Švamberková Eva, Doležal Jiří, Lepš Jan
Department of Botany, Faculty of Science, University of South Bohemia, Branišovská 1760, 370 05, Ceske Budejovice, Czech Republic.
Section of Plant Ecology, Institute of Botany, Czech Academy of Sciences, Dukelská 135, 379 82, Třeboň, Czech Republic.
Oecologia. 2019 Jun;190(2):459-469. doi: 10.1007/s00442-019-04415-y. Epub 2019 May 20.
Priority effects provide an advantage to early establishing species and are thought to significantly affect the course of succession. We conducted a 20-year long experiment sowing high- and low-diversity mixtures in an ex-arable field. We ask how long the effect of sowing persists and which sown species affect the course of succession. The experiment was established in the Czech Republic in five replicate blocks, each containing three random 10 × 10 m plots with three treatments: natural colonisation, sowing low- and high-diversity seed mixtures. The species cover was annually estimated in 12 permanent 1 m quadrates within each plot. To identify the effects of sowing, we used an innovative method analysing the data separately for each year using Redundancy analysis (RDA) with identity of sown species as explanatory variables. In the first year, the effect of sowing was small; the peak of explained variability occurred between third and fifth year. The legacy of sowing was detectable in the natural colonisers for 18 years and in the sown species for the whole 20-year period. For some species, the difference between the plots where they were and were not sown remained significant for the whole 20-year period (e.g. Lathyrus pratensis) although the plots were adjacent and the area was mown with the same machine. Other ones (e.g. Trisetum flavescens) colonised all the plots evenly. The long-lasting effect of the initial sowing confirms contingency of successional pathway on the propagule pressure in the time of start of succession due to the priority effects.
优先效应赋予早期定植物种优势，并被认为会显著影响演替进程。我们在一块弃耕农田中进行了一项为期20年的实验，播种高多样性和低多样性的混合种子。我们探究播种的影响会持续多久，以及哪些播种物种会影响演替进程。该实验在捷克共和国设立了五个重复区组，每个区组包含三个随机的10×10米样地，有三种处理方式：自然定植、播种低多样性和高多样性种子混合物。每年在每个样地内的12个1平方米的永久样方中估计物种覆盖度。为了确定播种的影响，我们使用了一种创新方法，以播种物种的身份作为解释变量，每年分别使用冗余分析（RDA）对数据进行分析。在第一年，播种的影响较小；解释变异的峰值出现在第三年到第五年之间。播种的遗留影响在自然定植物种中可检测到18年，在播种物种中则贯穿整个20年。对于一些物种，在整个20年期间，它们播种与未播种样地之间的差异仍然显著（例如草地香豌豆），尽管样地相邻且使用同一台机器进行割草。其他物种（例如黄花草）则均匀地定植在所有样地中。由于优先效应，初始播种的长期影响证实了演替路径在演替开始时对繁殖体压力的偶然性。
