, which the content of lignin and cellulose were released after increased in the porcess of decomposition. The content variation of Festuca arundinace Litter C, P presented that increased after released and N content variation from release to increase, K was decreased in the whole decomposition stage.The nutrition release velocity of C and N roughly showed a tendency of increasing-decreasing between the two lawn grass litter decomposition. P release velocity presented the complexities in the process of the litter decomposition. Above of the Festuca arundinace and underground of the Trifolium repens L. expressed the tendency that increased after decreased, the underground of Festuca arundinace and above of Trifolium repens L. expressed the variation in the opposite; K releasing velocity roughly increased after decreased; There are no obvious regularity with degradation velocity changes of lignin and cellulose; That is to say, there are some difference between in the species and decomposition time. It also indicated that species, time and other conditions also affected the process of litter decomposition.The litter substrate and chemical composition have an effect on the dynamic of lawn grass litter decomposition. There are some relations in the process of nutrition dynamics and the composition, dominant, functional groups, community structure and soil fauna diversity and ecological characteristics. It showed that the interaction between soil fauna and litter. On the one hand, soil fauna promoted the litter decomposition of lawn grass. On the other hand, litter substrate influenced the decomposition of soil fauna community structure profoundly.