Архитектура Аудит Военная наука Иностранные языки Медицина Металлургия Метрология
Образование Политология Производство Психология Стандартизация Технологии


Cloud Forests Fading in the Mist, Their Treasures Little Known



 

Cloud forests are nature's "water towers", providing billions of gallons of fresh, clean, filtered water. They are home to thousands of indigenous peoples, and storehouses of biodiversity, at least 80 per cent of which has not yet been catalogued. Yet in as little as ten years' time, biologists warn, the world's cloud forests – evergreen mountain forests that are almost permanently shrouded in mist and clouds – may be all but gone.

Cloud forests are under pressure: they are being cleared for cattle grazing and coca plantations, logged to provide fuel for heating and cooking, paved over and developed to make way for transportation and telecommunications networks. They are being damaged and dried out by air pollutants and global warming. Hunting, tourism and recreation, road building, mining, and geothermal development schemes further add to the pressure.

Now, when about 90 per cent of mountain forests are thought to have disappeared from the northern Andes, in South America, cloud forests are rising to the top of the world's scientific and conservation agenda. But will scientists learn enough about these important ecosystems to be able to convince the world to conserve them before they are gone forever?


Cloud forests are disappearing at such a rate that the cloud forest will all be gone in the next ten years. Yet scientists have barely begun assessing the wide range of species that clod forests harbour.

Now scientists are working with NASA, using satellite images to get some idea of what is there before it is gone.

Cloud forests are broadly defined as forests that are frequently covered in clouds or mist. They are found in tropical and subtropical mountainous regions of the world, where cooler temperatures on mountain slopes cause clouds to form.

In Central and South America, cloud forest stretches from Panama to northern Argentina. It is the belt between the jungle and the highlands and, as such, is narrow and delicate. It is also known as the eyebrow of the jungle. In total, 605 cloud forests in 41 countries have been identified. Most of them are in Latin America, especially Venezuela, Mexico, Ecuador, and Colombia.

On continental landscapes, cloud forests are found on mountains in the tropics, in areas that receive 500 to 10 000 millimetres of rain a year at 2000 to 3 500 metres above sea level. In exceptionally humid equatorial conditions – on oceanic islands, such as in the Caribbean and Hawaii – a cloud forest zone may develop on small and steep island mountains at elevations as low as 500 metres. The trees in cloud forests are generally 15,2 to 18,3 metres tall at lower elevations and much shorter and mossier at higher elevations.

The trees perform a crucial hydrological function. They strip water from windblown fog and clouds, aiding the healthy functioning of surrounding ecosystems. They are important for capturing water from clouds, which provides water downstream to industry, towns, and regions. And the importance of cloud forests to the year-round provision of fresh water cannot be overestimated. Many mountainside trees filter the water that feeds the headwaters of river systems. Cloud forests, however, capture water that would otherwise never fall to the ground as rain.

The extra water from this cloud-stripping effect amounts to 20 per cent of ordinary rainfall. In mossy forests that are particularly exposed to the elements, the extra water-trapping capacity can be as much as 60 per cent.

The cloud forest in La Tigra National Park in Honduras, for example, supplies 40 per cent of the water consumed by the 850 000 residents of Tegucigalpa. In Tanzania, the cloud forests of the Udzungwa mountains provide water needed to operate the hydroelectric dams that supply power to Dar es Salaam. The provision of abundant, fresh water ought to be reason enough to conserve cloud forests.

But these forests are also important because they are rich in biological diversity, and most of the species in cloud forests are believed to be still unknown to science.

Many cloud forests serve as refuges for endangered species, which are being marginalized by the transformation and destruction of ecosystems at lower
elevations. Large numbers of bird species and mammals, such as the spectacled bear and howler monkeys are dependent on cloud forest habitat for their survival.

In southern Peru ethnobiologists have found 30 000 to 40 000 plants more than a thousand of which are orchids. That amount only begins to scratch the surface. In a small area the size of Machu Picchu, we can find the same plant diversity as on the whole continent of Europe. So far scientists have described only 20 per cent of the species that live in this almost vertical landscape.

Much of the biodiversity found in cloud forests is endemic – it can be found nowhere else. For example, most of the shrubs, orchids, and insect-eating plants found on the Cerro de la Neblina in Venezuela are unique to the mountain's summit. And scientists say, there are different species found on each mountain range.

If managed sustainably, cloud forests can provide a wide range of valuable products and services to people in the surrounding area: fuel wood, timber, and food and medicine. Cloud forests protect watersheds as they maintain ground cover and minimize soil erosion. They are also important for climate regulation.

Biologists try to raise public awareness of the need to conserve cloud forests and obtain funding for conservation strategies, such as establishing private reserves and national parks. To achieve the conservation of remaining cloud forests before any more of these rare and valuable habitats are lost for good immediate action is required. Meanwhile, scientists are dedicated to documenting the diverse life of cloud forests and the traditional way of life of people who inhabit them, before the forests are gone.

John Roach. National Geographic News. 2001

 

 


Поделиться:



Последнее изменение этой страницы: 2019-04-19; Просмотров: 222; Нарушение авторского права страницы


lektsia.com 2007 - 2024 год. Все материалы представленные на сайте исключительно с целью ознакомления читателями и не преследуют коммерческих целей или нарушение авторских прав! (0.012 с.)
Главная | Случайная страница | Обратная связь