Determination of Parameters for Shrubs in the Global GrossPrimary Production Capacity Estimation Algorithm
Determination of Parameters for Shrubs in the Global GrossPrimary Production Capacity Estimation Algorithm
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DOI：
10.11440/rssj.36.236
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发表时间：
2016-07
期刊：
影响因子：
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通讯作者：
Yukiko Mineshita;Kanako Muramatu;N. Soyama;J. Thanyapraneedkul;M. Daigo
中科院分区：
文献类型：
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作者：
Yukiko Mineshita;Kanako Muramatu;N. Soyama;J. Thanyapraneedkul;M. Daigo
总初级生产能力（GPP）被定义为低胁迫下的GPP，其估计算法由Thanyapraneedkul等人（2012）利用光响应曲线提出。该算法背后的思想是，低胁迫下的光响应曲线与叶绿素含量有关。该参数是根据5种植被类型（草地、针叶落叶乔木、针叶常绿乔木、阔叶落叶乔木和农田（水田））的叶绿素指数卫星观测得出的植被指数估算的。全球GPP容量估算需要进行修改，以包括额外的植被类型，如占全球土地覆盖约13%的封闭和开放灌木。本研究利用AmeriFlux数据和卫星数据确定GPP容量估计算法中的开放和封闭灌木参数。在2000 PAR （μmol m−2 s−1）下，开放灌丛与禾草的最大光合作用估算参数基本一致，而封闭灌丛的最佳估算参数有所不同。我们认为，禾本科和开放灌木可以合并为一个类群，本研究和前人研究（Thanyapraneedkul, et al, 2012）的植物功能类型可以分为禾本科和木本植物两类。在此基础上，确定了两类的估计公式参数。此外，基于AmeriFlux数据和MODIS GPP产品（MOD17A2），研究了GPP容量的季节变化。如果植被没有经历高压力水平，GPP容量和AmeriFlux GPP观测值几乎相同。此外，我们的研究结果表明，GPP容量反映了干旱条件。
Gross primary production (GPP) capacity is defined as GPP under low stress, and the algorithm for its estimation was developed by Thanyapraneedkul et al.(2012) using a light response curve. The idea behind this algorithm is that the light response curve under low stress is related to chlorophyll content. The parameter is estimated from a vegetation index derived from satellite observations of the green chlorophyll index for five vegetation types: grass, needleleaf deciduous trees, needleleaf evergreen trees, broadleaf deciduous trees, and cropland (paddy fields). Global GPP capacity estimations require modifications to include additional vegetation types, such as closed and open shrubs, which account for approximately 13% of global land cover.In this study, the open and closed shrub parameters in the GPP capacity estimation algorithm were determined using AmeriFlux data and satellite data. The optimal parameter for maximum photosynthesis estimation at 2000 PAR (μmol m− 2 s− 1) of open shrubs was similar to that of grass, but for closed shrubs it differed. We concluded that grass and open shrubs could be combined into a single group, and plant functional types in this study and the prior study (Thanyapraneedkul, et al., 2012) could be divided into two categories: grass and woody plants. From this, estimation formulaʼs parameters were determined for the two categories. Additionally, seasonal changes in GPP capacity were investigated, based on AmeriFlux data and the MODIS GPP product (MOD17A2). GPP capacity and AmeriFlux GPP observations were nearly identical if the vegetation did not experience high stress levels. Also, our results indicated that GPP capacity reflected drought conditions.