The extreme species richness of some temperate grasslands is a globally relevant yet understudied phenomenon. Until now, few records from thoroughly sampled, though not permanently fixed, vegetation plots were available. We therefore established a network of 40 permanent 4 × 4-m2 plots in species-rich grasslands of the White Carpathians (Czechia), Ukraine, Hungary and Romania. Thirty-one of them form the main dataset comprising plots from discrete forest-steppe grasslands (the Brachypodio-Molinietum association of the Cirsio-Brachypodion pinnati alliance), while nine of them forms the local dataset from a single locality in the White Carpathians, whose vegetation lacks most forest-steppe species and is transitional between the Bromion erecti and Arrhenatherion elatioris alliances (the Anthoxantho-Agrostietum and Anthyllido vulnerariae-Trifolietum montani associations). The permanent plots contain a nested subplot of 1 m2, except for five plots from Ukraine and Romania. Most plots harboured at least 80 vascular plant species per 16 m2, with the mean richness of 16-m2 plots was 95.3 species in the main dataset and 84 species in the local dataset. Mean richness of the 1-m2 subplots, presumably reflecting local environmental conditions and competitive relationships more than that of 16 m2 plots, did not vary between the two datasets, with a general mean of 57.6 species. Species counts of 16-m2 plots and 1-m2 subplots correlated, albeit only moderately, only in the main dataset. The presented datasets may be used for comparative analyses as well as for a future revisiting of the plots and may bring novel insights into the dynamics of extreme species richness.

中文翻译：

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物种极其丰富的温带草原永久样地的新数据集

一些温带草原的极端物种丰富度是一个全球相关但尚未得到充分研究的现象。到目前为止，很少有来自彻底采样但不是永久固定的植被地块的记录可用。因此，我们在白喀尔巴阡山脉（捷克）、乌克兰、匈牙利和罗马尼亚的物种丰富的草原上建立了一个由 40 个永久性 4 × 4 平方米地块组成的网络。其中 31 个形成了主要数据集，包括来自离散森林草原草原（Cirsio-Brachypodion pinnati 联盟的 Brachypodio-Molinietum 协会）的地块，而其中 9 个形成了来自白喀尔巴阡山脉单个地点的本地数据集，其植被缺乏大多数森林-草原物种，并且在 Bromion直立和 Arrhenatherion elatioris 联盟（Anthoxantho-Agrostietum 和 Anthyllido vulnerariae-Trifolietum montani 联盟）之间过渡。除了乌克兰和罗马尼亚的五个地块外，永久地块包含一个 1 平方米的嵌套子地块。大多数地块每 16 平方米至少包含 80 种维管植物，其中 16 平方米地块的平均丰富度在主数据集中为 95.3 种，在本地数据集中为 84 种。1 平方米子地块的平均丰富度，大概比 16 平方米地块更能反映当地的环境条件和竞争关系，在两个数据集之间没有变化，一般平均值为 57.6 种。16 平方米地块和 1 平方米子地块的物种计数相关，尽管只是在主数据集中适度相关。