导　　师： 常杰;葛滢

学科专业： 071001

授予学位： 博士

作　　者： ;

机构地区： 浙江大学

摘　　要： 农业用地是导致陆地系统土壤碳损失的主要原因。寻找新的农业耕作方式,在高产、高投入的情况下,仍可以使系统保持碳汇能力,成为研究热点。近三十年,温室,特别是塑料大棚蔬菜种植/(plastic greenhouse vegetable cultivation, PGVC/)在中国的发展十分迅猛,使中国迅速成为面积第一/(占全球面积90/%/)的国家。PGVC为农民带来很大效益,但这种来自露天蔬菜种植/(conventional open field vegetable cultivation, CVC/)相对较新的耕作系统的碳平衡情况,尤其是将农业生产过程中碳释放考虑后新系统扮演了碳源还是碳汇角色,目前仍不确定。 本研究基于质量平衡法和碳循环全程分析法/(full carbon cycle analysis/),对中国PGVC系统净碳流进行了估算。研究样点遍及了中国23个省、4个直辖市、5个自治区,共39个区的195个样点。除碳平衡外,本文还简要分析了PGVC系统所提供的其他生态服务功能。研究结果如下： 1.考虑了建设成本和经营过程的人力投入后,中国PGVC系统相对于大气系统表现为净碳汇,净碳流为0.58±0.27 Mg C ha-1 yr-1 /(1Mg=106g/),碳吸收能力是CVC系统/(同样也是净碳汇,0.23±0.23 Mg C ha-1 yr-1/)的2.5倍。两种操作系统这种碳吸收增幅/(即△净碳流/)在中国呈现区域性差异,表现为北方高于南方。 2.CVC系统转变为PGVC系统后,耕层/(0-20 cm/)土壤有机碳含量在40年时间内增加了41/%/(变化率：0.96 Mg C ha-1 yr-1/);但PGVC系统SOC随耕作年限先增后减,最后趋于平缓。有机碳增加幅度呈现明显的区域性,中国北部处于温带的地区SOC增加幅度显著高于南部亚热带地区。PGVC仅对耕层C含量产生影响,对土壤深层/(20-100 cm/)影响不大。但由于耕层SOCD占1m深SOCD的比例较大,因此,PGVC系统1 m深土壤层SOCD同样高于CVC系统。 3. PGVC系统NPP是邻近CVC系统的约1.7倍/(PGVC:8.87±0.46 Mg C ha-1 yr-1; CVC:5.36±0.66 Mg C ha-1 yr-1/)。两种种� Farming is believed to be the primary cause of soil carbon loss, and this has led to discussion concerning ways in which to reduce CO2 emissions from anthropogenic exploitation and ways to sequester carbon within agroecosystems. Conservation tillage is a practice that has been adopted in agriculture in recent decades as has reduced tillage, no-till, and straw return practices to increase the potential of soil carbon sequestration while simultaneously decreasing carbon emissions associated with agricultural practices such as fertilizer input and fossil fuels typically used on farms. With relatively low agricultural inputs and consequent low crop production, these optimizing agricultural practices can act as small carbon sinks. Few studies have been carried out to show whether other types of intensified cultivation practices that incorporate large amounts of agricultural inputs to achieve high levels of production could also act as carbon sinks. Plastic greenhouse vegetable cultivation /(PGVC/) has played a vital role in increasing incomes of smallholder farmers. A dramatic expansion in PGVC usage has taken place in the last several decades. However, carbon sequestration potential after conversion from conventional open field vegetable cultivation /(CVC/) to PGVC has been poorly quantified with regards to carbon emissions that will occur due to the intensification in agricultural practices. A full carbon cycle analysis approach was used in this study to estimate the net carbon flux from PGVC systems. The study sample sites included 23 provinces,4 municipalities,5 autonomous regions throughout China. Besides the carbon balance, we also analyzed the ecosystems services of PGVC systems. The results shows as follow: 1. PGVC systems in China act as an carbon sink relative to atmosphere with the value 0.58±0.27 Mg C ha-1 yr-1 and the carbon absorption capacity is 2.5 times more than that of CVC systems /(0.23±0.23 Mg C ha-1 yr-1/). TheΔnet carbon flux /(e.g. the difference of net carbon flux between PGVC syst

关 键 词： 土壤有机碳 净碳流 农业碳释放 生态系统服务

领　　域： [农业科学]