Similar patterns of background mortality across Europe are mostly driven by drought in European beech and a combination of drought and competition in Scots pine

Abstract

Background tree mortality is a complex demographic process that affects structure and long-term forest dy-namics. Here we investigated how climatic drought intensity interacts with interspecific and intraspecificcompetition (or facilitation) in shaping mortality patterns across tree species ranges. To this aim, we used datafromfive European national forest inventories to perform logistic regression models based on individual treemortality in Scots pine (Pinus sylvestrisL.) and European beech (Fagus sylvaticaL.). We computed the relativeimportance of climatic drought intensity, basal area of conspecific and heterospecific trees (proxy of indirectintra- and interspecific competition or facilitation) and the effects of their interactions on mortality along theentire European latitudinal gradient of both species range. Increase in climatic drought intensity over the studyperiod was associated with higher mortality rates in both species. Climatic drought intensity was the mostimportant driver of beech mortality at almost all latitudes while Scots pine mortality was mainly driven by basalarea. High conspecific basal area was associated with high mortality rates in both species while high hetero-specific basal area was correlated with mortality rates that were high in Scots pine but low in beech. Overall,beech mortality was directly affected by climatic drought intensity while Scots pine mortality was indirectlyaffected by climatic drought intensity through interactions with basal area. Despite their different sensitivity todrought and basal area, the highest predicted mortality rates for both species were at the ecotone between thecool temperate and Mediterranean biomes, which can be explained by the combined effect of climatic droughtintensity and competition. In the context of global warming, which is expected to be particularly strong in theMediterranean biome, our results suggest that populations at the southern limit of species ranges may experienceincreased mortality rates in the near future.

Keywords

Tree mortality; Drought intensity; European latitudinal gradient; National forest inventories; Fagus sylvatica; Pinus sylvestris

Published in

Agricultural and Forest Meteorology
2020, Volume: 280, article number: 107772

SLU Authors

• Dahlgren, Jonas

  • Department of Forest Resource Management, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

SDG13 Climate action


UKÄ Subject classification

Forest Science
Climate Research


Publication identifier

DOI: https://doi.org/10.1016/j.agrformet.2019.107772

Permanent link to this page (URI)

https://res.slu.se/id/publ/103975