The main species composition drivers in temperate deciduous forests are environmental conditions, a stand's age and the site history, e.g., the succession stage and past land use, as well as disturbance regime and current management. We compared plant species diversity and composition in late successional and ancient forests, co-occurring on the same small river island applying species accumulation curves and nonmetric multidimensional scaling, respectively. Given the island's geomorphological characteristics, we expected these to be very similar before human intervention in the past. The forests experienced differing disturbance regimes in the past, while over the last 30 years, human intervention has been the same and reduced to a minimum. The ancient forest in this study had two major characteristics defining it as old, mature forest: continuity of presence for more than 200 years and specific composition. The late successional forest experienced major disturbance in the 20th century and was allowed natural regeneration by bordering on the ancient forest, representing a potential species pool, and by decades of minimum human intervention. Our results showed that, even though there was no difference in species richness, we could still detect differences between the forests, particularly in the abundance and species composition of the understorey, among which geophytes had the most indicative importance. To make our results useful on a broader scale, we composed from the literature a species list of plants indicative for ancient forest and tested its application. These results are important for distinguishing between old and mature secondary stands and particularly for identifying old forest stands, which should be conserved and, in the case of fragmented landscapes, included in a network connecting forest fragments.

温带落叶林的主要物种组成驱动因素是环境条件、林分年龄和场地历史，例如演替阶段和过去的土地利用，以及干扰机制和当前管理。我们分别应用物种积累曲线和非度量多维尺度比较了晚演替森林和古老森林的植物物种多样性和组成，它们同时出现在同一个小河岛上。鉴于岛上的地貌特征，我们预计这些在过去人类干预之前会非常相似。过去，森林经历了不同的干扰机制，而在过去的 30 年里，人类干预一直是一样的，并且减少到了最低限度。本研究中的古老森林有两个主要特征，将其定义为古老的成熟森林：存在的连续性超过 200 年和特定的组成。晚期演替森林在 20 世纪经历了重大干扰，通过与代表潜在物种库的古老森林接壤，以及数十年来最少的人为干预，得以自然再生。我们的结果表明，即使物种丰富度没有差异，我们仍然可以检测到森林之间的差异，特别是在林下层的丰度和物种组成方面，其中地生植物具有最重要的指示意义。为了使我们的结果在更广泛的范围内有用，我们根据文献编制了一份指示古代森林的植物物种清单，并测试了其应用。