深圳福田秋茄红树林生态系统碳循环的初步研究

滨海红树林的生产力极高,在全球碳循环中占有重要地位,但是其碳循环的系统测定却鲜见报道。以深圳福田秋茄林为研究对象,2011年4月-2012年4月对内滩天然林、中滩和外滩人工林的植被、凋落物、粗木质残体、土壤的碳密度和净增量,以及植被和土壤呼吸进行了实际观测,并探讨了土壤有机碳来源,初步构建了秋茄林沿不同滩位的生态系统碳循环模式。结果表明,深圳福田秋茄林的碳密度在234.58～694.46 t.hm^-2之间,其中植被碳密度为44.54～239.51 t.hm^-2,凋落物和粗木质残体碳密度为2.02～24.56 t.hm^-2,土壤碳密度（深度为50 cm）为188.02～430.39 t.hm^-2,生态系统碳密度整体上表现为自内滩向外滩降低的趋势。在研究时段内,3个滩位的植被碳密度净增量为4.31～13.28 t.hm^-2.a^-1,凋落物和土壤碳密度没有显著变化。红树林的凋落物生成量为2.17～10.55 t.hm^-2.a^-1,约有49.94～94.01%通过食草动物、冲入海洋和腐烂分解等途径消耗。植被呼吸量为2.20～12.08 t.hm^-2.a^-1,土壤微生物的异氧呼吸量为0.25～1.61 t.hm^-2.a^-1,甲烷排放为0.09～0.31 t.hm^-2.a^-1,土壤有机碳输入约18.99%～44.43%来自植被内源输入,其余来源于海洋碳输入。生态系统的总初级生产力介于8.68～35.91t.hm^-2.a^-1之间,约有47.38%～74.08%转变为净初级生产力（6.48～23.84 t.hm^-2.a^-1）。碳平衡分析表明,在研究时段内,内滩的天然林是个很大的碳汇,约20.08 t.hm^-2.a^-1,中滩和外滩的人工林碳汇量分别为9.98 t.hm^-2.a^-1和4.03 t.hm^-2.a^-1。相对于陆地森林,秋茄红树林有着显著的碳汇效益,在全球碳循环中起着不可忽视的作用。

Preliminary study on mangrove ecosystem carbon cycle of Kandelia candel in Futian nature reserve, Shenzhen, China

The coastal mangrove played an important role in the global carbon cycle with high productivity,but the systematic research on mangrove carbon cycle was rarely reported.This paper took Kandelia candel in Shenzhen Futian as the research object,and set three sample plots respectively in natural forest on inner beach,artificial forest on middle and exterior beach.In each sample spot,vegetation,litter,coarse woody debris,soil carbon density and its increase,as well as respiration of vegetation and soil were monitored thoroughly,and the mangrove ecosystem carbon cycle model along different beach was constructed initially.The results showed that,the carbon density of Kandelia candel in Shenzhen Futian was 234.58～694.46 t.hm^-2,and it decreased with decrease of tidal flat altitude.The vegetation carbon density was 44.54～239.51 t.hm^-2,the sum of litter and coarse woody debris carbon density was 2.02～24.56 t.hm^-2,and the soil carbon density was 188.02～430.39 t.hm^-2.In the study period,the net increment of vegetation carbon density of three sample plots was 4.31～13.28 t.hm^-2.,and there was little change for soil and litter carbon density.The amount of litter generation was 2.17～10.55 t.hm^-2.,about 49.94%～94.01% of which was depleted by herbivores,sea washing and decomposition.The vegetation respiration was 7.20～12.08 t.hm^-2.a^-1,the soil heterotrophic respiration was 0.25～1.61 t.hm^-2.a^-1,and the methane emission was 0.09～0.31 t.hm^-2.a^-1.About 18.99%～44.43% of soil organic carbon input came from endogenous input of vegetation,and the remainder came from exogenous input of sea water.The ecosystem gross primary production ranged from 13.67 to 35.91 t.hm^-2.a^-1,most of which translated to net primary production（6.48～23.84 t.hm^-2.a^-1）.Carbon balance analysis showed that,the natural forest on inner beach was a large carbon sink,about 20.08 t.hm^-2.a^-1,and the artificial forest on middle and exterior beach was 9.98 t.hm^-2.a^-1 and 4.03 t.hm^-2.a^-1 respectively.This study showed that,the Kandelia candel mangrove had significant carbon sequestration benefit relative to the terrestrial forest,and the mangrove played an important role in the global carbon cycle.