一块油松人工林夏日的净光合速率

<正> 油松(Pinus tabulaeformis Carr.)在华北分布广泛,解放后又营建了大面积人工林。研究油松生态系统的组成、结构和生产力,在林业理论和生产实践上都有重要意义。 绿色植物固定光能还原CO_2的过程是一切生态系统初级生产的基本过程。因此,群体光合速率问题必然成为研究森林生产力的基础。油松人工林群体光合速率的研究是北京林学院

A STUDY ON NET PHOTOSYNTHETIC RATE OF A PINUS TABULA- EFORMIS STAND IN MIDSUMMER

The net photosynthetic rate and dark respiratory intensity of a pinus tabulaeformis stand were studied by the aerodynamic method in midsummer, 1982 in the eastern part of Beijing.Age of the stand is 25 years old.with a density of 1345 trees/ha,mean height of the trees is 10m.and b.h.d. averages 14.6cm.Under good water condition,the net photosynthetic rate was increased with the increase of light intensity .The mean net photosynthetic rates were 1-1.4mg CO2/m2/s and the peak value was 2.4mg CO2/m2/s under high light intensity.When the light intensity was about 2500 Lux,the absorption and release of CO2 were almost at equilibrium,and the net photosynthetic rate was close to zero.The mean intensity of respiration in the stand was 0.3 mg CO2/m2/s at night,and that of the soil was 0.03 mg CO2/m2/s,The vertical distributions of mean wind speed and mean CO2 concentra-tion above the stand canopy both were logarithmic.The zero plane displac ement was 7.1m,and the roughness length of the stand was about 1.9m.