Pillar V D, Tornquist C G, Bayer C
Departamento de Ecologia, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Braz J Biol. 2012 Aug;72(3 Suppl):673-81. doi: 10.1590/s1519-69842012000400006.
The southern Brazilian grassland biome contains highly diverse natural ecosystems that have been used for centuries for grazing livestock and that also provide other important environmental services. Here we outline the main factors controlling ecosystem processes, review and discuss the available data on soil carbon stocks and greenhouse gases emissions from soils, and suggest opportunities for mitigation of climatic change. The research on carbon and greenhouse gases emissions in these ecosystems is recent and the results are still fragmented. The available data indicate that the southern Brazilian natural grassland ecosystems under adequate management contain important stocks of organic carbon in the soil, and therefore their conservation is relevant for the mitigation of climate change. Furthermore, these ecosystems show a great and rapid loss of soil organic carbon when converted to crops based on conventional tillage practices. However, in the already converted areas there is potential to mitigate greenhouse gas emissions by using cropping systems based on no soil tillage and cover-crops, and the effect is mainly related to the potential of these crop systems to accumulate soil organic carbon in the soil at rates that surpass the increased soil nitrous oxide emissions. Further modelling with these results associated with geographic information systems could generate regional estimates of carbon balance.
巴西南部草原生物群落包含高度多样的自然生态系统，这些生态系统几个世纪以来一直用于放牧牲畜，并且还提供其他重要的环境服务。在此，我们概述了控制生态系统过程的主要因素，回顾并讨论了有关土壤碳储量和土壤温室气体排放的现有数据，并提出了缓解气候变化的机会。对这些生态系统中碳和温室气体排放的研究尚属近期，结果仍然零散。现有数据表明，在适当管理下的巴西南部天然草原生态系统在土壤中含有重要的有机碳储量，因此其保护对于缓解气候变化具有重要意义。此外，当基于传统耕作方式将这些生态系统转变为农田时，土壤有机碳会大量且迅速流失。然而，在已经转变的地区，通过采用免耕和覆盖作物的种植系统，有潜力减少温室气体排放，其效果主要与这些作物系统在土壤中积累有机碳的潜力有关，这种积累速率超过了土壤一氧化二氮排放量的增加。将这些结果与地理信息系统相结合进行进一步建模，可以生成区域碳平衡估计值。
