AMAZON RAINFOREST Flashcards

Question

Human factors affecting stores and flows of water

Answer 1

Deforestation in Amazonia averaged around 17,500 km2/year between 1970 and 2013. Since 1970 almost one-fifth of the primary forest has been destroyed or degraded (Figure 4.14). Since 2009 annual rates have been lower than the average but have started to rise again in recent years In April 2014 devastating floods occurred on the Madeira River, the largest tributary of the Amazon River (Figure 4.14). At Porto Velho the river reached record levels of 19.68 m above normal. Vast expanses of floodplain were inundated; 60 people died; 68,000 families were evacuated; and there were outbreaks of cholera and leptospirosis. In the Upper Madeira drainage basin human activity has modified stores and flows in the water cycle. Deforestation has reduced water storage in forest trees, soils which have been eroded), permeable rocks (due to more rapid run-off) and in the atmosphere. At the same time fewer trees mean less evapotranspiration and therefore less precipitation. Meanwhile, total run-off and run-off speeds have increased, raising flood risks throughout the basin. Despite torrential rains in the upper basin of the Madeira River, the main driver of the floods was deforestation in Bolivia and Peru. Between 2000 and 2012, 30,000 km? of Bolivian rainforest was cleared for subsistence farming and cattle ranching. Much of this deforestation occurred on steep lower slopes of the Andes. The result was a massive reduction in water storage and accelerated run-off.

Answer 2

Converting rainforest to grassland increases run-off by a factor of 27, and half of all rain falling on grassland goes directly into rivers. Rainforest trees are a crucial part of the water cycle, extracting moisture from the soil, intercepting rainfall and releasing it to the atmosphere through transpiration, as well as stabilising forest albedo and ground temperatures. This cycle sustains **high atmospheric humidity** which is responsible for **cloud formation + heavy conventional rainfall** Deforestation breaks this cycle and can lead to permanent climate change

Answer 3

Projections of future deforestation in Amazonia predict a 20 per cent decline in regional rainfall as the rainforest dries out and forest trees are gradually replaced by grassland. Nor is it just deforested areas that experience a reduction in rainfall: disruption of the regional water cycle means that forests hundreds of kilometres downwind of degraded sites are affected too.

Answer 4

Present-day deforestation is most severe in the tropical rainforest. In primary rainforest, unaffected by human activity, the biomass of trees represents about 60 per cent of all the carbon in the ecosystem. The above ground carbon biomass in the rainforest is approximately 180 tonnes/ha. Most of the remaining carbon is found in the soil as roots and dead organic material.

Answer 5

Croplands and pasture contain only a small amount of carbon compared to forest trees. For example, the biomass of grasslands in areas of former rainforest is 16.2 tonnes/ ha; and for soya cultivation it is just 2.7 tonnes/ha. At the same time, deforestation drastically reduces inputs of organic material to the soil. Soils, depleted of carbon and exposed to strong sunlight, support fewer decomposer organisms, thus reducing the flow of carbon from the soil to the atmosphere

Answer 6

Rainforest soils contain only small reservoir of essential nutrients + forest is only sustained by rapid nutrient cycle. Deforestation destroys main nutrient store (forest trees) + removes most nutrients from ecosystem. Nutrients no longer taken up by root systems of trees are washed out of soils by rainwater; and soils, without protective cover of trees, are quickly eroded by run-off.

Answer 7

degrading or outright destruction of large areas of Amazon rainforest is an issue of international as well as national concern. This is because deforestation has implications for global climate change. Brazil is committed to restoring 120,000 km2 of rainforest by 2030. Indigenous people have lived sustainably in the rainforest for thousands of years, maintaining the water balance, carbon cycle and the forest's biodiversity. These people survived as hunter-gatherers and shifting cultivators - in contrast to exploitative commercial farming, logging + mining of past 50 years, indigenous people pursued way of life, perfectly adapted to limited resources + fragility of rainforest

Answer 8

• Protection through legislation of large expanses of primary forest so far unaffected by commercial developments. • Projects to reforest areas degraded/destroyed by subsistence farming, cattle ranching, logging + mining. • Improving agricultural techniques to make permanent cultivation possible.

Answer 9

These Amazon Regional Protected Areas now cover an area twenty times the size of Belgium. By 2015, 44 per cent of the Brazilian Amazon comprised national parks, wildlife reserves + indigenous reserves where farming is banned.

Answer 10

One such example is Parica project in Rondônia in the western Amazon. This sustainable forestry scheme aims to develop a 1000 km? commercial timber plantation on government-owned, deforested land. The plan is for 20 million fast-growing, tropical hardwood seedlings, planted on 4000 smallholdings, to mature over a period of 25 years. Financial assistance is given to smallholders for land preparation, planting and the maintenance of plots. Tree nurseries provide them with seedlings. Timber will be exported along the Amazon and its tributaries through Manaus or Port Velho. Although this project is a monoculture and cannot replicate the biodiversity of the primary rainforest, it is sustainable. It also sequesters carbon in the trees and soil; reduces CO, emissions from deforestation; re-establishes water and carbon cycles; and reduces life support systems run-off and the loss of plant nutrients and carbon from the soil.

Answer 11

The Suruí plant seedlings bred in local nurseries in deforested areas around their villages. The native species planted are chosen to provide them with timber for construction, food crops and, through logging, a sustainable source of income.

Answer 12

This scheme provides payment to the tribe for protecting the rainforest and abandoning logging. It is a market-based approach involving granting of carbon credits to the Suruí. These credits can be purchased by international companies which have exceeded their annual carbon emissions quotas. In 2013, Natura, a large cosmetics transnational corporation (TNC), purchased 120,000 tonnes of carbon credits from the Surui. This was the first carbon credit sale by indigenous people in Amazonia.

Answer 13

Farming has been the main cause of deforestation in Amazonia. However, low fertility of soils meant that permanent cultivation proved unsustainable. After a few years, smallholders abandoned their plots which were then converted to low quality grassland. Extensive ranching enterprises could scarcely support stocking levels of one head of cattle per hectare. One response to improve agriculture has been diversification. Soil fertility can be maintained by rotational cropping and combining livestock and arable operations. Integrating crops and livestock could allow a fivefold increase in ranching productivity and help slow rates of deforestation. European explorers observed that the Amazon rainforest, as late as the sixteenth century, supported high population densities, and many large urban centres. This appears to contradict the view that natural resources for farming in the region are too poor to support settled, permanent cultivation. The explanation is thought to be human-engineered soils: so-called dark soils made from inputs of charcoal, waste and human manure. Charcoal in these soils attracts micro-organisms and fungi and allows the soils to retain their fertility long-term. Scientists are currently investigating these dark soils. If they can be successfully recreated they would allow intensive and permanent cultivation which would drastically reduce deforestation and carbon emissions.