Carbon cycling in mangrove forests in Sawi Bay, Thailand

Measurements of above and below ground biomass and primary productivity of 4 mangrove forests (aged 3-yrs old (n=2), 5-yrs and 25-yrs) in Sawi Bay, Southern Thailand. Below ground root (live and dead) biomass measurements were made in October 1999. Above ground biomass and primary production estimates were made in April 2000. Measurements made on species identification, basal area, height at breast height were used to calculate stem density, which was in turn used to estimate biomass (t ha-1). Branch biomass was also calculated. Net canopy production was estimated using light interception method, using measurements of light readings to first estimate a leaf area index.Nutrients, light levels, community pelagic respiration, and phytoplankton primary production rates were estimated for Sawi Bay. Organic carbon and dissolved and particulate nutrient concentrations and fluxes from three mangrove lined creeks flowing in to Sawi Bay were measured.An organic carbon mass balance was constructed for the entire Sawi Bay based on the data collected and described above.On the basis of soil organic carbon deposition, accumulation, mineralisation and burial measurements in mangrove forests of Sawi Bay, these sites accumulated approx. 60% of the organic carbon input and are therefore storage sites of carbon.Accumulation, transformation and availability of sediment nitrogen in 4 mangrove forests of different age and type in Sawi Bay, Southern Thailand. Samples were taken during the dry (April 1999) and the wet (October 1999) monsoon seasons.Forest characteristics recorded were: type (Rhizophora apiculata or Ceriops decandra); age (3, 5, 25 years), sediment type; % tidal inundations per month; % soil total carbonMeasurements were made on sediment concentrations of ammonium, nitrite, nitrate, total nitrogen and carbon content. Measurements were also made on the total nitrogen and total carbon content of green leaves. Rainwater was analysed for dissolved nitrogen species.Soil samples were analysed for fluxes of ammonium and dissolved organic nitrogen (DON) across the sediment-water interface. Net ammonium production was estimated using a core incubation method, and the rate of nitrogen fixation was estimated using the acetylene technique, and denitrification was measured using the direct gas technique.Partitioning and storage of mineral nutrients and trace elements were examined in tree components and soils of Rhizophora apiculata forests of Sawi Bay. To examine benthic, pelagic and mangrove carbon flux within mangroves and tidal creeks of Sawi Bay.

泰国南部沙威湾（Sawi Bay）4个红树林林分（林龄分别为3年（样本量n=2）、5年和25年）的地上、地下生物量与初级生产力测定数据集。其中地下根（活根与死根）生物量测定于1999年10月完成，地上生物量与初级生产力估算则于2000年4月开展。研究通过物种鉴定、胸高断面积、胸高树高数据计算茎密度，进而估算生物量（单位为吨每公顷，t ha⁻¹），同时还计算了枝生物量。林冠净初级生产力采用光拦截法进行估算，先通过光照读数测定叶面积指数。沙威湾的营养盐水平、光照条件、群落浮游呼吸速率及浮游植物初级生产力速率均得到测定与估算；对汇入沙威湾的3条红树林岸线潮汐溪道的有机碳、溶解态与颗粒态营养盐浓度及通量进行了实地测定。基于上述采集的全部数据，研究团队构建了整个沙威湾的有机碳质量平衡模型。基于沙威湾红树林的土壤有机碳沉积、累积、矿化与埋藏测定数据，上述林分累积了约60%的有机碳输入量，因此属于碳储存库。针对泰国南部沙威湾4个不同林龄与林型的红树林林分，研究开展了沉积物氮的累积、转化与可利用性相关研究，采样分别于旱季（1999年4月）与雨季（1999年10月）完成，记录的林分特征包括：林型（秋茄（Rhizophora apiculata）或角果木（Ceriops decandra））、林龄（3、5、25年）、沉积物类型、月潮汐淹没比例、土壤总碳占比。研究测定了沉积物中铵态氮、亚硝态氮、硝态氮、总氮及碳含量，同时还测定了新鲜绿叶的总氮与总碳含量；对雨水样品开展了溶解态氮组分分析，对沉积物样品进行了沉积物-水界面铵态氮与溶解态有机氮（DON）的通量分析。研究采用培养柱法估算铵态氮净产率，采用乙炔还原法估算固氮速率，采用直接气体法测定反硝化作用速率。此外，研究还对沙威湾秋茄（Rhizophora apiculata）林分的林木组分与土壤中的矿质营养元素及微量元素的分配与储存特征进行了探究，并针对沙威湾红树林及潮汐溪道内的底栖、浮游与红树林碳通量展开了分析。