The interacting influences of competition, composition, and diversity determine successional community change

Community change is one of the few constants in nature, and the balance of mechanisms influencing this change is central to understanding the structure and functioning of communities and ecosystems. Newly established communities undergo succession and can change in diversity and composition as local environmental change, interspecific interactions, and immigration play out over time. Understanding the influence of initial conditions and priority effects (long-term consequences of the initial community composition and species identity) on community change is critically important for both evaluating ecological theory and predicting restoration outcomes. 
Here I evaluate how initial experimental conditions in 2012, such as initial sown species richness, phylogenetic diversity, and early biomass production, along with priority effects caused by the identity of sown species, influence subsequent plant community composition and the number of colonizing species after nine years of uninterrupte..., This experiment was conducted in an old field at the University of Toronto’s Koffler Scientific Reserve, located about 50 km away from Toronto, Ontario, Canada (44o02’ N, 79o31’ W), as is detailed in Cadotte (2013), but I supply important details here. In fall 2009 and early spring 2010, a 30 x 30 m field was plowed and disked, and then 100 2 x 2 m plots were set up and separated by pathways 1 m in width. 
In May 2010, the plots were seeded with 1, 2, and 4 plant species from a pool of 15 species, including: Andropogon gerardii (Vitman, Poaceae); Schizachyrium scoparium ([Michx.] Nash, Poaceae); Elymus canadensis (L., Poaceae); E. trachycaulus ([Link) Gould ex Shinners, Poaceae); Asclepias tuberosa (L., Asclepiadaceae); Rudbeckia hirta (L. Asteraceae); Solidago altissima (L., Asteraceae); Solidago nemoralis (Aiton, Asteraceae); Desmodium canadense (L., Fabaceae); Lespedeza capitata (Michx., Fabaceae); Monarda fistulosa (L., Lamiaceae); Pycnanthemum tenuifolium (Schrad., Lamiaceae); P. v..., ,

群落变化是自然界少数恒定规律之一，而影响该变化的机制平衡是理解群落与生态系统结构及功能的核心。新生群落会经历演替（succession）过程，随着局域环境变化、种间相互作用及物种迁入随时间推移而展开，其多样性与组成会发生改变。理解初始条件及优先效应（priority effects，初始群落组成与物种身份的长期后果）对群落变化的影响，对于评估生态学理论及预测恢复结果均至关重要。

本文评估了2012年的初始实验条件（例如初始播种物种丰富度、系统发育多样性（phylogenetic diversity）及早期生物量生产），以及由播种物种身份引发的优先效应，如何影响九年后植物群落的后续组成及定居物种数量……本实验在加拿大多伦多大学科夫勒科学保护区（Koffler Scientific Reserve）的一块旧田地中开展，该保护区位于安大略省多伦多市约50公里处（北纬44°02′，西经79°31′），详细信息见Cadotte（2013），但本文补充了重要细节。2009年秋季及2010年早春，研究人员对一块30×30米的田地进行了犁耕与耙耕，随后设置了100个2×2米的样方，样方间由1米宽的路径隔开。

2010年5月，研究人员从15个物种库中选取1、2及4种植物对样方进行播种，涉及物种包括：大须芒草（Andropogon gerardii，Vitman，禾本科Poaceae）；小须芒草（Schizachyrium scoparium，[Michx.] Nash，禾本科）；加拿大披碱草（Elymus canadensis，L.，禾本科）；糙茎披碱草（E. trachycaulus，[Link) Gould ex Shinners，禾本科）；块根马利筋（Asclepias tuberosa，L.，萝藦科Asclepiadaceae）；黑心金光菊（Rudbeckia hirta，L.，菊科Asteraceae）；高秆一枝黄花（Solidago altissima，L.，菊科）；草原一枝黄花（Solidago nemoralis，Aiton，菊科）；加拿大山蚂蝗（Desmodium canadense，L.，豆科Fabaceae）；头状胡枝子（Lespedeza capitata，Michx.，豆科）；拟美国薄荷（Monarda fistulosa，L.，唇形科Lamiaceae）；细叶石山薄荷（Pycnanthemum tenuifolium，Schrad.，唇形科）；P. v...