Note that, due to the CoVID-19 pandemic and the familiar commitments, the action has experienced some difficulties for its implementation and some tasks are still in progress.
The work performed by TreEsilience project was divided in three phases. First, two databases were gathered selecting and compiling data of tree growth (i.e. tree-ring width, TRW) of existing open databases: The International Tree Ring Data Bank (ITRDB) and TRW-mortality database. ITRDB compiles 172,054 tree-ring series that were manually grouped within 93,320 tree identities and 4,438 sites. TRW-mortality database gathers tree-ring data of 2,970 dead and 4,224 living trees from 190 sites (36 species) where mortality was mainly induced by stress, such as drought.
Second, drought events were identified for each site in the TRW-mortality database and, then, resilience of tree-ring growth to drought was computed. We found that, across the regions and species sampled, trees that died during water shortages were less resilient to previous non-lethal droughts, relative to coexisting surviving trees of the same species. In angiosperms, drought-related mortality risk was associated with lower resistance (low capacity to reduce impact of the initial drought), while it was related to reduced recovery (low capacity to attain pre-drought growth rates) in gymnosperms. The outstanding significance of these results allowed us to publish them as a paper in the top journal Nature Communications. This finding was covered for different media and thus, the results were highly disseminated between the general public.
Tree growth responds to climatic conditions displaying intraindividual variability in annual growth. I have explored the differences in intraindividual variation in tree growth among sites and species of the ITRDB. Moreover, maintaining variation might have costs in other functions and eventually might have consequences in tree survival. Here, I have analysed the intraindividual variability in radial growth and mortality in the populations and species of the TRW-mortality database. Preliminary results indicate that trees that died during water shortages show higher plasticity in growth than surviving trees.
Third, I will develop a protocol to select tree individuals less likely to overcome future droughts as candidates for harvesting within woodland stands. This protocol will follow Adaptive Forest Management, working in an iterative process of interaction between scientists, practitioners, policy-makers and stakeholders.
Besides the publication in the multidisciplinary journal Nature Communications (2020, 11:545), I have disseminated the research results of TreEsilience to the scientific community by publishing two more papers. I have been involved in dissemination activities for general public such as the “Science Week” and the “European Researchers’ Night”. Main results have been also disseminated in different general media, newspapers, radio and internet. Finally, I made a short-film about how tree rings can be used to detect tree sensitivity to drought and future mortality risk.
This work was done in collaboration with Prof J.M. Gómez (EEZA), Dr C. Armas (EEZA), Dr M. Cailleret (INRAE), Dr J. Martínez-Vilalta (CREAF), Dr R. Mateo (UAM) and Dr R. Torices (URJC).
