THIS IS SOME CONTENT ON THE TOPIC ON FIRE AND WATERSHED DEGRADATION. YOU CAN READ MORE ON THE SAME
By Obiero Kennedy (Unit Lecturer)
TOPIC 5 - EFFECTS OF FIRE AND GRAZING ON WATERSHED DEGRADATION TOPIC 5 – EFFECTS OF FIRE AND GRAZING ON WATERSHED DEGRADATION GRAZING AND WATERSHED DEFORESTATION -In watershed are graziers, popularly known as are part of ecosystems.They depend on grazing for their body organic and inorganic requirements. -Their nutrients, proteins and energy requirements are obtained from grass and related plants on which they feed. -In natural conditions, the PRIMARY CONSUMERS for a whole host of wild species that graze and browse on vegetation. -Each of them is a selective feeder and consequently maintains an ecological balance.NO OVERGRAZING with watershed vegetation. . Human Influence on Watershed Grazing and Degradation -When natural species are replaced by domesticated cattle and sheep, the watershed ecological balance is upset. -There arises much greater grazing pressure on certain species which are actively selected by domesticated animals. -When grazing is light, intermittent and carefully controlled, considering carrying capacities, pressure caused by the domesticated animals is kept at the minimum. -HOWEVER, due to heavier grazing with either more stock or longer grazing periods, there is a decrease in the favoured species and deterioration in the value of grazing land. -In dense cattle areas, there has been OVERGRAZING resulting in a very great decrease in palatable grass species. -In some areas this trend leads to reduction in vegetation cover that lead to SOIL EROSION, INCREASED SUSPENDED SEDIMENTS IN WATER and SEDIMENTATION. -During the wet season, there is sufficient grazing in most watersheds to support wildlife, cattle, sheep and goats populations. -HOWEVER, during the dry season, the reverse is true. Consequences of Cattle, Sheep and Goat Grazing in Watersheds -The effects especially by goats are more devastating and dramatic.All plants within the goats’ reach may be eaten resulting to loss of the herb stratum and prevention of tree regeneration. -The grazing animals lead to the elimination of the most palatable herbs and grasses.They tend to select species they prefer and leave the tougher less tasty plants. -With the removal of native plant species, weedy species invade the watersheds which are less nutritional. -As overgrazing progresses, hungry animals strip the ground bare and their hooves HASTEN SOIL EROSION further degrading the watershed. Obiero, 2008 -About 1/3 of the world’s rangelands are degraded by overgrazing making overgrazing the largest cause of soil erosion. -The process of overgrazing especially in rangelands initiates a desert-producing cycles that feeds on itself known as desertification. -With nothing to hold back surface runoff, rain drains off quickly before it can infiltrate.There is reduced infiltration to nourish plants. -Groundwater recharge/replenishment is also reduced. -Spring and wells are also likely to dry up -Will create a MICRO-CLIMATE not suitable for seed germination.The dry barren ground/surface reflects more of the sun’s heat, changing wind patterns, driving away moisture-laden clouds, leading to further desiccation (Saigo, 2001). -(READ MORE). Watershed Degradation due to Over-grazing per Continent Source: Saigo, 2001 Discussion -African watersheds are at a greater threat to degradation through overgrazing than in other continents. -Countries with most damage include: Sudan, Zambia, Somalia, Kenya among others. -In Asia, Iraq is the most susceptible. PROBE CLASS FOR REASONS. FIRE -Fire is also one aspect that contributes to watershed degradation. -Some fires are caused by natural causes such as lightning. -However, the largest percentage of fire is caused by human beings. -Annual burning in some regions such as the savanna has been going on for many centuries. -Severity of burning depends on season (e.g., on set of dry season), time of the day e.g., morning or mid-day or evening. -Moisture content of grass/vegetation will influence the severity of fire. -The presence of wind will fan the fire and increase its severity although it may also decrease its duration. Why Burning -Burning clears the land for cultivation especially in areas occupied by cultivators or farmers. -It drives game from cover thus facilitating their capture. -It is said to decrease ticks and other parasitic populations. -It has been used in warfare. -Man appears to enjoy the sight of a good blaze especially at night. Effects of Fire -Fire stimulates the renewed growth of some plant species in watersheds. -It severely damages the woody plant species in watersheds.Some species are affected more than others. -The damage resulting from fire depends on the intensity of the burning both in terms of frequency and severity. -With severe annual fires, vegetation degenerates trees reduce leading to shrub or grass. -Micro-organisms are destroyed particularly earthworms and microbial population. -The organic matter and nitrogen content of the soil decreases. -Light burning to some extent increase soil fertility.
