The Benefit Evaluation Of Three Different Types Grass-tree Complex System In The Lake Buffer Zones

Buffer zone is an important part of the lake ecosystem. Lake buffer zone is anisolation niche regarding to the lake protection，since it is a space for avoiding oralleviating the damage, interference and pollution from different types of humanactivities or natural processes. Grass-tree complex system is an important buffer zonepart. It plays an important role in water and soil conservation, reducing agriculturalwaste water pollution, improving the habitat and protecting biodiversity due to thespecial nature location, the unique vegetation structure and characteristics. In thispaper, taking three typical grass-tree complex systems of Zhushan Bay, Taihu Lake asa research subject. An ecological benefit evaluation system of grass-tree complexsystem in lake buffer zones was established, including three levels of13specificindicators. It is established base on the analysis of grass-tree buffer system status quoand function, guided by the ecological evaluation theory. The combination ofsubjective empower and objective empower methods was adopted to determine theweight of each index. According to the four different times the survey andexperimental data of each index, using the integrated benefit index model respectivelyto evaluate the three types of grass-tree systems benefit evaluation stages. Achievedthe following results:(1) An ecological benefit evaluation index system of grass-tree complex systemin Lake buffer zone was established. Eco-efficiency evaluation method of grass-treecomplex system in the lake buffer zones due to the special nature of its location, andthe vegetation of the unique structure and characteristics, so the aim and the means tobe evaluated differently, can not copy other ecological benefit evaluation methodsuch as forest, shelterbelts, etc.. Thus, the evaluation system established to fill thelake buffer zones’grass-tree complex system evaluation research in this field blank.(2) Quantitative calculation comprehensive benefit index of three typicalgrass-tree complexes. The comprehensive benefit index of wetland grass-tree complex system, poplar forest grass shelterbelt systems and rural tributaries buffer zonesgrass-tree complex system in winter respectively:1.837,1.799,1.577; in springrespectively:1.799,1.427,1.09; in summer respectively3.182,1.588,1.205; in autumnrespectively2.476,1.718,2.012. The assessment results shows that three types ofgrass-tree complex systems during different periods were evaluated to be ‘medium’state. This result indicates that the ecological benefit of grass-tree complex systemsoverall in a low state, its ecological protection function is not perfect or function isrelatively weak.(3) Five indicators such as runoff coefficient, soil erosion modulus, soilmicrobial number, grass and tree complex width and grass forest biomass wereidentified playing a decisive role in the overall efficiency of the system for the benefitof the grass-tree complex system. The results provide a reference on enhancing forestgrass’ecological benefits(4) Make a few suggestions for grass forest management based on the evaluationresults.