Ohse B, Jansen D, Härdtle W, Fichtner A
Ecology/Macroecology Lab, Institute of Biochemistry and Biology, University of Potsdam, Potsdam, Germany.
Department of Vegetation Ecology and Biodiversity Conservation, Institute of Ecology, Leuphana University of Lüneburg, Lüneburg, Germany.
Plant Biol (Stuttg). 2025 Mar;27(2):297-309. doi: 10.1111/plb.13758. Epub 2024 Dec 25.
Nitrogen (N) deposition and climate change are both known to threaten global biodiversity. However, we still have a limited understanding of how interactions between these global change drivers affect individuals and populations of specialist species, such as geophytes, within their natural habitat. We explored possible interactive effects of N, drought, and warming on population vitality (mean leaf length, leaf density, flowering probability) and morpho-physiological traits (e.g., leaf and bulb size, N allocation to leaves and bulbs) of the globally rare forest geophyte Gagea spathacea (Liliaceae) in deciduous forests of northern Germany by applying experimental N addition across a climate gradient over a 5-year period. Mean leaf growth and leaf density were not affected by N addition but were enhanced by warmer and drier conditions in the months before leaf emergence. N addition increased N allocation of individual plants towards their subterranean bulbs. Importantly, effects of N addition on morpho-physiological traits depended on warming and drought, with N-fertilized plants showing increased leaf length and decreased specific leaf and bulb N concentration after drier autumns and warmer winters. This indicates that N deposition may partially compensate for increased N demands during warming-induced growth, although this growth-promoting interaction effect is not (yet) reflected in population vitality. Our results highlight the importance of considering multiple global environmental change drivers and a whole plant perspective (above- and belowground traits) to predict long-term growth responses of (endangered) forest spring geophytes and to develop adapted long-term protection strategies.
已知氮（N）沉降和气候变化都会威胁全球生物多样性。然而，对于这些全球变化驱动因素之间的相互作用如何影响自然栖息地内的特有物种（如地生植物）的个体和种群，我们的了解仍然有限。我们通过在德国北部落叶林中的一个气候梯度上进行为期5年的实验性施氮，探究了氮、干旱和变暖对全球珍稀森林地生植物披针顶冰花（百合科）的种群活力（平均叶长、叶密度、开花概率）和形态生理特征（如叶和鳞茎大小、氮在叶和鳞茎中的分配）的可能交互影响。平均叶生长和叶密度不受施氮影响，但在叶片出现前的几个月里，温暖和干燥的条件会增强它们。施氮增加了个体植物向其地下鳞茎的氮分配。重要的是，施氮对形态生理特征的影响取决于变暖和干旱，在秋季更干燥和冬季更温暖之后，施氮的植物叶长增加，叶和鳞茎的单位氮浓度降低。这表明氮沉降可能部分补偿变暖诱导生长期间增加的氮需求，尽管这种促进生长的交互作用尚未体现在种群活力上。我们的研究结果强调了考虑多种全球环境变化驱动因素以及从整株植物的角度（地上和地下特征）来预测（濒危）森林春季地生植物的长期生长反应并制定适应性长期保护策略的重要性。
