Evaluation On Soil Fertility Quality Of Low-quality Forest After Transformation In Greater Hinggan Mountains

Because of times of over-cutting and natural calamities, Greater Higgnan Mountains regions formed crown density low, declined and serious soil erosion under the groud low-quality stands. It became urgent for us to make transformation in order to improve quality of low quality, restore original stand forest structure and function. This study researched that we had clear-cutting to broadleaf mixed secondary forest and Birch coppice by6m,10m,14m and18m wide in Greater Higgnan Mountains, then each was divided into3pieces, respectively,planted Pinus sibirica (Loud.) Mayr, Mongolica Litv and Larix gmelinii rupr widely. We chose the soil physical and chemical properties and soil carbon flux after transformation in the forest as the research object transformation.The paper discussed the effect of soil carbon flux and soil physical and chemical properties by different induced transformation. Using the improved analytic hierarchy process to comprehensive assess soil fertility quality after induced transformation of low-quality. The main research results were as follows:(1) In the two kinds of different renovation, compared to check plots, soil capillary hold water, maximum capacity, capillary porosity and total porosity all had certain degree increased except for soil bulk density reduced, but it had no significant variance. Soil area performed weak acidity with pH about6.0. Soil organic matter content of different way of forest land reformation basically kept balanced. In broadleaf mixed secondary forest transformation, soil total nitrogen, hydrolysis nitrogen, phosphorus and potassium content were all had certain degree increased, but total phosphorus, effective phosphorus content had different rate reduced. While in Birch coppice forest transformation, soil total nitrogen and effective phosphorus content had different rate reduced, but total phosphorus and nitrogen content had raised. Under different effect bandwidth, soil pH value, the effect of organic matter, total nitrogen, total nitrogen, hydrolysis K and rapidly-available potassium content transformation, variation coefficient of Pinus sibirica (Loud.) Mayr was the largest. After the multiple comparisons, in view of all transformation way to the low-quality forest with soil phosphorus content reduced significantly, we should intensify the P supplement to maintain long-term effectiveness of soil fertility in the subsequent production management.(2) Two kinds of low-quality stand under different transformation all represented soil carbon flux increased with the bandwidth increased.6m bandwidth and10m bandwidth soil carbon flux had no interference with check plots and no significant difference, but14m bandwidth and18m bandwidth soil carbon flux were much higher than those of plots. Under different measure, soil bulk density and soil carbon flux performed a significant negative correlation, and content of soil organic matter, half decomposition level falling object quality, soil temperature, soil moisture and soil carbon flux presented a significant positive correlation.(3) In broadleaf mixed secondary forest transformation,6m wide effect bandwidth, Pinus sibirica (Loud.) Mayr soil fertility quality index was less than check plots, while the rest indexes were all higher than those of plots. In14m bandwidth transformation, Larix gmelinii rupr soil fertility quality composite index was the highest for about0.744. In Birch coppice forest reformation, initiation in low quality, all soil fertility quality was higher than check plots.14m wide effect bandwidth Mongolica Litv soil fertility quality index was the highest for about0.617. According to Spearman’s correlation analysis, influences of the main factors were soil organic matter, total nitrogen, hydrolysis phosphorus content.The research results above discussed changes of soil physical and chemical properties and soil carbon flux after different induced transformation to low-quality stands, and it provided the theory basis to make efficient low-quality stands transformation model and realize the usage of efficiency management to forest land.