Natural soil warming in natural grasslands and a Sitka spruce forest in Iceland

Jun 4-8, 2018

The 4th intensive campaign in the GN/NT seasonal survey of ecosystem traits took place (and its 7th sampling out of 8). Sara Marañón, Albert Gargallo-Garriga, Palli, Ben and Gunnhildur also did the last 15N pulse labelling experiment in the same plots.

May 15, 2018

Palli and Ben took soil samples in FN and sent to Germany for fractionation analysis by Christopher Popelau.

May 7-10, 2018

May 7-10, 2018 Niel og Khadir came to ForHot in Iceland and prepared an intensive campaign in July in TNT and fertilized the TNT plots.


On May 29, 2008, there was an earthquake in S-Iceland that measured 6.3 on the Richter scale. One of its many implications was that geothermal systems close to its epicentre were disturbed. At Reykir, one of the campuses of the Agricultural University of Iceland, one such geothermal system moved from its previous location, to a new and previously “cold” area. The new belowground geothermal channels (in the bedrock) resulted in soil temperature to increase in the new area that is ca. 4 ha in size. The soil temperature increase varies with depth down to the geothermal channels in the bedrock, and ranges from +0 °C to +52 °C where the channels/bedrock are closest to the surface. The heated area is covered by two ecosystem types: a) a planted 50 year old Sitka spruce (Picea sitchensis) forest (termed FN = forest new) and b) a natural treeless grasslands dominated by Agrostis sp. and moss (termed GN = Grassland new).

This created a natural soil warming experiment that now (2016) has lasted for eight years. This natural experiment gives a unique opportunity for ecologists to study how various ecosystem processes are affected by temperature in two ecosystem types (FN and GN). The large range in temperature elevations at the ForHot site both offer conditions similar to the predicted climate change during the next century and more extreme temperatures that can give new insights into stress physiology.

 In Grændalur, only 2,5 km away from these new geothermal areas at Reykir are similar grasslands that have been warm for a long time (termed GO = Grassland old). They have been used as a comparison to GN to study the effect of the duration of warming on the ecosystem response.

Pictures from ForHot filed sites are here