The ‘Sixth Mass Extinction Crisis’ and Its Impact on Flowering Plants

Abstract

Human-induced environmental changes caused by habitat loss and its degradation, overexploitation of resources and climate change, have already pushed considerable number of plant and animal species to extinction, and a large number of them are at the verge of extinction. These catastrophic environmental changes have precipitated the ‘sixth mass extinction crisis’ in which a large proportion of the species would be lost in geologically a short time. As biological diversity and ecosystem functioning form the basis of human existence, human-induced environmental changes may eventually lead to serious repercussions on the biosphere and threaten the survival of the human race itself. Conservation of biodiversity and ecosystem functioning has, therefore, become a major challenge the humanity has to face in the coming decades. Flowering plants form the major component of plant diversity. Sustainability of the prevailing diversity depends on the ability of species/populations to reproduce and recruit new individuals to sustain populations. Recruitment is the final step in a long series of sequential events starting with the flower. Among these sequential events, pollination, a prerequisite for fruit and seed set, and seed dispersal, needed for effective recruitment of new individuals, are two of the most critical events, and both involve largely plant–animal mutualism. Human-induced environmental changes have imposed serious constraints on these mutualisms, thus seriously hampering recruitment. ‘Global pollinator crisis’ has been recognized as a major hazard not only for the sustainability of plant diversity but also for crop productivity and thus the food and nutritional security of human beings. Climate change, apart from inducing migration of species to higher altitudes and latitudes, brings about phenological changes particularly in the time of flowering and fruiting resulting in mismatches between the plant and animal partners involved in mutualistic interactions. There is an urgent need for concerted global action to reduce and reverse this trend of environmental degradation and thus conserve our biological diversity and ecosystem services to protect ourselves and our Planet.