Many types of ecosystems can be identified. The identification of an ecosystem is based on a degree of reciprocal interrelationships existing between the climate, parent rocks, soil, drainage, water, plants and animals within the environment. Examples of the different types of ecosystems include ocean (salt water) ecosystem, fresh water ecosystems and land ecosystems. Some of these ecosystems are water based (aquatic) while some are land based.
All ecosystems which are land based are called land ecosystems. Therefore, land ecosystem can be defined as the interactions and relationships which take place on and within the land surface as well as between the surface and the air in contact with it. In order words, we can use land form units as the main criterion for delineating land ecosystems.
Examples of land ecosystems are the various types of vegetation which have developed in an environment because of their interaction with the climate, parent rock, soil, water, vegetation and animals in the environment. The tropical rainforests ecosystem, for example, refers to the plants and animals viewed within the physical, chemical and biological factors of the tropical rainforest environment. Here, there exists a relationship which binds the plants and animals together with the forest environment. For instance, tropical rainforest can only occur where there is plenty of moisture and heat.
Each land ecosystem possesses distinctive attributes of local climate, relief, rock types, soil, drainage and vegetation to which the animal communities and micro organisms associated with them have adapted their lives and functions. That is to say, each ecosystem can be described on the basis of its geographical location and specific environmental conditions which should include climate (rainfall, humidity and temperature distribution); soil types, vegetation patterns and their plant varieties; the drainage network characteristics, animal life, and human activities dependent on the productivity of the soil and vegetation.
Interdependencies within the Land Ecosystems
As earlier mentioned, the physical or abiotic component of an ecosystem provides energy and matter that gives life to the system. This energy comes in the form of heat and light which are a necessity for the life and maintenance of the biotic component. Both plant and animal communities depend on that energy.
Raw materials in the form of gases, water and inorganic minerals, also come from the physical component. These materials are indispensable to the survival of the biotic component. Again, the physical component provides the space (or spatial dimension) which the biological community needs for living and use for growth and maintenance.
For further understanding of the interdependence within the land ecosystem, it is important to look closely at the way some components relate with one another.
1. Soil Component
The components of an ecosystem relate with one another in several other ways. The soils, for instance are developed from the landforms on which the underlying parent rocks provide the constituent weathered debris. The soils in turn provide a base for plant growth.
In another way, the landforms are closely related to the soils and plants through their basic attributes of relief pattern, slope forms and drainage aspects. This is why soils and vegetation types in certain land ecosystems are different as a result of the geomorphic attributes and other environmental factors. For instance, the depth and extent of soil horizons are influenced by geomorphic and environmental factors.
2. Climate Component
Climate is a factor and a physical component (abiotic) Of the ecosystem which interrelates with the soils and plants. The climatic elements of rainfall and temperature play a significant role in chemical weathering of parent rocks which produces weathered parent materials from which the ‘soil profiles develop. The supply of various inorganic minerals in soils depends on the composition of parent materials. Climate and vegetation are also interdependent in some ways. The climate is the source of moisture and temperature for the growth of plants. The plants in turn provide the screening effect to create conditions of micro-climates within the soils and their overlying vegetation cover. The variations that occur in the seasonal or animal distribution of rainfall and temperatures, have a strong influence on the soil – water balance over long periods and therefore, on the rate of decomposition of organic matter in the soils.
3. Biotic component
Significant interdependencies exist with the biotic component in the land ecosystem. The biotic component consists of plants, bacteria, protozoa, insects, worms, as well as animals (both herbivores and carnivores) and even man. All these living organisms exhibit a high level of interaction and interdependence which involve the energy flow and the cycling of matter within the ecosystem. The green plants in any of the land ecosystems is involved in the interaction and interdependence within the system. Each plant community in any ecosystem requires an amount of solar energy, gases, water and mineral to thrive in their different environments (locations). These plants capture and store up solar energy during the process of photosynthesis and release oxygen to the animals for their survival in the ecosystem.
The animals (herbivores) in turn feed on the plant (producers) and derive their energy from plant food. Then other animals (carnivores) get their energy by feeding on the herbivores. At another level man obtains his energy by eating the carnivores, herbivores and some green plants.
Finally, the soil fungi and bacteria with some protozoa and other microorganisms often referred to as the decomposers feed on dead plants, animals and man as food. The decomposers break down the decomposed substances and release the elements and compounds in them into the ecosystem. The decomposers convert the dead substances from plant and animal tissues into humus and later into minerals, gases and water. The minerals go back to the lithosphere and biosphere from where they were initially derived while the gases and water are absorbed back into the biosphere and the atmosphere.