Linking rainforest ecophysiology and microclimate through fusion of airborne LiDAR and hyperspectral imagery

Authors

  • Eben N. Broadbent,

    Corresponding author
    1. Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, California 94305 USA
    2. Department of Biology, Stanford University, Stanford, California 94305 USA
    3. Sustainability Science Program, Kennedy School of Government, Harvard University, Cambridge, Massachusetts 02138 USA
    Search for more papers by this author
    • Present address: Department of Geography, University of Alabama, Tuscaloosa, Alabama 35487 USA.

  • Angélica M. Almeyda Zambrano,

    1. Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, California 94305 USA
    2. Sustainability Science Program, Kennedy School of Government, Harvard University, Cambridge, Massachusetts 02138 USA
    3. Department of Anthropology, Stanford University, Stanford, California 94305 USA
    Search for more papers by this author
    • Present address: Department of Geography, University of Alabama, Tuscaloosa, Alabama 35487 USA.

  • Gregory P. Asner,

    1. Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, California 94305 USA
    Search for more papers by this author
  • Christopher B. Field,

    1. Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, California 94305 USA
    Search for more papers by this author
  • Brad E. Rosenheim,

    1. Department of Earth & Environmental Sciences, Tulane University, New Orleans, Louisiana 70118 USA
    Search for more papers by this author
  • Ty Kennedy-Bowdoin,

    1. Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, California 94305 USA
    Search for more papers by this author
  • David E. Knapp,

    1. Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, California 94305 USA
    Search for more papers by this author
  • David Burke,

    1. Department of Global Ecology, Carnegie Institution, 260 Panama Street, Stanford, California 94305 USA
    2. Department of Biology, Stanford University, Stanford, California 94305 USA
    Search for more papers by this author
  • Christian Giardina,

    1. Institute of Pacific Islands Forestry, Hilo, Hawaii 96720 USA
    Search for more papers by this author
  • Susan Cordell

    1. Institute of Pacific Islands Forestry, Hilo, Hawaii 96720 USA
    Search for more papers by this author

  • Corresponding Editor: D. P. C. Peters.

Abstract

We develop and validate a high-resolution three-dimensional model of light and air temperature for a tropical forest interior in Hawaii along an elevation gradient varying greatly in structure but maintaining a consistent species composition. Our microclimate models integrate high-resolution airborne waveform light detection and ranging data (LiDAR) and hyperspectral imagery with detailed microclimate measurements. We then use modeled microclimate and forest structural and compositional variables to explain variation in spatially explicit measurements of leaf traits, including gas exchange and structure. Our results highlight the importance of: (1) species differences in leaf traits, with species explaining up to 65% of the variation in some leaf traits; (2) differences between exotic and native species, with exotic species having greater maximum rates of assimilation and foliar δ15N values; (3) structural factors, with foliar %N and light saturation of photosynthesis decreasing in mid-canopy locations; (4) microclimate factors, with foliar %N and light saturation increasing with growth environment illumination; and (5) decreases in mean annual temperature with elevation resulting in closure of the nitrogen cycle, as indicated through decreases in foliar δ15N values. The dominant overstory species (Metrosideros polymorpha) did not show plasticity in photosynthetic capacity, whereas the dominant understory species (Cibotium glaucum) had higher maximum rates of assimilation in more illuminated growth environments. The approach developed in this study highlights the potential of new airborne sensors to quantify forest productivity at spatial and temporal scales not previously possible. Our results provide insight into the function of a Hawaiian forest dominated by native species undergoing simultaneous biological invasion and climatic change.

Ancillary