By Obiero Kennedy (Unit Lecturer)
TOPIC 5 - EFFECTS OF FIRE AND GRAZING ON WATERSHED DEGRADATION
TOPIC 5 – EFFECTS OF FIRE AND GRAZING ON WATERSHED DEGRADATION
GRAZING AND WATERSHED DEFORESTATION
- In watershed are graziers, popularly known as are part of ecosystems. They depend on grazing for their body organic and inorganic requirements.
- Their nutrients, proteins and energy requirements are obtained from grass and related plants on which they feed.
- In natural conditions, the PRIMARY CONSUMERS for a whole host of wild species that graze and browse on vegetation.
- Each of them is a selective feeder and consequently maintains an ecological balance. NO OVERGRAZING with watershed vegetation. .
Human Influence on Watershed Grazing and Degradation
- When natural species are replaced by domesticated cattle and sheep, the watershed ecological balance is upset.
- There arises much greater grazing pressure on certain species which are actively selected by domesticated animals.
- When grazing is light, intermittent and carefully controlled, considering carrying capacities, pressure caused by the domesticated animals is kept at the minimum.
- HOWEVER, due to heavier grazing with either more stock or longer grazing periods, there is a decrease in the favoured species and deterioration in the value of grazing land.
- In dense cattle areas, there has been OVERGRAZING resulting in a very great decrease in palatable grass species.
- In some areas this trend leads to reduction in vegetation cover that lead to SOIL EROSION, INCREASED SUSPENDED SEDIMENTS IN WATER and SEDIMENTATION.
- During the wet season, there is sufficient grazing in most watersheds to support wildlife, cattle, sheep and goats populations.
- HOWEVER, during the dry season, the reverse is true.
Consequences of Cattle, Sheep and Goat Grazing in Watersheds
- The effects especially by goats are more devastating and dramatic. All plants within the goats’ reach may be eaten resulting to loss of the herb stratum and prevention of tree regeneration.
- The grazing animals lead to the elimination of the most palatable herbs and grasses. They tend to select species they prefer and leave the tougher less tasty plants.
- With the removal of native plant species, weedy species invade the watersheds which are less nutritional.
- As overgrazing progresses, hungry animals strip the ground bare and their hooves HASTEN SOIL EROSION further degrading the watershed.
Obiero, 2008
- About 1/3 of the world’s rangelands are degraded by overgrazing making overgrazing the largest cause of soil erosion.
- The process of overgrazing especially in rangelands initiates a desert-producing cycles that feeds on itself known as desertification.
- With nothing to hold back surface runoff, rain drains off quickly before it can infiltrate. There is reduced infiltration to nourish plants.
- Groundwater recharge/replenishment is also reduced.
- Spring and wells are also likely to dry up
- Will create a MICRO-CLIMATE not suitable for seed germination. The dry barren ground/surface reflects more of the sun’s heat, changing wind patterns, driving away moisture-laden clouds, leading to further desiccation (Saigo, 2001).
- (READ MORE).
Watershed Degradation due to Over-grazing per Continent
Source: Saigo, 2001
Discussion
- African watersheds are at a greater threat to degradation through overgrazing than in other continents.
- Countries with most damage include: Sudan, Zambia, Somalia, Kenya among others.
- In Asia, Iraq is the most susceptible.
PROBE CLASS FOR REASONS.
FIRE
- Fire is also one aspect that contributes to watershed degradation.
- Some fires are caused by natural causes such as lightning.
- However, the largest percentage of fire is caused by human beings.
- Annual burning in some regions such as the savanna has been going on for many centuries.
- Severity of burning depends on season (e.g., on set of dry season), time of the day e.g., morning or mid-day or evening.
- Moisture content of grass/vegetation will influence the severity of fire.
- The presence of wind will fan the fire and increase its severity although it may also decrease its duration.
Why Burning
- Burning clears the land for cultivation especially in areas occupied by cultivators or farmers.
- It drives game from cover thus facilitating their capture.
- It is said to decrease ticks and other parasitic populations.
- It has been used in warfare.
- Man appears to enjoy the sight of a good blaze especially at night.
Effects of Fire
- Fire stimulates the renewed growth of some plant species in watersheds.
- It severely damages the woody plant species in watersheds. Some species are affected more than others.
- The damage resulting from fire depends on the intensity of the burning both in terms of frequency and severity.
- With severe annual fires, vegetation degenerates trees reduce leading to shrub or grass.
- Micro-organisms are destroyed particularly earthworms and microbial population.
- The organic matter and nitrogen content of the soil decreases.
- Light burning to some extent increase soil fertility.