Managed by the Centre for Ecology and Hydrology, this experiment was established in 1998, in Clocaenog Forest, North East Wales. The site uses simulated drought and warming treatments to test the effects of predicted climate change over the next 20-30 years on upland heathland ecosystems.

Upland heaths are of high conservation value and are important carbon stores. It is estimated that a quarter of heather-dominated heathlands have been lost since 1945.

The site is dominated by the evergreen shrub Calluna vulgaris (heather), which constitutes more than 60% of the plant biomass at the site. 

The site has high rainfall, on average 1550mm each year, and its ecosystem holds large pools of carbon.

Wytham design


The experiment uses solar and wind powered automated roof technology to produce drought and warming treatments, situated alongside procedural controls.

The drought treatments are imposed between April and October. When rainfall is detected, a plastic roof extends over the experimental plots (4m x 5m) excluding around 80% of the rainfall.  When rainfall events cease, the covers are then retracted.  

Warming treatments are imposed all year and are implemented by covering plots with a retractable aluminium mesh curtain at night. These curtains reflect 96-97% of infrared radiation, reducing night time heat loss by 64%. The warming roofs are retracted when rainfall is detected; however, due to time lags between the detection of rain and retraction of the roof, 14% of rainfall is excluded by the warming treatment. 


Please click here to download general information about the site, including site characteristics and precipitation data. For further information please visit the CEH website.