title: How eco-evolutionary principles can guide tree breeding and tree biotechnology for enhanced productivity.
abstract: Tree breeding and biotechnology can enhance forest productivity and help alleviate the rising pressure on forests from climate change and human exploitation. While many physiological processes and genes are targeted in search of genetically improved tree productivity, an overarching principle to guide this search is missing. Here, we propose a method to identify the traits that can be modified to enhance productivity, based on the differences between trees shaped by natural selection and 'improved' trees with traits optimized for productivity. We developed a tractable model of plant growth and survival to explore such potential modifications under a range of environmental conditions, from non-water limited to severely drought-limited sites. We show how key traits are controlled by a trade-off between productivity and survival, and that productivity can be increased at the expense of long-term survival by reducing isohydric behavior (stomatal regulation of leaf water potential) and allocation to defense against pests compared with native trees. In contrast, at dry sites occupied by naturally drought-resistant trees, the model suggests a better strategy may be to select trees with slightly lower wood density than the native trees and to augment isohydric behavior and allocation to defense. Thus, which traits to modify, and in which direction, depend on the original tree species or genotype, the growth environment and wood-quality versus volume production preferences. In contrast to this need for customization of drought and pest resistances, consistent large gains in productivity for all genotypes can be obtained if root traits can be altered to reduce competition for water and nutrients. Our approach illustrates the potential of using eco-evolutionary theory and modeling to guide plant breeding and genetic technology in selecting target traits in the quest for higher forest productivity.
authors.affiliation: Ecosystems Services and Management Program , International Institute for Applied Systems Analysis, A-2361 Laxenburg , Austria; franklin@iiasa.ac.at.
authors.forename: Oskar
authors.initials: O
authors.lastname: Franklin
authors.affiliation: Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27708 , USA;
authors.forename: Sari
authors.initials: S
authors.lastname: Palmroth
authors.affiliation: Department of Forest Ecology and Management , Swedish University of Agricultural Sciences, SE-901 83 Umeå , Sweden; Department of Forest Genetics and Plant Physiology , Umeå Plant Science Centre, Swedish University of Agricultural Sciences, SE-901 85 Umeå , Sweden.
authors.forename: Torgny
authors.initials: T
authors.lastname: Näsholm
mesh_terms: D005075:Biological Evolution; D018533:Biomass; D001709:Biotechnology; D001947:Breeding; D002980:Climate; D055864:Droughts; D004777:Environment; D008962:Models, Theoretical; D010641:Phenotype; D018526:Plant Transpiration; D012308:Risk Management; D014197:Trees / Q000235:genetics* / Q000254:growth & development / Q000502:physiology; D014867:Water / Q000502:physiology; D014934:Wood
chemical_list: D014867:Water
keywords: adaptation; anisohydric; aridity; climate; ecology; evolution; forestry; functional traits; genetic modification; gmo; hydraulics; life history; mathematical model; mortality; risk management; selection; strategy; transpiration; wood