Canal-U

[COLLOQUE] GENTREE Final Conference 27-31 January 2020 séance 12

GENTREE Final Conference :

Alexandre CHANGENET - INRAE Bordeaux · France

GENTREE Final Conference 'Genetics to the rescue - managing forests sustainably in a changing environment'

27-31 January 2020, Avignon, France

http://www.gentree-h2020.eu/

Alexandre CHANGENET - INRAE Bordeaux · France : Increased drought-induced tree mortality occurrence in the rear edge but mortality abundance did not show clear patterns on European tree species

Tree mortality is increasing worldwide, which can alter forest structure and dynamics and hence alter functioning and biodiversity.

Yet, the multi-factorial nature and stochasticity of tree mortality challenge its understanding at global scales.

Die-back mortality can be triggered by extreme events such as droughts or insect outbreaks, whereas background or regular mortality can be attributed to non-extreme abiotic and biotic factors.

However, patterns of mortality at the species distribution scale and changes in their underlying drivers remain unclear.

Here, we analysed tree mortality occurrence and abundance of 19 major forest species from almost 2 million of trees recorded from National Forest Inventories of Spain, France, Germany, Belgium, Sweden and Finland to understand the main patterns and drivers of tree mortality.

To this aim, we develop hurdle models of mortality to separate the amount of mortality and the occurrence of mortality.

Our objectives were to i) assess the main drivers of the amount and occurrence of tree mortality and ii) evaluate tree mortality patterns across species distribution ranges.

Our results show that patterns of European mortality patterns vary between mortality occurrence and amount, which could be due to different underlying drivers from background to die-back mortality events.

Furthermore, mortality occurrence was mostly related to drought whereas the amount of mortality depended on many other drivers in addition to drought.

The highest mortality occurrence was mostly found in the trailing edge of the species ranges whereas mortality abundance was patchily distributed across species ranges.