Data from: Species-driven phases and increasing structure in early-successional plant communities

Successional phases describe changes in ecological communities that proceed in steps rather than continuously. Despite their importance for the understanding of ecosystem development, there still exists no reliable definition of phases and no quantitative measure of phase transitions. In order to obtain these data, we investigated primary succession in an artificial catchment (6 ha) in eastern Germany over a period of 6 years. The data set consists of records of plant species and their cover values, and initial substrate properties, both from plots in a regular grid (20 m × 20 m) suitable for spatial data analysis. Community assembly was studied by analyses of species co-occurrence and nestedness. Additionally, we correlated lognormal and log series distributions of species abundance to each community. We here introduce a new general method for detection of successional phases based on the degree of transient spatial homogeneity in the study system. Spatially coherent vegetation patterns revealed nonoverlapping partitions within this sequence of primary succession and were characterized as two distinct ecological phases. Patterns of species co-occurrence were increasingly less random, and hence the importance of demographic stochasticity and neutral community assembly decreased during the study period. Our findings highlight the spatial dimension of successional phases and quantify the degree of change between these steps. They are an element for advancing a more reliable terminology of ecological successions.

演替阶段（successional phases）指以间断性而非连续性方式推进的生态群落变化过程。尽管其对于理解生态系统发育过程具有重要意义，但目前学界尚未形成关于演替阶段的可靠定义，也缺乏针对演替阶段转换的定量度量方法。
为获取相关数据，本研究对德国东部一处面积6公顷的人工集水区开展了为期6年的原生演替（primary succession）监测。本数据集包含来自规则网格（20米×20米）样地的植物物种记录、物种盖度数据，以及初始基质特性数据，该网格设计适配空间数据分析需求。
本研究通过物种共现（species co-occurrence）与巢式结构（nestedness）分析，对群落构建过程开展研究。此外，本研究将各群落的物种多度对数正态分布（lognormal distribution）与对数级数分布（log series distribution）分别与群落进行关联分析。
本研究基于研究系统中瞬时空间同质性程度，提出了一种可用于检测演替阶段的通用新方法。空间一致性植被格局表明，该原生演替序列存在非重叠的分区结构，且可被划分为两个截然不同的生态阶段。物种共现格局的随机性逐渐降低，因此在本研究周期内，种群统计随机性（demographic stochasticity）与中性群落构建（neutral community assembly）过程的重要性不断下降。
本研究结果凸显了演替阶段的空间维度，并量化了各演替阶段间的变化程度。该研究可为构建更严谨的生态演替术语体系提供支撑。