Assessing the impact of oilfield development on native grassland ecosystems with remote sensing

The native grassland ecosystems in the Canadian prairies, which have been reduced to remnants, continue to be threatened partially as a result of human activities such as agriculture and a significant increase in oilfields from oil exploration and production. The development of oilfields on grasslands often leads to the fragmentation and conversion of native grassland vegetation into oilfields. This is still an increasing trend with newly established oilfields and some of them becoming inactive. The total area occupied by the oilfield is relatively small, but the fragmentation and the effects on vegetation and soil at local and landscape levels for the ecosystem can be significant but are not fully understood. The research focused on understanding the effects of oilfields on native grassland ecosystems with remote sensing techniques, using Monet pasture in the mixed-grass ecoregion of Saskatchewan as the study site. Furthermore, the oilfields were identified and extracted from remotely sensed data using object- and pixel-based image analysis procedures. The spatio-temporal changes of oilfield disturbances in grasslands (over a period of 6 years) were also evaluated, and the local effects of oilfields in grassland were investigated using spectral vegetation indices derived from satellite images to assess vegetation and bare soil changes. The results indicated that a total of 48, 68, and 76 oilfields (distributed within 8 categories: abandoned, active, cased, completed, planned, preset, suspended, and uncategorized) were identified and extracted for the periods of 2016, 2019, and 2022, respectively, in the study area. Out of all the categories, the active oil well was sufficiently extracted. The area covered by the linear and non-linear oilfields increased by 101.6% and 119.1%, respectively (2016–2022). The grassland vegetation cover and water content at varying distances further away from the active oilfields increased and decreased in the study area; variations were observed at different distances (5–50 metres and 10–200 metres) further away from the active oil well and oil road in the years considered. This study will enhance the sustainable management of grasslands. It will also help researchers and grassland managers understand how to effectively identify and monitor oilfield disturbances in grassland ecosystems