What drives the long-term change in a key leaf functional trait across the globe? Insights from multispectral remote sensing
Abstract
Vegetation structure and composition is changing rapidly due to climate and human pressures. Plant functional traits at canopy scale offer a promising way to translate vegetation changes to changes in the processes of the biosphere, but its monitoring across spatial and temporal scales has remained a challenge. We developed a Landsat-based multispectral index, called iLMA, for the continuous monitoring of the mean Leaf Mass per Area (LMA) of canopies, a key trait that influences plant metabolism at all scales. We used this index, designed from biophysical principles and calibrated across the major terrestrial biomes, to monitor the variation of this key trait across the globe and, for the first time, its change across decades at high resolution (30 m). With this index we detected that the global LMA has decreased by 6.5% over the last 35 years, and show evidence that such decrease may be similarly driven by increasing temperatures (marginal R2 = 0.26) and human-induced changes. However, this long-term change is heterogeneous. For example, we show that LMA is twice as sensitive to temperature at tropical forests than mid-latitude evergreen forests. We further show high-resolution examples of how climate and human-induced changes are driving varying responses on the long-term LMA change across biomes and regions of the world. Further improving the monitoring of these plant traits and the understanding of its drivers of change will enable a better prediction of the biosphere, but also to orient efforts to manage the functional diversity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.B45L1882H