Changes in leaf functional traits of rainforest canopy trees associated with an El Niño event in Borneo

Bibliographic Data

ID15550395
AuthorsMatheus Henrique Nunes (0000-0001-9979-6456, University of Cambridge), Sabine Both (0000-0003-4437-5106, University of New England), Boris Bongalov (0000-0002-0252-2983, University of Cambridge), Craig C Brelsford (0000-0001-7084-352X, University of Helsinki), C Brelsford, Sacha Khoury (0000-0002-1980-5365, University of Cambridge), David F R P Burslem (0000-0001-6033-0990, University of Aberdeen), Christopher D Philipson (0000-0001-8987-7260, ETH Zurich), C Philipson, Noreen Majalap (0000-0002-6328-8529, Sabah Forestry Department), Terhi Riutta (0000-0002-8308-5307, University of Oxford), David A Coomes (0000-0002-8261-2582, University of Cambridge), Mark Cutler (0000-0002-3893-1068, University of Dundee, corresponding author)
Year2019
Volume14
Issue8
Pages085005-085005
Publication date2019-07-02
Open AccessYes
TypeARTICLE
VenueEnvironmental Research Letters (JOURNAL)
Journal identifiersISSN: 1748-9326 • E-ISSN: 1748-9326
PublisherIOP Publishing (PUBLISHER • GB)
DOI10.1088/1748-9326/ab2eae
OpenAlexW2955999797
LanguageEN
Citations received1
References cited83

El Niño events generate periods of relatively low precipitation, low cloud cover and high temperature over the rainforests of Southeast Asia, but their impact on tree physiology remains poorly understood. Here we use remote sensing and functional trait approaches—commonly used to understand plant acclimation to environmental fluctuations—to evaluate rainforest responses to an El Niño event at a site in northern Borneo. Spaceborne measurements (i.e. normalised difference vegetation index calculated from Moderate Resolution Imaging Spectroradiometer data) show the rainforest canopy greened throughout 2015, coinciding with a strengthening of the El Niño event in Sabah, Malaysia, then lost greenness in early 2016, when the El Niño was at its peak. Leaf chemical and structural traits measured for mature leaves of 65 species (104 branches from 99 tree canopies), during and after this El Niño event revealed that chlorophyll and carotenoid concentrations were 35% higher in mid 2015 than in mid 2016. Foliar concentrations of the nutrients N, P, K and Mg did not vary, suggesting the mineralisation and transportation processes were unaffected by the El Niño event. Leaves contained more phenolics, tannins and cellulose but less Ca and lignin during the El Niño event, with concentration shifts varying strongly among species. These changes in functional traits were also apparent in hyperspectral reflectance data collected using a field spectrometer, particularly in the shortwave infrared region. Leaf-level acclimation and leaf turnover could have driven the trait changes observed. We argue that trees were not water limited in the initial phase of the El Niño event, and responded by flushing new leaves, seen in the canopy greening trend and higher pigment concentrations (associated with young leaves); we argue that high evaporative demand and depleted soil water eventually caused leaves to drop in 2016. However, further studies are needed to confirm these ideas. Time-series of vegetation dynamics obtained from space can only be understood if changes in functional traits, as well as the quantity of leaves in canopies, are monitored on the ground

Atmospheric sciences · Biology · Botany · Canopy · Geography · Mediterranean climate · Precipitation · Rainforest · Sclerophyll · Tree canopy · Tropical rainforest · Ecology and Vegetation Dynamics Studies · Environmental Science · Leaf Properties and Growth Measurement · Remote Sensing in Agriculture · Ecology · Geology

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