Human Activity & Savanna Grasslands (AQA A Level Geography)
Revision Note
Written by: Jacque Cartwright
Reviewed by: Bridgette Barrett
Impact of Human Activity on the Savanna
Savannas provide water, grazing and foraging, food and fuel for millions of people
The unique biodiversity of savannas, encourages and supports wildlife tourism
However, human impacts are causing widespread and accelerating degradation of savannas
The main threat is land use change
Landscape fragmentation which disrupts herbivore communities
Human changes to fire regimes
Climate change and rising atmospheric CO2
Unsustainable water use and irrigation methods
Land clearance reduces grazing for herbivores and fragments the landscapes reducing their community connectivity
Grass is burned off to ensure improved grass growth the following season, it also prevents woodlands from taking over
Large fires decimate flora and fauna communities - especially those not fire-resistant, however, fires can also kill insects and small animals, providing food for predators
Woody plants are killed by cattle eating their foliage, allowing thorny, animal repellent trees to become dominant
Poor agricultural practice can lead to soil degradation and desertification
Over grazing further exposes the grasslands to erosion
Tourism attracts the use of transport which damages vegetation and disturbs wildlife and affects breeding grounds
Conservation through national parks if variable - some parks attract illegal trophy hunting
Products such as ivory and rhino horn - where the animal is killed just for their tusks
Hunters target large males, leading to an imbalance in the population
Animals can become embolden and attack people
Human rubbish can be poisonous to animals
Demand for illegal bushmeat is a growing commodity, adding pressure to the savanna ecosystem
Plants are overharvested due to their commercial value - baobab tree fruit, African Blackwood for carving, Gum Arabic for chewing gum etc.
The Gum Arabic tree is an important plant to the Sudan, as it supplies 80% of the worlds export of gum. Gum Arabic is used extensively in pharmaceuticals, food production, and traditional medicine
Examiner Tips and Tricks
Overgrazing is a positive feedback loop, because it reduces plant density, which increases pressure on the remaining grassland, this leads to more overgrazing and eventually soil degradation and erosion.
Development Issues in Savanna Grassland
Changes include population, economic activity and agriculture
Population Change | Economic Activity | Agriculture |
Many savannas are in LDEs and have an expanding human population, which increases pressure on the biome Increased conflict between people and animals of the savanna. Crop raiding, livestock or people killed by wildlife, can lead to retaliation against wild animals Nomadic communities are becoming more static, because of their growing community size and land now used for feeding and housing has grown. This results in livestock being grazed in smaller areas, leading to overgrazing More land is utilised for subsistence crops, to feed the growing local populations in savannas | Prosperity and development has increased; leading to increased demands in food and goods. This leads to agricultural land use changes Tourism can boost economic development and income can be used for further conservation Tourism brings habitat loss from road and hotel construction, disturbance of animals and their breeding | Advances in agricultural practices and crop types, have led to commercial farming on the savannas and planting large areas with cash crops, such as corn and wheat. Newly created varieties of soybeans are now grown in Brazil’s savanna, even though soybeans are only suitable for farming in temperate climates Overcultivation due to lack of crop rotation, had led to soil nutrient depletion as the soil cannot recover before being replanted Salts in the soil can dissolve in water when land is irrigated. As water evaporates, salts rise to the surface and form a salt crust which kills many plants Over abstraction of water, lowers the water table, so plants and animals cannot reach it |
Implication for biodiversity and sustainability
Sustainability | Biodiversity |
Overgrazing and intensive agriculture are unsustainable and often leads to soil erosion, due to lack of root binding Desertification is increasing due to poor management of these activities. Poor soil conditions make it hard for vegetation to regrow, creating patches of desert like conditions The problem is expected to worsen as climate change alters rainfall patterns Controlled fires are necessary, however, if fires are prevented or extinguished too quickly, organic material builds up and massive uncontrolled fires can occur, which decimate habitats and imbalances the ecosystem Water is scarce during the dry season, so it requires careful management in its usage (irrigation, domestic use etc.) Game reserves have been created in many areas, prohibiting local settlements, grazing and farming and hunting is strictly controlled. This can increase sustainability by allowing the ecosystem to operate without human interference. However, they also cause conflict between locals and officials, where locals have been used to foraging/farming within the park lands prior to exclusion | Humans are directly reducing savanna biodiversity by destroying habitats and killing wildlife Changing land use is also causing fragmentation, which can be problematic as grazing animals and predators need large areas to roam The presence of domestic livestock reduces the amount of vegetation and available water for native wild herbivores. Domestic species are replacing wild species in the ecosystem Native savanna species are also threatened by invasive species, e.g. cane toads were introduced in the Australian savanna as a form of crop pest control, but their population rapidly expanded, putting native species under threat through eating their food and secreting poison when threatened
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Examiner Tips and Tricks
Remember that fires in the savannas are an important feature of maintaining the health of the biome. Many species of vegetation rely on the fires to complete their life cycle, whilst other rely on the fires to reduce competition from trees.
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