A novel methodology to characterize and quantify regional farmscape non-production perennial vegetation carbon storage and potential for loss in Southwest British Columbia

Abstract

Temperate zone agriculture landscapes are often comprised of both croplands and non-production perennial vegetation (NPPV). The latter provides ecosystem services (ES), of which carbon sequestration is one. Estimation of aboveground carbon stocks in NPPV has incentivized carbon storage within the agricultural landscape. Remote sensing has significantly improved resolution of earth imaging and automated assessment of these often small, fragmented NPPV parcels. Novel methods of assessment have also been motivated by changes in land policy and concomitant loss of NPPV carbon stocks. To characterize and evaluate the carbon storage potential of agricultural NPPV in Southwestern British Columbia, we utilized a compliment of remote sensing and secondary data sources. Object- and pixel-oriented classification with RapidEye imagery enabled mapping of NPPV at 92.9% accuracy, covering 33.2% of the landscape. NPPV provided 3.34 Mt C in aboveground biomass, 38.4% of which was composed of fragments unlikely to be identified through coarser satellite imagery. Using secondary soil surveys and sub-regional characteristics, indicators of agricultural expansion suggested that small parcels of NPPV were more likely to persist on active farmland, while large forest stands (> 9 hectares) were less likely to occur alongside lands already in production and often located on lands amenable to farming. Were these large contiguous tracks of NPPV cleared for production agriculture, we estimate that 0.98–1.86 Mt of stored carbon could potentially be released. These stands represent important carbon sinks and their retention could be incentivized through ES services remuneration and conservation programs.