Moser Barbara, Walthert Lorenz, Metslaid Marek, Wasem Ulrich, Wohlgemuth Thomas
Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Birmensdorf, Switzerland.
Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Tartu, Estonia.
Oecologia. 2017 Feb;183(2):519-530. doi: 10.1007/s00442-016-3766-3. Epub 2016 Nov 10.
In anticipation of more severe summer droughts, forestry in temperate Europe is searching for drought-resistant ecotypes of native tree species that might maintain ecosystem services in the future. We investigated how spring precipitation and soil conditions interact with summer drought and affect the establishment of conifer seedlings from different climatic origin. Emergence, establishment and subsequent performance of seedlings originating from autochthonous, Central Alpine, continental Eastern European, and Mediterranean Pinus sylvestris and Picea abies populations were studied in the dry Alpine Rhine valley, Switzerland, at three sites with differing soil water holding capacities and in 3 years with contrasting weather conditions. In addition to this natural inter-annual variation, precipitation was manipulated within sites with throughfall reduction roofs. Seedling establishment and growth were principally affected by the spring weather in the year of emergence. In years with average to positive spring water balance, seedlings grown at the site with the highest water holding capacity had 2-5 times more aboveground biomass than seedlings grown at sites with less favourable soils. Effects of seed origin were marginal and only detectable at the drier sites: contrary to our expectations, seedlings from the Central Alpine Rhone valley, where the climatic spring water deficit is large, outperformed those from the Mediterranean. Consequently, plantation of non-native populations from dryer origin will mitigate the effects of increased summer drought at driest sites only, while the inter-annual variability of spring precipitation will continue to enable temperate conifers to regenerate on a wide range of forest soils independent of seed origin.
鉴于夏季干旱可能会更加严重，欧洲温带地区的林业正在寻找本土树种的抗旱生态型，以期在未来维持生态系统服务功能。我们研究了春季降水和土壤条件如何与夏季干旱相互作用，并影响来自不同气候源的针叶树幼苗的定植。在瑞士干旱的阿尔卑斯莱茵河谷，选取了三个土壤持水能力不同的地点，并在3个天气条件各异的年份，对源自本土、中阿尔卑斯地区、东欧大陆以及地中海地区的欧洲赤松和欧洲云杉种群的幼苗的出土、定植及后续表现进行了研究。除了这种自然的年际变化外，还通过穿透降雨减少棚在各地点对降水进行了调控。幼苗的定植和生长主要受出土当年春季天气的影响。在春季水平衡为平均或正值的年份，在持水能力最高的地点生长的幼苗地上生物量比在土壤条件较差的地点生长的幼苗高出2至5倍。种子来源的影响很小，仅在较干燥的地点可检测到：与我们的预期相反，来自气候春季水分亏缺较大的中阿尔卑斯罗纳河谷的幼苗表现优于来自地中海地区的幼苗。因此，种植来自较干燥地区的非本地种群仅会减轻最干燥地点夏季干旱加剧的影响，而春季降水的年际变化将继续使温带针叶树能够在各种森林土壤上再生，而与种子来源无关。
