Why is this a fragile environment?

http://www.youtube.com/watch?v=9e7nAQ41HX0&feature=player_embedded

Case Study Asa Wright Nature Centre, Trinidad, West Indies. Aims to preserve special or precious areas as a result of their wildlife, scenery, remoteness or culture. Built in 1967 in the Upper Arima Valley which cuts into rainforest in the Northern Ranges of the Island. It was built to preserve the fragile rainforest ecosystem in the area. Species lists for this island are impressive, including 97 native mammals, 400 birds, 55 reptiles, 25 amphibians, and 617 butterflies, as well as over 2,200 species of flowering plants. To educate people to increase their understanding and appreciation. The nature centre aims to promote public awareness of the importance of the rainforest by allowing 2000 guests to visit a year. The tourists can use 5 designated trails within the area and local guides teach tourists about the value of the wildlife in the area. The centre is of particular interest to birdwatchers due to the 400 species that can be found including cuckoos, toucans and parrots. Minimises impact on and damage to environment and local community. Only 10% of the site is accessible to tourists. The remainder is protected so wildlife is left undisturbed. Maximises local involvement – local control and benefits. Staff members are mostly local and are given education and training. They are also offered interest free loans to help with building and renovating their homes. Prevents leakage and creates a multiplier effect