Elevated CO interacts with nutrient inputs to restructure plant communities in phosphorus-limited grasslands.

Globally pervasive increases in atmospheric CO and nitrogen (N) deposition could have substantial effects on plant communities, either directly or mediated by their interactions with soil nutrient limitation. While the direct consequences of N enrichment on plant communities are well documented, potential interactions with rising CO and globally widespread phosphorus (P) limitation remain poorly understood. We investigated the consequences of simultaneous elevated CO (eCO ) and N and P additions on grassland biodiversity, community and functional composition in P-limited grasslands.

Sub-arctic mosses and lichens show idiosyncratic responses to combinations of winter heatwaves, freezing and nitrogen deposition.

Arctic ecosystems are increasingly exposed to extreme climatic events throughout the year, which can affect species performance. Cryptogams (bryophytes and lichens) provide important ecosystem services in polar ecosystems but may be physiologically affected or killed by extreme events. Through field and laboratory manipulations, we compared physiological responses of seven dominant sub-Arctic cryptogams (three bryophytes, four lichens) to single events and factorial combinations of mid-winter heatwave (6°C for 7 days), re-freezing, snow removal and summer nitrogen addition.

Arctic greening and browning: Challenges and a cascade of complexities.

Arctic greening (the increase in plant biomass and productivity at high latitudes) is one of the clearest large-scale vegetation changes seen in recent decades. However, despite being the subject of considerable research effort, our understanding of this phenomenon is far from complete. Challenges around remote sensing, process based understanding, and the spatial and temporal heterogeneity of greening-including the opposite process of Arctic browning-challenges our ability to model and predict Arctic vegetation change and its biogeochemical consequences.