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Báo cáo lâm nghiệp: "Standing crop, production, on dry, moderate, and wet"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: Standing crop, production, on dry, moderate, and wet. | Ann. Sci. for. 1985 42 2 113-142 Standing crop production and turnover of fine roots on dry moderate and wet sites of mature Douglas-fir in western Oregon D. SANTANTONIO 11 et R.K. HERMANN 1 2- Production Forestry Division Forest Research institute. Private Rag Rotorua New Zealand Departments of Forest Science and Forest Management Oregon State University Corvallis. Oregon 97551 USA Summary Standing crops of live and dead fine 1 mm diameter and small 1 to 5 mm diameter roots in the top 75 cm of soil were sampled from March 1977 to September 1979 in dry moderate and wet habitats of mature Douglas-fir Pseudotsuga menvesii . During this period large and statistically significant changes in standing crops of fine roots occurred within short intervals 3 months . Overall standing crops of small roots did not change significantly nor were they statistically different overall. Standing crops of live roots 2.5 to 3.5 Mg ha were not statistically different among sites but those of dead fine roots were 10.7 Mg ha on dry site 4.1 Mg ha on wet . On the basis of changes in standing crops of live and dead fine roots we estimated fine-root production on the dry moderate and wet sites to be 6.5 6.3 and 4.8 Mg ha year turnover to be 72 7.2 and 5.5 Mg ha year and decomposition to be 8.2 8 0 and 6.9 Mg ha year. The effect of site conditions may be indicated by the number of times that the mean standing crop of live fine roots turned over per year 2.8 on the dry site 2.0 on the moderate site and 1.7 on the wet site. Cyclic death and replacement of fine roots in a succession of favorable microsites may be an adaptive strategy to maintain the largest number of active roots at a minimum metabolic cost. Results of this study confirm the importance of fine roots as a major pathway of carbon cycling in temperate forests. Key words Douglas-fir Pseudotsuga menziesii roots fine roots root production root turnover root decomposition root growth moisture stress. 1 When this study was conducted D.