Today is International Mountain Day (IMD), and the theme of this year's celebration is 'mountain biodiversity'. Since 2003, IMD has been observed every year on 11 December to raise awareness on the importance of mountains for life. Mountains supply half of the world’s population with freshwater and host about half of the world's biodiversity hotspots. Approximately 75 percent of the world’s accessible freshwater comes from forested watersheds, among them Tropical Montane Cloud Forests (TMCF) are particularly important for water security

TMCF can be found in high altitude areas with high rainfall and are frequently covered in clouds or mist. The presence of clouds not only increases the water inputs from fog capture but also reduces loss via evapotranspiration. Due to their high altitude and high humidity, cloud forests regulate water supply, ensuring continuous high-quality water for communities and landscapes downstream.

TMCF are also important for biodiversity. Because cloud forests are naturally fragmented, they are characterized by high species richness and endemism, including a great diversity of epiphytes and insects, and are thus considered priority hotspots for biodiversity conservation.

Cloud forests are rare ecosystems, covering an area ranging from 1 - 14 percent of the total area of the world’s tropical forests. Unfortunately, these forests are under threat and risk being lost. Land cover change, illegal logging and cattle grazing are among the most common threats to cloud forests, resulting in forest degradation and deforestation. For example, in Veracruz, Mexico the area of TMCF decreased to almost half of their original surface during the period between 1973 and 2003 due to land cover changes. 

Their limited range and fragmented distribution means that TMCF are also highly affected by climate change. Increasing temperatures and changes in cloud distribution and precipitation patterns have a huge impact on cloud forests, resulting in biodiversity loss and affecting their ability to supply water.

Source: Global potential (red) and known (green) TMCF distribution. Reproduced from Bubb, P., I. May, L. Miles, and J. Sayer, 2004: Cloud Forest Agenda, UNEP-WCMC, Cambridge, UK. [Available online at http://www.unep-wcmc.org/biodiversity-series-20_105.html].

The conservation and restoration of TMCF are extremely important for preventing biodiversity loss and ensuring water supply for communities. Initiatives to protect and restore cloud forests exist, but efforts need to be scaled up. The Cloud Forest Blue Energy Mechanism, for example, aims to restore 60 million hectares of TMCF in Latin America, which will result in around 2.4 gigatonnes of carbon dioxide stored, and the creation of a green infrastructure opportunity worth around USD 30-40 billion for hydropower. Therefore, restoring and conserving cloud forests provides a range of benefits, improving social and economic well-being.

For more information on mountains and their forests, please check:

-  The International Mountain Day website. Access the history of IMD, key messages, tool kits and celebration events around the world.

- The Mountain Partnership, United Nations voluntary alliance of partners dedicated to improving the lives of mountain peoples and protecting mountain environments around the world.

- The Forest and Water Programme raises awareness on the importance of forest-water relationships, and provides guidance on how to manage forests for water.

- The latest worldwide news on mountain-related topics.