2023年第2期封面文章由巴西维索萨联邦大学Villa PM研究团队撰写。文章研究了在热带山区海拔对植物多样性和丰富度的影响。

Citation: Galván-Cisneros CM, Villa PM, Coelho AJP, et al. (2023) Altitude as environmental filtering influencing phylogenetic diversity and species richness of plants in tropical mountains. Journal of Mountain Science 20(2). https://doi.org/10.1007/s11629-022-7687-9

Downloads: https://doi.org/10.1007/s11629-022-7687-9

Highlights:

(1)   海拔高度的增加会对物种丰富度、系统发育多样性产生负面影响；

(2)   热带高海拔地区植物群落的形成是植物物种多样化的结果；

(3)   在3个热带山地、2个大陆山地和1个海洋山地中，环境过滤可能是植物群落沿海拔梯度分布的主导力量；

(4)  保护区的选择应优先考虑具有高地方性、高分类学多样性和高系统发育多样性的群落，以提高生物多样性保护的机会，特别是要优先保护热带山区山顶的植被。

 Cover Story

Plant communities in tropical mountain ecosystems play an important role in the provision of ecosystem services, such as water supply and carbon stock. However, current environmental changes are a worrying threat to these ecosystems. Understanding how altitude variation influences the assembly and adaptation processes of plant communities in these ecosystems is key to establishing conservation and management plans. Tropical mountains show more uniform and stable temperature patterns because summer and winter temperatures change little throughout the year compared to mountains in temperate regions. Thus, altitude can be a predictor for testing plant diversity patterns and community assemblages under environmental changes. For example, phylogeny diversity is an alternative that provides relevant information beyond taxonomic diversity. Phylogenetic diversity indicates the total amount of phylogenetic distance between species in a community. This diversity dimension of plant communities is increasingly being assessed in tropical mountain landscapes demonstrating the effects of abiotic filtering (e.g., altitude, temperature). Thus, areas that suffer intense environmental stress, such as high mountains are considered centers of neo-endemism. Neo-endemisms are taxa of recent evolution and probably have not yet reached their potential distribution due to their recent occurrence. In three important tropical mountains (i.e., Mount Haleakala, Mount Kilimanjaro, Mount Puracé), phylogenetic diversity and species richness decrease with increasing altitude. The decreasing phylogenetic distances between the closest relatives are indicative of neo-endemism processes. These findings are congruent with environmental filtering along evolutionary time scales promoted by increasing altitude with negative effects on species richness and phylogenetic diversity.

In this context, the alpine grasslands of tropical mountains are often considered to form cold climate "islands" in the hot tropics, such as Páramos, which are vulnerable to global climate changes. Large capital cities depend on páramos ecosystems for the water supply, such as the cover picture of Journal of Mountain Science (Vol. 20, No. 2) from Puracé páramo, Cauca, Colombia. In these mountains, the environmental conditions change rapidly, as temperature decreases with increasing altitude. These plant communities are affected by unique environmental conditions compared to plants at low and medium altitudes. Thus, low temperatures, high solar radiation, strong winds, and shallow soils are strong filters that determine plant physiological and survival strategies. Therefore, studying the phylogenies of alpine plant communities in tropical mountains may be an effective way to study altitude as a predictor of current and future climate change scenarios. Finally, knowing the diversity and assembly patterns of plant communities in montane ecosystems is important to identify vulnerability, threats, and risk of extinction of species, and plan conservation strategies for this ecosystem.

封面故事

热带山地生态系统的植物群落在供水、储碳等方面发挥了重要的生态系统服务功能，然而，当前的环境变化对这些生态系统的威胁令人担忧。了解海拔高度的变化如何影响生态系统中植物群落的组合及其适应过程是制定保护管理计划的关键。与温带地区的山区相比，热带山区在夏季和冬季的温度变化很小，因此，全年温度更均匀、更稳定。因此，海拔高度可以作为环境变化下植物多样性格局和群落组合的预测因子。系统发育多样性是指群落中物种间系统发育距离的总和。系统发育多样性可以作为分类多样性之外评价植物多样性的替代方法。在热带山地景观评估中，越来越多地利用植物群落多样性来评价海拔、温度等非生物因素对植物多样性的影响。因此，高山等受强烈环境胁迫的地区常被认为是新地方种的中心。新地方种是最近进化的分类群，由于出现的时间较晚，可能还没有达到其潜在的分布范围。在哈雷阿卡拉山、乞力马扎罗山、普拉塞火山3个重要的热带山脉，系统发育多样性和物种丰富度随海拔升高而降低。亲缘关系最近的物种之间的系统发育距离的减少指示着新地方种的形成。这些发现与进化时间尺度上的环境过滤相一致，海拔升高对物种丰富度和系统发育多样性的负面影响加速了这种环境过滤作用。

在这种背景下，热带山区的高寒草原往往被认为是炎热的热带地区的气候冷岛，如高寒生态系统，极易受全球气候变化的影响。大型省会城市依靠高寒生态系统提供水源，如《山地科学学报（英文）》2023年20卷第2期封面图片中的哥伦比亚考卡普拉塞火山的高寒生态系统。在这些山区，温度随着海拔的升高而降低，环境条件变化迅速。与中、低海拔地区的植物群落相比，高海拔地区的植物群落受到独特环境条件的影响，低温、高太阳辐射、强风和土壤瘠薄均是决定植物生理和生存策略的强大过滤因素。因此，研究热带山区高寒植物群落的系统发育可能是研究以海拔作为当前和未来气候变化场景的预测因子的有效途径。最后，了解山地生态系统植物群落的多样性和组合模式，对于识别物种的脆弱性和所面临的威胁和灭绝风险，并规划该生态系统的保护策略具有重要意义。

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Pinto-Junior, HV, Villa PM, de Menezes LFT, et al.(2020) Effect of climate and altitude on plant community composition and richness in Brazilian inselbergs. J Mt Sci 17: 1931–1941. https://doi.org/10.1007/s11629-019-5801-4

 Liu, SR, Fornacca D, Yang DD, et al. (2020) Species richness and biodiversity significance of alpine micro-waterbody systems in Gaoligong Mountain, Northwest Yunnan, China. J Mt Sci 17: 907–918. https://doi.org/10.1007/s11629-019-5487-7

 Chandra S, Singh A, Singh CP, et al.(2018) Vascular plants distribution in relation to topography and environmental variables in alpine zone of Kedarnath Wild Life Sanctuary, West Himalaya. J Mt Sci 15: 1936–1949. https://doi.org/10.1007/s11629-017-4738-8

 Wangchuk K, Darabant A, Rai PB, et al. (2014) Species richness, diversity and density of understory vegetation along disturbance gradients in the Himalayan conifer forest. J Mt Sci 11: 1182–1191. https://doi.org/10.1007/s11629-013-2942-8

Chawla A, Rajkumar S, Singh KN, et al.(2008) Plant species diversity along an altitudinal gradient of Bhabha Valley in western Himalaya. J Mt Sci 5: 157–177. https://doi.org/10.1007/s11629-008-0079-y

Chun, JH, Lee CB (2018) Diversity patterns and phylogenetic structure of vascular plants along elevational gradients in a mountain ecosystem, South Korea. J Mt Sci 15: 280–295. https://doi.org/10.1007/s11629-017-4477-x