| In this study, we use the mixed planting of precious tree species Erytbropldeum fordii, Dalbergia odorifera and E. grandis×E. urophyll builded by the Chinese forestry science institute of tropical forestry experiment center as the research object. By means of investigation and studying trees growth, soil physical and chemical properties and litter standing crop of mixed forest of different mixed mode and mixed species, evaluation the effect of different mixed mode. The results showed that:1. In the two mode of Erytbropldeum fordii and E. grandis×E. urophyll, Dalbergia odorifera and E. grandis×E. urophyll, the annual DBH growth of E. grandis×E. urophyll were respectively3.7cm,3.8cm, the annual tree height growth were respectively3.9m,3.5m, crown annual growth were0.76m. The average individual volume of the two modes were respectively0.06713m3/plant,0.05944m3/plant, and hectare amount were respectively74.51518m3/hm2、65.98133m3/hm2. In mixed early, E.grandis×E. urophyll was little impact on growth, and there was no significant difference of DBH, tree height, crown width, individual volume, hectare of E. grandis×E. urophyll in both mixed mode. The growth of Erytbropldeum fordii, Dalbergia odorifera had not been much affected.2. In the two kinds of mixed modes, soil physical properties was insignificant, and no significant effect on the growth of E. grandis×E. urophyll. Soil physical properties showed that capillary water is greater than field capacity, capillary porosity is far greater than the proportion of non-capillary porosity, A layer is greater than layer B on total porosity. The water-holding capacity of soil aeration in mode Erytbropldeum fordii and E. grandis×E. urophyll slightly larger than Dalbergia odorifer and E. grandis×E. urophyll. The simple correlation between individual volume of E.grandis×E. urophyll and the physical properties of soil A, B layer was not significant. It illustrated that soil physical properties had little effect on the urophylla growth. 3. In the wo kinds of mixed modes, nutrients and soil organic nitrogen content were significantly different, and there had a significant positive correlation between organic nutrients, total nitrogen content and growth of E. grandis×E. urophyll. Soil of two kinds of mixed modes are acidic. Performance of each nutrient content was organic matter> organic carbon> TN> phosphorus> effective potassium. Between the levels of soil, organic carbon, organic matter, total nitrogen, available phosphorus, available potassium levels of the A layer were much higher than the B layer; but available phosphorus, available potassium was not significant between the two modes. And soil nutrient content of A, B layer of Erytbropldeum fordii and E. grandisxE. urophyll mode was slightly higher than Dalbergia odorifera and E.grandis×E. urophyll.The individual volume of E. grandisxE. urophyll was highly positive significant correlated with organic carbon, organic matter, total nitrogen content of soil A layer, highly significantly negatively correlated with pH value of soil A layer. The individual volume of E. grandisxE. urophyll was positive significant correlated with organic carbon, organic matter, total nitrogen content of soil B layer, significantly negatively correlated with pH value of soil B layer, and not significantly correlated with phosphorus content and available potassium of both A and B layer.4. Absolute content of soil nutrients of two kinds of mixed mode were no significant differences. Individual volume of E. grandis×E. urophyll were significantly positively correlated with the absolute organic nutrients and total nitrogen content layer of A and B. Two kinds of mixed modes soil absolute nutrient content of Erytbropldeum fordii and E. grandis×E. urophyll mode higher than Dalbergia odorifera and E. grandisxE. urophyll mode. The absolute nutrient content of A layer were higher than B layer in the two modes, and organic carbon, organic matter, total nitrogen content difference of no more than14%between the two levels, while phosphorus of layer A was far higher than the B layer. Phosphorus of A layer of Erytbropldeum fordii and E. grandisxE. urophyll mode was2.961times for B layer, and while it was2.883times for B layer of Dalbergia odorifera and E. grandisxE. urophyll mode.5. Litters of two kinds of mixed mode were significantly different. Litter dry mass of two kinds of mixed modes were1435.2kg/hm2above, moisture content of litter was between15%to22.6%. Litter dry mass of Dalbergia odorifera and E. grandisxE. urophyll mode was higher than Erytbropldeum fordii and E. grandisxE. urophyll mode, and the difference was significant, while the moisture content of litter was Erytbropldeum fordii and E. grandisxE. urophyll mode higher than Dalbergia odorifera and E. grandisxE. urophyll mode, and extremely significant difference.6. Mixed early, litter influenced little on soil physical properties, and significantly affected on soil pH of A layer, but has not much improvement to nutrient content. Litter existing dry mass of Erytbropldeum fordii and E. grandis×E. urophyll mode has no significant correlation with physical properties of two levels. Litter existing dry mass significantly positive correlated with soil pH of A layer, and had no significant correlation with the soil pH of B layer, was highly significantly negatively correlated with of organic carbon, organic matter, total nitrogen content of A layer, was significantly negatively correlated with the organic carbon, organic matter, total nitrogen content of B layer, was no significant correlation with the available phosphorus, available potassium, and the influence to potassium bigger than phosphorus content.7. Litter existing dry mass was highly significant negative correlation with absolute content of organic carbon, organic matter, total nitrogen of A layer, were significantly negatively correlated with absolute content of organic carbon, organic matter, total nitrogen of whole layer, has no correlation with absolutely content of available phosphorus and available potassium. Litter existing dry mass had no correlation with absolutely nutrient content of layer B. Since afforestation life was short, the effect on absolutely nutrient content of B layer was not yet significant.In summary, E. grandis×E, urophyll mixed planting with Erytbropldeum fordii and Dalbergia odorifera, trees growth was little effected too heavy in the early, and Erytbropldeum fordii and E. grandis×E. urophyll mixed mode was better. |
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