Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland.
Hintermann Weber AG, Reinach, Switzerland.
Conserv Biol. 2021 Dec;35(6):1766-1776. doi: 10.1111/cobi.13744. Epub 2021 Jun 11.
Nitrogen (N) deposition from agriculture and combustion of fossil fuels is a major threat to plant diversity, but its effects on organisms at higher trophic levels are unclear. We investigated how N deposition may affect species richness and abundance (number of individuals per species) in butterflies. We reviewed the peer-reviewed literature on variables used to explain spatial variation in butterfly species richness and found that vegetation variables appeared to be as important as climate and habitat variables in explaining butterfly species richness. It thus seemed likely that increased N deposition could indirectly affect butterfly communities via its influence on plant communities. To test this prediction, we analyzed data from the Swiss biodiversity monitoring program for vascular plants and butterflies in 383 study sites of 1 km that are evenly distributed throughout Switzerland. The area has a modeled N deposition gradient of 2-44 kg N ha year . We used traditional linear models and structural equation models to infer the drivers of the spatial variation in butterfly species richness across Switzerland. High N deposition was consistently linked to low butterfly diversity, suggesting a net loss of butterfly diversity through increased N deposition. We hypothesize that at low elevations, N deposition may contribute to a reduction in butterfly species richness via microclimatic cooling due to increased plant biomass. At higher elevations, negative effects of N deposition on butterfly species richness may also be mediated by reduced plant species richness. In most butterfly species, abundance was negatively related to N deposition, but the strongest negative effects were found for species of conservation concern. We conclude that in addition to factors such as intensified agriculture, habitat fragmentation, and climate change, N deposition is likely to play a key role in negatively affecting butterfly diversity and abundance.
氮（N）沉积来自农业和化石燃料的燃烧是对植物多样性的主要威胁，但它对更高营养级生物的影响尚不清楚。我们研究了氮沉积如何影响蝴蝶的物种丰富度和丰度（每个物种的个体数量）。我们回顾了有关用于解释蝴蝶物种丰富度空间变化的变量的同行评议文献，发现植被变量似乎与气候和栖息地变量一样重要，可用于解释蝴蝶物种丰富度。因此，增加的氮沉积可能会通过对植物群落的影响间接影响蝴蝶群落。为了检验这一预测，我们分析了瑞士生物多样性监测计划中 383 个 1 公里研究点的血管植物和蝴蝶数据，这些研究点在瑞士各地均匀分布。该地区的模拟氮沉积梯度为 2-44 公斤 N ha 年。我们使用传统的线性模型和结构方程模型来推断瑞士蝴蝶物种丰富度空间变化的驱动因素。高氮沉积与蝴蝶多样性低有关，这表明通过增加氮沉积，蝴蝶多样性净损失。我们假设，在低海拔地区，由于植物生物量增加导致的微气候冷却，氮沉积可能会导致蝴蝶物种丰富度减少。在较高海拔地区，氮沉积对蝴蝶物种丰富度的负面影响也可能受到植物物种丰富度降低的调节。在大多数蝴蝶物种中，丰度与氮沉积呈负相关，但对于受保护关注的物种，负相关最强。我们的结论是，除了集约化农业、生境破碎化和气候变化等因素外，氮沉积可能在负面影响蝴蝶多样性和丰度方面发挥关键作用。
