A STUDY ON DISTRIBUTION AND CYCLE OF MICROELEMENTS IN LARCH PLANTATION ECOSYSTEM
Liu Shirong(Research Institute of Foreatry, Chinese Academy of Forestry, Beijing 100091) Li Jin(Forestry Bureau of Chaoyang, Liaoning Province, Chaoyang 122000)
Based on determinations of the four microelements, including Cu, Zn, Fe,and Mn, whthin Dahurian larch plantation ecosystem in the eastern part of no-rthern China, analyses of nutrient concentrations, distribution, accumulation,removement and cycle through the ecosystem were conducted. The results wereas follows, The total amount of the microelements accumulated in the ecosystemwas 173493.368kg/ha, in which nearly 99% was stored in the soil pool, whileno more than 1% in the vegetation system; The annual absorption of the mic-roelements was 6. 4483kg/ha, in which the annual retention and the annual re-turn were 3.3250kg/ha and 3. 1233kg/ha, respectively, and the return/absorp-tion ratio was 48.440; The input thrfough hydrologic way into the ecosystemand the output through runoff out of the ecosystem were 0.8720kg/ha·a and0.4114kg/ha, respectively, and thus the net gains of the system was 0.4606kg/ha·a and the average net change ratio was 52.8% with the highest value of77.8% for Cu; The circulation diagram of microelemental cycle within the eco-system was described and the dynamic models were established.