Tang Tao, Stevenson R Jan
State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
Department of Integrative Biology, Michigan State University, East Lansing, MI 48824, USA.
Sci Total Environ. 2023 Nov 20;900:165849. doi: 10.1016/j.scitotenv.2023.165849. Epub 2023 Jul 27.
Consistency in ecological assessments is challenging across large diverse landscapes because natural geological, climatic, and hydrological factors vary greatly. As a result, large landscapes are often subdivided into ecoregions and assessments are based on ecoregion specific indices. In the present study, we developed and compared multimetric indices (MMIs) using benthic diatom data from the 2008-2009 dataset from the United States (US) National Rivers and Streams Assessment. Nationwide and separate ecoregion specific MMIs were developed with reference, moderately disturbed, and highly disturbed sites selected using criteria based on physicochemical condition of the habitat or based on watershed land use (% agriculture and % urban). Metrics were adjusted to account for variation in natural conditions when needed. We found only land use criteria selected reference sites with consistently low median % watershed disturbance (%WD) and large differences in %WD between reference and highly disturbed sites. <38 % of sites were identified as reference or highly disturbed by both physicochemical and land use criteria. All MMIs displayed substantial discrimination ability between reference and highly disturbed sites. At the national scale, MMIs based on land use outperformed MMIs based on physicochemical conditions for all performance attributes tested. When national scale MMIs were applied to ecoregions, MMIs based on land use were again better than MMIs based on physicochemical conditions for most performance attributes and even had better or comparable performance to the land use MMIs developed separately for each ecoregion. Our findings show that developing MMIs using land use criteria and adjusting metrics for natural variation could improve assessment consistency without losing MMI performance across large, diverse landscapes as in the US National Rivers and Streams Assessment.
在广阔多样的景观中进行生态评估时，保持一致性具有挑战性，因为自然地质、气候和水文因素差异很大。因此，大型景观通常被细分为生态区，评估基于特定生态区的指标。在本研究中，我们利用来自美国国家河流和溪流评估2008 - 2009年数据集的底栖硅藻数据，开发并比较了多指标指数（MMIs）。在全国范围内以及针对各个特定生态区，通过根据栖息地的物理化学条件或流域土地利用（农业百分比和城市百分比）标准选择参考、中度干扰和高度干扰的地点，开发了MMIs。必要时，对指标进行了调整以考虑自然条件的变化。我们发现，只有土地利用标准选择的参考地点具有始终较低的流域干扰中位数百分比（%WD），并且参考地点和高度干扰地点之间的%WD差异很大。<38%的地点通过物理化学和土地利用标准都被确定为参考或高度干扰地点。所有MMIs在参考地点和高度干扰地点之间都表现出显著的区分能力。在国家尺度上，对于所有测试的性能属性，基于土地利用的MMIs优于基于物理化学条件的MMIs。当将国家尺度的MMIs应用于生态区时，对于大多数性能属性，基于土地利用的MMIs再次优于基于物理化学条件的MMIs，甚至与为每个生态区单独开发的基于土地利用的MMIs具有相同或更好的性能。我们的研究结果表明，使用土地利用标准开发MMIs并针对自然变化调整指标，可以提高评估的一致性，而不会像在美国国家河流和溪流评估中那样，在广阔多样的景观中失去MMIs的性能。
