ABSTRACT

Globally, significant land conversions of traditionally managed temperate grasslands to croplands were taking place. Among these is South-Central Uruguay where changes in recent decades have highly likely impacted plant productivity, soil quality, and carbon fluxes at a regional scale. A geospatial version of the biophysical model EPIC was developed and validated (Geospatial-EPIC-UY). An analysis of the potential impact of the land use change on the carbon fluxes was performed, considering the conversion of all the suitable cropping areas over a 15-year period. Modeled net ecosystem exchange (NEE) showed that, on average, grasslands C emissions were close to neutral (0.1 Mg CO₂ ha⁻¹ year⁻¹), while croplands contributed almost 7 times this value. Also, the inter-annual variation of grassland NEE was significantly less than that of the cropland. These results highlight the potential C losses under extended land conversions, which could be attenuated or even reverted if best management practices were implemented.

摘要

在全球范围内，传统管理的温带草原正在发生大量土地转变为农田。其中包括乌拉圭中南部地区，那里近几十年来的变化很可能在区域范围内影响了植物生产力、土壤质量和碳通量。开发并验证了生物物理模型 EPIC 的地理空间版本 (Geospatial-EPIC-UY)。考虑到所有适宜种植区在 15 年期间的转换，对土地利用变化对碳通量的潜在影响进行了分析。模拟的净生态系统交换 (NEE) 显示，平均而言，草原碳排放接近中性（0.1 Mg CO ₂ ha ^-1年^-1)，而农田贡献了该值的近 7 倍。此外，草地NEE的年际变化显着小于农田。这些结果突出了延长土地转换的潜在碳损失，如果实施最佳管理实践，这种损失可能会减弱甚至恢复。