Li Meng, Duan Wen-biao, Chen Li-xin
College of Forestry, Northeast Forestry University, Harbin 150040, China.
Ying Yong Sheng Tai Xue Bao. 2011 Apr;22(4):880-4.
Taking the forest gaps of natural Pinus koraiensis broadleaved mixed forest in Xiao Xing'an Mountains as test object, and by the method of grids, the photosynthetic photon flux density (PPFD) in the gaps was continuously measured during growth season, and the spatiotemporal distribution patterns of the PPFD were analyzed by fundamental statistics and geostatistics methods. In the forest gaps, the high-value region of PPFD presented an obvious diurnal change, with the maximum PPFD appeared at 12:00 and in the northern part of the gaps. The mean monthly PPFD was the highest in June, and then decreased in the sequence of July, August, and September, with the largest coefficient of variation at different locations occurred in July and the medium variability in all the months. In different months, the intensity and the scale of PPFD spatial heterogeneity in the gaps differed, with the variation degree being the highest in June and the sill and proportion being the largest in July. The complex degree of the monthly PPFD patches also differed, with the maximum located in the northeast part of the gaps. The variation sequence of the mean monthly PPFD in understory and open ground was consistent with that in gap, and the mean monthly PPFD was the highest in open ground, medium in forest gap, and the lowest in understory.
以小兴安岭天然红松阔叶混交林的林隙为研究对象，采用网格法，在生长季对林隙内光合有效辐射（PPFD）进行连续测定，并运用基础统计学和地统计学方法分析其时空分布格局。在林隙内，PPFD高值区呈现明显的日变化，最大值出现在12:00且位于林隙北部。月平均PPFD在6月最高，随后依次为7月、8月和9月降低，不同位置变异系数7月最大，各月均为中等变异程度。不同月份，林隙内PPFD空间异质性的强度和尺度不同，6月变异程度最高，7月基台值和比例最大。月PPFD斑块的复杂程度也不同，最大值位于林隙东北部。林下和林外空地月平均PPFD变化顺序与林隙一致，月平均PPFD林外空地最高，林隙次之，林下最低。
