Aboveground litter quality changes may drive soil organic carbon increase after shrub encroachment into mountain grasslands
Aboveground litter quality changes may drive soil organic carbon increase after shrub encroachment into mountain grasslands
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DOI：
10.1007/s11104-010-0512-1
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发表时间：
2010-08
期刊：
影响因子：
4.9
通讯作者：
F. Montané;J. Romanyà;P. Rovira;P. Casals
中科院分区：
文献类型：
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作者：
F. Montané;J. Romanyà;P. Rovira;P. Casals
灌木侵入草地是普遍存在的，但其对土壤有机碳（SOC）的影响尚不清楚。在以前的工作中，我们已经观察到，灌木侵入到梅西奇山地草原增加SOC含量。在这里，我们寻求这种增长的机制。为此，我们评估了针叶灌木（杜松），豆科灌木（红蜘蛛），地上和地下生产。López & Jarvis）Muñoz Garmendia）和草（Festuca eskiaRamond ex DC），以及地上凋落物和根系的分解率。地下碳净输入不能解释土壤有机碳增加的原因：草根的生产力高于灌木，草根的分解速率最低。灌木林凋落物C净输入仅略大于草地，但两种灌木林凋落物分解速率均远低于草地。针叶林凋落物的分解受N限制，而豆科灌木凋落物的分解受P限制。因此，我们认为灌木入侵后，土壤有机碳增加，可能是由于灌木地上凋落物相对于草地凋落物具有更高的吸收能力。
Shrub encroachment into grasslands is ubiquitous but its impact on soil organic C (SOC) remains unclear. In previous work we had observed that shrub encroachment into mesic mountain grasslands increased SOC content. Here we sought the mechanisms of this increase. To this end, we assessed aboveground and belowground production for a conifer shrub (Juniperus communisL), a legume shrub (Cytisus balansaessp.europaeus(G. López & Jarvis) Muñoz Garmendia) and grass (Festuca eskiaRamond ex DC), together with decomposition rates for both aboveground litter and roots. Belowground C net inputs do not clearly explain SOC increase: grass root production was higher than that of either shrub and the decomposition rate of grass roots was the lowest. Aboveground C net inputs were only slightly greater in shrubs than in grass, but the decomposition rate of litter of both shrubs was much lower than that of grass. The decomposition of conifer litter was N-limited, whereas that of legume shrub litter was P-limited. Thus we conclude that the SOC increases after shrub encroachment into mesic grasslands probably as a result of higher recalcitrance of shrub aboveground litter relative to grass litter.