兴安落叶松林通量观测足迹与源区分布

Flux Footprint of Larix gmelinii Forest and the Distribution of Source Area

基于Korman和Meixner理论提出的适用于涡动相关系统通量足迹方法,利用内蒙古自治区大兴安岭森林生态系统国家野外科学观测研究站兴安落叶松林生态系统的不同风向、大气稳定状态、生长季和非生长季通量观测数据,分析兴安落叶松林通量足迹以及贡献源区的分布,为今后大兴安岭地区兴安落叶松生态系统通量变化及影响因素对比研究提供依据。结果表明,以80%通量源区为测算对象,不同风向下大气处于稳定状态时,观测的通量源区主风向东北风-北风风向下面积最大,最大主风向源区面积要比不稳定时主风向源区面积大近36%。生长季源区在任何状态时均<非生长季,在大气稳定状态时生长季源区面积<非生长季近15%,大气不稳定状态时生长季源区面积<非生长季9%。在大气处于稳定状态时不同风向下,源区横风峰值<不稳定状态时的峰值,源区达到峰值距离约为稳定时的2倍。当大气处于稳定状态时,生长季的横风积峰值和源区峰值距离均>非生长季。兴安落叶松林生长季时呼吸、光合作用加强,使得地与气之间的湍流物质交换频繁;主风方向通量源区面积<非生长季,在大气稳定状态时,湍流混合充分,通量塔的信息来自主风方向,使得通量源区面积和空间范围扩大。

Based on the flux footprint method suitable for eddy correlation system proposed by Korman and Meixner theory,by using the observed data collected in growing season and non-growing season in different wind directions in Daxinganling Forest Ecological Station,the flux footprint of Larix gmelinii forest and the distribution of contribution source areas were investigated to provide a basis for the comparative study on the changes of ecosystem fluxes and influencing factors of L.gmelinii in the Greater Xing'an Mountains.The results showed that when 80%of the source area of flux was used as the calculation object,and when the atmosphere was steady under different wind directions,the area was the largest under the northeasterly-northeasterly wind direction of the main flux direction of the observed flux source area was the largest,and the area of the source area of the largest main wind direction was 36%larger than the source area of the main wind direction when unstable.Under all conditions,the source area in growth season was less than that in non-growing season,and the source area in the growing season under atmospheric stability was less than 15%in non-growing season,and the source area in growing season under the unstable atmosphere was 9%smaller than in non-growing season.When the atmosphere was in a steady state,the peak value of cross winds in the source area under steady wind conditions was less than that under unstable conditions and the peak distance in the source area was about 2 times more than that of a stable one.When the atmosphere was in stable condition,the cross wind peak area and the source area peak distance in growing season were greater than those in the non-growing season.L.gmelinii forest respiration and photosynthesis during growth season strengthened,making the exchange of turbulent substances between ground and gas frequent,the main wind direction flux source area was smaller than in non-growing season.Under atmospheric stability conditions,turbulents were fully mixed,flux tower recieved information from the main wind direction,making the flux source area and the expansion of space area.