Department of Natural Sciences, School of Arts and Sciences, University of Alaska, Southeast, 11120 Glacier Highway, Juneau, Alaska, 99801, USA.
Department of Natural Resources Management & Environmental Sciences, California Polytechnic State University, 1 Grand Avenue, San Luis Obispo, California, 93407, USA.
Ecology. 2017 Jun;98(6):1513-1523. doi: 10.1002/ecy.1848.
Understanding plant community succession is one of the original pursuits of ecology, forming some of the earliest theoretical frameworks in the field. Much of this was built on the long-term research of William S. Cooper, who established a permanent plot network in Glacier Bay, Alaska, in 1916. This study now represents the longest-running primary succession plot network in the world. Permanent plots are useful for their ability to follow mechanistic change through time without assumptions inherent in space-for-time (chronosequence) designs. After 100-yr, these plots show surprising variety in species composition, soil characteristics (carbon, nitrogen, depth), and percent cover, attributable to variation in initial vegetation establishment first noted by Cooper in the 1916-1923 time period, partially driven by dispersal limitations. There has been almost a complete community composition replacement over the century and general species richness increase, but the effective number of species has declined significantly due to dominance of Salix species which established 100-yr prior (the only remaining species from the original cohort). Where Salix dominates, there is no establishment of "later" successional species like Picea. Plots nearer the entrance to Glacier Bay, and thus closer to potential seed sources after the most recent glaciation, have had consistently higher species richness for 100 yr. Age of plots is the best predictor of soil N content and C:N ratio, though plots still dominated by Salix had lower overall N; soil accumulation was more associated with dominant species. This highlights the importance of contingency and dispersal in community development. The 100-yr record of these plots, including species composition, spatial relationships, cover, and observed interactions between species provides a powerful view of long-term primary succession.
理解植物群落演替是生态学的最初追求之一，形成了该领域最早的一些理论框架。这在很大程度上是基于威廉·S·库珀（William S. Cooper）的长期研究，他于 1916 年在阿拉斯加的冰川湾建立了一个永久性样地网络。该研究现在是世界上运行时间最长的原生演替样地网络。永久性样地的有用之处在于它们能够在没有时间替代（年代序列）设计中固有的空间假设的情况下，随着时间的推移跟踪机械变化。经过 100 年，这些样地在物种组成、土壤特性（碳、氮、深度）和盖度方面表现出惊人的多样性，这归因于库珀在 1916-1923 年期间首次注意到的初始植被建立的变化，部分原因是扩散限制。在一个世纪的时间里，几乎完全取代了群落组成，物种丰富度普遍增加，但由于 100 年前建立的柳属物种的优势，有效物种数量显著下降（这是原始队列中唯一剩下的物种）。在柳属占主导地位的地方，不会有像云杉这样的“后期”演替物种建立。靠近冰川湾入口的样地，因此在最近一次冰川作用后，接近潜在的种子源，在 100 年内一直保持较高的物种丰富度。样地的年龄是土壤 N 含量和 C:N 比的最佳预测因子，尽管仍由柳属主导的样地的整体 N 含量较低；土壤积累更多地与优势物种有关。这突显了偶然性和扩散在群落发展中的重要性。这些样地的 100 年记录，包括物种组成、空间关系、盖度以及观察到的物种之间的相互作用，为长期原生演替提供了一个强大的视角。
