Water is one of the key ecological factors that has a great impact to development and productivity of lowland species such as Quercus robur. This paper deals with water regime influence to site conditions of these species and how actually changeable soil moisture affects Q. robur. Studied area includes a protective embankment built on the river bank in order to eliminate flooding effect, which means that all needs for water these associations provide from rainfalls and groundwater. Water regime was monitored during two critical years (extremely dry and extremely wet) on four soil types – Planosol, Fluvisol and Gleysol that belong to hydromorphic (three experimental plots) and Chernozem which belongs to automorphic soils (three experimental plots), respectively. It was studied the distribution of rainfalls and groundwater during the growing seasons and how it affects total and available water amount in the soil. The main focus should be given to available water, because it is located in capillary pores and plants can utilize it. Bearing in mind rainfalls makes just 15–20% of the total water amount in the soil it is much more significant to evaluate its proportion in available water. Based on obtained results, we can deduce that much more suitable site conditions for Q. robur are present on hydromorphic soils due to much greater proportion of groundwater.

中文翻译：

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低地森林的土壤湿度状况——水的数量和可用性

水是对低地物种的发育和生产力有重大影响的关键生态因素之一，例如夏栎。本文讨论了水情对这些物种的立地条件的影响以及土壤湿度的实际变化如何影响强韧栎。研究区域包括在河岸上修建的防护堤，以消除洪水影响，这意味着这些协会的所有用水需求都来自降雨和地下水。在两个关键年份（极干和极湿）期间，对四种土壤类型进行了水情监测：分别属于水形态土（三个试验地）的 Planosol、Fluvisol 和 Gleysol 以及属于自质土（三个试验地）的黑钙土。研究了生长季节降雨和地下水的分布以及它如何影响土壤中的总水量和可用水量。应主要关注可用水，因为它位于毛细孔中，植物可以利用它。考虑到降雨量仅占土壤总水量的 15-20%，因此评估其在可用水中的比例更为重要。根据获得的结果，我们可以推断出更适合的场地条件强韧栎由于地下水比例大得多，因此存在于水形态土壤上。