Community Structure and Composition

There is some generalization that competition for nutrient alone is primary factor that control species composition in plant communities. The modification in composition and distribution of plant species on limestone and granite soil as a results of improvement in soil properties has been reported. Similar results of modifications in community stability with enrichment of organic matter were observed on reclaimed phosphatic mine spoils. Richness, diversity and evenness of vegetation upon rehabilitation of gypsum mine spoiled lands in the Indian arid zone. They found that two perennial species increased in richness with time. It was concluded that natural succession process was accelerated by rehabilitation providing stability to the habitat. Existing plant communities in Eastern coalfield areas to describe the vegetation type quantitatively in terms of species frequency, structure density and distribution. They found that agricultural land were dominated by rice waster lands acieballatus, herbs (Argerbob maxicana and Andrographis paniculata & shurbs Lantana camara and forests dominated by Bassica latifolia, Madhuca longifolia, Shorea robusta & Azadiracta indica. Forest ecosystem on mine spoil in central Germany found a strong relation existed between mined land site conditions and tree species composition development and productivity. The restoration of tropical moist forest on bauxite mined lands in the Brazilian Amazon. They evaluated forest structure and composition in 9 to 12 year old stands establish on bauxite mined land using four different restoration techniques following initial site preparation and top soil replacement. Vegetation mapping on 15 dumps of the Thuringia mining areas using Brann Blanquet technique. He founded that the plant communities are dominated by Robina pseudoacecia, Populus sps and Betula sps. The vegetation dynamics of cliff faces in abandoned limestone quarries in southern Ontario, Canada. It was found that the quarry walls had the strongest influence on vegetation community composition and abundance. During the first 70 year after abandonment, species richness was high and variable, community composition was also extremely variable during this period. The final form of the vegetation community on the vertical cliff was similar to the naturally occurring community on neighboring areas. 12-year-old rehabilitation mined area was found that the vegetation present in those areas showed species composition, which was similar between seed store and the vegetation. There was a large difference in the densities with which species occuring at much higher densities in the topsoil. After 17 years, regeneration of mined sites at tomago, Austalia is subsequently slower and the mined site had not returned to the vegetation structure of the predisturbed state. Under story height and the amount of vegetation on mined sites have not achieved the levels in the original forest, although canopy cover did seem to have reached pre-distrubance state. Cho An analysis of Raunkiacr plant life forms and composition over a 10-year period following various restoration treatments of mined low in Korea Republic. No of species and species diversity index tender to increase for the first a years but the indices tended to decrease on sites 11 year after restoration. The community structure of vegetation and biomass production in an ecologically restored rock-phosphate mine after ten yeas of restoration. They found that the total above ground standing crop biomass was 43-44 tonnes per hectare was mainly contributed by tree species. Soni et al, (1989) studied the succession on one year old (unreclamimed) and 2,3 and 5 years old r4eclamied rock phosphate mine spoils at Maldeota, Dehradun. Relative contribution of herbs and grasses increase with age while contribution of shrubs and trees decreased because dense herbaceous vegetation discouraged the invasion of tree and shrub species and 7 grasses and sedge species invaded the spoils. Diversity of naturally colonized species showed no co-relation with the diversity of planted species. Reclamation of mine spoil in Himalayan moist temperate forest areas helps in achieving richer species diversity as compared to natural forest. In composition of naturally colonizing species in 607 year old bauxite over burdens at Amarkantak and 3 years old cola mine over burden at Dhanpuri, Madhya Pradesh, India planted with difference tree species. Coalmine overburden were comparatively more hospitable than bauxite spoil. Vegetation structure and development of soil on mined lands when once proceeds, changes with age of vegetation. Recent research in a number of tropical countries has shown that tree planting on degraded mined sites can dramatically increase the other wise slow rate of natural forest succession by ameliorating soil and under storey microclimatic conditions and providing habitat for seed dispersing wildlife that can lead to enrichment of floristic diversity. The biological diversity of mine areas increased significantly and was higher than that of the adjoining area after 3 years of reclamation of mined area. Plant communities are often subjected to disturbances and these conditions may facilitate co-existence and maintain high diversity. Revagetating the mined disturbed sites with various species contributes to the full development of ecosystem by encouraging the survival of less aggressive plant species. Argued that the change in species composition could be affected by positive feedback from nutrient cycling in the ecosystem. This positive feedback modifies the environment and makes it more suitable to facilitate invasion and a long-term succession change. Species composition of 49 reclaimed coal strip mines ranging in age from 10 to 70 years and reported that structural characteristic of the vegetation were similar to mature upland forest on the older and favourable sites. Reported that plant community composition changed and species diversity increased with age in coalmines in Madhya Pradesh One of the most obvious features of a biological community is the pattern of relative abundance among the species. A low value of evenness indicated that one or few species are highly dominant, while other are present in very small amounts. A high value of evenness indicates that all the species in the community have rather similar abundance and share the reverse equally. Variation in resource availability has been found to affect the abundance pattern. Species richness increases with increase in phosphorus status in soil. Diversity and floristic composition are highly predictable from environmental and geographical factors.