When we talk about the conservation of rainforests, our minds often drift to the Amazon rainforest of South America, or the tropics of central Africa or Southeast Asia. Yet, closer to home, temperate rainforests are equally deserving of our attention and protection.
These internationally rare habitats are increasingly recognised as important ecosystems which might aid us in conservation of biodiversity and attempts to mitigate climate change. How and where we restore these rainforests should concern us all.
What are temperate rainforests?
Temperate rainforests are woodlands which support humid environments in temperate zones, allowing plants to grow on substrates with no or minimal amounts of existing soil (e.g. epiphytes) such as the bark of trees and other surfaces (e.g. rocks).
Temperate rainforests are consequently characterised by verdant growth of specialist arboreal lichens, bryophytes (mosses and liverworts) and ferns, communities which thrive in moist and mild environments.
Temperate rainforests, although less studied than their tropical counterparts – are known to be key hotspots for biodiversity, important habitats for long term carbon storage, and ecosystems which might help us mitigate the worst effects associated with climate induced river drought and flooding.
Rainforest conditions have previously been characterised as requiring:
- greater than 1,400 mm annual precipitation, with 10% or more occurring during the summer months
- cool frequently overcast summers with July isotherm < 16oC
- minimal temperature fluctuations with year-round mild temperatures.
Understanding of where temperate rainforest sites can be found and how quickly they might develop are still developing with differences in character across their range. For example, within UK it is thought that mean temperature of the coldest month being no lower than 2oC is an important additional defining criteria for their potential extent (Averis 2023).