Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America.
The Nature Conservancy, Eastern Conservation Science, Eastern Regional Office, Boston, Massachusetts, United States of America.
PLoS One. 2018 Jun 20;13(6):e0198439. doi: 10.1371/journal.pone.0198439. eCollection 2018.
Describing the physical habitat diversity of stream types is important for understanding stream ecosystem complexity, but also prioritizing management of stream ecosystems, especially those that are rare. We developed a stream classification system of six physical habitat layers (size, gradient, hydrology, temperature, valley confinement, and substrate) for approximately 1 million stream reaches within the Eastern United States in order to conduct an inventory of different types of streams and examine stream diversity. Additionally, we compare stream diversity to patterns of anthropogenic disturbances to evaluate associations between stream types and human disturbances, but also to prioritize rare stream types that may lack natural representation in the landscape. Based on combinations of different layers, we estimate there are anywhere from 1,521 to 5,577 different physical types of stream reaches within the Eastern US. By accounting for uncertainty in class membership, these estimates could range from 1,434 to 6,856 stream types. However, 95% of total stream distance is represented by only 30% of the total stream habitat types, which suggests that most stream types are rare. Unfortunately, as much as one third of stream physical diversity within the region has been compromised by anthropogenic disturbances. To provide an example of the stream classification's utility in management of these ecosystems, we isolated 5% of stream length in the entire region that represented 87% of the total physical diversity of streams to prioritize streams for conservation protection, restoration, and biological monitoring. We suggest that our stream classification framework could be important for exploring the diversity of stream ecosystems and is flexible in that it can be combined with other stream classification frameworks developed at higher resolutions (meso- and micro-habitat scales). Additionally, the exploration of physical diversity helps to estimate the rarity and patchiness of riverscapes over large region and assist in conservation and management.
描述溪流类型的物理生境多样性对于理解溪流生态系统的复杂性很重要，同时对于管理溪流生态系统也很重要，尤其是那些稀有类型的溪流生态系统。我们开发了一个包含六个物理生境层（大小、坡度、水文学、温度、河谷约束和基质）的溪流分类系统，用于对美国东部大约 100 万条溪流进行清查，以调查不同类型的溪流并检验溪流多样性。此外，我们还将溪流多样性与人为干扰模式进行比较，以评估溪流类型与人类干扰之间的关系，同时确定可能在景观中缺乏自然代表性的稀有溪流类型。基于不同层的组合，我们估计在美国东部的溪流中，存在着 1521 到 5577 种不同的物理类型。考虑到类别成员的不确定性，这些估计范围可以从 1434 到 6856 种溪流类型。然而，总溪流长度的 95%仅由总溪流生境类型的 30%代表，这表明大多数溪流类型都很稀有。不幸的是，该地区 1/3 的溪流物理多样性已经受到人为干扰的影响。为了说明溪流分类在管理这些生态系统方面的实用性，我们选择了该地区整个区域的 5%的溪流长度，这些溪流长度代表了溪流物理多样性的 87%，以便优先保护、恢复和生物监测溪流。我们认为，我们的溪流分类框架对于探索溪流生态系统的多样性非常重要，并且具有灵活性，因为它可以与其他在更高分辨率（中观和微观生境尺度）开发的溪流分类框架结合使用。此外，对物理多样性的探索有助于估计大区域河流景观的稀有性和斑块性，并有助于保护和管理。
