| Masson pine caterpillar (Dendrolimus punctatus) is the common insects in pine forest ecosystem, to harm serious pine forests of the southern provinces in our country, also seriously affects the pine the normal life of residents. This article through to the study area counties of dendrolimus punctatus pest monitoring, select XinShao county and Chen creek sample area and so on three years ago, when the sample area and so on as the paper test sample, mainly from pinus massoniana MAO pests of forest biodiversity, biomass and carbon deposits, soil water-holding performance, forest landscape structure, etc, this paper discusses the dendrolimus punctatus effects on stand. The main results were as follows:(1) the study of biological diversity, according to the results of XinShao county creek each test sample and Chen happened three years ago and so on to Shannon-Wiener index and Simpsond index is to do> sample area, and Chen creek county was so to Shannon Wiener index and Simpsond index value (1.42,0.70)"the sample (1.80,1.80), is mainly due to the sample area vegetation species occurred more than to do, and for monitoring time in dendrolimus punctatus occurrence period, in addition to cause massive is the food of masson pine needles, the other has not yet other effects.(2) three years ago to forest volume (XinShao108.8m3· hm-2, Chen xi206.3m3· hm-2)<three years ago to the same tree volume (XinShao121.7m3· hm-2, Chen xi220.9m3· hm-2), three years ago sample area forest biomass (XinShao68.77t·hm-2, Chen xi125.52t·hm-2)<three years ago to the same forest biomass (XinShao74.84t·hm-2, Chen xi142.40t· hm-2), mainly due to dendrolimus punctatus feed off the pine needles, lead to weakened trees photosynthesis, carbon sequestration ability, growth speed is slow, and even small plants die, so dendrolimus punctatus sample volume is less than to do, some plants die, stop growing, will also affect and biomass of pinus massoniana stand volume with the size.(3) research on tree layer forest carbon deposits suggests that Calvin creek county and XinShao monitoring happened three years ago to test sample and so on are showed, three years ago sample area forest carbon deposits (XinShao34.74t· hm-2, Chen xi63.41t·hm-2)<three years ago to the same forest carbon deposits (XinShao37.81t· hm-2, Chen xi71.941· hm-2).(4) XinShao county, Chen xi county sample each test sample in three years ago to live ground cover biomass>to still live three years ago by biomass, mainly in the shrub layer is most obvious, three years ago to happen (XinShao0.327kg, Chen xi0.646kg)>three years ago to the same0.128kg (XinShao, Chen xi0.359kg), mainly because of the occurrence of pests and pinus massoniana changed the stand inside the light conditions, to stand within the dwarf shrub growth and development. Each test sample in litter decomposition layers not biomass sample performance for three years ago (XinShao0.348kg, Chen xi0.105kg)<three years ago to just (XinShao0.512kg, Chen xi0.269kg), to the scene (XinShao0.322kg, Chen xi0.334kg)<that year to just (XinShao0.384kg, Chen xi0.390kg), mainly because of pinus massoniana occurred within the sample area, a large number of pine needle by dendrolimus punctatus feed off, resulting in a decrease of forest litter content within a lot of litter accumulation is reduced, the accumulation of litter decomposition not reduce, litter decomposition layers not biomass decreased. Creek and Chen county litter sample happened three years ago to the total biomass (0.674kg)> litter three years ago to the same total biomass (0.629kg), is mainly affected by three years ago after the outbreak of dendrolimus punctatus big, after two years of litter biomass accumulation gradually increase, coupled with the massive death dendrolimus punctatus, dendrolimus punctatus waste rot and insect body into the forest, litter sample made three years ago to the accumulation of total biomass growth is faster than to just three years ago, after three years of accumulation, so more than total litter biomass to total litter biomass.(5) XinShao county forest soil bulk density is happened three years ago to test sample (1.30g/cm3)<three years ago to the same (1.13g/cm3), parties of dendrolimus punctatus in sample to the capillary porosity of, to do the capillary porosity> sample to the capillary porosity, sample creek and Chen county happened three years ago to the capillary porosity (9.30)> to just three years ago (5.15), the capillary porosity creek, mainly because of Chen county after the outbreak of dendrolimus punctatus big three years ago, after two years of good growth, in sufficient lighting at the same time, the appropriate water condition, sample made three years ago to soil structure returned to normal, and stand in massive death dendrolimus punctatus, insect body rot into the soil, to sample to provide adequate nutrition circulation, promote the benign development of soil. For soil water storage capacity, sample XinShao county happened three years ago to maximum capacity (99.49mm)>3years ago to the same maximum water holding capacity (79.19mm), the largest storage capacity for three years ago (994.86t/hm2)> control (791.93t/hm2) three years ago.(6) on the forest landscape structure analysis, the influence of different landscape types can of dendrolimus punctatus happened even caused the spread of the adult disasters have isolation effect, so as to control the occurrence of disasters and expanded. In accidentally in the disaster areas and no disaster and disaster in key area divided into three types, and for the study area is often in the disaster area, the area divided into landscape evenness and diversity index was small, and the number of forest patches and accounts for the proportion of its area is larger, relative advantage degree is very big, but for the landscape developed no disaster analysis that the landscape structure characteristic compared with often in the disaster areas, contrary, showed that mixed forest can effectively control the pests. |
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