Evidence for a climate-induced ecohydrological state shift in wetland ecosystems of the southern Prairie Pothole Region
Evidence for a climate-induced ecohydrological state shift in wetland ecosystems of the southern Prairie Pothole Region
复制标题
草原坑洼地区南部湿地生态系统气候引起的生态水文状态转变的证据
作者：
O. McKenna;D. Mushet;D. Rosenberry;J. Labaugh
改变降水的幅度、频率和时间可以影响水生系统的水文、地球化学和生物过程，在某些情况下会导致整个系统向交替状态的转变。自20世纪90年代初以来，南部大草原坑洼地区一直受到延长期的增加湿度导致显着变化的水生系统定义这一地区。我们探索了许多证据来确定：（1）最近的湿润期与历史变化的比较，（2）水文，地球化学和生物反应，以及（3）这些反应如何代表该地区湿地生态系统的状态转变。我们分析了长期的气候记录，并比较了不同的水文变量如何在这个潮湿的时期相比，几十年前观察到的转变。此外，我们使用了水禽种群的数十年记录和地下瓷砖排水记录来探索野生动物和人类对气候变化的反应。自1993年以来，一种新的降水制度对应于增加池塘数量，积水深度，湖泊水位，溪流流量，地下水高度，土壤水分，水禽种群，并安装在农业领域的地下瓷砖排水。这些观察到的变化反映了整个景观的水储存和运动的改变，这反过来又改变了草原坑洼湿地的溶质来源和浓度，并增加了池塘的持久性。结合起来，这些变化是该地区湿地生态系统的生态水文功能的状态转变的重要证据，这种转变可能需要对以前开发的“湿地连续体”概念进行重大改进。
Changing magnitude, frequency, and timing of precipitation can influence aquatic-system hydrological, geochemical, and biological processes, in some cases resulting in system-wide shifts to an alternate state. Since the early 1990s, the southern Prairie Pothole Region has been subjected to an extended period of increased wetness resulting in marked changes to aquatic systems defining this region. We explored numerous lines of evidence to identify: (1) how the recent wet period compared to historical variability, (2) hydrological, geochemical, and biological responses, and (3) how these responses might represent a state shift in the region’s wetland ecosystems. We analyzed long-term climate records and compared how different hydrological variables responded in this wet period compared to decades before the observed shift. Additionally, we used multi-decadal records of waterfowl population and subsurface tile drain records to explore wildlife and human responses to a shifting climate. Since 1993, a novel precipitation regime corresponded with increased pond numbers, ponded-water depths, lake levels, stream flows, groundwater heights, soil-moisture, waterfowl populations, and installation of subsurface tile drains in agricultural fields. These observed changes reflect an alteration in water storage and movement across the landscape that in turn has altered solute sources and concentrations of prairie-pothole wetlands and has increased pond permanence. Combined, these changes represent significant evidence for a state shift in the ecohydrological functioning of the region’s wetland ecosystems, a shift that may require a significant refinement of the previously developed “wetland continuum” concept.