Ecosystem establishment

Andrews, S.M., M.S. Johnson, and J.A. Cooke. 1989. Distribution of trace element pollutants in a contaminated grassland ecosystem established on metalliferous fluorspar tailings. 2 zinc. Environ. Pollut. 59A 241-252. 

Reclamation/ restoration soil, vegetation, and ecosystem establishment... 

The assembly of a resident community of microorganisms in the gut represents one of the most fascinating examples of ecosystem establishment it is when the host lays the foundations for entering into a life-long relationship with his microbial partners. The early colonization pattern of gut microbiota is heavily influenced by mode of delivery, as this determines microbial exposure at the time of birth. Naturally delivered infants are firstly exposed to maternal vaginal and fecal bacteria, so Lactobacillus, Prevotella, Atopobium are prevalent in their gut, whereas the microbiota of cesarean section babies are more similar to the skin communities of the mothers, with an abundance of Staphylococcus spp. Microbial colonization of the gut in infants delivered by caesarean section is delayed compared to naturally delivered infants. Infants bom through cesarean section have lower numbers of Bifidobacterium (Figure 3.1) and Bacteroides, whereas they are more colonized by Clostridium species. 

Determination of the content of organochlorine insecticides in the drinking water is primal for establishing the level of contamination of the water ecosystem and for human health protection. 

Wind-throw and wind-snap of forest trees is a normal process in natural forests (Spurr Barnes, 1980). Runkle (1982) has estimated that, annually, as much as 1% of the area of a forested ecosystem may be blown (or fall) over and create canopy gaps. Such a figure appears to be appropriate for a range of forested ecosystems from equatorial to boreal. The canopy gaps are critical for the establishment of new species and maintaining species diversity in the forest (Woodward, 1987). 

The fate of areas of south-eastern American deciduous forests which were dominated, before the arrival of the pathogen, by chestnut and species of oak has been traced (Fig. 10) over nearly 40 years (Day Monk, 1974). The demise of chestnut from its standing as a canopy dominant was rapid, taking about 20 years, with a complete failure to return. During this period eeosystem productivity was reduced (as shown by a reduction in tree basal area. Fig. 10). However, the place of chestnut in the forest has been taken by a number of species, in particular oak and tulip tree, which have steadily increased in dominance. The community has clearly changed markedly but the ecosystem as a whole has shown complete recovery, in terms of re-establishing tree basal area. The place of chestnut in the oak-chestnut forests has been taken by other native species. So in the context of conservation, although the loss of chestnut is unfortunate, it has not been at the eost of an invasion of alien species of tree. 

In order to establish a link among the exposure of freshwater and marine ecosystems to environmental toxicants and observable effects on these ecosystems, there are basically two approaches (1) the deterministic approach that focuses on an understanding of functions, processes and mechanisms and (2) the stochastic approach that focuses on an identification of relationships by statistical means. 

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