Mapping vernal pools

The development of a mapping method for vernal pools using LiDAR and multispectral satellite images
– CERFO – Centre d’Enseignement et de Recherche en Foresterie de Sainte-Foy
Jean Fink, biologist; Mathieu Varin, geomatician, M.Sc.; Philippe Bournival, forestry engineer, M.Sc.; Martin Dupuis, professor, M.Sc., Céjep de Sainte-Foy

Vernal pools, also called seasonal ponds or temporary wetlands, perform many ecological functions. Unstable because of their short hydroperiod, they are formed by a depression in the land where water temporarily accumulates on a seasonal basis. They are specialized wildlife habitats due to their isolation from water systems. This gives them an increasingly recognized importance, especially as breeding habitats for invertebrates, amphibians and reptiles. Vernal pools are also used by waterfowl for food, especially in the spring. Some species at risk are also known to inhabit these environments or at least use them. It is important to identify all species at risk to ensure their adequate protection and maintain their ecological functions. Vernal pools are small in size (<0.1 ha) and temporary, making them difficult to identify and therefore protect. They are usually mapped by photo interpretation, a tedious and expensive technology when applied regionally. Often hidden by the forest canopy, they are difficult to spot despite the use of pictures taken during the spring, when leaves still aren’t present. One approach for identifying vernal pools quickly is the use of semi-automated satellite imagery which has the potential to accurately map them, and ultimately, make sure they are taken into account in biodiversity conservation strategies.

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