耕地造林和撂荒2种植被恢复方式碳储量差异

Carbon storage differences for farmland with two rehabilitation approaches

为了解耕地在造林和撂荒这2种恢复方式下生态系统碳储量的差异和分配特征,并为估算森林碳汇提供基础数据支撑,在2016年7-8月,采用野外样地调查并结合室内测定对湖南会同恢复14 a的退耕还林地(即耕地造林)和农田撂荒地(即耕地撂荒)进行植被、凋落物以及土壤碳储量的调查。结果表明:(1)退耕还林地的生物量碳储量显著(P<0.05)高于农田撂荒地。其中,退耕还林地的乔木层碳储量高于农田撂荒地,并且前者是后者的2.76倍,但灌木层和草本层正好相反。(2)耕地在2种恢复方式下土壤碳质量分数均随土壤深度的增加而依次减小。农田撂荒地土壤碳储量随土壤深度的增加也依次减小,但退耕还林地土壤碳储量的大小为20~40 cm>0~10 cm>40~60 cm>10~20 cm>60~80 cm。退耕还林地0~80 cm深土壤碳储量略高于农田撂荒地,但两者没有显著差异(P>0.05)。(3)退耕还林地生态系统碳储量要高于农田撂荒地。2种恢复方式下各组分碳储量大小均为土壤层>乔木层>凋落物层>草本层>灌木层。研究显示,在试验时段内,耕地采用造林的方式其固碳能力要优于撂荒的方式。

To understand the differences and allocation of carbon storage on farmland with afforestation versus abandonment and to provide basic accounting data for forest carbon storage.When farmland through afforestation and abandonment had been restored 14 years respectively,the carbon storage of vegetation,litter,soil were estimated through field investigation and laboratory bioassay.Results showed that(1)biological carbon storage of returning farm to forest was significantly higher than that of abandoned farmland(P<0.05).The tree layer of returning farm to forest was 2.76 times the abandoned farmland;whereas,the shrub layer and the herb layer were lower than the latter.(2)Soil carbon content for the two rehabilitation approaches decreased with an increase in soil depth.Soil carbon storage on abandoned farmland also decreased with an increase of soil depth.Soil carbon storage from 0 to 80 cm depths for returning farm to forest was in the order of 20-40 cm>0-10 cm>40-60 cm>10-20 cm>60-80 cm.The soil carbon storage of 0-80 cm deep for returning farm to forest was not significantly different(P>0.05)from abandoned farmland.(3)Carbon storage for the ecosystem in returning farm to forest was higher than that of abandoned farmland(P<0.05).Carbon storage of the ecosystem with the two rehabilitation approaches was soil layer>tree layer>litter layer>herb layer>shrub layer.This study showed that during this period the carbon sequestration capacity with afforestation on farmland was better than abandonment.