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Vegetation analysis of the forest ecosystem of Similipal Biosphere Reserve (SBR) was carried out at 10 sites to study changes in structure and composition in plant community distributed in the core (undisturbed) and buffer (disturbed) areas of the reserve. The study reveals a higher number of herbs and shrubs and a lower number of trees in the buffer area indicating greater anthropogenic disturbance. Total tree basal area varied from 48.7 to 78.61 m 2 ha -1 in the buffer area and 81.4 to 104.9 m 2 ha -1 in the core area. The density of saplings and seedlings was nearly equal both at the disturbed and undisturbed sites. However, the rate of conversion of saplings to trees was greater at undisturbed sites. The lower rate of conversion at disturbed sites is due to the removal of seedlings of most of the tree species. The high herb diversity (2.14 -3.50) and low tree diversity (2.14 -2.98) in buffer area is a result of Environmental openings providing greater opportunity for the recruitment of herbs and shrubs. The presence of only a few individuals of major tree species in larger diameter classes and more in young diameter classes in buffer areas indicate that the plant community was subjected to disturbance and are in the regenerating stage. Greater fluctuation in the species / genus ratio in the herbaceous species at sites of the buffer area in comparison to core area has led to variation in developmental status of plant communities among the core and buffer areas of the reserve. However, the presence of the seedlings of dominant tree species in the buffer area may help in the restoration of the plant communities in the long-run, provided protection means are strengthened and biotic stress reduced.

Global environmental changes are challenging the structure and functioning of ecosystems. However, a mechanistic understanding of how global environmental changes will affect ecosystems is still lacking. The complex and interacting biological and physical processes spanning vast temporal and spatial scales that constitute an ecosystem make this a formidable problem. A unifying framework based on ecological theory, that considers fundamental and realized niches, combined with metabolic, evolutionary, and climate change studies, is needed to provide the mechanistic understanding required to evaluate and forecast the future of marine communities, ecosystems, and their services. The Future of Marine Ecosystems The ocean absorbs most (93%) of the heat generated by greenhouse gas emissions, resulting in a predicted increase in the sea surface temperature of 1-10 C over the next 100 years [1]. The ocean also absorbs CO 2 released to the atmosphere from anthropogenic sources (currently 1/3 of this CO 2), resulting in a profound change in the carbonate chemistry and predicted increased acidity of seawater [1] to 100-150% above pre-industrial era values [1]. In addition to ocean warming and acidification, anthropogenic stressors are decreasing the concentration of dissolved oxygen and consequently expanding oxygen minimum zones [2] as well as potentially modifying large-scale oceanic circulation patterns [3]. These environmental changes might also impact fundamental community-structuring processes (i.e., selection, dispersal, drift, and speciation) [4], changing the relative importance of ecological processes for structuring of communities. Collectively, these changes will alter the structure and functioning of marine organisms and ecosystems and, consequently, the biogeochemical cycles of the ocean [5-8]. Generally recognized predictions regarding climate-induced changes on the composition and distribution of the marine biota include shifts in the species distribution from lower to higher latitudes, shifts from near-surface to deeper waters, shifts in annual phenology, declines in calcifying species, and increases in the abundance of warm-water species [1,9]. However, most models of the response of biological communities to climate change assume a fixed, genetically determined environmental niche for each species, and the migration of intact (i.e., nonadapting or nonevolving) populations, so that their distribution on our future planet is basically governed by the environmental conditions [10-12]. Yet, local populations may evolve, acclimate, and adapt to environmental changes. In fact, local adaptation is a recognized phenomenon in ecological studies on terrestrial systems [13,14]. In contrast to terrestrial systems where most (z96%) of the living biomass are plants, most of the biomass of the ocean (z70%) is microbial [15]. Since microbes have short generation times and large population sizes, it is possible that these engines of the Earth's biogeochemical cycles might be particularly capable of adapting to global envir...