Severe dry winter affects plant phenology and carbon balance of a cork oak woodland understorey |
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| Affiliation: | 1. Centro de Estudos Florestais, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1349-017 Lisbon, Portugal;2. Ecosystem Physiology, University Freiburg, Georges-Köhler-Allee 54, 79110 Freiburg, Germany;3. Thünen Institute of Climate-Smart Agriculture, Bundesallee 50, 38116 Braunschweig, Germany;1. Departamento de Ciências Naturais, Herbário FURB, Universidade Regional de Blumenau – FURB, Rua Antônio da Veiga, 140, Bairro Victor Konder, 89012-900, Blumenau, SC, Brazil;2. Embrapa Florestas, Estrada da Ribeira, km 111, 83411-000, Colombo, PR, Brazil;3. Programa de Pós-graduação em Ecologia e Evolução, Laboratório de Ecologia Teórica e Síntese, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Campus Samambaia, Caixa Postal 131, 74690-900, Goiânia, GO, Brazil;4. Departamento de Engenharia Florestal, Universidade Regional de Blumenau – FURB, Rua São Paulo, 3250, 89030-000, Blumenau, SC, Brazil;1. Department of Plant Ecology and Environmental Conservation, Biological and Chemical Research Centre, Faculty of Biology, University of Warsaw, ul. Żwirki i Wigury 101, 02-089 Warsaw, Poland;2. Department of Botany, Kherson State University, ul. Universytetska 27, 73000 Kherson, Ukraine;1. Agroécologie, AgroSup Dijon, INRA, Univ. Bourgogne Franche-Comté, F-21000, Dijon, France;2. ITRA/CRAL, BP 1163, Lomé, Togo;3. Ecologie Systématique Evolution, CNRS, Univ. Paris-Sud, AgroParisTech, Université Paris-Saclay, 91400, Orsay, France;1. Disturbance Ecology, BayCEER, University of Bayreuth, Germany;2. Department of Forestry and Environmental Science, Shahjalal University of Science and Technology, Sylhet, 3114, Bangladesh;3. Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald University, Germany;4. Biogeography, BayCEER, University of Bayreuth, Germany;1. Department of Ecology, Instituto Nacional de Pesquisas da Amazônia, Manaus, Amazonas, Brazil;2. Laboratory of Genetics and Biodiversity, Institute of Biological Sciences, Federal University of Goias, Goiania, Goias, Brazil |
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| Abstract: | Mediterranean climates are prone to a great variation in yearly precipitation. The effects on ecosystem will depend on the severity and timing of droughts. In this study we questioned how an extreme dry winter affects the carbon flux in the understorey of a cork oak woodland? What is the seasonal contribution of understorey vegetation to ecosystem productivity?We used closed-system portable chambers to measure CO2 exchange of the dominant shrub species (Cistus salviifolius, Cistus crispus and Ulex airensis), of the herbaceous layer and on bare soil in a cork oak woodland in central Portugal during the dry winter year of 2012. Shoot growth, leaf shedding, flower and fruit setting, above and belowground plant biomass were measured as well as seasonal leaf water potential. Eddy-covariance and micrometeorological data together with CO2 exchange measurements were used to access the understorey species contribution to ecosystem gross primary productivity (GPP).The herbaceous layer productivity was severely affected by the dry winter, with half of the yearly maximum aboveground biomass in comparison with the 6 years site average. The semi-deciduous and evergreen shrubs showed desynchronized phenophases and lagged carbon uptake maxima. Whereas shallow-root shrubs exhibited opportunistic characteristics in exploiting the understorey light and water resources, deep rooted shrubs showed better water status but considerably lower assimilation rates. The contribution of understorey vegetation to ecosystem GPP was lower during summer with 14% and maximum during late spring, concomitantly with the lowest tree productivity due to tree canopy renewal. The herbaceous vegetation contribution to ecosystem GPP never exceeded 6% during this dry year stressing its sensitivity to winter and spring precipitation.Although shrubs are more resilient to precipitation variability when compared with the herbaceous vegetation, the contribution of the understorey vegetation to ecosystem GPP can be quite variable and will ultimately depend of tree density and canopy cover. |
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| Keywords: | Shrubs Herbaceous Climate change Winter drought Mediterranean |
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