红松阔叶混交林林隙光量子通量密度、气温和空气相对湿度的时空分布格局

以小兴安岭原始红松阔叶混交林林隙为研究对象，通过对林隙内光量子通量密度(PPFD)、气温和空气相对湿度进行连续观测，比较其间的时空分布格局.结果表明：晴天和阴天阔叶红松林林隙的PPFD日最大值均出现在11:00—13:00，晴天林隙内各个时段最大值出现位置不同，日最大值出现在林隙北侧林冠边缘处；而阴天各个时段最大值均处于林隙的中心.林隙内月平均PPFD 为6月最高、9月最低，极差7月最大.林隙内晴天气温的峰值出现在9:00—15:00，而阴天气温峰值在15：00—19：00，均位于林隙中心南8 m.5:00—9:00林隙各点阴天的气温都高于晴天，9:00—19:00则相反.月平均气温为6月最高、9月最低.晴天和阴天空气相对湿度的峰值均出现在5:00—9:00，日最大值在林隙西侧林冠边缘处，且阴天的相对湿度始终大于晴天.月平均相对湿度为7月最高、6月最低.晴天PPFD的异质性大于阴天，而气温和相对湿度的异质性则不明显.生长季内不同月份PPFD、气温和空气相对湿度的最大值所处位置不同.PPFD和气温的月均值在林隙中心及附近变化梯度较大，而相对湿度的月均值则在林隙边缘变化梯度较大.

Spatiotemporal distribution patterns of photosynthetic photon flux density, air temperature, and relative air humidity in forest gap of Pinus koraiensis-dominated broadleaved mixed forest in Xiao Xing'an Mountains

A continuous measurement of photosynthetic photon flux density ( PPFD), air temperature, and relative air humidity was made in the forest gap in primary Pinus koraiensis-dominated broadleaved mixed forest in Xiao Xing'an Mountains to compare the spatiotemporal distribution patterns of the parameters. The diurnal maximum PPFD in the forest gap appeared between 11:00 and 13:00 on sunny and overcast days. On sunny days, the maximum PPFD during various time periods did not locate in fixed locations, the diurnal maximum PPFD occurred in the canopy edge of northern part of the gap; while on overcast days, it always occurred in the center of the gap. The mean monthly PPFD in the gap was the highest in June and the lowest in September, with the largest range observed in July. The maximum air temperature happened between 9:00 and 15:00 on sunny days, between 15:00 and 19:00 on overcast days, the locations were 8 m in the southern part of gap center both on sunny and overcast days. From 5:00 to 9:00, the air temperature at measured positions in the gap was higher on overcast days than on sunny days; but from 9:00 to 19:00,it was opposite. The mean monthly air temperature was the highest in June, and the lowest in September. The maximum relative humidity appeared between 5:00 and 9:00 on sunny and overcast days,and occurred in the canopy border of western part of the gap, with the relative air humidity on orer-cast days being always higher than that on sunny days. The mean monthly relative humidity was the highest in July, and the lowest in June. The heterogeneity of PPFD was higher on sunny days than on overcast days, but the heterogeneities of air temperature and relative humidity were not obvious.The maximum PPFD, air temperature, and relative humidity were not located in the same positions among different months during growing season. For mean monthly PPFD and air temperature, their variation gradient was higher in and around the center of gap; while for mean monthly relative humidity, it was higher in the edge of forest gap.