A previously unrecorded native species, Scirpus radicans (Cyperaceae), was discovered in the southern part of Lithuania in 2020. Although this species has a large distribution area in other parts of Eurasia, it is currently recognised as threatened in many European countries. Recordings of S. radicans in Lithuania had been expected, as these plants do occur or have been reported to occur in neighbouring regions. The aim of this study was to analyse the distribution of S. radicans in southern Lithuania, to determine the occupied areas and the size of populations, to study their capacity of vegetative reproduction, their habitats and associated plant communities, as well as to perform an assessment of the species' conservation status within the country. We studied S. radicans populations at two sites on the shores of Lake Pabezninkai and of Lake Netečius in the Varėna District (southern Lithuania), from August to October 2020. A total of 993 individuals of S. radicans were counted and their stands comprised 0.73 ha. The density of individuals in the studied plots ranged from 0.02 to 0.78 plants/m2. Only 0.5% of individuals at Lake Pabezninkai and 20.7% of individuals at Lake Netečius were at the stage of generative reproduction. Individuals at the stage of vegetative reproduction comprised 56.4%, whereas generative individuals amounted to 1.7% of all studied plants. One to seven stolons developed per plant and the mean number of rosettes per stolon was 2.8 ± 1.2. Potentially, a total of ca. 2860 rosettes could be expected from all individuals of the studied plots, but the actual realised rate of vegetative reproduction is unknown. A more detailed study of the reproductive capacities of S. radicans would be required for better understanding the causes of the lately observed decrease of this species in most of the countries of Central Europe. Our analysis of the associated plant communities has enabled us to confirm the presence of a Scirpetus radicantis Nowiński 1930 association previously not recorded in Lithuania. By assessing S. radicans in accordance with the IUCN Criteria, we conclude that this species should be classified as endangered (EN) in Lithuania. Based on this assessment, we propose to include this species on the list of legally protected species of Lithuania. Conservation of shallow lakes with sandy or muddy shores and with significant natural fluctuations of the water level is the main measure for ensuring the survival of S. radicans, as well as other rare and endangered species adapted to such a type of habitat.

中文翻译：

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立陶宛新发现的本地物种Scirpus radicans（莎草科）：种群，生境和威胁

2020年，在立陶宛南部发现了一种先前未记录的原生物种，Scirpus radicans（莎草科）。尽管该物种在欧亚大陆的其他地区分布面积很大，但目前在许多欧洲国家被认为是濒危物种。预计在立陶宛有萝卜链球菌的记录，因为这些植物的确存在或据报道在邻近地区发生。这项研究的目的是分析立陶宛南部的S. radicans分布，确定被占领的地区和人口规模，研究其无性繁殖的能力，其栖息地和相关的植物群落，并进行评估该物种在国内的保护状况。我们研究了S。2020年8月至2020年10月，位于瓦尔纳纳区（立陶宛南部）的帕贝兹宁凯湖和内特希乌斯湖沿岸两个地点的类种群。统计到总共993个of类链球菌，其林分包括0.73公顷。研究地块中个体的密度范围为0.02至0.78株植物/平方米。Pabezninkai湖只有0.5％的人和Netečius湖有20.7％的人处于生殖繁殖阶段。营养繁殖阶段的个体占56.4％，而繁殖个体占所有研究植物的1.7％。每株植物生长一到七个茎，每茎的平均莲座丛数为2.8±1.2。潜在地，总共约。研究样地的所有个人都有望获得2860个玫瑰花结，但营养繁殖的实际实现速度尚不清楚。为了更好地了解最近在中欧大多数国家中发现的该物种减少的原因，需要对萝卜的繁殖能力进行更详细的研究。我们对相关植物群落的分析使我们能够确认以前没有在立陶宛记录的Sirpetus radicantisNowiński1930协会的存在。通过根据IUCN标准评估辐射链霉菌，我们得出结论，该物种在立陶宛应被列为濒危物种（EN）。基于此评估，我们建议将该物种列入立陶宛受法律保护的物种清单。