Ongoing climate change is apparently increasing tree mortality rates, and understanding mechanisms of drought-induced tree decline can improve mortality projections. Differential drought impact on conspecific individuals within a population has been reported, but no clear mechanistic explanation for this pattern has emerged. Following a severe drought (summer 2012), we monitored over a 3-year period healthy (H) and declining (D) Pinus nigra trees co-occurring in a karstic woodland to highlight eventual individual-specific physiological differences underlying differential canopy dieback. We investigated differences in water and carbon metabolism, and xylem anatomy as a function of crown health status, as well as eventual genotypic basis of contrasting drought responses. H and D trees exploited the same water pools and relied on similar hydraulic strategies to cope with drought stress. Genetic analyses did not highlight differences between groups in terms of geographical provenance. Hydraulic and anatomical analyses showed conflicting results. The hydraulic tracheid diameter and theoretical hydraulic conductivity were similar, but D trees were characterized by lower water transport efficiency, greater vulnerability to xylem conduit implosion and reduced carbohydrate stores. Our results suggest that extreme drought events can have different impacts on conspecific individuals, with differential vulnerability to xylem embolism likely playing a major role in setting the fate of trees under climate change.
1.Univ Trieste, Dipartimento Sci Vita, Via L Giorgieri 10, I-34127 Trieste, Italy 2.Univ Nat Resources & Life Sci, Div Viticulture & Pomol, Dept Crop Sci, Konrad Lorenz Str 24, A-3430 Tulln, Austria 3.Univ Udine, Dipartimento Sci Agroalimentari Ambientali & Anim, Via Sci 91, I-33100 Udine, Italy 4.Univ Nat Resources & Life Sci, Inst Bot, Gregor Mendel Str 33, A-1180 Vienna, Austria 5.Univ Ca Foscari Venezia, Dipartimento Sci Ambientali Informat & Stat, Via Torino 155, I-30170 Venice, Italy
Recommended Citation:
Savi, Tadeja,Casolo, Valentino,Dal Borgo, Anna,et al. Drought-induced dieback of Pinus nigra: a tale of hydraulic failure and carbon starvation[J]. CONSERVATION PHYSIOLOGY,2019-01-01,7