Impacts of 3 °C Warming on Agronomy and Greenhouse Gas Emissions in a Northern Norwegian Meadow – Ecosystem Manipulation Experiment.

Boreal and arctic terrestrial ecosystems are central to the climate change debate, because future warming is expected to be disproportionate as compared to world averages. Likewise, greenhouse gas (GHG) emissions from terrestrial ecosystems exposed to climate warming are expected to be the largest in the arctic zone. Artic agriculture is a unique and economically relevant feature of Northern Norway (e.g. Finnmark Province). We conducted an ecosystem warming experiment on a meadow at Eastern Finnmark, NE Norway.

The experiment was established during summer 2013 by ploughing and reseeding the site with a mixture of common meadow grasses (Phleum pratense, Festuca pratensis L., Poa pratensis L.) and clovers (Trifolium pratense L., Trifolium repens L). A normal agricultural practice for the area  was applied. Five out of 10 circular plots (3.6m diameter) are warmed to be 3 degrees higher than the ambient with infrared heaters. The experimental design is a randomized split plot design where half of each main plot is amended with biochar to study its potential for mitigating the anticipated warming effects.  During 2014 and 2015 we have intensively measured the carbon, nitrogen and GHG dynamics, as well as various soil parameters (including pH, nitrate and ammonium concentrations) and vegetation parameters  (including species composition, dry matter production, herbage quality and canopy dynamics of the sward (using Normalized Difference Vegetation Index (NDVI)-imaging)).     

Based on preliminary data analyses, most pronounced effects of the warming are on vegetation parameters whereas the changes in carbon dynamics are small and non-significant.  Warming of the arctic meadow resulted in shifted species composition so that the percentage cover of clover species is now higher in warmed plots than in control plots. The total annual dry matter yield was also increased by warming; more so in the 2^nd than in the 1^st year after the establishment of the vegetation.