In this study, we compared stand structure, biomass and soil carbon pools, and litterfall production between a mixed mangrove forest consisting of Aegiceras corniculatum inter-planted with the exotic Sonneratia apetala and a native monospecific forest dominated by A. corniculatum in the intertidal area of Zhanjiang, Guangdong Province, southeast China. The goal of this study was to test the hypothesis that inter-planting fast growing exotic mangrove S. apetala into subtropical native mangrove forests will significantly increase C sequestration. Although the tree heights and basal diameters of S. apetala were significantly higher than those of A. corniculatum, the density of the 12-year-old S. apetala trees in the mixed forest was much smaller than that of A. corniculatum in the monospecific forest. In contrast to several previous studies on S. apetala forests planted directly on mangrove-free mudflats, the mixed mangrove forest showed no significant difference in either standing biomass or soil carbon pools from the native monospecific mangrove forest (p = 0.294 and 0.073, respectively) twelve years after inter-planting with S. apetala. Moreover, carbon cycling was likely speeded up after inter-planting S. apetala due to higher litterfall input and lower C/N ratio. Thus, inter-planting fast-growing S. apetala into native mangrove forest is not an effective way to increase carbon sequestration in this subtropical mangrove forest. Given that exotic plant species may exert negative impact on native mangrove species and related epifauna, this fast-growing mangrove species is not suitable for mangrove plantation projects aiming mainly at enhancing carbon sequestration.

通过群落调查、异速生长法计算以及样品测定,分别对2010～2011年期间广东湛江高桥红树林生态系统中次生桐花树和原生木榄群落的植物和土壤储量进行了计算,并利用掉落物收集筐对掉落物动态进行了比较研究.研究结果表明,高桥桐花树与木榄群落的植物碳库(以C计,下同)分别为(51.16±12.06)×106 g/hm2和(38.52±6.94)×106 g/hm2,地上部分明显高于地下部分;土壤碳库分别为(111.86±7.96)×106 g/hm2和(106.13±11.12)×106 g/hm2,明显高于植物碳库;次生与原生红树林群落的总碳库没有差异(P＞0.05).桐花树和木榄群落的年均掉落物产量分别为556.00g/m2和971.13g/m2,均以凋落叶居多,但原生木榄群落的掉落物产量明显高于次生桐花树群落(P＜0.001).由此可见,次生红树林桐花树群落与原生红树林木榄群落的碳储量相当,但均显著低于热带地区的原生红树植物群落.

随着对海洋"蓝碳"研究的日益深入,滨海湿地生态系统的碳汇功能越来越受到重视。然而对滨海湿地生态系统的研究则相对薄弱,特别是在红树林生态系统碳源汇特征以及碳汇潜力方面。本文通过综述当前红树林、盐沼、海草床等滨海湿地碳循环研究的最新进展,结合本研究组近几年来开展的野外研究工作,揭示红树林等滨海湿地碳库(植被生物量碳库以及沉积物有机碳库)的现状及其碳汇潜力。研究结果显示:(1)单位面积基础上盐沼、红树林和海草床分别比成熟的热带雨林能封存高得多的碳,全球的盐沼、红树林和海草床每年可固定的碳足以抵消全球因使用交通工具释放碳总量的1/3左右;(2)不同地点以及不同群落类型的红树林生物量碳库(单位面积生物量)存在较大的差异;(3)红树林沉积物有机碳密度随着沉积底质和群落类型的不同存在显著的差异;(4)红树林湿地显示出较强的固碳能力,广东湛江和福建云霄两地的红树林生态系统净生态系统交换量相近,且略低于美国佛罗里达的红树林,但显著高于同纬度的陆地生态系统;(5)红树林碳库与河口以及周边海域联系紧密,在潮汐作用的影响下,红树林的掉落物不断输送到周边海域,影响了近海海洋碳的循环与平衡。由此可见,全球范围的红树林等滨海湿地恢复和保护可以有效抵消人类活动每年向大气排放的CO2,但人类活动和气候变化会对红树林碳库及其动态变化产生显著影响。

An AFLP technique for the genetic diversity analysis of Egretta eulophotes was established in this study.13 genomic DNA samples of Egretta eulophotes were taken as a population DNA pool.The conditions of genomic DNA extraction,enzyme digestion,ligation,preamplification,selective amplification,electrophoresis and silver staining were optimized in the Pst I/Mse I AFLP analysis.The AFLP technique established in this study was applicable for the genetic diversity analysis of Egretta eulophotes in the future.