Use of multi-temporal remotely sensed data for monitoring land reclamation in Sudbury, Ontario (Canada)

The industrial mining activities, conducted in the Sudbury area (Ontario, Canada) over the last 100 years, have had a significant environmental impact on the local ecosystems in the region. These impacts include habitat disturbance due to mine development, the impact of acid-generating tailings, and the effects of airborne pollution from smelting activities. The natural vegetation in the region was seriously affected, resulting in the loss of a significant portion of the vegetated cover and leading to soil erosion. As most mining regions, the city of greater Sudbury was faced with the challenges of restoration for the areas with significant ecological damage. Towards the end of the seventies, an ambitious Regional Reclamation Program was initiated for re-vegetating affected regions. Areas with significant disturbance and barren regions were limed to reduce soil acidity and immobilize metal contaminants. The planting of mixed grasses, trees and shrubs followed this process. The major species of interest were pines (Pinus resinosa, P. strobus, P. banksinana), birch (Betula papyrifera) and trembling aspen (Populus tremuloides). Planning ecological restoration activities and monitoring the results of these activities can be time consuming and expensive relying on field measurements alone. Multi-temporal remotely sensed imagery provides extensive repetitive coverage over large areas, with valuable geospatial and biological information. In this study, a multi-temporal data set of six Landsat TM images spanning a period of 20 years, was used to monitor the status of the vegetation cover, evaluate the success of the restoration program, and provide a base of information for the long-term monitoring of restored sites. In this study, a set of environmental indicators was developed for characterizing the vegetation status at selected restoration sites. Indicators, such as the Normalized Difference Vegetation Index (NDVI), Leaf Area Index (LAI), canopy crown closure and land cover type, were used to identify the status of the vegetation over time. The changes of the environmental indicators were monitored during the 20-year period and the progress (or lack of) of the vegetation at each restoration site was assessed. The information, derived from the multi-temporal data set, was stored in a geographic information system (GIS) for evaluating the success of the re-vegetation efforts. The results of the study indicate that as the soil and atmospheric conditions improved, the vegetation cover showed reasonable expansion in size for a larger number of restoration sites. Fewer restoration sites showed either no progress or rather a negative progress. The results, obtained from the analysis of the satellite data, showed reasonable agreement with the field measurements. Thus far, our preliminary results show that multi-temporal remote sensing data can produce useful information about the health of vegetation in the restored areas that are key in evaluating the success of the restoration program in Sudbury. The city of Sudbury will significantly benefit from the comprehensive study and make useful and informed decisions concerning the overall reclamation program.