Abstract: Mangrove forest is an important part of the global carbon cycle, and the study of the photosynthetic characteristics of different mangrove plants and the difference in carbon sequestration and oxygen release capacity is an important basis for the cumulative assessment and protection and restoration of carbon pool of mangrove biomass. The daily dynamics of photosynthesis rate of mangrove trees and leaf area index were determined by using Li-6800 Portable Photosynthesizer and TOP-1300 Canopy Analyzer, to analyze the daily capacity of carbon sequestration and oxygen release of the target species. Carbon sequestration per unit land area was used as a measure of the CO2 absorption capacity of mangrove plants for cluster analysis to further analyze the main factors affecting the oxygen sequestration capacity of plants. The results showed that: (1) The net photosynthetic rate of six species was unimodal curve, including Cerbera manghas, Kandelia obovata, Heritiera littoralis, Acanthus ilicifolius, Hibiscus hamabo and Volkameria inermis, and the remaining five species showed a bimodal curve due to photosynthetic lunch break, among which Cerbera manghas was the lowest and Volkameria inermis was the highest. (2) In terms of carbon sequestration and oxygen release capacity per unit land area, 3 species of shrubs (Acanthus ilicifolius, Hibiscus hamabo, Volkameria inermis ) and 4 species of trees (Aegiceras corniculatum, Excoecaria agallocha, Heritiera littoralis, Sonneratia apetala ) performed better. (3) The results of the clustering of daily carbon sequestration per unit land area of 11 mangrove species were divided into three categories, the first category included Hibiscus hamabo and Volkameria inermis with the highest daily carbon sequestration, the second category was Aegiceras corniculatum, Excoecaria agallocha, Heritiera littoralis, Acanthus ilicifolius and Sonneratia apetala with medium daily carbon sequestration, and the third category was Cerbera manghas, Thespesia populnea, Bruguiera gymnorhiza and Kandelia obovata with the lowest daily carbon sequestration. (4) The main influencing factors of daily carbon sequestration and oxygen release per unit land leaf area were transpiration rate (Tr) and stomatal conductance (Gs).

Key words: mangrove; photosynthetic day variation; leaf area index; carbon sequestration amount; oxygen release amount

摘要： 为探究红树植物的光合特性及其固碳释氧能力差异性，以广东省福田红树林自然保护区11种红树植物为材料，采用Li-6800便携式光合仪和TOP-1300冠层分析仪测定红树的光合速率日动态和叶面积指数，分析各目标树种的固碳释氧能力，以单位土地面积固碳量作为衡量红树植物吸收CO2能力的特征向量进行聚类分析，进一步分析影响植物固碳释氧能力的主要因素。结果表明：(1) 海杧果Cerbera manghas、秋茄Kandelia obovata、银叶树Heritiera littoralis、老鼠簕Acanthus ilicifolius、海滨木槿Hibiscus hamabo和苦郎树Volkameria inermis 等6种植物的净光合速率日变化呈单峰型曲线，其余5种植物因光合午休现象呈双峰型曲线，其中海杧果最低，苦郎树最高。(2) 在单位土地面积固碳释氧能力方面，3种灌木(老鼠簕、海滨木槿、苦郎树)和4种乔木(桐花树Aegiceras corniculatum、海漆Excoecaria agallocha、银叶树、无瓣海桑Sonneratia apetala)的表现较优秀。(3) 11种红树植物单位土地面积固碳量聚类结果分为三类，第一类是固碳量最高的海滨木槿和苦郎树，第二类是固碳量中等的桐花树、海漆、银叶树、老鼠簕和无瓣海桑，第三类是固碳量最低的海杧果、杨叶肖槿Thespesia populnea、木榄Bruguiera gymnorhiza和秋茄。(4) 单位土地叶面积固碳释氧量的主要影响因素是蒸腾速率(Tr)、气孔导度(Gs)。

关键词: 红树林；光合日变化；叶面积指数；固碳量；释氧量