Drought effect on isoprene production and consumption in Biosphere 2 tropical rainforest

Authors

  • EMILIANO PEGORARO,

    1. Biosphere 2 Center, Columbia University, Oracle, AZ 85623, USA,
    Search for more papers by this author
    • 1Present address: Estacion Experimental de Zonas Aridas, Consejo Superior de Investigaciones Cientificas, General Segura n. 1, Almeria, Spain.

  • ANA REY,

    Search for more papers by this author
    • 1Present address: Estacion Experimental de Zonas Aridas, Consejo Superior de Investigaciones Cientificas, General Segura n. 1, Almeria, Spain.

  • LEIF ABRELL,

    1. Biosphere 2 Center, Columbia University, Oracle, AZ 85623, USA,
    Search for more papers by this author
    • 2Present address: Department of Chemistry, University of Arizona 1306 E., University Blvd., Tucson, AZ 85721, USA.

  • JOOST VAN HAREN,

    1. Biosphere 2 Center, Columbia University, Oracle, AZ 85623, USA,
    Search for more papers by this author
    • 3Present address: Department of Soil, Water and Environmental Science, University of Arizona, Shantz, Tucson, AZ 85721, USA.

  • GUANGHUI LIN

    1. Biosphere 2 Center, Columbia University, Oracle, AZ 85623, USA,
    2. Key Laboratory of Quantitative Vegetation, Institute of Botany, The Chinese Academy of Science, 20 Nanxincun, Xiangshan, Beijing 100093, China
    Search for more papers by this author
    • 4Present address: Department of Global Ecology, Carnegie Institution of Washington, Stanford, CA 94305, USA.


Emiliano Pegoraro, e-mail: emi@eeza.csic.es

Abstract

Isoprene is the most abundant of the hydrocarbon compounds emitted from vegetation and plays a major role in tropospheric chemistry. Models predict that future climate change scenarios may lead to an increase in global isoprene emissions as a consequence of higher temperatures and extended drought periods. Tropical rainforests are responsible for more than 80% of global isoprene emissions, so it is important to obtain experimental data on isoprene production and consumption in these ecosystems under control of environmental variables. We explored isoprene emission and consumption in the tropical rainforest model ecosystem of Biosphere 2 laboratory during a mild water stress, and the relationship with light and temperature. Gross isoprene production (GIP) was not significantly affected by mild water stress in this experiment because the isoprene emitters were mainly distributed among the large, canopy layer trees with deep roots in the lower soil profile where water content decreased much less than the top 30 cm. However, as found in previous leaf level and whole canopy studies, the ecosystem gross primary production was reduced by (32%) during drought, and as a consequence the percentage of fixed C lost as isoprene tended to increase during drought, from ca. 1% in wet conditions to ca. 2% when soil water content reached its minimum. GIP correlated very well with both light and temperature. Notably, soil isoprene uptake decreased dramatically during the drought, leading to a large increase in daytime net isoprene fluxes.

Ancillary