湖北省农田生态系统温室气体排放特征与源/汇分析

为了深入了解湖北省农田生态系统的源/汇变化特征,采用《省级温室气体清单编制指南》和IPCC（政府间气候变化专门委员会）2014年推荐的温室气体计算方法,利用2007-2017年湖北省农作物产量、耕地面积等相关统计数据及土壤检测数据,对湖北省农田生态系统的源/汇特征进行分析。结果表明：湖北省农田生态系统的温室气体排放呈先增后降趋势,总体分为较快增长阶段（2007-2010年）、缓慢增长阶段（2011-2014年）和缓慢下降阶段（2015-2017年）三个阶段;农作物碳吸收量波动较大,不同农作物的碳吸收量不同,其中水稻、小麦、油菜籽、玉米的碳吸收量较高,分别占农田生态系统碳吸收总量的44.01%、14.11%、10.66%、9.24%;单位年内,农作物碳吸收量高于温室气体排放量,湖北省农田生态系统具有较强的"汇"功能,然而农作物碳吸收量并不稳定,容易受到微生物分解和秸秆燃烧的影响而减少;2007-2017年农田耕地土壤有机碳增量为13.52 Tg,耕地土壤呈现"汇"的特征。研究表明,湖北省农田生态系统整体呈现"汇"的状态,农作物碳吸收量对农田生态系统源/汇特征变化具有较大影响。适当增加水稻、玉米、芝麻等碳吸收强度较高的农作物种植量,减少秸秆燃烧量,有利于维持农田生态系统"汇"特征,减少向系统外排放温室气体。

Greenhouse gas emission characteristics and source/sink analysis of farmland ecosystem in Hubei Province

The greenhouse gas calculation method recommended by the Provincial Greenhouse Gas Inventory Guidelines and IPCC(2014) was adopted to analyze and understand the source/sink characteristics of farmland ecosystems in Hubei Province based on relevant statistical data such as crop yield, cultivated land area, and soil testing data from 2007 to 2017. Results showed that the greenhouse gas emission of farmland ecosystems in Hubei Province showed a trend of first increasing and then decreasing, which was generally divided into three stages:a rapid growth stage(2007-2010), slow growth stage(2011-2014), and slow decline stage(2015-2017). The carbon absorption capacity of crops fluctuated greatly, with different crops having different carbon absorption capacities. The rice, wheat, rapeseed, and corn had higher carbon absorption capacities, which respectively accountted for 44.01%, 14.11%, 10.66%, and 9.24% of the total carbon absorption of farmland ecosystem. In a unit year, crops absorbed more carbon than other greenhouse gases. Farmland ecosystems in Hubei Province had a strong sink function. However, the carbon absorption of crops was not stable and was easily reduced by microbial decomposition and straw burning. From 2007 to 2017, the organic carbon increment of farmland soil was 13.52 Tg and the cultivated soil showed sink characteristics. Results showed that the farmland ecosystem in Hubei Province was in an overall sink state and the amount of crop carbon absorption had a great influence on the change of the source/sink characteristics of farmland ecosystems. Appropriately increasing crops with high carbon absorption intensity, such as rice, corn, and sesame, and reducing straw burning is conducive to maintaining the sink characteristics of farmland ecosystems and reducing the emission of greenhouse gases out of the system.