To better understand the pattern of variation in biocomplexity of springs and first-order streams, it is essential to explore how the characteristics of spring communities may vary from the spring source (eucrenal) to the first reach of the originating springbrook (hypocrenal). For these reasons, we assessed spatial and temporal variation of crenic assemblages and leaf-litter breakdown along a 45-m reach of a spring–springbrook system in Central Italy. We found that physicochemical and hydrological parameters of Vera Spring did not vary significantly along the 45-m reach investigated. In contrast, total richness of assemblages was significantly higher at 20 and 45 m from the spring source, while abundances were more variable and did not show significant differences between seasons and among sites. The composition of assemblages did not show significant temporal trends in all sites investigated, while spatial differences along the eucrenal–hypocrenal ecotone were more prominent. The functional organization of assemblages was relatively stable in both space and time, and no spatial differences were observed in the rate of leaf-litter breakdown, though the dry mass loss of poplar leaves was slightly higher at the most downstream site. We conclude that immediately after groundwater emergence, spring communities are less stable and more variable while they tend to be better organized at short distance downstream. Small and gradual spatial changes in the strength of competitive interactions and predation pressures may have a fundamental role in structuring spring communities more than variation in abiotic parameters and/or differences in quantity and quality of food resources.

中文翻译：

---

沿着意大利中部流平泉的真脑-下脑交错带的底栖无脊椎动物组合和落叶分解：是否存在空间和季节差异？

为了更好地理解泉水和一级河流生物复杂性的变化模式，有必要探索泉水群落的特征如何从泉水源（eucrenal）到起源泉溪（hypocrenal）的第一段变化。出于这些原因，我们评估了意大利中部 45 米长的春-春溪系统的裂缝组合和凋落物分解的时空变化。我们发现维拉泉的物理化学和水文参数在所调查的 45 米范围内没有显着变化。相比之下，在距泉源 20 和 45 m 处，组合的总丰富度显着更高，而丰度变化更大，并且在季节和地点之间没有表现出显着差异。在所有调查的站点中，组合的组成并未显示出显着的时间趋势，而沿 Eucrenal-hypocrenal 交错带的空间差异更为突出。组合的功能组织在空间和时间上都相对稳定，凋落物分解率没有空间差异，但最下游站点的杨树叶干质量损失略高。我们得出的结论是，在地下水出现后，泉水群落的稳定性较差且变化较大，而它们往往在下游的短距离内组织得更好。