Research On Photosynthetic Characteristics Of Pinus Tabulaeformis Plantation Of Taiyue Mountain In Shanxi Province

Using Li-6400portable photosynthesis to study on Photosynthetic of Pinus tabulaeformis plantation of Taiyue Mountain, the study content as follow:First, The key ecological factors that have affect on photosynthetic of Pinus tabulaeformis during different periods; Second, spatial heterogeneity of photosynthetic characteristics of Pinus tabulaeformis canopy; Third, The Artificial tending effect on photosynthesis of Pinus tabulaeformis plantation. The results of studies show:(1) The key ecological factors that have affect on photosynthetic of Pinus tabulaeformis were different within different periods, the prior period was mainly impacted by atmospheric relative humidity, photosynthetic available radiation and stomatal conductance; stomatal conductance was the key factor in the middle term, the late period was mainly restricted by the CO2concentration of Intercellular.(2) Pinus tabulaeformis needles of different canopy positions and leafages were measured and relevant light and CO2response curves were produced, the results showed that canopy positions, leafages and sides had effects on the physiological indices including net photosynthetic rate (Pn), light saturation point (LSP), light compensation point(LCP), dark respiration(Rd) and apparent quantum efficiency (a).Moreover, with the drop of the canopy position, the majority of indices decreased; the increase of leaf age, the majority of indices also decreased. Pinus tabulaeformis on the shady slope showed higher a, Pmax than those on the sunny slope; while those on the sunny slope indicated greater LSP, LCP, Rd and CO2carboxylation efficiency.(3) That leaf photosynthetic of Pinus tabulaeformis plantation response to the change of environment show:after artificial tending interference, the environmental factors(photosynthetic active radiation (PAR), air temperature (Ta), air relative humidity (RH) and atmospheric CO2concentration (Ca)) daily presente dsingle peak change, and the key factor to limit the net photosynthetic rate of Pinus tabulaeformis is light(p<0.01).Moreover, light saturation point (LSP), maximum net photosynthetic rate, the mean value of net photosynthetic rate, light compensation point(LCP) and dark respiration(Rd) of the experimental groupare greater than the control group, and under the medium level of artificial tending interference, the daily means of the first three indices are maximum, but the change of light compensation point(LCP) and dark respiration(Rd) are minimum. In addition, apparent quantum efficiency (a), Chlorophyll a, Chlorophyll b and total chlorophyll of the experimental group are less affected than the control group, but the artificial tending interference is the most obvious one under the medium level. In summary, the study of the artificial tending interference effect on photosynthesis of Pinus tabulaeformis plantation in Taiyue Mountain is significance in the maximization of economic benefit and ecological benefit of plantation under different ways of forest management, the research on the spatial heterogeneity of photosynthetic characteristics of the canopy could significantly contribute to reveal carbon sequestration capacity of the plant and estimate plant productivity.