Manu National Park Expeditions

Manu National Park Expeditions

Globally, tropical cloud forests are at least as threatened as lowland rainforest, and, in some places, probably more so. This threat comes from the same sources that attack lowland forests: commercial logging, the expansion of subsistence agriculture, the exploitation of forest products, and cropland clearing for coca plants. Added to this is a rise in the number of human-caused fires due to the increased human activity. In addition, this higher degree of human activity has presented threats from introduced plants and animals.

The ecological importance of cloud forests comes from their function as watersheds and for their unique biodiversity. This means their value should be considered equally alongside that of lowland rainforest. Cloud forests too are in need of the development of comprehensive conservation and management plans for sustainable use

RIVER BEACHES  .Manu National Park Expeditions

A vast tonnage of sediments is washed from the Andes and carried by the tributaries and Manu. These sediments are often deposited along the river edge or as bars in the river itself. As Andean sediments are rich in nutrients, it does not go uninhabited for long. The deposited area is subject to colonization by pioneer plant species typical of early succession. Quick invasion takes place by various plant species, which can often become sufficiently dense to stabilize the soil. Sandbar scrub is composed of a low diversity of fast- growing colonizing plant species that typically makes it dense.

It is common to see one side of a river bend formed from a high clay bank covered in canopy forest. Away from the brunt of the current, the opposite side consists of a sandy beach during the dry season, behind which is a gradually rising slope of vegetation. When floods strip an area and then beach formation fills the gap, the first invading vegetation of the elevated section is herbaceous annuals and rapidly-growing trees, for example the genus Tess aria. After a period of three or four years, small groves of Tess aria will be formed 10 meters (30 feet) high.

Then these groves are themselves subject to gradual invasion by thickets of bamboo-like cane, or caña brava (Gynérium sagittum). This is a monocot or grass-relative which uses a vegetative root to propagate itself. Following the process of a predictable progression, gradually the Tessaria grove will die out as the Caña brava takes over, eventually forming dense thickets of its own. Once established, the Caña brava faces slow invasion by pioneer forest plants such as the rapidly-growing genus Cecropia. In time the Cecropia trees will form their own canopy. This canopy is about 15-18 meters (45-55 feet) high. Underlying Caña brava is killed by the shade from this canopy. Cecropia is short-lived, however, and it too succumbs. This opens up light gaps, which a number of other forest species are ready to exploit rapidly. Many of the trees that punch through the low canopy are much longer lived in comparison to the Cecropia and eventually form a new canopy layer, this time 40 or more meters ( 120 feet +) above the ground.

The seasons revolve and the river will gradually snake away. The rate of forest change on the once inundated land also continues, albeit at a much slower pace. The process may take half a millennium or more to complete, but eventually, from its origins of small annual herbs, a «climax» forest community is reached. That is, a forest in which the relative composition of species remains more or less the same.

Unique habitats are provided by the sand beaches. They are nesting sites for many species of animals such as Caimans, Turtles; and for birds such as Black skimmers, two species of Terns, Sand-colored Nighthawks, and Orinoco Geese

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