Diversity of Lower Plants
Diversity of Lower Plants
About this eBook
PREFACE If you plan for one year, plant rice If you plan for ten years, plant trees But, if you plan for one hundred years, educate the people. Biodiversity is the natural biological capital of the mother Earth. It refers to variety of life forms, i.e., plants, animals and microorganisms. It has been defined as the variability, among the living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part, this includes diversity within species, between species and of ecosystems . In recent years, biodiversity has become a global issue in all important international foray. The Convention on Biological Diversity a specific document on biodiversity, was discussed and adopted in Rio de Janeiro Brazil during the United Nations Conference June 1992 on Environment and Development, also known as the Earth Summit . The Earth Summit made the term biological diversity a political catch phrase. Since then it has become clear to a wide public that are increasingly being confronted with a dramatic loss of animal and plant species. At the same time, we are becoming aware that more than 905 of our cohabitats on this planet currently remain undiscovered. A great number of them presumably disappear forever without our ever having known them. Biodiversity includes the variability in both, i.e., plant and animal species. Phytodiversity at global scale is a balance between the rate of speciation and the rate of extinction. At a regional level, it is a balance between the rate of immigration invasion and that of local regional extinction. These rates determine the persistence of the communities. It can be assessed at genetic, population, species, and ecosystem and landscape levels, at three spatial scales, viz., local, regional and global. While the assessment at genetic level, molecular techniques are most profitably used, assessment at other levels depends upon field sampling. Depending upon the objectives, the inventory could focus on single species or multiple taxa. For single species inventories, the focus could be on high impact, indicator, umbrella, flagship, threatened or economically important species. Phytodiversity provides to the humankind enormous benefits in the form of food, medicine and industrial products, and has the potential for providing many more yet unknown benefits. It also provides an array of essential services through natural ecosystems. These include maintenance of the gaseous composition of the atmosphere, shaping the climate and producing the soil. It is essential for the ecosystem function and stability. There are several hypotheses being tested for relationship between biodiversity and ecosystem function.
viii Preface Contents Phytodiversity is not uniformly distributed on the earth. There are broad patterns, such as increasing variations in plants and animals from poles to equator. It is more concentrated in the tropics because of conditions which permit higher rates of speciation and lower rates of extinction. About 44 of vascular plants and 35 of vertebrates are concentrated as endemic species in 25 hot spots, which account for only 1.4 of the local land area. The pool of living diversity is dynamic, it increases when new gene variation is produced, a new species is created or a novel ecosystem formed and it decreases when the genetic variation within the species decreases, a species become extinct or an ecosystem complex is lost. Today, as ever, human beings are dependent on their sustenance, health well being and enjoyment of life on fundamental biological systems and processes. Humanity derives all of its food, many medicines and industrial products from wild or domesticated components of biological diversity. Biotic reservoirs are source of recreation, and tourism and underpin the ecosystem which provides us with many services. Plant diversity as a global resource remains poorly understood, inadequately documented