ABSTRACT

The Andean páramo is notable for high soil carbon storage and its contribution to ecosystem services. However, the páramo’s ability to maintain high soil carbon levels is threatened by land use change from tussock grassland and shrublands to agricultural uses. A chronosequence study was conducted in the páramo around Quito, Ecuador, to determine the rate of soil carbon loss from traditional fallow agriculture. In parallel, a land use and land cover classification of Landsat images was used to measure the change in agricultural areas between 1991 and 2017. There was a significant negative relationship between the time since initial cultivation of a field and soil C: Older agricultural sites had significantly less C compared to natural ecosystems due to an average loss of 0.045 percent soil C per year. Undisturbed sites had significantly more soil C than cultivated sites but not pastures or fallow fields, indicating that cultivation is the most detrimental stage of the fallow agricultural cycle for soil C storage. There was an 838 percent increase in cultivated land between 1991 and 2017 but a 10 percent decrease in pastures, indicating a trend away from traditional regenerative agriculture toward land use types that lead to substantial losses in soil carbon.

摘要

安第斯山脉（Andeanpáramo）以高土壤碳储量及其对生态系统服务的贡献而著称。然而，帕拉莫保持高土壤碳水平的能力受到了从use草草地和灌丛土地到农业用途的土地利用变化的威胁。在厄瓜多尔基多附近的帕拉莫进行了时间序列研究，以确定传统休耕农业造成的土壤碳损失率。同时，使用Landsat影像的土地利用和土地覆被分类来衡量1991年至2017年农业面积的变化。自田间耕种以来的时间与土壤C之间存在显着的负相关性：较旧的农业用地由于每年平均损失0.045％的土壤碳，因此与自然生态系统相比，碳的含量要低得多。未受干扰的地点的土壤碳含量明显高于耕种地点，但没有牧场或休耕地，表明耕作是土壤农业碳储量休耕农业循环中最有害的阶段。1991年至2017年间，耕地增加了838％，但牧场减少了10％，这表明从传统的可再生农业转向土地使用类型的趋势已导致土壤碳的大量流失。