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Physical Geography of Northern Eurasia
Biodiversity and Productivity of Ecosystems
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Biodiversity: Definition and Functions
Biodiversity (an abbreviation for biological diversity) is both a scientific and
emotive term which is becoming increasingly popular in various areas of fundamental and
applied science pertaining to ecology and the environment. Until recently, biodiversity
was understood as the diversity of genotypes and species (i.e., as taxonomic richness of
biological systems at a level higher than organism) (Wilson, 1988; Chernov, 1991; Zlotin
and Yasny, 1992). Now, biodiversity is defined more broadly as the variety of genes,
species, and ecosystems that characterizes the Earth's biosphere (UNCED, 1992). By
emphasizing the spatiotemporal hierarchy (i.e., from genes to biosphere), this definition
reflects both the richness of life on Earth and ecological functions of living matter at
all levels of its development through time and space (Wilson, 1988; Zlotin and Yasny,
1992). Biodiversity is of crucial importance to planetary health, local habitats, and
single organisms. Indeed, as early as in the middle of the 19th century, Charles Darwin
(1859) suggested that more biologically diverse ecosystems are more productive (i.e., they
assimilate more carbon dioxide than less biologically diverse ecosystems), if other
environmental variables are equal. Since then there has been a debate about this issue and
now evidence is emerging that Darwin was correct in his assumption (Mannion, 1996).
Biotic cover (or biosphere) comprises three major groups of organisms —
microorganisms (bacteria and fungi), plants, and animals. Biotic cover is a thin film with
a global thickness of just 2 cm (Kobak, 1988). The activity of this thin layer, however,
results in biological production (global cycling of carbon, nitrogen, and other important
nutrients) and maintenance of the equilibrium between production and destruction of
organic matter. Biosphere and other components of the natural environment, such as
atmosphere, hydrosphere, and pedosphere (soil cover) and components of lithosphere, are
intimately linked through global biogeochemical cycles. Thus, the composition of the
atmosphere, which is the key to the Earth functioning as an environmental system, depends
on the biosphere. These ideas were pioneered by the Russian scientist Vladimir Vernadsky
at the beginning of the 20th century (Vernadsky, 1926, 1945, 1980; Kadatsky, 1986).
Because of the intimate links between vegetation and climate, the biosphere together with
the oceans is implicated in global environmental change. Biodiversity is particularly
important in carbon cycling. Destruction diminishes the capacity of vegetation communities
to fix carbon and thus the capacity of the biosphere to counteract global warming.
The biosphere and biodiversity are influenced by factors working at present and over
large time scales. There are three groups of factors: (1) abiotic factors, mainly
climatic, and edaphic (soil and geology); (2) biotic relationships, such as trophic
linkages and competition; and (3) anthropogenic (human-induced) factors.
The contemporary geography of biodiversity is determined by the combined impact of all
these factors evolving in time. Contemporary environmental science does not consider life
as merely passive, evolving as environmental change occurs. On the contrary, the
anthropogenic factor is becoming increasingly important. Vernadsky (1926, 1945, 1980)
characterized the relationship between humans and biosphere as the 'noosphere' (from the
Greek word nods, mind), emphasizing by the introduction of this concept the reciprocal
dependence and control of humans and biosphere. Vernadsky had a firm faith in humanity and
technology as a force producing change for the benefit of both people and the biosphere.
In retrospect, this approach appears Utopian. However, the idea of mutualism remains
central to the sustainable use of biodiversity. Studying biodiversity, in the terms of
spatial and temporal organization of biotic cover, variety of functional links within
environmental systems, and the role of the biosphere in the maintenance of the global
ecological balance, remains a key issue in contemporary science (Steffen and Shvidenko,
1996).
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