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Just like an organism, an ecosystem passes from being young to being an adult in several months or years. Most of them, however, do not move but remain for long time once their climax phase has been reached. This process of changes is the ecological sucession. The variations it is subject to and the final aspect of an ecosystem are alway very similar in zones with similar conditions.Human activities can affect the successions:-They can transform them completely , creating unnatural ecosystem (a cirbfuekd,a city, etc)-They may alter only components of, or relations within, the ecosystem (ploughing the soil).-They may prevent it from advancing, keeping it in its initial phases (ecological regressions)-They may accelerate the developmet, favouring certain changes in the place of others (transforming a lake into a reservoir, for example).In the final stage you can recognise signs of what has been left behing with the passing of time, as features remain from previous periods such as borders of vegetation on the banks of lakes, superimposed strata of plants and animals, and so on. Natural changes
Ecologicalsuccesion Ecological succesion is the process of change in time of an ecosystem. There are initial, youthful and mature succesional factors. It is even possible to find features from past stages which remains visible in the mature ecosystem. The succession last for variable periods of time. Sometimes, they require days or months until they reach maturity of the ecosystem; others, decades, up to 150-200 years. It all depends on what the initial ecosystem is like and, in part, how it develops. However, beginning with the same ecosystem, in similar places and under similar conditions, the changes are always very similar and end up as analogous communities.
Types and examples of succesions These modifications are developed spontaneously in nature. It is the organism themselves that transform the elements of their biotope, making it more appropriate for other new elements. For example, the roots of the bushes retain particles of the soil increasing its depth. In this way, large trees will be able to grow later. Also, the interaction between biotic factors changes little by little. -Primary successions: Are those in which man takes no part; they are natural. This is the case of the colonization of volcanic soils, successions in non polluted lakes or variations in coastal dunes. -Secondary successions: Human being can build simple ecosystems (a field of cereals for example) or, interfere in a natural successions (polluting the water), accelerating or slowing it down. *Other examples of successions: The regeneration of a forest after a fire, the colonization of a fluvial meander, the advance of a mangrove swamp on tropical coasts, etc…
Theclimaxphases. • Two similar areas whit similar environmentalconditions develop, in time, similar ecosystem. The climax phases is the last aspect and composition adquired. Whilst variations between two climax phases may exist in one kind of ecosystem, they are unimportant such as some accessory species or changes in abiotic factor. • In a climas ecosystem we can recognise sings of the passing of time.
The vegetable strata of a forest (crustaceus, herbaceous, bushes, trees) contain species analogous to other past successional phases( lichens and moss, grass, brush and trees) going from the oldest to the newest. • The edges of concentric vegetation established by the banks of a lake correspond to other succesional phases, such a way that those furthest from the water have taken longer in forming
In all ecosystems and succession, the following tendencies are seen with over time. -The complexity of the ecosystem increases: more species and more examples. -An increase in the weight and volume of the organism (its biomes). -The mechanisms of self-control are perfected and impede the disappearance of species. -The organisms make the most of the improved environmental resources. -The ecosystem becomes more resistant to change. Generaltendencies
Anthropic changes: environmental impact • The anthropic climatic change is all the alterations produced by the human activities like the production of greenhouse gases, because of the industries, cars gases, deforestation, adaptation of places for farming and agriculture… • There are three important examples of theanthropic environmental impact.
1. DEFORESTATION: this happen for many time ago. The deforestation can cause the extinction of lots of animal and floral species, soils destruction because of the erosion, alteration of the water cycle, droughts…
2. HUMAN EMISSIONS: these gases contribute to the greenhouse effect. The greenhouse effect is a process by which thermal radiation from a planetary surface is absorbed by atmospheric greenhouse gases, and is re-radiated in all directions. Without the greenhouse effect the earth will be too cold but with lots of greenhouse gasses emitted by the human activities the planet are getting to hot, the global warming.
3. RADIOACTIVE WASTES: the advantage of the nuclear energy is that doesn´t produces emission to the atmosphere but produces radioactive wastes, that are the substances that can´t be used again to generate electricity. These substances can have a high level of radioactive so the wastes are stored, but it takes hundreds or thousands of years that the wastes lose their radioactive. The nuclear power stations can have accidents (Chernóbil, Fukushima…) and they are continuously producing radioactive around their place.
We can protecttheenvironment individual or in community. Community. For example the Kyoto Protocol , It brought agreement between most countries that greenhouse gases should be reduced, Vienna Convention on the Protection of the Ozone Layer, which claim to protect the Ozone Layer against the human emissions and Rio Declaration on Environment and Development, which promote the sustainable development. • Individual: For example, taking off the lights, closing the tap water, taking a shower instead of a bath, helping in the forests reforestation, recycle…
Exercisesaboutecology. 1.- Explain the primary successions of ecology. 2.- Name 2 different types of general tendencies in ecology. 3.- Why we should reduce the anthropic environmental impact?
