Lesser celandine (Ficaria verna Huds.), an invasive plant from Europe, is becoming widespread in river valleys throughout the northeastern United States and the Pacific Northwest. Its high rate of asexual bulbil and tuber production creates dense infestations threatening native spring ephemerals. Ficaria verna abundance and reproductive output (seeds, bulbils, and tubers) were examined in invaded transects spanning a disturbance gradient away from a river. Site characteristics (photosynthetically active radiation [PAR], soil pH, moisture, texture, and nutrients) were quantified to examine their roles in plant abundance and reproduction. A larger-scale study examined random transects not specifically chosen based on F. verna infestations. Soil characteristics and slope were hypothesized to drive F. verna abundance and reproduction; we also hypothesized that reproductive output and biomass would be highest at intermediate distances from rivers, where disturbances are infrequent. Ficaria verna abundance and reproductive output varied considerably by site; soil characteristics, rather than landscape placement, appeared to drive plant abundance and reproduction. Lower percent sand was associated with significantly higher F. verna stem density and bulbil and tuber production. CEC was significantly negatively related to F. verna biomass and tuber counts. In the larger-scale survey, slope and PAR were significantly negatively related to F. verna presence and percent cover, respectively. Overall, these findings suggest that soil texture and slope can help explain higher abundance and reproductive outputs. However, reproductive output and biomass were not significantly greater at intermediate distances, contrary to expectations. We did not observe any seed production in any of the plots, although we did see a few plants with seeds outside our study area in the second year, demonstrating a near-complete reliance on asexual reproduction in these populations. This study expands on the current limited understanding of F. verna and can help management by identifying areas likely to support dense infestations.

中文翻译：

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土壤特性驱动 Ficaria verna 丰度和繁殖产量

小白屈菜（无花果Huds.) 是一种来自欧洲的入侵植物，正在美国东北部和太平洋西北部的河谷中广泛分布。它的无性鳞茎和块茎产量很高，造成密集的侵扰，威胁着原生春季短暂的植物。无花果在跨越远离河流的干扰梯度的入侵样带中检查了丰度和生殖产量（种子、鳞茎和块茎）。对场地特征（光合有效辐射 [PAR]、土壤 pH 值、水分、质地和养分）进行量化，以检查它们在植物丰度和繁殖中的作用。一项更大规模的研究检查了未基于以下具体选择的随机样带F. verna虫害。假设土壤特性和坡度可以驱动F. verna丰富和繁殖；我们还假设在距离河流中等距离的地方，生殖产量和生物量最高，那里的干扰很少。无花果丰度和繁殖产量因地点而异；土壤特征，而不是景观位置，似乎推动了植物的丰度和繁殖。较低的沙子百分比与显着较高的沙子有关F. verna茎密度和球茎和块茎产量。CEC显着负相关F. verna生物量和块茎计数。在更大规模的调查中，斜率和 PAR 显着负相关F. verna存在和百分比覆盖，分别。总体而言，这些发现表明土壤质地和坡度可以帮助解释更高的丰度和生殖产出。然而，与预期相反，中间距离的生殖产量和生物量并没有显着增加。我们没有观察到任何地块中的任何种子生产，尽管我们确实在第二年在我们的研究区域之外看到了一些有种子的植物，这表明这些种群几乎完全依赖无性繁殖。本研究扩展了目前对F. verna并且可以通过识别可能支持密集感染的区域来帮助管理。