This is a fantastic course for any nature lover.
It is an interdisciplinary course that introduces the student to a range of skills that can be applied to a variety of workplaces, producing skilled and capable graduates. This course allows you to select an area that you wish to study in greater depth, as well as covering the foundations of Horticulture and Nature Park Management.
These issues and others are discussed in Nature Park Management I and Nature Park Management II. The focus of this course is understanding how humans impact on natural environments, and how park management seeks to provide quality recreational and educational experiences without compromising the parks’ natural environment.
Landscapes and their associated plant and animal life are a result of responses to millions of years of naturally occurring disturbances, such as fire, flood, earthquakes, volcanic eruptions, climate changes and changes in sea levels. Living communities have survived and developed because they have the ability to adapt and perpetuate themselves in a constantly changing environment.
The first thing to understand about natural environments is that they are constantly changing. The manager of a nature park is the manager of change.
A nature park manager should not expect, or attempt to stop natural changes, but he/she should exercise control over "unnatural influences" which could cause change faster than the natural environment can adapt to.
Human interference can accelerate change in an environment, causing such things as:
• an increased rate of soil erosion
• changes to water runoff patterns
• salinity
• soil compaction
• soil acidification
• land slips
• weed infestation
• loss of native vegetation
• pollution of soil, air and waterways
Nature parks, in general, attempt to redress environmental problems caused by human interference. In most cases the aim of park management is to preserve natural ecosystems and to stabilise or improve degraded environments. The natural ecosystems that nature parks provide have a diversity of plants and animals; a continual succession of plant and animal populations; recycle energy within the parameters of the ecosystem; efficiently utilise resources; have multiple functions and elements; and demonstrate the principles of relative location.
The Ecosystem
An ecosystem is made up of abiotic substances (eg. soil, water, air), producers, consumers and decomposers. The producers are the plants. They are the only organisms which are able to absorb and store energy from the sun. The other organisms (ie. animals) depend on the producers for their source of energy. Consumers are animals which eat producers, or other consumers. Decomposers are organisms which break down (rot) the structure of other organisms when they die. Through the action of decomposers, nutrients are returned to the soil and made available so that plants can use them over and thus keep the cycle of life going. From all this, you should begin to see that there are a lot of interrelationships existing in any ecosystem.
Constituents of the Ecosystem
These can be summarised as follows:
1. Abiotic Components: The physical features plus the basic inorganic compounds of the environment. They are the inputs and outputs required to keep the ecosystem and life functioning.
Inputs
*Solar energy
*Water
*Oxygen
*Carbon dioxide
*Nitrogen
*Other elements and compounds
Outputs
*Heat from respiration
*Water
*Oxygen
*Carbon Dioxide
2. Biotic Components: The living organisms, including producers, consumers and decomposers.
a) Autotrophic components ‑ Organisms which require only simple inorganic substances; they fix light (or chemical) energy in simple organic compounds, then use this stored energy to build up complex substances. They include producers, which are autotrophic organisms, largely green plants which are able to manufacture the food they use from simple inorganic substances using light energy.
b) Heterotrophic components ‑ Organisms which cannot manufacture the food they utilise. They rearrange and ultimately decompose the compounds manufactured by autotrophs. They are the consumers: Heterotrophs (animals) ingest other organisms or particles of organic matter.
a. Primary Consumers ‑ Feed on plants (e.g. herbivores ‑ cattle, insects).
b. Secondary Consumers ‑ Primary carnivores feeding mainly on herbivores (eg. frogs, lizards).
c. Tertiary Consumers ‑ Secondary or top carnivores feeding mainly on other carnivores (eg. snakes).
d. Decomposers: The heterotrophs (mainly bacteria and fungi) which break down complex compounds of dead animals or plants, absorb some of the products and release simple inorganic substances useable once more by the autotrophs.
