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Airborne Remote Sensing Of The Effects Of Anthropogenic Disturbance On Biogeochemical Processes

Supervisor: David Coomes and External Co-Supervisors.

Reference Code: B112

Importance of the area of research:  Rapid land-use change in the tropics is leading to irrevocable changes in biodiversity and substantial shifts in ecosystem biogeochemistry, altering key processes such as net primary productivity and nutrient cycling (Gibson et al. 2011). Yet we still have a poor understanding of how human-driven changes in biodiversity feed back to alter biogeochemical processes, hampering efforts to model the response of tropical ecosystems to current and future environmental change. A new NERC-funded consortium aims to explore these issues in Malaysia (http://www.nerc.ac.uk/research/programmes/forests/). Changes in biodiversity and ecosystem processes will be quantified along human-modification gradients, including those within the SAFE experiment (http://www.safeproject.net/). A key unifying hypothesis underpinning this work is that leaf functional traits play a pivotal role in linking taxonomic diversity to ecosystem function:  by measuring how disturbance shifts the balance of leaf traits within forest canopies, the project aims to come to a better understanding of the landscape-level implications of human disturbance.

What the project will involve:  We will use recently developed airborne spectranomic approaches to produce landscape-scale maps of the taxonomic identity and foliar chemistry of crowns within the canopy (Asner et al. 2011). Cutting-edge remote sensing data will be collected within a 350 km2 region encompassing all the study sites. The NERC-ARSF aircraft (http://arsf.nerc.ac.uk/) is fitted with two imaging spectrometers that measure light reflected from canopies in up to 380 narrow spectral bands, at 2 m spatial resolution, and a high resolution LiDAR device capable of producing 3-D maps of forest canopies.  Recent work from Amazonia indicates that hyperspectral signatures of fully-illuminated upper-canopy leaves are often sufficiently distinct, and the taxonomic organization of leaf traits sufficiently strong, to identify tree crowns by taxonomic group and determine a plants’ life history strategy (Asner and Martin 2011b). By combining hyperspectral canopy information with plot-level carbon and nutrient cycling measurements, the project aims to quantify how canopy properties are linked to ecosystem processes.

What the student will do:  The student will work with a postdoc to find linkages between the datasets produced by remote-sensing and ground-based studies, thereby enabling information from individual trees and plots to be scaled up to entire landscapes. There will be opportunities for fieldwork in Malaysia (e.g. measuring the spectral properties of individual leaves).

Training that will be provided: The student will be given training in computational techniques, computer programming, the handling of large data sets and eco-physiological field research. The project would suit an applied mathematician or engineer (e.g. with an interest in image analysis), or a numerate biologist interested in a multidisciplinary project combining remote sensing and field work.

References:

  1. Gibson L. et al. 2011. Primary forests are irreplaceable for sustaining tropical biodiversity. Nature 478, 378-81.
  2. Asner G.P. et al. 2011. Spectroscopy of canopy chemicals in humid tropical forests. Remote Sensing of Environment, 115, 3587-3598.
  3. Asner G.P. and Martin R.E. 2011. Canopy phylogenetic, chemical and spectral assembly in a lowland Amazon forest. New Phytologist, 189, 999-1012.