Topp Simon N, Pavelsky Tamlin M, Dugan Hilary A, Yang Xiao, Gardner John, Ross Matthew R V
Department of Geological Sciences University of North Carolina at Chapel Hill Chapel Hill NC USA.
Center for Limnology University of Wisconsin-Madison Madison WI USA.
Water Resour Res. 2021 May;57(5):e2020WR029123. doi: 10.1029/2020WR029123. Epub 2021 May 17.
Lakes are often defined by seasonal cycles. The seasonal timing, or phenology, of many lake processes are changing in response to human activities. However, long-term records exist for few lakes, and extrapolating patterns observed in these lakes to entire landscapes is exceedingly difficult using the limited number of available in situ observations. Limited landscape-level observations mean we do not know how common shifts in lake phenology are at macroscales. Here, we use a new remote sensing data set, LimnoSat-US, to analyze U.S. summer lake color phenology between 1984 and 2020 across more than 26,000 lakes. Our results show that summer lake color seasonality can be generalized into five distinct phenology groups that follow well-known patterns of phytoplankton succession. The frequency with which lakes transition from one phenology group to another is tied to lake and landscape level characteristics. Lakes with high inflows and low variation in their seasonal surface area are generally more stable, while lakes in areas with high interannual variations in climate and catchment population density show less stability. Our results reveal previously unexamined spatiotemporal patterns in lake seasonality and demonstrate the utility of LimnoSat-US, which, with over 22 million remote sensing observations of lakes, creates novel opportunities to examine changing lake ecosystems at a national scale.
湖泊通常由季节性周期定义。许多湖泊过程的季节性时间安排，即物候，正随着人类活动而发生变化。然而，长期记录存在的湖泊很少，而且利用有限的现有原位观测数据将这些湖泊中观察到的模式外推到整个景观是极其困难的。有限的景观层面观测意味着我们不知道湖泊物候变化在宏观尺度上有多普遍。在这里，我们使用一个新的遥感数据集LimnoSat-US，分析1984年至2020年期间美国26000多个湖泊的夏季湖水颜色物候。我们的结果表明，夏季湖水颜色季节性可以归纳为五个不同的物候组，它们遵循着众所周知的浮游植物演替模式。湖泊从一个物候组转变为另一个物候组的频率与湖泊和景观层面的特征有关。入流高且季节性表面积变化小的湖泊通常更稳定，而气候和集水区人口密度年际变化大的地区的湖泊稳定性较差。我们的结果揭示了湖泊季节性中以前未被研究的时空模式，并证明了LimnoSat-US的实用性，该数据集有超过2200万个湖泊遥感观测数据，为在国家尺度上研究不断变化的湖泊生态系统创造了新机会。
