title: Tree diversity affects chlorophyll a fluorescence and other leaf traits of tree species in a boreal forest.
abstract: An assemblage of tree species with different crown properties creates heterogeneous environments at the canopy level. Changes of functional leaf traits are expected, especially those related to light interception and photosynthesis. Chlorophyll a fluorescence (ChlF) properties in dark-adapted leaves, specific leaf area, leaf nitrogen content (N) and carbon isotope composition (δ13C) were measured on Picea abies (L.) H.Karst., Pinus sylvestris L. and Betula pendula Roth. in monospecific and mixed boreal forests in Europe, in order to test whether they were affected by stand species richness and composition. Photosynthetic efficiency, assessed by induced emission of leaf ChlF, was positively influenced in B. pendula by species richness, whereas P. abies showed higher photosynthetic efficiency in monospecific stands. Pinus sylvestris had different responses when it coexisted with P. abies or B. pendula. The presence of B. pendula, but not of P. abies, in the forest had a positive effect on the efficiency of photosynthetic electron transport and N in P. sylvestris needles, and the photosynthetic responses were positively correlated with an increase of leaf δ13C. These effects on P. sylvestris may be related to high light availability at the canopy level due to the less dense canopy of B. pendula. The different light requirements of coexisting species was the most important factor affecting the distribution of foliage in the canopy, driving the physiological responses of the mixed species. Future research directions claim to enhance the informative potential of the methods to analyse the responses of pure and mixed forests to environmental factors, including a broader set of plant species' functional traits and physiological responses.
authors.affiliation: Department of Agri-Food Production and Environmental Science, University of Florence, Piazzale delle Cascine 28, 50144 Florence, Italy.
authors.forename: Martina
authors.initials: M
authors.lastname: Pollastrini
authors.affiliation: Department of Physical, Chemical and Natural Systems, University Pablo de Olavide, Carretera de Utrera, Km. 1, 41013 Seville, Spain.
authors.forename: Ana Garcia
authors.initials: AG
authors.lastname: Nogales
authors.affiliation: Albert-Ludwings-Universitat Freiburg, Schanzlestrasse 1, 79104 Freiburg, Germany.
authors.forename: Raquel
authors.initials: R
authors.lastname: Benavides
authors.affiliation: UMR 1137 Ecologie et Ecophysiologie Forestières, INRA, 54280 Champenoux, France.
authors.forename: Damien
authors.initials: D
authors.lastname: Bonal
authors.affiliation: Finnish Forest Research Institute, PO Box 68, Yliopistokatu 6, FI-80101 Joensuu, Finland.
authors.forename: Leena
authors.initials: L
authors.lastname: Finer
authors.affiliation: Forest Research Institute, Vassilika 57006, Thessaloniki, Greece.|Department of Forestry and Management of the Environment and Natural Resources, Democritus University of Thrace, Pantazodou 193, N. Orestiada 68300, Greece.
authors.forename: Mariangela
authors.initials: M
authors.lastname: Fotelli
authors.affiliation: Forest Dynamics, Swiss Federal Research Institute WSL, Zurcherstrasse 111, CH-8903 Birmensdorf, Switzerland.
authors.forename: Arthur
authors.initials: A
authors.lastname: Gessler
authors.affiliation: Earth and Environmental Sciences Division, MS-J495, Los Alamos National Lab, Los Alamos, NM 87545, USA.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Grossiord
authors.affiliation: Forest Research Institute, Vassilika 57006, Thessaloniki, Greece.|Department of Forestry and Management of the Environment and Natural Resources, Democritus University of Thrace, Pantazodou 193, N. Orestiada 68300, Greece.
authors.forename: Kalliopi
authors.initials: K
authors.lastname: Radoglou
authors.affiliation: North West University South Africa, Unit for Environmental Sciences and Management, Potchefstroom Campus, Potchefstroom 2520, South Africa.
authors.forename: Reto J
authors.initials: RJ
authors.lastname: Strasser
authors.affiliation: Department of Agri-Food Production and Environmental Science, University of Florence, Piazzale delle Cascine 28, 50144 Florence, Italy.
authors.forename: Filippo
authors.initials: F
authors.lastname: Bussotti
mesh_terms: D044822:Biodiversity; D002734:Chlorophyll / Q000378:metabolism*; D000077194:Chlorophyll A; D005453:Fluorescence; D010788:Photosynthesis / Q000502:physiology; D014197:Trees / Q000145:classification / Q000378:metabolism*
chemical_list: D002734:Chlorophyll; D000077194:Chlorophyll A
keywords: FunDivEUROPE; mixed forest; species composition; species richness