Northward shift of agriculture: opportunities and challenges
Why northern agriculture?
Key points
- Agriculture-feasible areas in the boreal zone might treble by the end of the 21st century.
- Latitudinal shifts, rather than altitudinal shifts, dominate the projected global expansion – particularly at higher latitudes (>50° N).
- Such a trend could be transformational to local land use if this potential is acted upon.
- Temporal variation may complicate short-term development and planning; inner-continental regions are more likely to see non-linear change, with regular cooling and warming cycles.
- These patterns underline the need for both short- and long-term planning, and for locally relevant approaches to any proposed expansion.
A critical risk
Boreal expansion of agriculture may occur in advance of the understanding and assessment needed to: (1) mitigate climate risks; (2) be environmentally sustainable; (3) identify and address the best cropping options; (4) address key elements of food security; and (5) consider the concerns, desires, needs, and constraints of local communities.
Context
Climate change increases the growing degree-days in boreal ecosystems, prompting considerations of land-use conversion (LUC) for agriculture. If climate predictions are realized, current breadbaskets may no longer sustain the demands of present and future populations – increasing demand for arable land in cold climates and accelerating northern land-use conversion and intensification (LUC/LUI).
The most common soils in the wet, cool circumboreal region are Podzols. In Canada their cultivation is common only in eastern Canada and some coastal areas of British Columbia, mostly in areas traditionally considered unsuitable for agriculture. In Newfoundland and Labrador – a region whose agriculture is fully based on converted boreal lands – 55% of soils are Podzols, of which 44% are Ferro-Humic Podzols. Converted Podzols have limited agronomic productivity due to their water-holding capacity, low organic matter, and coarse parent material. During conversion the organic surface horizons and the Ae horizon are often removed, so the resulting Ap horizon may largely reflect a podzolic B horizon. Re-purposing formerly abandoned lands is another option, but non-tilled soils may undergo partial re-podzolization, altering soil layers even before full podzolic horizonation is evident.
Altered precipitation will affect runoff, drainage, soil moisture and nutrient kinetics. With LUC, the major impact of agriculture is the risk to watersheds – especially from soluble nutrients including nitrogen and even water-soluble phosphorus. Replacing a natural boreal forest with an agroecosystem increases nutrient demand as soil organic matter is depleted, altering biochemical cycles and affecting the soil’s capacity as a sink or source for carbon and nutrients. Specific to Podzols, LUC favours phosphorus fixation as aluminium and iron phosphates, increasing the need for fertilization.
Challenges
- Heterogeneity in socio-economic and environmental conditions between and within regions (e.g. between Fennoscandia, the Canadian prairies or Russia, or between Canadian provinces and territories).
- Growing urban populations.
- Fragmented research-support systems, development models and policies that focus on regional and local concerns while neglecting global challenges.
Critical knowledge gaps concern whether and how northern regions can incorporate, adapt or develop practices as the northward shift of the agricultural zone allows expansion, intensification and diversification. Development must account for divergences between sustainable-development goals – food security and self-sufficiency, climate-change mitigation, and biodiversity – and requires site-specific, long-term agricultural experiments that are currently scarce in the north. Wherever expansion is deemed necessary, development ought to guarantee locally adapted plant varieties and sustainable agro-ecological and soil-management practices – for example, converting marginal lands naturally low in organic matter to promote net carbon fixation, while protecting organic-carbon-rich peatlands.