土地利用变化对闽江河口湿地表层土壤有机碳含量及其活性的影响

Impacts of LUCC on Soil Organic Carbon Contents in Wetland of Minjiang River Estuary

对闽江河口原生植被芦苇沼泽,以及由其转化的不同其它土地利用类型(滩涂养殖地、水田、草地、撂荒地和池塘养殖地)的表层(0-50 cm)沉积物(或土壤)有机碳和活性有机碳含量的研究,结果表明,滩涂养殖地、水田、池塘养殖地、草地和撂荒地的土壤有机碳含量分别比芦苇沼泽地低27%,75%,67%,1%,60%;在有机碳储量方面,滩涂养殖地、水田、池塘养殖地和撂荒地比天然芦苇沼泽地分别低11%,50%,37%,24%,草地有机碳储量比芦苇高44%;草地土壤有机碳含量和储量随土层加深而递减的幅度比芦苇地大;水田有机碳含量和储量垂直变化不明显,弃耕后,表层有机碳含量提高,垂直变化明显。不同土地利用方式间土壤活性有机碳含量的差异比有机碳的差异大,与芦苇地相比,滩涂养殖地、水田、池塘、草地活性有机碳含量分别低24%,83%,84%,42%;撂荒10年的弃耕地与水稻田土壤相比,活性有机碳含量提高了47%。

Coastal wetlands are sensitive to global climate change and may play an important role in the global carbon cycle. However, the dynamics of carbon cycling in coastal wetlands and its response to LUCC is still poorly understood. In this study, the influence of LUCC from native reed wetland to tidal aquaculture land, paddy field,grassland, abandoned land and pond aquaculture land on sediment or soil （0--50 cm） organic carbon and labile soil organic carbon（LSC） concentration was investigated in the wetland of Min River estuary. The results showed that the concentration of SOC in 0--50 cm soil layer under tidal aquaculture land,paddy field, pond aquaculture land, grassland and abandoned land was 27 %, 75 %, 67 %, 1%, 60 % lower than that under native reed wetland, respectively. When native reed wetland was converted to tidal aquaculture land, paddy field,pond aquaculture land and abandoned land, the SOC stocks decreased by 11%,50%,37% and 24%,but when native reed wetland was converted to grassland SOC stocks was increased by 44%. The decreasing magnitude of SOC concentration and SOC stocks with soil profile depth under grassland was greater than native reed wetland. Vertical distribution characteristic of SOC concentration and SOC stocks under paddy field was not distinctness; the SOC concentration（0-30 cm layer） increased when paddy field was a- bandoned, Vertical distribution characteristic of SOC concentration was distinctness. In general, the difference in LSC among the different land use types and changes with depth were greater for the SOC concentration. The concentration of LSC under tidal aquaculture land,paddy field, pond aquaculture land and grassland was 24%,83%, 84%,42% lower than that under native reed wetland, respectively. The concentration of LSC was increased by 47 %when paddy field was abandoned.