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Magnolias as urban trees – a preliminary evaluation of drought tolerance in seven magnolia species

Sjöman, Henrik, Hirons, Andrew D., Bassuk, Nina L.
TheArboricultural journal 2018 v.40 no.1 pp. 47-56
Magnolia loebneri, Magnolia virginiana, arboriculture, drought, drought tolerance, ecosystem services, gardens, genotype, leaves, trees, turgor, urban areas, water potential
Tree selection must ensure that trees are capable of thriving in the environment in which they are placed. Inappropriate species or trees of poor quality will never develop any substantial capacity for delivering ecosystem services. The aim of this study is to evaluate seven species of Magnolia for their drought tolerance by estimating their water potential at leaf turgor loss to help provide quantitative data for their capacity to tolerate dry urban sites. According to the results, Magnolia virginiana is ranked as the most drought-tolerant, while Magnolia x loebneri “Leonard Messel” is the most sensitive to drought. However, in comparison with other plant groups previously studied, magnolias have to be treated as drought sensitive. Consequently, magnolias used in this study should be used in garden and park environments, as their potential for use along streets can be limited by their vulnerability to drought. The turgor loss point methodology used in the study provides an efficient alternative to decades of observation, especially when new genotypes or underutilised trees are being evaluated. It is now possible to show the group’s general sensitivity to drought as well as quantifying individual species sensitivity to drought.