Data from: Lichen traits responding to aridity

1. Climate change is expected to cause several impacts at the global scale and drylands will be among the most affected areas. Thus, investigating how these changes will affect the composition, structure and functioning of dryland ecosystems has become a priority. From an ecological indicator point of view, several works have shown that functional diversity is better than species richness to understand ecosystem functioning or response to environmental factors. However most of these works focus on plants while those of other organisms remain largely unknown. Lichens are amongst the ecosystem components more sensitive to climatic changes due to several physiological and ecological characteristics. Their poikilohydric nature (therefore highly dependent on the atmosphere for water supply) and their ubiquity on terrestrial ecosystems underlie their potential as indicators of climate. Nonetheless, works specifically aiming to identify lichen functional traits that respond to aridity remain poorly explored, particularly in drylands. 2. We proposed to identify lichen functional traits and respective functional groups responding to aridity in a Mediterranean drylands ecosystem. 3. Lichen diversity was sampled in open holm-oak woodlands along an aridity gradient in SW Europe (Iberian Peninsula). Lichen functional traits that could be easily identified and related to water uptake were selected to be tested: type of photobiont, growth form and reproduction strategy. 4. Lichen species composition was related to the aridity gradient. The three traits chosen were related with the community's response to aridity, but with contrasting responses in different functional groups. More specifically crustose and fruticose lichens, isidiate species and the ones with Trentepohlia as photobiont were related to the less arid part of the gradient. Foliose species and cyanolichens, on the contrary, were associated with the most arid areas. 5. Synthesis We were able to identify lichen traits responding to aridity. Type of photobiont was particularly responsive, with Trentepohlia and cyanobacteria functional groups, responding clearly in contrasting ways to aridity in this drylands ecosystem. This work emphasizes functional diversity role on understanding and assessing the response to environmental factors, namely to climate. It also highlights the potential use of lichen functional groups as ecological indicators of climate change.1. 气候变化预计将在全球尺度引发多重影响，而干旱区（drylands）将是受影响最严重的区域之一。因此，探究此类变化如何作用于干旱区生态系统的组成、结构与功能，已成为研究的重点课题。从生态指示物（ecological indicator）的研究视角出发，已有多项研究证实，相较于物种丰富度（species richness），功能多样性（functional diversity）更适于解析生态系统功能及其对环境因子的响应。然而，此类研究大多聚焦于植物类群，针对其他生物类群的相关探索仍较为匮乏。地衣（lichen）凭借诸多生理与生态特性，成为对气候变化最为敏感的生态系统组分之一。其变水特性（poikilohydric nature，即高度依赖大气获取水分）以及在陆地生态系统中的广布性，使其具备作为气候指示物的潜力。但专门识别响应干旱的地衣功能性状的研究，在干旱区中仍未得到充分开展。 2. 本研究旨在明确地中海干旱区生态系统中响应干旱的地衣功能性状及其对应的功能群。 3. 研究于欧洲西南部（伊比利亚半岛）沿干旱梯度分布的开放圣栎林中开展地衣多样性采样。本研究选取了易于识别且与水分吸收相关的地衣功能性状进行测试：光合共生伙伴类型（type of photobiont）、生长型（growth form）以及繁殖策略（reproduction strategy）。 4. 地衣物种组成与干旱梯度显著相关。所选的三类性状均与群落对干旱的响应相关，但不同功能群的响应模式存在显著差异。具体而言，壳状地衣（crustose lichens）、枝状地衣（fruticose lichens）、具粉芽物种（isidiate species）以及以头孢藻属（Trentepohlia）为光合共生伙伴的类群，均与干旱梯度中干旱程度较低的区域呈显著关联。相反，叶状地衣（foliose lichens）与蓝藻地衣（cyanolichens）则与干旱程度最高的区域显著相关。 5. 结论 本研究成功识别出响应干旱的地衣功能性状。其中光合共生伙伴类型的响应性尤为显著，头孢藻属（Trentepohlia）与蓝细菌（cyanobacteria）功能群在该干旱区生态系统中对干旱呈现出截然相反的响应模式。本研究强调了功能多样性在理解与评估生态系统对环境因子（尤其是气候因子）响应方面的重要作用，同时也凸显了地衣功能群作为气候变化生态指示物的应用潜力。