Agriculture in the Boreal Forest: Understanding the Impact of Land Use Change on Soil Carbon for Developing Sustainable Community Food Systems

Abstract:

Climate change is causing rapid warming at northern high latitudes and disproportionately affecting ecosystem services that northern communities rely upon. In Canada’s Northwest Territories (NWT), climate change is impacting the access and availability of traditional foods that are critical for community health and well-being. With climate change potentially expanding the envelope of suitable agricultural land northward, many communities in the NWT are evaluating including agriculture in their food systems. However, the conversion of boreal forest to agriculture may degrade the carbon rich soils that characterize the region, resulting in large carbon losses to the atmosphere. Here we summarize the results of 30 publications that address land use change from boreal forest to agriculture. Our goal was to synthesize how land use change from forest to fallow, cropland or grassland affects soil carbon. We also present preliminary results assessing variation in soil carbon stocks for two communities in the NWT who are interested in including agriculture into their food system. We collected 192 soil cores from these two communities to determine carbon stocks along gradients of potential agriculture suitability. Our literature synthesis shows that conversion of boreal forest into fallow, cropland or grassland is associated with a decline in mean soil carbon stocks of up to 88%, 34% and 64% respectively, with cumulative maximum declines occurring between 10-20 years after land use change. Our field soil carbon measurements in collaboration with NWT communities show that land use conversions associated with agricultural development could translate to carbon losses ranging from 2.7-11.4 kg C/m² depending on the type of soil, agricultural suitability class, and land use change associated with cultivation. These results highlight the importance of managing soil carbon in northern agricultural systems and can be used to emphasize the need for new research on agricultural land use change in the NWT. As communities look to expand agricultural production to build resilience into their food systems, agricultural practices have to be implemented to maintain ecosystem services such as soil carbon retention and maintaining the culturally important traditional food system.