Light environment and canopy structure of a Pinus tabulaeformis community in the mountainous area of Beijing

Key words: 
• forest ecology /
• Pinus tabulaeformis community /
• light radiation /
• leaf area index /
• light extinction coefficient

Abstract: Light is a dynamic factor that affects the course of community succession and plant survival strategies. To reveal the light environment and provide reference for improving plantation structure，five Pinus tabulaeformis communities of different diameter classes in Beijing’s Miao-feng Hill Forest Farm were studied. Photos were produced with WinSCANOPY，and light characteristic indexes，along with canopy structure parameters，such as photosynthetic photon flux density （PPFD），canopy openness，leaf area index （LAI），and the light extinction coefficient（k），were analyzed by using standard plots method. Results showed that in the same habitat，total PPFD under the canopy ranging from 14.64 to 22.43 MJ·m-2·d-1 or about 64.59% of the PPFD above the canopy，decreased with increasing diameter at breast height （DBH）. Canopy openness was between 24.91% and 43.77%，whereas LAI ranged from 2.23 to 4.50 with an average of 3.67. Also，light extinction coefficients of all five communities were less than 0.20. Therefore，the light environment under these P. tabulaeformis communities was sufficient for growth and regeneration，to some degree，of the shrub and herb layers. ［Ch，4 fig. 1 tab. 30 ref.］