Assess the potential causes and impacts of changes to the water balance within a tropical rainforest
that you have studied (20)
Water balance is important in sustaining rainforests such as The Amazon as they are becoming rare
due to deforestation. With the Amazon losing 17% of its primary rainforest in the last 50 years, its
water cycle has drastically changed, having many impacts on the fertility of the forest on a local and
national scale as well as having an impact globally. This leading to less precipitation due to the
decreasing number of trees within the forest, this also showing that the water cycle and carbon cycle
are interlinked due to decreasing precipitation and increasing temperature, which will lead to drastic
changes.
Firstly, with the decreasing size of the Amazon due to activities such as cattle ranching which is
responsible for 80% of deforestation, the water cycle will be affected tremendously. With the
canopy acting as a protective layer for catching rainfall, it was able to catch rainfall that would have
increased the surface runoff of the Amazon. As its soil is already poor in nutrients, it is vital to
maintain them, which is done by the huge Amazonian rainforest trees, but without these trees and
approximately 3000mm of rain failing annually, this soil is washed away in surface runoff which can
lead to more complications such as flooding in near by rivers. Not only does this impact in flooding
but without the trees of the Amazon, carbon dioxide levels will increase as the function of plant
respiration cannot take place; on a national scale, it causes CO₂ levels to increase which could lead to
many people suffering from breathing difficulties. As well as that, on an international scale, the
release of CO₂ from the deforestation of the trees and the production, activities of brazil, the output
of greenhouse gases will drastically increase causing a positive feedback loop. This will have long
term effects such as faster evaporation due to the warming on the Earth, decreasing water supplies
and changing the dynamic equilibrium in the water balance not just within rainforests but through
many biomes. This a severe impact as it effects both the carbon and water cycle, which as human
beings, we need in balance so that the planet remains sustainable for the present day and for future
generations. However, there are many ways to combat this, one being afforestation. With NGOs
doing projects such as replanting trees, the Amazon is then able to start to take carbon back in, to
reverse the damage done. Although this is helpful, trees take around 50 years to fully grown
meaning that this tactic is not effective enough for the current situation due to it being time
consuming as well as costly due to illegal loggers continuously cutting trees down which will lead to
spending more money just to replant them. To make this effective, the government would need to
put in measures to stop illegal activity, showing that it is not effective due to illegal logging
accounting for 32% of total deforestation and without these laws or sanctions put in place, the
primary amazon forest will become less and less each year.
Secondly, with deforestation being rife in the Amazon, it can cause many problems for the remaining
rainforest and can be hard to maintain. A cause of the deforestation would be reduced
evapotranspiration from cleared areas due to there being no plants or trees, this leads to less
moisture being put into the atmosphere resulting in a reduction in cloud cover as there is not
enough moisture in the air to produce clouds. An effect of this would be increased solar radiation
being reflected by clear land back into the atmosphere which will ultimately lead to a temperature
increase. This has many impacts such as the warming of the earth but on a national scale of Brazil, it
could lead to the rainforest becoming inhabitable for many animals. Approximately, there is 2100
different spices of animals living in the Amazonian rainforest (including birds, reptiles, and
mammals), this number drastically decreasing due to the cutting down of trees and the rising
temperatures making the forest slowly become uninhabitable. A knock-on impact of this would be a
decrease in biodiversity and a disruption in the food chain, potentially causing many animals to go