title: Contrasting nonstructural carbohydrate dynamics of tropical tree seedlings under water deficit and variability.
abstract: Drought regimes can be characterized by the variability in the quantity of rainfall and the duration of rainless periods. However, most research on plant response to drought has ignored the impacts of rainfall variation, especially with regard to the influence of nonstructural carbohydrates (NSCs) in promoting drought resistance. To test the hypothesis that these components of drought differentially affect NSC dynamics and seedling resistance, we tracked NSC in plant tissues of tropical tree seedlings in response to manipulations of the volume and frequency of water applied. NSC concentrations decreased in woody tissues under infrequent-high watering but increased under no watering. A faster decline of growth relative to stomatal conductance in the no watering treatment was consistent with NSC accumulation as a result of an uncoupling of growth and photosynthesis, while usage of stored NSCs in woody tissues to maintain function may account for the NSC decline under infrequent-high watering. NSCs, and specifically stem NSCs, contributed to drought resistance under severe water deficits, while NSCs had a less clear role in drought resistance to variability in water availability. The contrasting response of NSCs to water variability and deficit indicates that unique processes support seedling resistance to these components of drought.
authors.affiliation: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: O'Brien
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, UK.
authors.forename: David F R P
authors.initials: DFRP
authors.lastname: Burslem
authors.affiliation: Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
authors.forename: Alexa
authors.initials: A
authors.lastname: Caduff
authors.affiliation: School of International Tropical Forestry, University Malaysia Sabah, Jalan UMS, 88400, Kota Kinabalu, Sabah, Malaysia.
authors.forename: John
authors.initials: J
authors.lastname: Tay
authors.affiliation: Department of Plant Sciences, University of Oxford, Oxford, OX1 3RB, UK.
authors.forename: Andy
authors.initials: A
authors.lastname: Hector
mesh_terms: D000222:Adaptation, Physiological; D050260:Carbohydrate Metabolism; D055864:Droughts; D010788:Photosynthesis; D018547:Plant Stems / Q000378:metabolism*; D054046:Plant Stomata / Q000502:physiology; D018526:Plant Transpiration; D011891:Rain; D036226:Seedlings / Q000378:metabolism; D013312:Stress, Physiological; D014197:Trees / Q000254:growth & development / Q000378:metabolism*; D014867:Water; D014934:Wood
chemical_list: D014867:Water
keywords: climate change; drought resistance; nonstructural carbohydrates (NSCs); plant-climate interactions; relative growth response; stomatal conductance; tropical forests