Vegetation changes in Jasper National Park assessed from resampling of ecological land classification plots established in the 1970s

Canada’s mountain ecosystems are changing as a result of climate change and a host of natural and anthropogenic disturbances. Understanding the kinds, rates, and causes for those changes is important for informed ecosystem management. To assess changes in the vegetation of Jasper National Park (JNP), we documented changes in plant community composition by resampling 41 ecological land classification (ELC) plots first assessed in the 1970s. In 2023, we documented the presence and percent cover of vascular, hepatic, moss, and lichen species within each plot and compared those data to the 1970s data. Within each plot, we determined the change in cover for each taxon. The communities have become more species rich since the 1970s and community type diversity has increased. Despite rates of species turnover that exceed 50%, plant diversity shows no signs of decline. Multidecadal succession, perhaps influenced by climatic change and human disturbances, is altering the vegetation composition independent of wildfire and mountain pine beetle. Ecologically important species that decreased over time included <i>Pinus contorta, Rosa acicularis, Vaccinium cespitosum, V. scoparium</i>, and <i>V. vitis-idaea</i>. Important increasers included <i>Picea glauca, Pseudotsuga menziesii</i>, and <i>Hylocomium splendens</i>. Younger and drier sites changed more than did older and moister sites.

加拿大山地生态系统因气候变化及一系列自然与人为干扰正持续发生变化。明晰此类变化的类型、速率与成因，可为生态系统的科学化管理提供决策依据。为评估贾斯珀国家公园（Jasper National Park, JNP）的植被变化情况，本研究通过重新采样41个首次于20世纪70年代开展调查的生态土地分类（ecological land classification, ELC）样地，对植物群落组成的变化进行了记录。2023年，我们对每个样地内的维管植物、苔类植物、苔藓植物以及地衣物种的存在状态与盖度百分比进行了详实记录，并将该批次数据与1970年代的原始调查数据进行了对比分析。针对每个样地，我们还计算了各分类单元的盖度变化幅度。自1970年代以来，研究区域内的植物群落物种丰富度与群落类型多样性均有所提升。尽管物种周转速率超过50%，但植物多样性并未出现下降趋势。多十年尺度的群落演替，或受气候变化与人为干扰的共同影响，正独立于野火与山松甲虫虫害之外，持续改变着区域植被组成。随时间推移出现种群衰退的重要生态物种包括：扭叶松（*Pinus contorta*）、尖刺蔷薇（*Rosa acicularis*）、丛生越橘（*Vaccinium cespitosum*）、V. scoparium 以及 V. vitis-idaea。种群数量显著增加的重要物种包括：白云杉（*Picea glauca*）、花旗松（*Pseudotsuga menziesii*）以及丝绢藓（*Hylocomium splendens*）。相较于更为成熟湿润的样地，年轻且干旱的样地植被变化幅度更为显著。