农牧交错带玉米农田生态系统碳储量变化特征及分布格局

摘要

Organic carbon storage and sequestration potential change in agricultural soils has been suggested to be an important issue in the study of terrestrial carbon cycling and global climatic change .To study the carbon storage and distribution pattern of corn farmland ecosystem at different stages (after plowing ,seeding stage ,maturity ,before plowing in the next year) in the way of traditional deep-tillage operation and film-mulch planting ,the local main crop ,corn ,was used to conduct the investigation in a typical ecotone between agriculture and animal husbandry in northern China .The result showed that the aboveground carbon storage was obviously higher than the belowground one .The change of soil car-bon density was not evidently associated with the depth of soil layer .The average carbon rate of single maize was 43 .3% .Except for root ,leaf and stalk had higher organic carbon rate at seedling stage than that at maturity stage .And the carbon storage of single maize at maturity was more than that at seedling stage .The soil carbon densities in the corn farmland ecosystem at different stages were in the following order :maturity > seeding stage > before plowing in the next year> after plowing .Soil density after plowing was obviously decreased compared with other stages ( P < 0 .05) .The changing law of soil carbon density was the same as the total carbon density of the corn farmland ecosystem .After a whole crop growing season ,soil carbon density in the corn farmland ecosystem was increased by 13 415 kg・hm - 2 more at the stage before plowing in the next year than that after plowing in the past year ,reaching 10 974 .8 kg・hm - 2 .Therefore , corn farmland ecosystem played an obvious role in fixing carbon and reducing discharge to atmosphere ,allowing strong carbon sequestration capacity .%农田生态系统碳储量变化是陆地碳循环和全球气候变化研究中的一个重要问题。选取我国北方典型农牧交错区当地主要作物玉米为研究对象，对该地区在传统深耕覆膜种植方式下不同时期（翻耕后、幼苗期、成熟期、次年翻耕前）的玉米农田生态系统碳储量及分布格局进行研究。结果表明：在该地区传统耕作方式下玉米农田生态系统地上碳储量显著大于地下碳储量，而土壤碳密度随着土层加深变化规律不明显；单株玉米平均碳含率为43．3％，除根系外，玉米叶片、茎秆有机碳含率变化规律表现为幼苗期＞收获期；单株玉米碳储量为收获期＞幼苗期；玉米农田生态系统土壤碳密度为收获期＞幼苗期＞次年翻耕前＞翻耕后，土壤碳密度在翻耕后较其他时期显著降低（P＜0．05）；农田生态系统总碳密度与土壤碳密度变化规律一致。玉米农田生态系统经过一个完整的作物生长季后土壤碳密度在次年翻耕前较前一年翻耕后增加了13415 kg・hm －2；而作物的碳密度在收获期高达10974．8 kg・hm －2。由此可见，玉米农田生态系统对大气有明显的固碳减排作用，其“碳汇”能力较强。