薇甘菊入侵对深圳湾红树林生态系统碳储量的影响

Effect of invasion plants (Mikania micrantha H.B.K.) on carbon stock of mangrove ecosystem in Shenzhen bay

外来植物入侵对生态系统碳过程的影响已经成为入侵生态学研究的热点问题。采用比较研究的方法分析了薇甘菊(Mikania micrantha H.B.K.)入侵对深圳湾红树林生态系统碳储量的影响,分别设置红树林(Kandelia candel)群落、红树林-薇甘菊群落、薇甘菊群落以及光滩等样地,采集植被、凋落物和土壤剖面样品,分析生态系统各组分的碳储量变化。结果表明,薇甘菊入侵对红树林生态系统碳储量有着显著的影响,碳储量从未被入侵下215.73 tC/hm2减少到轻、高度入侵下的197.56tC/hm2和166.70 tC/hm2,分别减少8.42%和22.72%。其中植被和土壤碳储量显著减少,凋落物碳储量显著增加。薇甘菊入侵一方面导致红树林枯萎,减少植被生物量,增加凋落物量,另一方面促进了土壤微生物活动,使土壤有机碳分解释放,降低土壤碳储量。薇甘菊入侵后红树林碳储量的降低将大大削弱生态系统的碳汇功能。

Alien species invasion has become one of the most important globle environmental problems due to its tremendous effects on community structure and ecosystem function. Recently, many studies have devoted to documenting the impact of exotic plant invasion on different ecosystems. To examine the effects of alien plants （Mikania micrantha H.B.K.） invasion on carbon stock of mangrove （Kandelia candel） ecosystem, we collected vegetation, litter and soil samples in mangroves, mangroves-alien species and alien species, and we used comparative method to analyze the differences of ecosystem carbon stock under different stages of alienvegetation invasion. The results showed that Mikania micrantha invasion had significant effect on the carbon stock of mangrove ecosystem, and the carbon stock decreased with the increase of intrusion intensity. The carbon stock reduced from 215.73 tC/hm^2 to 197.56 tC/hm2 （8.42%） and 166.70 tC/b_m2 （22.72%） under light invasion and high invasion, with vegetation and soil carbon stock decreasing remarkably and litter carbon stock increasing notably. Mikania micrantha invasion caused mangrove withered, reduced vegetation biomass, increased litter on one hand, and promoted microorganisms, decomposed soil organic carbon, decreased soil carbon stock on the other hand. Mikania micrantha invasion weakened the carbon sink function of mangrove ecosystem as it diminished the carbon stock.