Data from: Incorporating interspecific competition into species-distribution mapping by upward scaling of small-scale model projections to the landscape

There are a number of overarching questions and debate in the scientific community concerning the importance of biotic interactions in species distribution models at large spatial scales. In this paper, we present a framework for revising the potential distribution of tree species native to the Western Ecoregion of Nova Scotia, Canada, by integrating the long-term effects of interspecific competition into an existing abiotic-factor-based definition of potential species distribution (PSD). The PSD model is developed by combining spatially explicit data of individualistic species’ response to normalized incident photosynthetically active radiation, soil water content, and growing degree days. A revised PSD model adds biomass output simulated over a 100-year timeframe with a robust forest gap model and scaled up to the landscape using a forestland classification technique. To demonstrate the method, we applied the calculation to the natural range of 16 target tree species as found in 1,240 provincial forest-inventory plots. The revised PSD model, with the long-term effects of interspecific competition accounted for, predicted that eastern hemlock (Tsuga canadensis), American beech (Fagus grandifolia), white birch (Betula papyrifera), red oak (Quercus rubra), sugar maple (Acer saccharum), and trembling aspen (Populus tremuloides) would experience a significant decline in their original distribution compared with balsam fir (Abies balsamea), black spruce (Picea mariana), red spruce (Picea rubens), red maple (Acer rubrum L.), and yellow birch (Betula alleghaniensis). True model accuracy improved from 64.2% with original PSD evaluations to 81.7% with revised PSD. Kappa statistics slightly increased from 0.26 (fair) to 0.41 (moderate) for original and revised PSDs, respectively.在大空间尺度的物种分布模型研究中，生物交互作用的重要性是科学界诸多核心议题与学术争论的焦点。本文提出了一套用于修订加拿大新斯科舍省西部生态区本土树种潜在分布的研究框架：将种间竞争的长期效应整合进现有基于非生物因子的潜在物种分布（potential species distribution, PSD）定义中。该PSD模型通过整合物种个体对归一化入射光合有效辐射（normalized incident photosynthetically active radiation）、土壤含水量以及生长度日数（growing degree days）的空间显式响应数据构建而成。经修订的潜在物种分布模型则加入了通过稳健的森林林隙模型（forest gap model）模拟得到的百年尺度生物量输出结果，并借助林地分类技术将其拓展至景观尺度。为验证该方法的有效性，我们将其应用于加拿大新斯科舍省1240个省级森林调查样地中记录的16种目标树种的自然分布范围。纳入种间竞争长期效应的修订潜在物种分布模型预测显示：与香脂冷杉（Abies balsamea）、黑云杉（Picea mariana）、红云杉（Picea rubens）、红枫（Acer rubrum L.）以及黄桦（Betula alleghaniensis）相比，东部铁杉（Tsuga canadensis）、美洲山毛榉（Fagus grandifolia）、白桦（Betula papyrifera）、红栎（Quercus rubra）、糖枫（Acer saccharum）以及颤杨（Populus tremuloides）的原有分布范围将出现显著缩减。模型整体准确率从原始潜在物种分布评估的64.2%提升至修订后模型的81.7%。Kappa统计量也从原始模型的0.26（一致性程度一般）小幅提升至修订后模型的0.41（一致性程度中等）。