Department of Natural Resources and Environmental Science, The University of Nevada, Reno, Reno, Nevada, USA.
Department of Life and Environmental Sciences, University of California Merced, Merced, California, USA.
Ecol Appl. 2022 Oct;32(7):e2677. doi: 10.1002/eap.2677. Epub 2022 Jul 15.
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 year and soil C stocks (0-15 cm) increased by 232.9 g C m year across the chronosequence. Increases in soil C concentration (2.99 g C kg year ) were tightly coupled with increases in soil N concentration (0.21 g N kg year ) 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.
高山草甸是生产力极高的生态系统，其土壤碳（C）和氮（N）密度很高。然而，导致河道切割和洪泛区水文过程中断的人为干扰改变了许多高山草甸的碳平衡，使它们从碳汇转变为碳源，向大气中排放碳。旨在重新连接洪泛区水文过程的恢复工作可能会减缓退化草甸土壤碳损失的速度，并恢复碳固定和氮固定的条件，但这些努力的长期影响仍存在疑问。在这里，我们使用了一个 22 年的高山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十年影响。草本植被生物量的增加先于土壤碳储量的变化，最大的增加发生在地下。根系生物量（0-15 cm）以 270.3 g m year 的速度增加，土壤碳储量（0-15 cm）在整个时间序列中增加了 232.9 g C m year。土壤碳浓度（2.99 g C kg year）的增加与土壤氮浓度（0.21 g N kg year）的增加密切相关，土壤碳氮比随恢复时间的变化而变化。傅里叶变换红外光谱结果表明，土壤中易分解的脂肪族 C-H 和羧酸盐 C-O（COO）化合物的比例随着恢复年龄的增加而增加，并且与土壤 C 和 N 浓度呈正相关。我们的研究结果表明，在恢复后的头二十年里，高山草甸洪泛区水文过程的恢复对地下碳和氮储量、土壤碳和氮浓度以及土壤碳化学有显著影响。
