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）指生态群落以阶段性而非连续性的方式发生的变化。尽管其对理解生态系统发育具有重要意义，但目前尚未有针对演替阶段的可靠定义，也缺乏量化阶段转变的有效方法。为获取相关研究数据，我们在德国东部一处面积为6公顷的人工集水区（artificial catchment）开展了为期6年的原生演替（primary succession）调查。本数据集包含植物物种及其盖度值的记录，以及初始底物属性数据，所有数据均采自适用于空间数据分析的20米×20米规则网格样地。本研究通过物种共现性（species co-occurrence）与嵌套性（nestedness）分析，对群落组装（community assembly）过程展开了研究。此外，我们将物种丰度的对数正态分布（lognormal distribution）与对数序列分布（log series distribution）与各群落进行了关联分析。本研究提出了一种基于研究系统中瞬时空间同质性程度的通用演替阶段检测新方法。空间一致性植被格局揭示了该原生演替序列内的非重叠分区，并将其界定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，因此种群动态随机性与中性群落组装过程在研究期间的重要性不断下降。本研究结果凸显了演替阶段的空间维度，并量化了各阶段间的变化程度。该研究成果可为构建更为可靠的生态演替术语体系提供重要支撑。