阔叶红松林林隙对凋落物碳和氮的影响

Effects of Forest Gaps on Litter Carbon,Nitrogen in Broad-leaved Korean Pine Forest

为了解林隙大小及林隙内位置对凋落物组成的影响，在伊春市带岭区东北林业大学凉水国家级自然保护区原始阔叶红松林内，选取3个大小不同的林隙作为试验样地，并以郁闭林分为对照。在每个林隙的中心点、通过中心点的南北一东西方向到扩展林隙边缘的中点以及对应的郁闭林分取样，将2012年6—10月在采样点收集的凋落物及时带回室内，经风干、粉碎后测定其碳、氮含量，分析林隙大小、林隙内位置及采样时间对凋落物碳、氮的影响。结果表明：采样时间对凋落物碳、氮均有显著的影响，凋落物碳、氮含量分别在8月达到谷值和峰值；林隙大小及不同位置对凋落物碳、氮影响均不显著，凋落物氮含量表现出中林隙〉大林隙〉小林隙的趋势，凋落物碳含量在郁闭林分0点最高；凋落物氮含量在郁闭林分0点最低。

To understand the effect of gap size and within-gap positions on litter composition, three different size gaps and closed-stand as con- trol were selected in broad-leaved Korean pine forest in Liangshui National Nature Reserve. During June and October, 2010, litter samples on forest floor in each gap and its control were taken and carried back to soil laboratory immediately. After litter samples were processed, total nitro- gen, total carbon content were determined. The effect of gap size, within-gap positions and sampling date on litter was analyzed. The results showed that ： the influence of the sampling date on litter total nitrogen, carbon content was significant, the former peaked in August, the latter reached the lowest value in August. However the influence of the gap size and within-gap positions on them was not significant, litter nitrogen content showed medium gap 〉 large gap 〉 small gap trend; both highest litter carbon content and lowest litter nitrogen content were found in closed-stand O point.