Previous meta-analyses suggested that carnivorous plants—despite access to N, P, and K from prey—have significantly lower leaf concentrations of these nutrients than noncarnivores. Those studies, however, largely compared carnivores in nutrient-poor habitats with noncarnivores in more nutrient-rich sites, so that the differences reported might reflect habitat differences as much as differences in nutrient-capture strategy. Here we examine three carnivorous and 12 noncarnivorous plants in the same nutrient-poor bog to compare their foliar nutrient concentrations, assess their patterns of nutrient limitation using leaf NPK stoichiometry, and estimate percentage N derived from prey by carnivores using a mixing model for stable N isotopes. We hypothesized that (1) carnivore leaf nutrient concentrations approach or exceed those of noncarnivores in the same nutrient-poor habitat; (2) species in different functional groups show different patterns of stoichiometry and apparent nutrient limitation; and (3) noncarnivores might show evidence of using other means of nutrient acquisition or conservation to reduce nutrient limitation. At Fallison Bog in northern Wisconsin, carnivorous plants (Drosera rotundifolia, Sarracenia purpurea, Utricularia macrorhiza) showed significantly lower leaf percentage C and N:P ratio, higher δ¹⁵N, and no difference from noncarnivores in leaf N, P, K, and δ¹³C. Sedges had significantly lower leaf percentage P, percentage C, and N:K ratio, and higher K:P ratio than nonsedges restricted to the Sphagnum mat, and may tap peat N via aerenchyma-facilitated peat oxidation (oxipeditrophy). Evergreen ericaceous shrubs exhibited significantly higher levels of percentage C and lower values of δ¹⁵N than mat nonericads. Calla palustris—growing in the nutrient-rich moat at the bog's upland edge—had very high values of leaf N, K, δ¹⁵N, and N:P ratio, suggesting that it may obtain nutrients from minerotrophic flows from the adjacent uplands and/or rapidly decaying peat. Stoichiometric analyses indicated that most species are N limited. A mixing model applied to δ¹⁵N values for carnivores, noncarnivores, and insects produced an estimate of 50% of leaf N derived from prey for Utricularia, 42% for Sarracenia, and 41% for Drosera.

中文翻译：

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叶 NPK 化学计量学、δ15N 以及同时发生的食肉和非食肉植物的表观营养限制

之前的荟萃分析表明，食肉植物——尽管可以从猎物那里获取 N、P 和 K——与非食肉植物相比，这些营养素的叶片浓度显着较低。然而，这些研究主要比较了营养贫乏栖息地的食肉动物与营养更丰富地点的非食肉动物，因此报告的差异可能反映了栖息地差异以及营养捕获策略的差异。在这里，我们检查了同一个营养贫乏的沼泽中的三种食肉植物和 12 种非食肉植物，以比较它们的叶面养分浓度，使用叶片 NPK 化学计量学评估它们的养分限制模式，并使用稳定 N 的混合模型估计食肉动物从猎物中获得的 N 百分比同位素。我们假设 (1) 食肉动物叶片的养分浓度接近或超过相同营养贫乏栖息地的非食肉动物；(2) 不同功能组的物种表现出不同的化学计量模式和表观营养限制；(3) 非食肉动物可能会显示出使用其他获取或保存养分的方式来减少养分限制的证据。在威斯康星州北部的 Fallison Bog，食虫植物（Drosera rotundifolia、Sarracenia purpurea、Utricularia macrorhiza ) 表现出显着较低的叶百分比 C 和 N:P 比率，较高的 δ ¹⁵ N，并且在叶 N、P、K 和 δ ¹³ C 方面与非食肉动物没有差异。莎草的叶百分比显着较低P、C 百分比和 N:K 比率，以及比仅限于泥炭藓垫的非莎草更高的 K:P 比率，并且可能通过通气组织促进的泥炭氧化（氧化土壤营养）利用泥炭 N。常绿杜鹃花科灌木的 C 百分比水平和 δ ¹⁵ N 值明显高于无花果植物。马蹄莲- 生长在沼泽高地边缘营养丰富的护城河中 - 具有非常高的叶片 N、K、δ ¹⁵ N 和 N:P 比值，表明它可能从邻近高地和/或迅速腐烂的泥炭 化学计量分析表明大多数物种都受 N 限制。应用于食肉动物、非​​食肉动物和昆虫的 δ ¹⁵ N 值的混合模型产生了 50% 的叶氮来源于狸藻属猎物的估计值、 42% 的瓶子草属和 41% 的茅膏菜属。