Impacts of snow season on ground-ice accumulation, soil frost andprimary productivity in a grassland of sub-Arctic Norway

摘要

Europe’s and the World’s northernmost agriculture is very vulnerable to harsh overwinteringconditions. It is important from both an economic and societal standpoint to have accurate methodsof predicting the severity and impact of the current snow season. Technology has advanced to enablesuch measurements to be regularly recorded but despite this, a detailed assessment, involving remotesensing , of the impacts of various types of snow season on agricultural yields in northernmost Europehas not previously been undertaken. Here we characterize variation in snow types and concomitantsoil frost and ground-ice accumulation at a Norwegian sub-Arctic, maritime-buffered site (Tromsø,Troms County, 69 °N) during the period 1989/90 to 2013/14 and analyse how winter conditionsaffect agricultural productivity (both measured in the field and using remote sensing). These data werethen used to build important predictive modelling approaches. In total, five contrasting types of snowseason were identified, from snow-rich with no soil frost and no ground-ice to low snow andconsiderable soil frost and ground-ice. Conditions of low snow and low soil frost and ground-ice thatresult from numerous warming events were rare within the time period studied but are predicted tobecome the dominant snow season type. Agricultural productivity was lowest and claim settlementspaid to farmers were highest after winters with high accumulation of plant-damaging, hermeticground-ice. Deep soil frost per se did not affect primary productivity. Overall, our results together withinformation from other sources, suggest that icy, low snow conditions are the most challenging of allseasonal types for both the environment and livelihoods in sub-Arctic Norway. Winters withextremely deep snow also cause considerable problems. As winters are expected to warm more thansummers, it is likely that the winter climate will become an even stronger regulator of northernprimary productivity. To better understand the physical and biological effects of the changing winterclimate, there is a requirement for continued and increasing monitoring of winter processes, especiallyrelated to frost and ice in the rhizosphere, as this is currently not well covered in national monitoringprograms. Continued monitoring will enable further refinement of predictions and will support thebetter community planning for greatest agricultural benefit.climate change, crop yield, ice, NDVI, plant mortality, snow dynamics, winter climate