This spring I have been checking in with my local temperate rainforest fragments in South Devon. They are places I associate with damp air, water trickling from stones, and the quiet hum of the thriving epiphytes- plants that grow on other plants -that characterise Britain’s remaining patches of temperate rainforest. But this past few weeks something is changing. The ferns drooping from the tree branches are what I can only describe as ‘crispy’. The air feels parched. And now I’m asking: what does drought mean for a habitat defined by rain?
A Rare and Vulnerable Habitat
Temperate rainforests in the UK are rare, fragmented, and often overlooked. Found on the western seaboard—places like Dartmoor, the Lake District, and the Atlantic coast of Scotland—they depend on high humidity and consistent rainfall. The bryophyte- moss, liverwort, lichen, and fern -communities here are globally significant, with some species at the southern edge of their range. These forests support myriad life forms, from lungwort lichens to pied flycatchers, and play a vital role in carbon storage and water regulation.
But these ecosystems are extremely sensitive to changes in moisture. And this year, they are showing visible signs of drought stress.
The Data Behind the Dry
According to the Met Office, England had only 21% of its long-term average rainfall in March 2025, with the southwest (where Dartmoor lies) receiving just 11%. River flows across the region have dropped, and groundwater levels remain below normal. The Environment Agency’s February water situation report noted that rainfall for the past six months was just 74% of the long-term average in Devon and Cornwall.
Local Weather Snapshot: Teignmouth, South Devon
(Based on Teignmouth Weather Station Data – Feb to early April 2025)
🌧️ Rainfall & Soil Moisture
- While February had a normal amount of rainfall, March was notably dry.
- Soil moisture at 10cm depth has dropped into the “dry to bone dry” range (>100), indicating drought conditions in the upper soil layers.
- April (to date) has brought only minimal rainfall, insufficient to restore soil moisture to normal spring levels.
💧 Humidity & Dew
- Relative humidity has shown a slight overall decline since February, especially during settled, sunny periods.
- Leaf wetness data suggest reduced dew and fog formation—limiting overnight moisture that bryophytes and epiphytes rely on.
This isn’t an isolated event. Climate change is making dry springs more frequent, and even the rainiest corners of the UK are not immune. A Met Office analysis confirms that “there is an increasing risk of multi-season droughts in the UK due to climate change”.
Lessons from the Southern Hemisphere
If we want to understand what’s at stake, we can look to other temperate rainforest regions. In southern South America, researchers have modelled the impacts of declining rainfall on evergreen rainforests in Chile. The results are sobering: up to 27% reductions in above-ground biomass and 15% drops in evapotranspiration for old-growth stands are predicted under future drought conditions. These ecosystems, like ours, rely on continual moisture input to maintain structure and function.
While the species differ, the processes are strikingly similar. The modelling highlights how reduced rainfall alters soil moisture and plant productivity, leading to changes in forest composition, canopy dynamics, and carbon cycling.
Could the same be happening—quietly, gradually—in our own ancient woods?
Seeing the Signs
Drought stress isn’t always dramatic. Trees may survive several dry years without immediate dieback, but bryophytes, ferns, and lichens often show the earliest symptoms. These organisms lack deep roots or protective cuticles, making them excellent indicators of microclimatic shifts.
In the photos I took this week, curled moss leaves and faded greens hint at water scarcity. We know these responses are reversible—if rain returns. But what happens when dry springs become the norm?
Time to Pay Attention
Temperate rainforests are often associated with resilience, but they are not immune. Their dependence on consistent rainfall makes them vulnerable in a changing climate. Monitoring visible signs—like bryophyte health—can help us detect ecological stress before it cascades into broader declines.
More research is needed into how these habitats are responding to drought, and what we can do to support them. Restoration, connectivity, and hydrological resilience must become priorities.
Because a rainforest without rain isn’t just an oxymoron—it’s a warning.
Sources:
- Met Office. UK and Global Extreme Events – Drought. Link
- Environment Agency (2025). Water Situation Reports – England & South West
- Gutiérrez, A. et al. (2014). Increased Drought Impacts on Temperate Rainforests from Southern South America. PLoS ONE
- University of Leeds (2023). Climate change threatens rare temperate rainforests. Link
Moor Questions 