The sky's the limit: Using drones to assess the health of mahampy wetlands in southeast Madagascar
Freshwater ecosystems cover less than 1% of the Earth’s surface, yet are home to a staggering 10% of all species (Strayer & Dudgeon, 2010). Comprising rivers, lakes, and inland wetlands, these ecosystems present disproportionately high levels of biodiversity and endemism across multiple taxonomic groups (Tickner et al., 2020). These unique environments also provide sustenance, income, and other ecosystem services for millions of people globally, many of whom are vulnerable and live in poverty (Clarkson et al., 2013; Bamford et al., 2017). Due to unsustainable human action and increased demand on natural resources, these ecosystems are vanishing at a rate three-times faster than terrestrial forest, all while the relationships surrounding these issues continue to be under-researched and poorly understood (Guo et al., 2010, Tickner et al., 2020).
Madagascar is no exception, experiencing rapid degradation and loss – particularly within wetlands (Bamford et al., 2017). The Anosy region of southeast Madagascar is home to a variety of wetlands populated by a diverse range of flora and fauna. One floral species that composes many of these wetlands is the reed called Lepironia mucronata (L. mucronata), locally known as mahampy (Figure 1). Mahampy wetlands have great cultural and economic importance, particularly for the women of Sainte Luce, yet are vastly understudied and little is known about their current health and the biodiversity that they support.
However, studying mahampy and understanding its threats is not straightforward. Mahampy wetlands are notoriously hard to study because of their large size, remote location, and often wet and ‘boggy’ nature, amongst other reasons. Learning more about these wetlands therefore required a little bit of help from technology in the form of drones.
Drones are remotely piloted devices, typically aircraft, which have become increasingly affordable, portable, and easy to use in recent years. They present a relatively risk-free opportunity to quickly and methodically observe all kinds of natural phenomena in high detail (López & Mulero-Pázmány, 2019). These various attributes make drones the ideal tool for assessing and monitoring ecosystems – and it is for this reason that SEED are utilising their powers.
As part of the Sustainable Livelihoods project, Mahampy, and the Conservation Research Programme, SEED are supplementing ongoing on-the-ground research with novel aerial data. We aim to answer a variety of questions about the mahampy wetlands of the greater Sainte Luce region, such as: What is the spatial extent of mahampy in the region? How much of this mahampy is accessible for collection by weavers? What is the general health of the mahampy plants and does this vary from wetland to wetland? Is the current rate and method of mahampy harvest ensuring it as a sustainable resource? These are just a few of the questions that SEED are seeking to answer in order to safeguard this important resource.
To answer these questions SEED has programmed a drone to fly specific routes on repeated occasions while taking incredibly high resolution photographs of the wetlands below. These photographs have coordinates attached to their metadata, allowing all of the images to be stitched together to create one image of the entire wetland. An example of an aerial photograph taken by SEED’s drone can be seen in Figure 2. The resolution of these photographs are high enough for specific measurements and characteristics of the wetlands to be made. These measurements include ground elevation, the height of individual bunches of mahampy plants, and even the health of the stems of the plants themselves. Together with data collected by researchers on the ground, these findings will help to provide SEED and local organisations with current and accurate assessments of the wetlands. Furthermore, these assessments can be used to develop sustainable management strategies to protect existing wetlands and enhance the growth of mahampy in other wetlands too.
While the remote nature of the study sites and demanding environmental conditions have proved challenging for researchers and drones alike, SEED have successfully mapped six different wetlands on two separate occasions – which is quite the achievement considering limited capacity to charge and that each aerial survey requires an entire fully-charged battery! While this only signifies the very early stages of the data collection process, interesting and important findings are already being produced. Figure 3 presents two images of Wetland 14; the first taken in August 2020 (top), and the second taken recently in January 2021 during an active fire. This comparison shows the scale to which fire has affected the wetland in addition to quantifying the amount of mahampy that may have been lost or damaged. Findings like these can help inform future management actions such as allocation of resources for restoration and identify regions more susceptible to fire.
Fires are a natural occurrence in this part of Madagascar. It is also frequently used for agricultural purposes to clear forest and brush for grazing pasture, a process known locally as Tavy. Consequently, the frequency and magnitude of the fires experienced in the region seem to be increasing. Furthermore, fire is frequently used for agricultural purposes SEED are hoping to extend the uses of drones to identify fires and map the extent of the damages to accurately understand and quantify how fires in the area are changing, and to identify what can be done to mitigate the impacts. While the global pandemic has provided many challenges, SEED’s engagement with using ever-evolving methodologies such as drones to aid ongoing and future research is helping to enhance understanding of a variety of issues. Drones present the next exciting step in this evolution and it is hoped that their varied applications will prove incredibly helpful for future research.
- Bamford, A. J., Razafindrajao, F., Young, R. P., & Hilton, G. M. (2017). Profound and pervasive degradation of Madagascar’s freshwater wetlands and links with biodiversity. PLoS One, 12(8), e0182673.
- Clarkson, B. R., Ausseil, A. G. E., & Gerbeaux, P. (2013). Wetland ecosystem services. Ecosystem services in New Zealand: conditions and trends. Manaaki Whenua Press, Lincoln, 192-202.
- Guo, Z., Zhang, L., & Li, Y. (2010). Increased dependence of humans on ecosystem services and biodiversity. PloS one, 5(10), e13113.
- Jiménez López, J., & Mulero-Pázmány, M. (2019). Drones for conservation in protected areas: present and future. Drones, 3(1), 10.
- Strayer, D. L., & Dudgeon, D. (2010). Freshwater biodiversity conservation: recent progress and future challenges. Journal of the North American Benthological Society, 29(1), 344-358.
- Tickner, D., Opperman, J. J., Abell, R., Acreman, M., Arthington, A. H., Bunn, S. E., & Young, L. (2020). Bending the curve of global freshwater biodiversity loss: an emergency recovery plan. BioScience, 70(4), 330-342.