Study On The Productivity In Abies Fabri Rofest Of Eastern Slope In Gongga Mountain

As the primary producer of forest ecosystems the forest productivity reflects the structure and function of plant community synthetically. In the past, most of studies on productivity of forest ecosystems are focused on the index of dry weight production which was failed to reflect the function and the ecological efficiency of forest ecosystems deeply and completely Thus, based on the investigation of biomass , with the help of CI-3O1PS gas analyzer ,a field study on the photosynthesis rate and respiration of A bEes fabri and also the radiation utilization ratio, estimating the latent productivity of A.fabri community was made systematically on eastern slope of Gongga mountain in the west of Sichuan Province. The main results and conclusions are summarized as the follows: 1 .The biomass of the A bEes mid-aged forest and the Abies mature forest is 267.015 and 351.844 t/hm2 respectively, higher than the average value 200 t/hm2 of dark coniferous forest in different areas of world which summarized by Whittaker & Linkens in 1973. The net primary productivity is 13.077 and 11.943 t/hm2 a of the Abies mid-aged forest and the A bEes mature forest respectively which was measured by gas exchange methods, higher than the average value 11 .8 t/hm2 a of sub-cold zone (subalpine zone) dark coniferous forest in China that calculated by Fang-Jingyun in 1996. 2.Applied the three climate productivity models in the region of A.fabri forest of Gongga Mountain, it shows that Chikugo model can be used to estimate the NPP of A.fabri community. 3 .Jt was also found in the studies that leaf area index has much compact on gross productivity .For example, the LAJ of tree layer for Abies mid-aged forest is 7.620 and for A bEes mature forest is 4.53 7, with which the gross productivity 32.642 and 19.739 was found correspondingly. Secondly, community structure also has much compact on net primary productivity. For instance, the biomass proportion (tree layer: shrub layer: herb layer) in A bEes mid-aged forest is 100:0.6:0.2, but in A bEes mature forest is 100:3.9:0.4, the leaf area index in both community are 7.620, 0.375, 0.032 and 4.537, 3.291, 1.143 respectively. Owing to this difference, the Abies mid-aged forest used up 61 percent of photosynthetic production by respiration and Abies mature forest only expended 53 percent of that. Thirdly, analyzing the photosynthesis rate of A.fabri and the meanwhile ecological factors, it was found that light intensity was the leading factor affecting on the primary optical productivity synthesizing. 2 4.The utilization ratio of total solar radiation is 0.71 percent and the utilization ratio of PAR is 1.92 percent. Latent optical productivity isl4.85 t/hm2a, higher 24 percent than the measured value 1 1.94 t/hm2a. It shows that the productivity in A bEes fabri mature forest is a big higher, but it appear to have more potential for increasing the utilization ratio of radiation and the productivity by the way of using proper management and measures.