Controls on the Storage and Loss of Soil Organic Carbon with Reforestation of Abandoned Pastures

在全球范围内，土壤碳储量一般随着粘粒含量的增加而增加，根据年平均温度和降雨量可以相对较好地预测土壤呼吸造成的碳损失。在生态系统尺度上，碳保留和流失的机制还不是很清楚。这项研究将使用一个长期的、重复性良好的从草地到森林的时间序列来研究影响土壤碳储存和流失的因素。这项研究将跟踪碳从植物凋落物输入到分解再到土壤储存，以及通过二氧化碳流失的过程。植物组织的化学性质在次生演替过程中发生变化，因此凋落物化学对生态系统过程的影响也可能随着时间的推移而改变。这项研究将使用田间和实验室实验以及稳定和放射性同位素来比较和对比凋落物化学、地上和地下凋落物输入以及土壤化学性质在82年重新造林的地下碳循环中的作用。这项研究将有助于了解植物对土壤碳动态的影响，并提高预测重新造林和植树造林对土壤碳汇影响的能力。

At a global scale, soil carbon storage generally increases with clay content, and carbon loss via soil respiration can be relatively well predicted from mean annual temperature and rainfall. At an ecosystem scale, the mechanisms responsible for C retention and loss are less well understood. This study will use a long-term and well-replicated pasture-to-forest chronosequence to study the factors that contribute to soil C storage and loss. The research will follow C from plant litter inputs through decomposition to storage in soils, and loss via CO2. Chemical properties of plant tissues change during secondary succession, and thus the impact of the litter chemistry on ecosystem processes is also likely to change over time. The research will use field and laboratory experiments and stable- and radioisotopes to compare and contrast the roles of litter chemistry, above- and belowground litter inputs, and soil chemical properties in belowground C cycling over 82 yr of reforestation. This research will contribute to understanding of how plants influence soil C dynamics, and improve the ability to predict the effects of reforestation and afforestation on C sequestration.