Physiological responses of fen mosses along a nitrogen gradient point to competition restricting their fundamental niches

Nutrient availability determines vegetation patterns and ecological functioning of intact groundwater-fed peatlands (fens). Bryophytes, commonly referred to as ‘brown mosses’, dominate calcareous fens (rich fens), are an integral part of their unique biodiversity and contribute significantly to peat formation and carbon sequestration. Brown mosses are replaced by vascular plants as nutrient availability increases. The decline of brown mosses may either be due to their physiological intolerance of high nutrient levels or to them being outcompeted by vascular plants. We aimed to distinguish between these two hypotheses by investigating whether the ecological optima reflect the physiological optima of brown mosses. Eight brown moss species, common in calcareous fens of the northern hemisphere, were grown under a gradient of nitrogen and phosphorus availability. Biomass increment, chlorophyll content and biomass nutrient concentration were measured. All brown moss species studied achieved t...

养分有效性决定了完整地下水补给型泥炭地（fens，即富养泥炭沼泽）的植被格局与生态功能。苔藓植物（Bryophytes）通常被称为“褐藓（brown mosses）”，是钙质富养泥炭沼泽（calcareous fens）的优势类群；褐藓不仅是该生境独特生物多样性的核心组成部分，更在泥炭形成与碳固持（carbon sequestration）过程中发挥关键作用。随着养分有效性提升，褐藓会逐渐被维管植物（vascular plants）取代。褐藓的衰退可能源于两种潜在机制：一是其对高养分水平的生理不耐受，二是其在种间竞争中被维管植物压制。本研究旨在通过验证褐藓的生态最适值（ecological optima）是否与其生理最适值（physiological optima）相符，以区分这两种假说。研究选取了北半球钙质富养泥炭沼泽中常见的8种褐藓，在氮（nitrogen）、磷（phosphorus）有效性梯度条件下开展培养实验，并测定了其生物量增量（biomass increment）、叶绿素含量（chlorophyll content）以及生物量养分浓度（biomass nutrient concentration）。本研究所考察的全部褐藓物种均实现了……