Abstract：
Montane meadows are highly productive ecosystems that contain high densities of soil carbon (C) and nitrogen (N). However, anthropogenic disturbances that have led to channel incision and disconnected floodplain hydrology have altered the C balance of many meadows, converting them from net C sinks to net sources of C to the atmosphere. Restoration efforts designed to reconnect floodplain hydrology may slow rates of soil C loss from degraded meadows and restore the conditions for C sequestration and N immobilization, yet questions remain about the long-term impact of such efforts. Here, we used a 22-year meadow restoration chronosequence to measure the decadal impact of hydrologic restoration on aboveground and belowground C and N stocks and concentrations. Increases in herbaceous vegetation biomass preceded changes in soil C stocks, with the largest gains occurring belowground. Root biomass (0-15 cm) increased at a rate of 270.3 g m-2 year-1 and soil C stocks (0-15 cm) increased by 232.9 g C m-2 year-1 across the chronosequence. Increases in soil C concentration (2.99 g C kg-1 year-1 ) were tightly coupled with increases in soil N concentration (0.21 g N kg-1 year-1 ) and soil C:N did not vary with time since restoration. Fourier transform infrared spectroscopy results showed that the fraction of labile aliphatic C-H and carboxylate C-O (COO) compounds in the soil increased with the age of restoration and were positively correlated with soil C and N concentrations. Our results demonstrate that restoration of floodplain hydrology in montane meadows has significant impacts on belowground C and N stocks, soil C and N concentration, and soil C chemistry within the first two decades following restoration.
摘要：
Montane草甸是高产生态系统，含有高密度的土壤碳（C）和氮（N）。然而,导致河道切口和洪泛区水文断开的人为干扰改变了许多草地的C平衡，将它们从净碳汇转换为大气中的净碳源。旨在重新连接洪泛区水文学的恢复工作可能会减缓退化草甸的土壤碳流失速度，并恢复碳固存和氮固定的条件。然而，这种努力的长期影响仍然存在疑问。这里,我们使用了22年的草甸恢复时间序列来测量水文恢复对地上和地下碳和氮储量和浓度的年代影响。草本植被生物量的增加先于土壤碳储量的变化，最大的收益发生在地下。在整个时间序列中，根生物量（0-15厘米）以270.3gm-2year-1的速度增加，土壤C存量（0-15厘米）增加了232.9gCm-2year-1。土壤C浓度的增加（2.99gCkg-1year-1）与土壤N浓度的增加（0.21gNkg-1year-1）紧密相关，并且自恢复以来土壤C：N随时间变化。傅里叶变换红外光谱结果表明，土壤中不稳定脂肪族C-H和羧酸盐C-O（COO）化合物的比例随恢复年龄的增加而增加，并与土壤C和N浓度呈正相关。我们的结果表明，恢复山地草甸的洪泛区水文对地下碳和氮储量有重大影响，土壤C和N浓度，和土壤碳化学在恢复后的头二十年内。
