Study site and plant material
The six angiosperm species studied included Betula pendula ,Carpinus betulus , Fagus sylvatica , Liriodendron
tulipifera , Prunus avium , and Quercus petraea . Samples
were collected at Ulm University, Germany (48°25’20.3” N, 9°57’20.2”
E). Except for L. tulipifera , all species are common, native
angiosperm trees to Ulm. Various individuals of L. tulipiferawere grown at the Botanical garden of Ulm University. Most species
studied were diffuse porous, except for Q. petraea , which was
ring-porous. Also, C. betulus and Q. petraea were
considered as species with marcescent leaves during winter, with partial
marcescent leaves in F. sylvatica . The remaining three species
are deciduous. We selected four to five mature trees for each species.
Healthy, mature and sun-exposed branches were sampled between June and
September 2019 for experiment 1 and 3, and in May 2020 for experiment 2.