Alatalo Juha M, Jägerbrand Annika K, Erfanian Mohammad Bagher, Chen Shengbin, Sun Shou-Qin, Molau Ulf
Environmental Science Center, Qatar University, Doha, Qatar.
Department of Environmental and Biosciences, School of Business, Innovation and Sustainability, Halmstad University, Halmstad, Sweden.
AoB Plants. 2020 Nov 24;12(6):plaa061. doi: 10.1093/aobpla/plaa061. eCollection 2020 Dec.
Climate change is expected to affect alpine and Arctic tundra communities. Most previous long-term studies have focused on impacts on vascular plants, this study examined impacts of long-term warming on bryophyte communities. Experimental warming with open-top chambers (OTCs) was applied for 18 years to a mesic meadow and a dry heath alpine plant community. Species abundance was measured in 1995, 1999, 2001 and 2013. Species composition changed significantly from original communities in the heath, but remained similar in mesic meadow. Experimental warming increased beta diversity in the heath. Bryophyte cover and species richness both declined with long-term warming, while Simpson diversity showed no significant responses. Over the 18-year period, bryophyte cover in warmed plots decreased from 43 % to 11 % in heath and from 68 % to 35 % in meadow (75 % and 48 % decline, respectively, in original cover), while richness declined by 39 % and 26 %, respectively. Importantly, the decline in cover and richness first emerged after 7 years. Warming caused significant increase in litter in both plant communities. Deciduous shrub and litter cover had negative impact on bryophyte cover. We show that bryophyte species do not respond similarly to climate change. Total bryophyte cover declined in both heath and mesic meadow under experimental long-term warming (by 1.5-3 °C), driven by general declines in many species. Principal response curve, cover and richness results suggested that bryophytes in alpine heath are more susceptible to warming than in meadow, supporting the suggestion that bryophytes may be less resistant in drier environments than in wetter habitats. Species loss was slower than the decline in bryophyte abundance, and diversity remained similar in both communities. Increased deciduous shrub and litter cover led to decline in bryophyte cover. The non-linear response to warming over time underlines the importance of long-term experiments and monitoring.
气候变化预计将影响高山和北极苔原群落。此前大多数长期研究都集中在对维管植物的影响上，而本研究考察了长期变暖对苔藓植物群落的影响。使用开顶式生长室（OTC）对一个中生草甸和一个干燥石南高山植物群落进行了18年的实验性增温处理。在1995年、1999年、2001年和2013年对物种丰度进行了测量。石南群落中物种组成与原始群落相比发生了显著变化，但中生草甸中的物种组成仍保持相似。实验性增温增加了石南群落的β多样性。苔藓植物的覆盖度和物种丰富度均随长期变暖而下降，而辛普森多样性无显著变化。在这18年期间，增温地块中苔藓植物的覆盖度在石南群落中从43%降至11%，在草甸中从68%降至35%（分别下降了原始覆盖度的75%和48%），而丰富度分别下降了39%和26%。重要的是，覆盖度和丰富度的下降在7年后才首次出现。增温导致两个植物群落中的凋落物显著增加。落叶灌木和凋落物覆盖度对苔藓植物覆盖度有负面影响。我们发现苔藓植物物种对气候变化的反应并不相同。在实验性长期增温（升高1.5 - 3°C）条件下，石南群落和中生草甸中的苔藓植物总覆盖度均下降，这是由许多物种的普遍减少导致的。主响应曲线、覆盖度和丰富度结果表明，高山石南中的苔藓植物比草甸中的更容易受到变暖的影响，这支持了苔藓植物在较干燥环境中可能比在较湿润生境中抗性更弱的观点。物种丧失速度比苔藓植物丰度的下降速度慢，且两个群落中的多样性仍保持相似。落叶灌木和凋落物覆盖度的增加导致苔藓植物覆盖度下降。随时间对变暖的非线性响应凸显了长期实验和监测的重要性。
