Mangrove forests play crucial roles in the coastal ecosystems of the tropics. Few studies have addressed long-term changes in the net primary productivity (NPP) of mangroves in relation to the tropical monsoon climate. We conducted a tree census from 2008 to 2018 in a permanent plot at a secondary mangrove forest under the tropical monsoon climate of Eastern Thailand. During this period, the mortality of fast-growing species and the increasing number of newly recruited trees revealed a temporal change in the plant composition and distribution. Total tree biomass linearly increased from 283.64 to 381.72 t·ha⁻¹ during the study period. The NPP was calculated by using the summation method, which included fine root production. The NPP ranged from 21.19 to 29.04 t·ha⁻¹·yr⁻¹. The fluctuation in NPP and its components were analyzed in relation to climatic factors by the linear regression model. The NPP did not relate with the annual climatic factors, such as the mean temperature and annual rainfall. However, both increments in the basal area and living tree biomass, which is a major component of NPP, were negatively related with the maximum and mean monthly temperatures in the dry season. The annual mortality rate related positively with annual rainfall and the maximum monthly temperature in the dry season. Linear regression analyses showed that some major components of NPP were chiefly affected by the temperature environment in the dry season. These results indicated that the weather in the dry season was largely restricting the mangrove NPP due to effects on the saline water dynamics of the soils under the tropical monsoon climate, which were revealed by our recent study. It implies that the hot-dry season may lead to high mortality, long-term reduction in the increment of living-trees biomass, and thus lowered the ability to maintain high NPP of mangrove forests over the long-term.

中文翻译：

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泰国东部热带季风气候下红树林森林净初级生产力的十年估计：干旱季节温度环境的意义

红树林在热带沿海生态系统中起着至关重要的作用。很少有研究探讨红树林的净初级生产力（NPP）与热带季风气候有关的长期变化。从2008年至2018年，我们在泰国东部热带季风气候下的次生红树林中的永久性地块中进行了一次树木普查。在此期间，快速生长的物种的死亡和新近采伐的树木数量的增加揭示了植物组成和分布的时间变化。在研究期间，树木总生物量从283.64线性增加到381.72 t·ha ^-1。NPP是通过求和法计算得出的，其中包括细根生产。NPP范围从21.19到29.04 t·ha ^-1 ·yr ^-1。通过线性回归模型分析了NPP及其成分的波动与气候因素的关系。NPP与年平均温度和年降雨量等年度气候因素无关。然而，作为核电厂主要组成部分的基础面积和活树生物量的增加都与干旱季节的最高和平均月温度负相关。年死亡率与旱季的年降雨量和最高每月气温成正比。线性回归分析表明，NPP的一些主要成分主要受干旱季节的温度环境影响。这些结果表明，由于对热带季风气候下土壤盐分水动力学的影响，干旱季节的天气在很大程度上限制了红树林的NPP，这是我们最近的研究揭示的。这暗示着炎热的干燥季节可能导致高死亡率，长期减少活树生物量的增加，从而长期降低维持红树林高NPP的能力。