| The XiaoXing′An mountains is one of the important timber production base in China.However,due to the interference of excessive logging and natural factors for many years,this area has formed a large area of low quality forest with low canopy density and forest decline.In order to change the low-quality forest stands into qualify forest stands with desirable productivity and water and soil conservation ability,it is necessary to carry out transformation on the low-quality forests by adjusting the stand structure and functions of the low-quality forest stands.In this paper,the material flow analysis and life cycle assessment were applied to establish a material accumulation and circulation model for the transformation system of low quality forest,then applied in the low-quality forest stands in XiaoXing′An mountains and 1 hm2 low-quality forest plot with 10 m transverse cutting strip width was quantitatively analyzed in terms of material accumulation and circulation,and quantified the process of low quality forest transformation process.The Simapro life cycle assessment software is used to analyze and evaluate the impact of environment on the transformation of low quality forest.The purpose is to grasp the dynamic change information of the low quality forest transformation operation,and clarify the storage and transformation of the material in the process of low quality forest transformation,so as to provide a scientific and reasonable guidance basis for the operation and management of the transformation of low quality forests in the region.Get the following conclusion:(1)During the 1997-2007,1 hm2 low-quality forest plot with 10 m transverse cutting strip width,the nutrient accumulation,flow,circulation,to 2007 low-quality forest cutting transformation,standing wood containing N,P,K nutrient element 236.91 kg,65.28 kg,108.55 kg,soil containing 212.74 kg N,9.35 kg P,98.88 kg K.During 2008-2015,the regeneration system in 1 hm2 absorbed the accumulated nutrient per hectare in forest soil were 289.08 kg N,14.27 kg P,and 124.75 kg K,trees accumulated nutrients to 25.02 kg N,4.03 kg P,10.57 kg K.(2)As of 2007,1 hm2 low-quality forest plot with 10 m transverse cutting strip width,growth to form a total of 94.61 t biomass.Among them,the biomass stored in the trees is 82.65 t/hm2,the biomass used in the form of logs is about 31.32 t/hm2,and the biomass used in other forms is about 3.7t/hm2.During the 2007-2015,By 2015,a total of 2.81 t/hm2 biomass was formed per hectare of forest,and the litter biomass was 0.26 t/hm2.(3)The largest consumption of 1 hm2 low-quality forest plot with 10 m transverse cutting strip width is crude oil(827.53 g/m3),followed by N,P,K,limestone,iron and coal;the most environmental pollution is CO2(3211.41g/m3),followed by NOX,CO,PM,SO2,HC,CH4.(4)The environmental impact of 1 hm2 low-quality forest plot with 10 m transverse cutting strip width on the environment of 5.75 pt,the environmental impact of environmental impacts including harvesting transformation operation system of 4.54 pt and the 1.21 pt operating system update tending.Different harvesting intensity(30%~70%)was used to reconstruct the low quality forest,and the boundary value of resource consumption and environmental impact was between 3.15~8.25 pt.With the increase of the harvesting intensity of low quality forest,the influence of resource consumption and environment was also increased,but not linearly increased. |
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