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）指以阶段性而非连续性方式推进的生态群落变化过程。尽管其对理解生态系统发育过程至关重要，但目前尚无公认的演替阶段可靠定义，也缺乏针对阶段转换的定量度量方法。为获取相关数据，我们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）监测研究。本数据集包含植物物种及其盖度值的记录，以及初始基质属性数据，所有数据均采自适用于空间数据分析的20 m × 20 m规则网格样地。本研究通过物种共存（species co-occurrence）与嵌套性（nestedness）分析，对群落构建（community assembly）过程展开研究；此外，我们将各群落的物种丰度（species abundance）分别与对数正态分布（lognormal distribution）及对数级数分布（log series distribution）进行拟合关联分析。本研究提出一种基于研究系统暂态空间同质性程度的通用新方法，用于识别演替阶段。具有空间一致性的植被格局揭示出该原生演替序列存在互不重叠的分区，并将其界定为两个截然不同的生态阶段。研究期间，物种共存格局的随机性逐渐降低，种群统计随机性（demographic stochasticity）与中性群落构建（neutral community assembly）的作用权重随之不断下降。本研究结果凸显了演替阶段的空间维度，并量化了各阶段间的变化程度，可为构建更严谨的生态演替术语体系提供支撑。