Plant reproductive success varies widely within and among natural populations and understanding the factors, which developed the variation, could enhance the pollination and dispersal process. The basic premise is that as individuals become increasingly isolated reproductive processes, such as pollination and seed dispersal, begin to function less efficiently leading to Allee effects whereby declining population density or abundance results in a disproportionate decline in reproductive output and population viability. Density, fragmentation, area cover, relative frequency, and population size have great influence on the process of pollination and seed dispersal. Nevertheless, low plant density and low pollinator could enhance the decline of the reproduction success. Pollinators reduce visit to single species and became generalist if there is no dominant. Invasive species reward the pollinator by providing enough nectar and pollen using extended flowering period. Pollinators are sensitive to vegetation cover, dead wood and percent grass land. Declining floral resource could be a cause for pollinator deficits. In low density of plants, most of the pollinator does not have preference (Bumblebees and Hummingbirds). A speciose pollinator could interact with wide range of plant distribution (temporally and spatially). High plant richness favors high pollinator diversity that, in turn, maintains high plant richness. For conservation purpose, several small population, but high density is important. Population purity and invasive species need to be checked. It is imperative, therefore, that future studies separate the effects of population size, local density and purity, and patch isolation on plant reproductive ecology.

Keywords: Pollination, dispersal, fragmentation, co-evolution, invasive, Allee effect