<正>综述了热带森林碳通量的研究结果，指出随着电子测量和存储技术的发展，微气象涡度相关法已应用于森林碳通量的测量和研究；热带森林是碳源还是碳汇仍是一个存在争议的问题，热带森林的利用方式以及森林火灾在很大程度上决定了热带森林是碳源还是碳汇。夜间通量测量的不准确性，水平平流以及垂直平流都会在一定程度上影响碳通量测量的准确性，因此只有尽量减小测量误差，提高数据分析及处理技术，才能更准确地了解热带森林的作用。

The effects of different nitrogen forms (NH+4-N and NO-3-N) and ratios on the photosynthetic characteristics of the Pinus koraiensis seedlings were studied by pot experiment and the physiological mechanism was discussed. The results showed that the nitrogen treatments decreased the plasmalemma permeability and increased the net photosynthetic rate,the stomatal conductance, the RuBPcase activity, the sugar contents and the electron transport activities of PS Ⅰ and PS Ⅱ in comparison with the control. The increase of the physiological indexes mentioned above was the highest in the mixed treatment of NH+4-N and NO;-N, then was in the NO3--N treatment and the lowest in the NH4+-N treatment. The most benefit revealed as n(NH+4+-N)/n(NO;-N) ratio was 1/3～2/2. It is suggested that the rational ratios of different nitrogen forms be considered when the seedlings are to be fertilized.