Microbiology_Experiment

KWAME NKRUMAH UNIVERSITY OF SCIENCE AND TECHNOLOGY COLLEGE OF SCIENCE ENVIRONMENTAL SCIENCE Write an essay on Evidences of Vegetation Dynamics. Vegetation dynamics refers to the changes that occur in the composition and structure of vegetation. The plants grow and change in their forms and arrangement and this affects the shape and composition of the vegetation there is competition and seasonal modifications among plants. This however creates different appearances in the vegetation from time to time. There are five types of vegetation dynamics and these are seasonal, succession, fluctuations, regeneration and zonation. Some of these changes that occur with these types of vegetation dynamics are predictable, repetitive or unpredictable. Others are seasonal and perpetual. Evidences of vegetation changes show that there was previously a type of vegetation growth that occurred at a place which has been replaced at another type of vegetation; this is usually observed in seral changes as it is difficult in knowing the previous vegetation that occurred at a place. Some of this evidence which shows vegetation change includes written records, unwritten records, zonation, fossil and sub fossil remains and dendro chronology (age of the plants). An evidence of vegetation change is unwritten records. This type of record was brought about by stories told by grandparents their tribesmen. Such people told their tribesmen the type of vegetation that occurred at a given place but since most of them were illiterates, they could not write in order to document these records. Other people who told stories about the vegetation that could be found on a particular land were travelers and traders as they moved from one place to another. This type of evidences is not safe as for records keeping since it is in the form of oral delivery. Such evidences if not taken noticed of can easily be lost totally and a type of vegetation which occurred at a particular place at some point could no more be known. Written records are also another evidence of vegetation dynamics but this type has some form of documentation. Technocrats like geographers, ecologists, physicists etc studied, researched, took pictures and wrote down information of vegetations from time to time which served as evidences which have been kept as records. However, modern methods of documenting vegetation include remote sensing using satellites and computers. This type of evidence is safe and even uses advanced technology in the form of documentation. Many generations to come will be able to identify with such documents and know the type of vegetation that occurred at a place many years ago. Another evidence of vegetation dynamics is known as dendro-chronology which deals with the age of trees and plants. As such, the growth rings of matured or cut down trees are studied by scientists to know the age of such trees. Through this, scientists know the time the trees might have evolved or the seral stages that might have taken place. Another observation that could be made to obtain some evidences of vegetation dynamics is through the observation of seasonal changes that causes the plants. These changes cause plants to show different growth habits. The transverse section of plants also depicts the growing pattern of the tree. Fossil fuel and sub fossil remains of plants preserved in soils or rocks especially during landslides are also another type of vegetation dynamics. This natural act enables plant species of certain periods to be known. Sub fossils can be however be found in areas rich with the growth of mosses. Peat (hard carbon) occurs where water cover and high temperature prevents the total decomposition of floral remains. During these excavations, pollen grains, spores etc can be analyzed in the laboratories. Zonation which is a type of vegetation dynamics also shows some evidences of vegetation dynamics. This involves the successions that could occur in the glaciers, deserts or the coastal habitats. In water, roots of early plants collect soil and raise the soil level which creates a new microhabitat. As such, the previous plants move lower into the water to maintain their environmental conditions. The process repeats till the original site becomes terrestrial since the water level moved down. Forests can then be observed while less developed plants are seen down toward the water. Zonation can also be observed along the semi deciduous regions during deforestation when the margin drifts from time to time and can be estimated. The different ecotones of savanna vegetation can also shift in favour of the real savanna. There is however some difficulties and setbacks in the study of evidences concerning vegetation change. In the absence of data for critical areas or periods of interest, the written records or documentation becomes difficult to do. As such, some information is likely to be lost. An unwritten or written record becomes difficult to keep when there is continuous and different interpretation and description of existing vegetation. This comes about when people have conflicting ideas about the type of vegetation which occurred or occurs at a place. When there is a delay in the seral growth of vegetation, it makes the study of evidences of vegetation change difficult. This type of vegetation is referred to as deflected succession. A complication that comes about during fossilization processes also makes it difficult for the study of vegetation change. This comes about when fossils cannot be identified in the first place or the handling is not done properly. REFERENCES * Lori Martinez (1996). “Useful Tree Species for Tree- Ring Dating. (Retrieved 2008-11-08) * Thompson, R.S. and Fleming, R.F., 1996. Middle Pliocene vegetation: Reconstructions, paleoclimatic inferences, and boundary conditions for climate modeling. Marine Micropaleontology, 27, 27-49. * Tinner, W. and Lotter, A.F., 2001. Central European vegetation response to abrupt climate change at 8.2 ka. Geology, 29, 551-554. * Watts, W.A., Late-Tertiary and Pleistocene vegetation history: Europe, 1988. In Huntley, B. and Webb, T., III, (eds.), Vegetation History. Dordrecht: Kluwer Academic Publishers, pp. 155-192. * Williams, J.W., Shuman, B.N., and Webb, T., III, 2001. Dissimilarity analyses of late-Quaternary vegetation and climate in eastern North America. Ecology, 82, 3346-3362.