Abstract Numerous contributions indicate that the distribution of trees in floodplains is determined by hydrological dynamics and that some plants are more tolerant than others to flood periods, however very little scientific information allows to link the regulation of the pulse regime by the dams with the impacts they produce on river vegetation. We assume that the frequency curves of the trees in the floodplain are a synthetic representation of the niche of each species with respect to the macrofactor that conditions their distribution. We compared two surveys of vegetation: one before to the reservoir -in 1980-, and another in 2014, thirty-fourth years after building of Yacyreta, in the same places, with the same method in a 175 km stretch of the Upper Parana floodplain, downstream of the Yacyreta dam. Using as an indicator the distribution curves densities based on frequency of the dominant trees and its relationship with the hydrological regime we establish the response of the floodplain forest to pulsing regime in both periods. Our results indicate that during 34 years after Yacyreta, there were significant changes in the hydrological regime and in the occurrence of some species at each site and between sites. We found that selected species show changes in distribution after 34 years of operation of the Yacyreta reservoir, despite which we only found statistically significant changes in 40% of the species surveyed. The results of our study provide a criterion for the analysis of the impacts of hydrological regulation on the distribution of floodplain forests in large rivers.

中文翻译：

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Yacyretá 大坝对巴拉那洪泛区树木分布的影响

摘要 大量贡献表明，洪泛区树木的分布是由水文动力学决定的，有些植物比其他植物更能耐受洪水期，但是很少有科学信息允许将大坝对脉动状况的调节与其影响联系起来。生产河流植被。我们假设洪泛区树木的频率曲线是每个物种的生态位相对于影响其分布的宏观因素的综合表示。我们比较了两次植被调查：一次是在 1980 年的水库之前，另一次是在 2014 年，即 Yacyreta 建成 34 年后，在相同的地方，使用相同的方法在上巴拉那漫滩的 175 公里延伸，Yacyreta 大坝下游。使用基于优势树木频率的分布曲线密度及其与水文状况的关系作为指标，我们建立了洪泛区森林在两个时期对脉动状况的响应。我们的结果表明，在 Yacyreta 之后的 34 年中，水文状况发生了显着变化，每个站点和站点之间的某些物种的出现也发生了显着变化。我们发现，在 Yacyreta 水库运行 34 年后，所选物种的分布发生了变化，尽管如此，我们仅发现 40% 的调查物种发生了统计学上的显着变化。我们的研究结果为分析水文调控对大河漫滩森林分布的影响提供了一个标准。