| Poplar is an important afforestation tree species on plain area in China.The 4-year-old plantations of clones Nanlin 95,Nanlin 895 and Nanlin 797 were studied to learn their biomass productivity, litter decomposition characteristics and dynamics of physical and chemistry properties of the soil at different planting patterns with various densities, clones and sites. The results from this study would provide technical support for oriented cultivation of poplar plantations. The main results are as follows:1.There were significant differences in biomass productivity in different poplar plantations. The proportions of different components to the total biomass were larger different between the different stands. Also a small difference in macroelement content was observed among the different poplar plantations.2. There existed a larger difference in the litter production per year, and more litter was produced in larger densities stands. Litter dynamics basically showed a single peak for all poplar plantations, but the peak date of litter production was different, usually in August.3. The largest decomposition rate of litters was observed within 61～244 day in different poplar plantations, while the decomposition rate slowed down between 244 and 305 days. Monthly dynamics of litter weight loss rate in different poplar plantations also showed a single peak trend. The range and peak dates of weight lose rate were various among different plantations. The litter decomposition rates in different poplar plantations were different.4. The macroelement (N,P,K,Ca,Mg) content in the litters of different poplar plantations had very different dynamics in its decomposition process, which was influenced by the density, poplar clones and site conditions. So the time of enrichment or release of nutrients was also different in various poplar plantations.5. Soil bulk density, total porosity, field capacity, and saturated soil moisture were increased as soil depth increasing, and difference was found among different poplar plantations. Generally, soil pH showed a continuous slight increasing trend.6. The soil organic carbon had a same trend with higher in surface soil and lower as soil depth increase. A great discrepancy in soil organic carbon content was observed in different poplar plantations. Soil available nutrients content were decreased with soil depth increasing for all poplar plantations, but significant differences exited in some plantations.In a word, the characteristics of litter decomposition in different poplar plantations was different, and the physical and chemical properties of soil were affected by the decomposition process, which make biomass productivity different in various poplar plantations. |
