Conservation: Down to the last tree

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Conservation: Down to the last tree
Conservation: Down to the last tree
Anonim

To the last tree

The green lungs of the earth are dying a kind of smoking death, because larger and larger areas are charred in the clearing fires of international agricultural corporations. Only new ways and finally the strict enforcement of existing laws can save Brazil's rainforest. But it can be done. The list of examples of man-made natural disasters is long: it ranges from the collapse of cod stocks due to overfishing off Newfoundland, to the extinction of countless species of cichlids in East Africa's Lake Victoria due to deliberately introduced predatory fish, to the drying up of the Aral Sea in Central Asia. Its vital inflow was literally turned off by huge irrigation measures in cotton cultivation, so that it simply evaporates in the desert climate. And at the top of this list of ecological sins is of course the overexploitation of the Amazon rainforest in Brazil.

Every year up to 40,000 square kilometers fall victim to the land hunger of soybean farmers and cattle breeders, who produce cheap cattle feed and meat on their lands for the always ready markets of the industrialized countries. And despite all the appeals from politicians, scientists and conservationists, this work of destruction is not progressing any more slowly today than it was ten years ago - on the contrary: the pace even seems to be accelerating in some places, as satellite data show.

What do these developments promise for the future of the Amazon Basin? And are there ways to slow or even stop this frightening trend? After all, there is a lot at stake with the loss of what is still the largest area of rainforest on earth: from biodiversity to its influence on the global climate.

Therefore, scientists led by Britaldo Soares-Filho from the Remote Sensing Institute in Belo Horizonte, Brazil, and Daniel Nepstad from the Woods Hole Research Center in Massachusetts simulated what the region could look like under various protection and utilization scenarios by the year 2050 [1]. In their models, they took into account, among other things, the progress of road construction projects, the designation of protected areas and their actual legal enforcement and consideration, as well as the reactions and influences of international markets on products from the rainforest.

In the worst case of their two main calculations, the destruction continues as usual. Outside of protected areas, 85 percent of the areas in the Brazilian Amazon basin are being cleared, while within the designated protected areas – which cover a third of this region – there is still 40 percent. Overall, this threatens a loss of two million square kilometers of forest area, so that only just over half of the original extent would remain. Typical vegetation types such as the rather dry forest types in the state of Mato Grosso are threatened with almost complete destruction.

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Contrast this with the optimistic case where the system of parks and Indian reservations are extended to forty percent of the area and actually enforced. Outside of that, only half of the tree population falls from chainsaws and fires. In addition, the overall deforestation rate, although initially increasing after major roads are paved, is falling as the Brazilian government and local landowners recognize and better conserve the alternative monetary value of rainforests due to emerging emissions trading to mitigate global warming. If all of this actually succeeds, at least three quarters of the current forest area will be spared by 2050.

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But would it really be that bad if, in four decades, only just under half of the Amazon basin could still be called the "green hell"? This question can be answered briefly and concisely with a yes: In addition to its immense - and for the most part not yet scientifically recorded - species abundance, this primeval forest plays an important, active and passive role in global and regional climate processes. If the worst possible turn of events predicted by Nepstad and his colleagues does occur, an additional 24 to 40 billion tons of carbon dioxide could enter the atmosphere and further fuel the greenhouse effect. In any case, Brazil has already become one of the leading air polluters on the planet – because of the burning of the Amazon.

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In addition, the rainforest partly creates its own climate: Its trees evaporate so much water that every drop of precipitation is recycled several times and transported further west until it finally reaches the foothills of the Andes and from there in the rivers to the sea is transported back. But this requires closed forest areas from the Atlantic coast to the Andes, if they are perforated and broken up into small islands, the system can collapse and the rainforest can turn into grassy savannah.

This peculiarity is also reflected in studies by a team led by Alfredo Huete from the University of Arizona in Tucson [2]. The comparison of satellite data and observations on the ground proves: The Amazon rainforest really turns green during the few dry months, while in most other ecosystems on earth the vegetation usually dries up and turns brown. However, in undisturbed forests with their large trees, the roots of many plants still reach water in deeper soil layers.

The situation is completely different on cattle pastures or soybean plantations, where the grass and crops do not have this ability: they usually dry up during this hot phase and thus heat up the area even more. In addition, they prevent the evaporation of the water and thus the formation of clouds, which is why the extremely progressive deforestation in the east of the region appears extremely worrying.

And since the forests are not used as regulators, the researchers around Nepstad fear massive fluctuations in the water level of twelve river systems in the east and south of the Amazon basin if massive clearing activity continues, which in future will face major flooding during the rainy season and water shortages in the dry season - the extensive drought of last year with low water levels, supply bottlenecks for the local population and medical emergencies was probably a first foretaste of this.

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