Thoen Riley D, Hendricks Lauren B, Bailes Graham T, Johnson Bart R, Pfeifer-Meister Laurel, Reed Paul B, Roy Bitty A, DeMarche Megan L
Department of Plant Biology, University of Georgia, Athens, GA, USA.
Environmental Studies Program, University of Oregon, Eugene, OR, USA.
Am J Bot. 2025 Jan;112(1):e16446. doi: 10.1002/ajb2.16446. Epub 2024 Dec 17.
Understanding how population dynamics vary in space and time is critical for understanding the basic life history and conservation needs of a species, especially for narrow endemic species whose populations are often in similar environments and therefore at increased risk of extinction under climate change. Here, we investigated the spatial and temporal variation in population dynamics of Ranunculus austro-oreganus, a perennial buttercup endemic to fragmented prairie habitat in one county in southern Oregon.
We performed demographic surveys of three populations of R. austro-oreganus over 4 years (2015-2018). We used size-structured population models and life table response experiments to investigate vital rates driving spatiotemporal variation in population growth.
Overall, R. austro-oreganus had positive or stable stochastic population growth rates, though individual vital rates and overall population growth varied substantially among sites and years. All populations had their greatest growth in the same year, suggesting potential synchrony associated with climate conditions. Differences in survival contributed most to spatial variation in population growth, while differences in reproduction contributed most to temporal variation in population growth.
Populations of this extremely narrow endemic appear stable, with positive growth during our study window. These results suggest that populations of R. austro-oreganus are able to persist if their habitat is not eliminated by land-use change. Nonetheless, its narrow distribution and synchronous population dynamics suggest the need for continued monitoring, particularly with ongoing habitat loss and climate change.
了解种群动态如何随空间和时间变化，对于理解一个物种的基本生活史和保护需求至关重要，尤其是对于那些分布范围狭窄的特有物种，其种群通常处于相似的环境中，因此在气候变化下面临更高的灭绝风险。在此，我们研究了俄勒冈州南部一个县的碎片化草原栖息地特有的多年生毛茛——奥勒冈毛茛（Ranunculus austro - oregonus）种群动态的空间和时间变化。
我们在4年时间（2015 - 2018年）内对三个奥勒冈毛茛种群进行了种群统计学调查。我们使用大小结构种群模型和生命表响应实验来研究驱动种群增长时空变化的关键率。
总体而言，奥勒冈毛茛的随机种群增长率为正或稳定，尽管各个关键率和总体种群增长在不同地点和年份之间存在很大差异。所有种群在同一年都有最大的增长，这表明可能存在与气候条件相关的同步性。存活率的差异对种群增长的空间变化贡献最大，而繁殖率的差异对种群增长的时间变化贡献最大。
这种分布极其狭窄的特有物种的种群似乎是稳定的，在我们的研究期间呈正增长。这些结果表明，如果其栖息地不被土地利用变化所消除，奥勒冈毛茛的种群能够持续存在。尽管如此，其狭窄的分布和同步的种群动态表明需要持续监测，特别是考虑到持续的栖息地丧失和气候变化。
