Final SAC Parameter Dataset

Species accumulation curves (SACs) were created based on a combination of Ecoregion, Land Cover Class (LCC) and Watershed Position (WSP) within the Great Lake Basin Watershed (GLBW). This dataset contains parameters from the SACs fitted using the Lomolino function. The parameters included are slope, asymptote and xmid. Slopes of the Lomolino models represents the slope at the inflection point, or the point on the slope where the concavity of the curve changes (Lomolino, 2001). In terms of the Lomolino model, this inflection point also represents the maximum rate of increase in species richness (Lomolino, 2001). Fitted slope is therefore the parameter that allows for estimating the rate of species accrual at its greatest point. The asymptote represents the maximum richness of the sites sampled (Lomolino, 2001). The xmid is the number of points at which half the total species richness is achieved. 

Lomolino, M. V. (2001). The species-area relationship: new challenges for an old pattern. Prog. Phys. Geogr., 25, 1-21. https://doi/10.1177/030913330102500101

本数据集基于大湖流域（GLBW）内的生态区域、土地覆被类型（LCC）和水系位置（WSP）的复合，构建了物种累积曲线（SACs）。数据集包含利用Lomolino函数拟合的SACs参数，包括斜率、渐近线和xmid。Lomolino模型中的斜率代表拐点处的斜率，或曲线斜率上曲率变化的位置（Lomolino, 2001）。在Lomolino模型中，此拐点亦代表物种丰富度增加的最大速率（Lomolino, 2001）。拟合的斜率因此成为允许在最大点估计物种累积速率的参数。渐近线代表采样地点的最大丰富度（Lomolino, 2001）。xmid代表达到总物种丰富度一半的点数。