Alternative Methods for Assessing and Monitoring Mangrove Forests

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Globally, mangrove forests provide an essential resource to local inhabitants of coastal regions of the tropics and the subtropics. For example they provide coastal protection from storm surges and are a source of numerous renewable products that sustain many impoverished communities. Ecologically, these wetlands act as a nursery for numerous aquatic organisms and are crucial staging areas for migratory birds. They have also recently been found to be among the most carbon-rich forests of the tropics. Unfortunately, they are experiencing some of the fastest rates of deforestation and those forests that remain are often severely degraded. A key reason for their loss is a lack of methods for assessing and monitoring what remains of these forested wetlands. Mangroves are often located in remote regions and as tidal forests they are extremely difficult to access and to traverse. Consequently, I aim to develop new methods for remotely mapping and monitoring these forests. Employing radar space-borne satellite imagery, which can be acquired at night and is not inhibited by cloud cover, I hope to develop means for accurately mapping the condition (i.e. health) of these trees as well as for extracting mangrove biophysical parameter data (e.g. tree height, tree density, biomass). In addition, I hope to examine whether imagery collected from Canadian Unmanned Aerial Systems (UAS) can be used alone or in conjunction with the radar data to rapidly map and monitor biophysical and biochemical parameters of these threatened forests. If successful, these platforms could be quickly deployed to assess impacts to mangroves from acute causes (e.g. oil spills, tsunamis). Since the majority of mangroves are located in developing countries, expensive ground surveys of mangroves are rarely conducted and thus historical records are almost non-existent. Consequently, I also propose to use historical and current satellite imagery to examine spatial patterns of mangrove loss and degradation with available hydrological data from large rivers that sustain them. Chronic indirect impacts from upland water diversion projects may in fact be a major reason for their current demise. Finally, I also propose to test whether mangrove tree rings and/or isotope data collected from them can be used to track past perturbations thus linking observed mangrove loss or degradation to causal agents. With these data, resource managers can best mitigate further damage to the mangroves and select the most appropriate means for restoration.