Factors driving unexpected drought-induced Nothofagus dombeyi mortality in a Valdivian Temperate Rainforest, Argentina

SUAREZ, MARÍA LAURA; SASAL, YAMILA; FACCIANO, LORETA

Forests

MDPI

Año: 2024 vol. 15 p. 1 - 21

Understandingthe drivers of drought-induced tree mortality remains a significant scientific challenge.Here, we investigated an unexpected mortality event of Nothofagus dombeyi (Mirb.)Oerst. following the 2014–15 drought in a Valdivian rainforest, Argentina. Ourfocus was on long term growth trend differences between vital and dead trees,and how the mixing of species in tree neighborhoods drives tree growth duringdrought. The inter-annual variation of basal area increments of vital and2014–15-dead N. dombeyi trees showed a similar pattern through the1930–2015 period, while the climate–growth relationships indicated thatprecipitation during the growing season promoted growth in both vitalityclasses, regardless of whether they were in the wettest location. For theperiod 1990–2015, both vitality classes showed similar estimated growthregardless of competition level, whereas species mingling in the neighborhoodsignificantly affected the dead tree growth. Network analysis revealed thatdrought performance covaried positively with a neighborhood dominated byspecies functionally different from the focal species only in vital trees. Thesefindings suggest a nuanced response of N. dombeyi to drought, shaped bymultifaceted interactions at both the individual tree and neighborhood levels.This research underscores that species-specific relationships under differentmixtures imply different tree responses within a stand, and add complexity tounderstanding drought response at the individual level.