| The paper studied the Daxing’an Mountains low-quality broad-leaved mixed forest, that transformed through different strip transformation models 6m (S1),10m (S2).14m (S3),18m (S4), and massive transformation models 25m2(G1),100m2(G2),225m2(G3),400m2(G4). 625m2(G5),900m2(G6), for all plots of litter water-holding capacity, soil properties, soil respiration rate, species diversity, vegetation growth and other indicators. It carried out five consecutive years of observation, analyzed the dynamic changes of the indicators of different transformation model, and established a comprehensive evaluation model, and the transformation of the different models of the comprehensive evaluation. Research results can accurately grasp the low-quality forest transformation in the restoration process and the present situation, help in low quality forest improvement measures of development and adjustment, improve the management level of the low-quality forest in Daxing’an Mountains forest region, improve the quality, productivity and ecological function of forests, and has a very important significance on the sustainable development of Daxing’an Mountains forest region. The results were as follows:(1) The transformation plots’litter amount, maximum water-holding capacity and available water-holding capacity of litter increased first and then decreased in the process, in the first year (2010) after the transformation, the plots S2, G2 litter amount, maximum water-holding capacity and available water-holding capacity of litter were significantly higher than indexes of the control plot(P<0.05), in the second and third year(2011 and 2012) after the transformation, each transformation plots indexes were lower than the control plot’s, in the fifth year (2014) after the transformation plots S2, G1, G2, G3 were higher than indexes of the control plot’s litter, the litter amount (11.14t·hm-2), maximum water-holding capacity (60.19t-hm"2) and available water-holding capacity (47.31t·hm-2) of plot S2 were highest in the strip transformation plots, the litter amount (10.37t·hm-2), maximum water-holding capacity (58.50t·hm-2) and available water-holding capacity (46.19t·hm-2) of plot G2 were highest in the massive transformation plots. Each transformation plots’litter amount, maximum water-holding capacity and available water-holding capacity of semi-decomposed litter were higher than non-decomposed litter. In the fifth year(2014) after the transformation, the relationship between water-holding capacity of litter and immersing time suited the logarithmic curve, the relationship between water absorbing speed of litter and immersing time suited the power curve.(2) The transformation plots’soil structure were seriously damaged, soil bulk density were higher, soil moisture content and porosity were poor in the first year after transformation, with the growth of updating vegetation, soil physical properties gradually improved in the volatility process. The soil pH value showed first decreased and then increased over time, the soil pH value increased with the plots of land area increased in the same year. The soil organic matter, total nutrient and available nutrient content of transformation plots were significantly higher than that in control plots in the first two years after transformation, and then began to drain down over time, even lower than that of the control plots, with the growth of artificial regeneration seedlings and natural regeneration of vegetation, the soil nutrient content increased. The soil bulk density were lower, water-holding capacity and porosity were higher, soil nutrient content were higher in strip transformation plots S2, S3 and massive transformation plots G2, G3 in the fifth year (2014) after transformation.(3) The soil respiration rates of strip transformation plots and control plots during the day were higher than that in the night, the highest rate occurred between 12:00 to 15:00, the lowest rate occurred between 23:00 to 3:00. The soil respiration rate of transformation plots increased and then decreased, then increased over time. The soil respiration rate of transformation plots were lower than that of the control plot in 2014, and the difference was significant (P<0.05), soil respiration rate of plot S3 (5.84μmol·m-2·s-1) was the highest. The fitting relationship of soil respiration rate and soil temperature are suitable for the exponential model (R2 between 0.79～0.90), the Q10 value in the range of 2.23-2.66, soil respiration rate and soil moisture (9%-27%) was quadratic curve relationship (R2 between 0.65-0.85), the application of two factor model fitting the effect were better than that of single factor model, soil temperature and moisture can explain the soil respiration rate of 70.7%～92.5%. There were significant positive correlations between soil respiration rate and soil total porosity, organic matter content, the correlations between soil respiration rate and soil pH, nitrogen content, amount of semi-decomposed litter were higher.(4) The tree layer species diversity index of transformation plots were lower than that of the control plot in the fifth year (2014) after transformation, tree layer Shannon-wiener diversity index (1.37) and Pielou evenness index (0.98) in the plot S3 were the highest; shrub layer Shannon-wiener diversity index and Pielou evenness index of transformation plots were higher than that of the control plot, the plot S4 were the highest, reached 1.52,0.95; herb layer species richness index and Shannon-wiener diversity index of transformation plots were higher than that of the control plot, the herb layer Shannon-wiener diversity index and Pielou evenness index of G6 were the highest, reached 2.08 and 0.87. The tree DBH and height growth of transformation plots higher than that of the control plot in the first five years after transformation, the tree DBH and height growth of plot S2 reached 0.58cm,0.76m, were the highest in the strip transformation plots, the tree DBH and height growth of plot G3 reached 0.56cm,0.72m, were the highest in the massive transformation plots. In the fifth year (2014) after transformation, annual growth rate of Pinus koraiensi in plot S3 (20.47%) was the highest, annual growth amount was 6.91cm, annual growth rate of Pinus sylvestris in plot S2 (20.69%) was the highest, annual growth amount was 5.02cm, annual growth rate of Larix gmelinii in plot G4 (22.05%) was the highest, annual growth amount was 14.64cm. The seedling survival rate of transformation plots decreased over time, Finus koraiensi, Finus sylvestris and Larix gmelinii seedling survival rate of plot S2 reached 80.77%,78.85%,82.31%, were the highest in the fifth year (2014) after transformation.(5) A model used to comprehensively evaluate different transformation models in the fifth year after transformation was established by using the gray correlation analysis, and selected 28 indicators, calculated the grey correlation degree of 10 kinds of transformation model to evaluate the effect of different transformation models, the strip transformation models were better than the massive transformation models with a comprehensive comparison, the transformation effect of S2 and S3 were better in the strip transformation models, the transformation effect of G2 and G3 were better in the massive transformation models. |
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