Travel Reference
In-Depth Information
The Amazon: a guide to the issues
The Amazon rainforest is the largest and most biodiverse tropical forest on
Earth. It is culturally diverse too: home to over 300,000 indigenous people,
some still isolated, speaking over two hundred languages. Many Brazilians
react with outrage at being lectured on the preservation of the Amazon
and the protection of native peoples by North Americans and Europeans.
Justifiable as Brazilian accusations of hypocrisy may be, they cannot hide the
fact that there is a real environmental crisis in the Amazon. It has increasingly
high visibility as an issue inside Brazil as well as abroad, and as climate
change moves up political agendas in Brazil as elsewhere, there is now real
momentum for reform - and some grounds for hope.
The Amazon contains one fifth of the world's fresh water, sustaining the world's largest
rainforest - over six million square kilometres - which in turn supports millions of
animal and plant species, many of them still unknown. At the heart of the forest, the
Rio Amazonas is a staggering 6500km from source to mouth. About seventeen percent
of the Brazilian Amazon has been deforested, mostly in the last forty years, and at least
as much again has been affected by selective cutting of trees and other environmental
stresses, like over-hunting.
Lands and rivers
The Amazon is generally thought of as flat, steamy, equatorial forest. This is
misleading - it has mountains, parts of it suffer droughts, and by no means all
of it is jungle. Around twenty-five percent of the Amazon is actually savannah,
known in Brazil as
cerrado
, and concentrated in a vertical band through the central
Amazon from Roraima to southern Mato Grosso, where soil and rain conditions are
markedly dry. Between five and ten percent of the Amazon, depending on the time
of year, is
várzea
(flood plain), a zone of marshes, lakes, wetlands and annually
flooded forest (
igapó
) that is the most varied and among the most biodiverse of
the Amazon's ecosystems; it's also one of the most threatened, since for historical
reasons all of the Amazon's larger cities and most of its human population are
concentrated on the flood plain. But the bulk of Amazonian forests are
terra firme
(upland) that never flood; upland forest topography is typically made up of gentle
hills and occasional steep escarpments. The Amazon also has a long
coastline
, where
mangroves alternate with sand dunes, and the largest and most ecologically complex
river estuary in the world.
Amazonian rivers
are equally varied. There are three main river types. The Amazon
itself is laced with
sediments
scoured from the Andes giving it the colour of milky
tea or coffee; other rivers of this type include the Madeira, Juruá and Purus.
Blackwater
rivers drain granite uplands with few sediments, and are stained black by
chemicals released by decomposing vegetation; they are much poorer in nutrients
and have much less aquatic biodiversity as a result, but have the side benefit of
being blessedly free of insects in general. Rivers of this type in the Amazon include,
as the name suggests, the Rio Negro, but many other smaller rivers, like the
Arapiuns near Santarém. The third type of river drains areas between these two
extremes and is the most beautiful of all, with a blueish-green colour; the Tapajós is
the largest river of this type.
