月南方冰雪灾害前后的 NPP,评价了森林生态系统灾后的恢复能力。 结果表明:乡土树种马尾松(Pinus massoniana) 与杉木 (Cunninghamia lanceolata) 比外来树种湿地松(Pinus elliottii) 抗灾害能力强;在个体水平上,胸径(D) 较大的树木抗灾害能力较 差。 灾后马尾松与杉木的 D 增长率降低,而湿地松增大。 冰雪灾害导致大量碳(10.44 t C / hm 2) 从乔木层碳库转移到死生物量 碳库,占乔木层碳储量的 18.28%。 灾前 NPP 和碳利用效率(CUE) 分别为 736.23 g C m-2 a-1 和 0.41;灾后经过近 4 年的恢复, NPP 和 CUE 分别为 683.08 g C m-2 a-1 和 0.38。

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The eddy covariance technique is a micrometeorological method to directly measure the exchanges of carbon, water and energy between the vegetation and atmosphere. The spatial resolution of meteorological observation of fluxes can expand from tens of meters to kilometers. The eddy covariance method is most accurate when the contributing area of the fluxes is topographically flat, and vegetation extends uniformly within the footprint area. Currently there are more than 100 eddy covariance flux observation sites in China. Most of them are established in non鄄ideal conditions such as forest, undulating surface, patchy canopy area. Therefore, it is important to accurately interpret the ecological representativeness of flux data by evaluation of the spatial representativeness of its footprint in China. This paper reviews basic theories of the footprint, along with progress and applications about footprint functions. It discusses the research focus and difficulties when

Ground鄄level ozone (O 3) is a major pollutant with adverse effects on plant growth and yield. The impact on plants is generally studied by controlling the O 3 concentration using the open top chamber (OTC) method. The effects of O 3 on ecosystems are studied by combining assessment models and indices, calculated using O 3 concentration or flux measurements over the vegetation. As these effects are related to the level of O 3 entering into the plant忆s gas exchange, compared with concentration鄄based indices, the O 3 stomatal flux鄄based indices are considered the better standards for evaluating the influence of O 3 on ecosystems. In China, the rapid industrialization and urbanization has resulted in elevated O 3 concentration which is threatening crop production and yields. Studies are required to elucidate the O 3 risk鄄assessment indices, including consideration for the status of the plant. In this paper, we analyze the advantages and disadvantages of two kinds of assessment indices. We then introduce several O 3 flux observation and stomatal uptake estimation methods at ecosystem scale. We also review the progress in O 3 flux observations, stomatal uptake estimations and risk assessment across different ecosystems. Additionally, we present case studies and the future prospects of O 3 research in China. Concentration鄄 based indices are easily observed and calculated, but these types of indices are often lacking sufficient, robust experimental design and data. In contrast, O 3 flux鄄based indices are difficult to obtain, although they incorporate the status of the ecosystem. The method used for measuring O 3 flux is mainly the eddy covariance technique, generally seen as the best modern technique. However, this method is inferior compared with CO 2 / H 2 O flux measurements. The lack of a fast鄄response

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