Ecological Concepts
Knowing the basic components of an ecosystem leads to learning of the basic ecological concepts. Different authors might list concepts in different ways, however, the following are basic, universally accepted and essential to any ecosystem:
1. The sun is the source of all energy.
All energy in any organisms originally came from the sun. Other energies in the environment also originated from the sun (eg. wind, tides, water cycle, light, etc). The sun warms the earth, and provides energy for photosynthesis in plants. The synthesis of carbon compounds through photosynthesis converts sunlight energy into chemical energy that directly, or indirectly, provides food for almost all other organisms.
2. Everything is connected to everything else.
All living things interact with other things (both living and not living) in their environment. The climate affects the living things in an area. The plants influence the insect population and the insects eat the fish ... and on it goes.
3. Everything must fit how and where it lives.
'Adaption' is the key word of this concept! (ie: Unless a species adapts to a situation, it will not survive). A principle related to this concept is the 'Dam Law'. The Dam Law states .... 'die, adapt or move'.
4. Everything is going somewhere and becoming something else. We can never really throw it away.
An ecosystem is dynamic; in a constant state of change. In death there is no waste matter ... it is continually recycled among biotic or abiotic components. Rocks are worn down into soil, soil is used by plants, changed, moved and leached by the forces of the environment etc.
5. All action has a consequence.
For every action there is a reaction. For every event there is a consequence. There is a delicate balance of nature between producers and consumers which allows both to exist. If this interrelationship becomes and remains unbalanced, one and/or both members of the interrelationship will die.
WATER IN NATURE PARKS
Water is vital for all forms of life, but is a scarce resource, distributed unevenly in time and space. The increasing demand for water and the decreasing quality of the available water calls for a very high standard of water management.
Water is used for:
* making soil
* reducing the particle size of rocks
* regulating the temperature of the planet
* breeding grounds of animals and plants
* ingredients within cells of plants and animals
* transportation of minerals to plants for uptake by their roots.
Although most of the planet is covered in water, the distribution of rainfall is uneven both in terms of location and time spread throughout the year. Saudi Arabia actually imports water from the Philippines; Kauai in Hawaii receives about 11,400mm of rain every year. The average rainfall is 850mm a year over the entire surface of the earth.
Environmental occurrences such as El Nino can put rainfall and drought into cycles. Australia is known to go through a seven year cycle. In South Africa, a nine year cycle occurs: 9 years of good rain then 9 years of poor rain - this cycle has been recorded for the last century.
Water is not lost like soil. The earth will always have the same amount of rain, while the soil can be lost forever into dams and the seas. However, although water cannot be lost, it can be rendered unusable. The collection of silt also reduces the capacity to store water and it can increase the evaporation effect. When a dam becomes shallower because of silting, the water depth decreases and it is more prone to evaporation.
Evaporation can also cause a lack of rain. In some countries (e.g. the High veldt in South Africa, semi-arid regions of Australia), during summer it is possible to see rain falling high above the ground in long dark streaks, but because of the heat (air and ground temperatures) the rain evaporates before it reaches the ground. A remedy is to provide a good ground cover - PLANTS. Hence it is possible to see the necessity of plants and forests to encourage good rainfall.
DAMS
Dams have both positive and negative ecological effects. The positive are:
· the flow of the river is regulated, reducing flood damage;
· the flow can be regulated so that it is perennial as opposed to seasonal;
· sediment is deposited in the dam and assists the growth of aquatic plants that remove excess nutrients from the water. The water leaving the dam is thus cleaner than the water entering.
The negative are:
· the ecological impacts reduce the strong water flow, lessening the river's scouring capacity, which in turn, can lead to the silting of estuaries;
· when the dam is being created humans and animal have to be moved;
· the creation of a dam causes the loss of valuable plant life that could be used for other purposes;
· the creation of large water surfaces affect the weather of the area and even adjacent areas.
