Bianchi Eva, Bugmann Harald, Bigler Christof
Forest Ecology, Department of Environmental Systems Science, Institute of Terrestrial Ecosystems ETH Zurich Zurich Switzerland.
Ecol Evol. 2019 Jul 3;9(14):8238-8252. doi: 10.1002/ece3.5399. eCollection 2019 Jul.
Global warming is expected to result in earlier emergence of tree seedlings that may experience higher damages and mortality due to late frost in spring. We monitored emergence, characteristics, and survival of seedlings across ten tree species in temperate mixed deciduous forests of Central Europe over one and a half year. We tested whether the timing of emergence represents a trade-off for seedling survival between minimizing frost risk and maximizing the length of the growing period. Almost two-thirds of the seedlings died during the first growing period. The timing of emergence was decisive for seedling survival. Although seedlings that emerged early faced a severe late frost event, they benefited from a longer growing period resulting in increased overall survival. Larger seedling height and higher number of leaves positively influenced survival. Seedlings growing on moss had higher survival compared to mineral soil, litter, or herbaceous vegetation. . Our findings demonstrate the importance of emergence time for survival of tree seedlings, with early-emerging seedlings more likely surviving the first growing period.
预计全球变暖将导致树木幼苗更早出土,而这些幼苗可能会因春季晚霜而遭受更高的损害和死亡率。我们在中欧温带混交落叶林中对十种树木的幼苗出土、特征和存活情况进行了为期一年半的监测。我们测试了出土时间是否代表了幼苗在最小化霜冻风险和最大化生长季节长度之间的生存权衡。近三分之二的幼苗在第一个生长季节死亡。出土时间对幼苗的存活至关重要。虽然早期出土的幼苗面临严重的晚霜事件,但它们受益于更长的生长季节,从而提高了总体存活率。较高的幼苗高度和较多的叶片数量对存活有积极影响。与生长在矿质土壤、凋落物或草本植被上的幼苗相比,生长在苔藓上的幼苗存活率更高。我们的研究结果表明出土时间对树木幼苗存活的重要性,早期出土的幼苗更有可能在第一个生长季节存活下来。