Understanding patterns of biodiversity is a key goal of ecology and is especially pressing in the current human‐caused biodiversity crisis. In wetland ecosystems, human impacts are centered around hydrologic manipulation including the common practice of wetland diking and impoundment. Constraining how wetland management influences plant biodiversity patterns across spatial scales will provide information on how best to modify actions to preserve biodiversity and ecosystem function in managed wetlands. Here, we compare patterns of plant diversity and species presence, abundance, and community composition at several spatial scales among tidal wetlands along an estuarine salinity gradient and managed wetlands that were formerly tidal. Managed impounded wetlands had decreased alpha and gamma diversity of rare species, with less than 60% of the species richness found in tidal brackish wetlands at several spatial scales. There was little change in the overall pattern of alpha, beta, and gamma diversity for common species in impounded wetlands; however, dominant tidal brackish species, primarily perennial rhizomatous graminoids, were replaced with management target plants and non‐native annual grasses in impounded wetlands. This species replacement led to over 60% of impounded sites being classified as containing novel plant assemblages. An additional 25% of impounded sites were classified as containing tidal saline plant assemblages, suggesting potential soil salinization. Along the estuarine gradient, patchiness and codominance of common plant species drove high diversity and turnover in tidal brackish wetlands, while it remains unclear whether tidal fresh or brackish wetlands maximize rare plant diversity. With reduced species richness, altered functional dominants, and novel or saline assemblages, impounded brackish wetlands may require careful water management to balance native plant biodiversity, associated ecosystem processes, and waterfowl requirements.

中文翻译：

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季节性蓄水在空间尺度上改变潮汐湿地植物多样性的模式

了解生物多样性的模式是生态学的主要目标，尤其是在当前人为造成的生物多样性危机中。在湿地生态系统中，人类影响集中在水文操纵上，包括湿地堤防和蓄水的常规做法。限制湿地管理如何影响整个空间尺度上的植物生物多样性模式，将提供有关如何最好地修改行动以保护受管理湿地中生物多样性和生态系统功能的信息。在这里，我们在沿河口盐度梯度的潮汐湿地和以前为潮汐管理的湿地之间的几个空间尺度上，比较了植物多样性和物种存在，丰度和群落组成的格局。有管理的蓄水湿地减少了稀有物种的α和γ多样性，在几个空间尺度上，潮汐微咸湿地的物种丰富度不到60％。蓄水湿地中常见物种的α，β和γ多样性总体格局几乎没有变化。然而，主要的潮汐微咸物种，主要是多年生的根茎类蠕虫类，在蓄积的湿地被管理目标植物和非本地一年生禾本科植物取代。这种物种的替代导致超过60％的蓄水地点被归类为包含新型植物组合。另有25％的蓄水地点被归类为含有潮汐盐类植物，表明潜在的土壤盐渍化。沿河口梯度，常见植物物种的斑块和共生带动了潮汐微咸湿地的高多样性和高周转率，虽然尚不清楚潮汐湿地或微咸的湿地能否使稀有植物多样性最大化。随着物种丰富度的降低，功能优势的改变以及新的或盐渍组合，蓄水的微咸湿地可能需要谨慎的水管理，以平衡本地植物生物多样性，相关的生态系统过程和水禽需求。