Eutrophication is another problem with dams. This process is triggered off by too many nutrients entering the body of water. The nutrients from sewage works, industrial effluent and fertilisers impregnated runoff from farm use blooms in dams and lakes. The blooms are sudden flushes of algae growth. This bloom is toxic to humans and animals such as cattle. Ironically, the more life in the dam, the more death there is. The dead algae and water weeds sink to the bottom of the dam and begin to decay. In this process they take oxygen from the water (as oxygen is required for decay and decomposition) which results in suffocation of the fish. The result of eutrophication is that the water dies and becomes a swamp, giving off methane gas.
Eutrophication is not an easy problem to remedy. The phosphates and nitrates come from the outflow of sewage works. These chemicals are potent fertilisers. The principles of sewage treatment is to turn the harmful organic wastes into inorganic wastes. Unfortunately the nitrates and phosphates, both inorganic, emerge as by-products and the eventually end up down-stream and cause a boost in plant life. Eliminating these two chemicals is difficult.
Another problem associated with sewage disposal is not really causing problems in lakes and dams.
What to do with the sludge after the pathogens have been removed? It can be incinerated, but this causes air pollution. It can also be dumped into the sea - again pollution. Can it be used as a saleable product for domestic and council garden use (after treatment) - this has been used successfully in some countries. Can it be used as an energy source - as discussed in last lesson, yes.
RIVER CATCHMENTS
The river catchment, or drainage basin, is the land from the top of the mountains to the sea shore, drained by a single river and its tributaries. This is the catchment area of a particular river.
Catchment areas vary in size. A large river may have a catchment areas of several thousand square kilometres, while a small river's catchment areas may be only a few hectares. The catchment are separated from each other by watersheds.
The biological, physical or chemical characteristics of any river are determined by the nature of the catchment area and its activities. These may be natural or man-induced.
Maintaining good ground cover is very important for catchment areas. In those undeveloped catchment areas the ground cover, or vegetation, is still in place. In developed areas this cover may have been removed. Ground cover is important because:
* plants slow down the water as it soaks over the land. This lets the water soak into the ground and replenish the supplies of underground water. Water seeps from these supplies into rivers flowing throughout the year.
* plants prevent soil erosion because their roots hold the soil in position. This stops it from washing away. The presence of plants also breaks up the impact of raindrops before they hit the soil. This reduces the erosion potential of heavy rain. The rivers flowing through an undisturbed catchment area are clean and erosion is slow, limited to periods of heavy rainfall.
* vegetation in wetland and on the banks of rivers is very important. The roots of the reeds, sedges, trees, shrubs and grasses bind the soil of the riverbank and prevent erosion. They also regulate the flow of water and act as a cleaning agent.
Much of the silting of rivers and dams is caused by the erosion of the riverbanks due to removal of ground cover vegetation.
WETLANDS
Wetlands are difficult to define because of the variations in size and location. The most important features are:
· they consist of waterlogged soils covered in shallow water. This covering of water may be seasonal or permanent
· the soil becomes unique
· the plants are distinctive and adapted to water-saturated soils
· the migratory birds and wetland bird species specifically require this ecosystem.
Wetlands associated with rivers and streams slow flood water because they act as large bowls. The flood water flowing into these bowls loses its velocity and spreads out. The plants in the wetland hold back the water.
The wetland acts like a sponge that stores the flood water and slowly releases it downstream. If the wetland was not there, the flood would rush straight out to sea. In brief, wetlands reduce flood damage, erosion and ensure a steady supply of water throughout the year.
The wetland acts as a filter to trap and remove sediment, bacteria, nutrients and other pollutants for the flowing water. Water leaving a wetland is therefor cleaner than the water entering it.
These filtering plants, besides offering filter abilities, also act as fauna draw cards. Birds, fish, insect plus many others are attracted to this ecosystem.
Unfortunately, may people associate wetlands with the four D's: Dampness, Disease, Difficulty and Danger. As a result, mankind has often converted these wondrous sites into dams, dumps, pastures, industry, airports, harbours, pastures, etc. Many are drained to prevent ross river fever, malaria, etc.
