Interaction of stomatal behaviour and vulnerability to xylem cavitation determines the drought response of three temperate tree species

Zhicheng Chen; Shirong Liu; Haibo Lu; Xianchong Wan

doi:10.1093/aobpla/plz058

Interaction of stomatal behaviour and vulnerability to xylem cavitation determines the drought response of three temperate tree species

AoB Plants. 2019 Sep 23;11(5):plz058. doi: 10.1093/aobpla/plz058. eCollection 2019 Oct.

Authors

Zhicheng Chen¹, Shirong Liu², Haibo Lu², Xianchong Wan¹

Affiliations

¹ Institute of New Forestry Technology, Chinese Academy of Forestry, Beijing, China.
² Key Laboratory of Forest Ecology and Environment of State Forestry Administration, Institute of Forest Ecology, Environment and Protection, Chinese Academy of Forestry, Beijing, China.

Abstract

How the mortality and growth of tree species vary with the iso-anisohydric continuum and xylem vulnerability is still being debated. We conducted a precipitation reduction experiment to create a mild drought condition in a forest in the Baotianman Mountains, China, a sub-humid region. Three main sub-canopy tree species in this region were examined. After rainfall reduction, Lindera obtusiloba showed severe dieback, but two other co-occurring species did not show dieback. The water potential at stomatal closure of Dendrobenthamia japonica, L. obtusiloba and Sorbus alnifolia was -1.70, -2.54 and -3.41 MPa, respectively, whereas the water potential at 88 % loss in hydraulic conductivity of the three species was -2.31, -2.11 and -7.01 MPa, respectively. Taken together, near-anisohydric L. obtusiloba with vulnerable xylem was highly susceptible to drought dieback. Anisohydric S. alnifolia had the most negative minimum water potential, and its xylem was the most resistant to cavitation. Isohydric D. japonica conserved water by rapidly closing its stomata. Ultimately, the hydraulic safety margin (HSM) of L. obtusiloba was the smallest among the three species, especially in precipitation-reduced plots. In terms of the stomatal safety margin (SSM), L. obtusiloba was negative, while S. alnifolia and D. japonica were positive. Of the two species without dieback, rainfall reduction decreased growth of D. japonica, but did not influence growth of S. Alnifolia; meanwhile, rainfall reduction led to a decrease of non-structural carbohydrates (NSCs) in D. japonica, but an increase in S. alnifolia. It is concluded that HSM as well as SSM allow interpreting the sensitivity of the three sub-canopy species to drought. The drought-induced dieback of L. obtusiloba is determined by the interaction of stomatal behaviour and xylem vulnerability, and the species could be sensitive to climate change-caused drought although still in sub-humid areas. The isohydric/anisohydric degree is associated with NSCs status and growth of plants.

Keywords: Anisohydric; carbon starvation; climate change; hydraulic failure; isohydric; xylem vulnerability.