Biodiversity refers to the wide variety of ecosystems and living organisms: animals, plants, their habitats, and their genes. It is crucial for the functioning of ecosystems that provide products and services essential for life.
Biodiversity is present everywhere. The breadth of the concept of biodiversity reflects the interrelationship of genes, species, and ecosystems.
The planet supports between 3 and 30 million species of plant systems, animals, and fungi, single-celled prokaryotes such as bacteria, and single-celled eukaryotes such as protozoans.
Of this total biological system, only about 1.4 million species have been identified and named so far. A little more than half the named species are insects, which dominate terrestrial and freshwater communities worldwide.
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Comprehensive Meaning of Biodiversity Across Agricultural Systems
Biodiversity is the variability among living organisms from all sources, including 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.
Biodiversity forms the foundation of the vast array of ecosystem services that critically contribute to human well-being.
It plays an important role in both human-managed and natural ecosystems. Decisions made that influence biodiversity affect the well-being of all living beings.
Biodiversity is defined as “the variability among 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.”
The significance of this definition lies in the attention it draws to the many dimensions of biodiversity. It explicitly recognises that every biota can be characterised by its taxonomic, ecological, and genetic diversity and that the way these dimensions of diversity vary over space and time is a key feature of biodiversity.
Thus, only a multidimensional assessment of biodiversity can provide insights into the relationship between changes in biodiversity and changes in ecosystem functioning and services.
Cultivated systems alone now account for more than 24% of Earth’s terrestrial surface; therefore, any decision concerning biodiversity or ecosystem services addresses the maintenance of biodiversity in these largely anthropogenic systems.
Features allowing for a high diversity of ungulate species include the system being spatially very diverse, with animals using different parts at different times. It is an open system, with considerable movement of migratory species.
On the 100 km² of the central Savuti grassland, animal numbers vary annually from virtually zero (for all species) to 16,500 zebra, 2,500 buffalo, 1,500 Tsessebe, and 600 wildebeest.
Zebra and buffalo are present during the rainy season and Tsessebe during the dry season, while wildebeest are more variable. Elephant numbers can be high, depending on the availability of surface water.
The strength of biological interactions is variable and often weak. Feeding overlap and resource competition between species are impossible to estimate, either due to species moving out of the area or due to sudden influxes of large numbers of other ungulates.
Predation is opportunistic; environmental conditions are never constant for long enough to permit strong biological interactions to develop.
The system is driven by external, episodic events, such as the supply of surface water in the Savuti Channel, drought, fire, and disease.
Assessment of Biodiversity for Conservation and Management
A key feature of biodiversity assessment is the very duality of its nature. When considering the species and ecosystems in a given region, the first viewpoint is to examine the geographical distribution and the ecological niche of each species; a second is to study the various ecosystems and characterise their floristic composition and structure.
To address this duality, the following approaches are carried out at the FIP and are being integrated under Geographic Information Systems (GIS).
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The Habitat/Ecosystem Oriented Approach in Biodiversity Assessment
This approach is derived from biogeography and phytoecology and was the cornerstone of the ecological mapping programme initiated in the late 50s by the FIP.
It consists of studying and classifying vegetation regarding ecological conditions (climate and soil), characterising the species composition, structure, and physiognomy of the vegetation units, and analysing their dynamics and succession under ‘natural’ and ‘disturbed’ regimes.
The ultimate outputs of this approach are the following vegetation and land use maps, along with floristic lists attached to each vegetation type.
The Species Oriented Approach in Biodiversity Studies
This approach is in the direct lineage of taxonomic and botanical studies. It is best illustrated by the “Atlas of Endemic Plants of the Western Ghats” published by the FIP (Ramesh & Pascal 1997).
The species-oriented approach consists of collecting information on the location of the species from various sources: herbaria, literature, and field surveys.
This information may be extended to include the ecological conditions (bioclimate, soil, altitude, topography) and the type of ecosystems in which the plant is encountered, the role it plays in these ecosystems, as well as its biological traits (morphology, architecture, growth, and reproductive strategy).
The ultimate goal is to have a sort of ‘identity card’ for each species. This information is most crucial for rare and endangered species in the perspective of their in situ conservation.
GIS to Integrate Habitat and Species Approaches
Both of the above approaches end with large sets of spatial information and especially with maps. A major issue is to ensure the consistency of this information and to recombine it according to various viewpoints.
To perform this, different ‘layers’ of GIS data have been created using Arc/Info to generate the following information:
- Vegetation physiognomy and human pressures (deduced from the density of population or road network) to assess disturbance levels.
- The spatial distribution of several species to determine biodiversity ‘hotspots’.
- Past and present maps for monitoring land cover and land use changes.
- Conservation value maps using biodiversity indicators (richness, diversity, endemicity, uniqueness, etc.) to prioritise areas for conservation and management.
Developing Information Systems to Prioritise Biodiversity Conservation in Agricultural Landscapes
Developing a good strategy requires a highly reliable and meaningful information system at different levels. In the wide field of biodiversity, the French Institute of Pondicherry (FIP) research programmes have been focusing for about four decades on species and ecosystem diversity at the local (i.e., stand and community), landscape, and regional levels.
The Institute has been concentrating on plant ecology with a strong emphasis on trees and forests, from open woodland to dense moist evergreen forests, considering their present status as well as their long-term history.
Geographically, most of the studies are being carried out in the Western Ghats and some projects in the Eastern Ghats and mangroves.
The biodiversity-related programmes of the FIP could be listed under two main headings: ‘assessment of biodiversity’ and ‘monitoring the dynamics of biodiversity’.
These programmes are being carried out in collaboration with Forest Departments in Karnataka, Kerala, Tamil Nadu, and Andhra Pradesh, the School of Environmental Sciences (JNU), the Kerala Forest Research Institute, the Centre for Ecological Sciences (IISc), the Salim Ali School of Ecology (Pondicherry University), and the National Remote Sensing Agency (Department of Space).
Monitoring the Dynamics of Biodiversity in Agricultural and Natural Systems
Biodiversity assessment has the following outputs: lists of species, sets of values for several diversity indices, and land use and vegetation maps. More often these statistics bear no meaning by themselves. Their significance depends more on their absolute and relative variations over space and time.
Thus, it is crucial not only to study biological diversity but also to monitor it concerning factors (ecological, human, and social), which influence its dynamics, and to study the processes (biological, ecological, human, and social) that govern its evolution.
Land Use and Land Cover Changes as Indicators of Biodiversity Dynamics
The first step in monitoring changes in biodiversity consists of comparing successive observations. At the local level, this can be done by observing the appearance and disappearance of species, which requires that the same sites be sampled on several occasions.
To observe this, two permanent plots have been set up in the Biligirirangan hills (3.5 ha) and the Kadamakal RF (28 ha), both in Karnataka.
In addition to these, initial data have also been collected from one hundred 1-ha permanent plots, established by the Karnataka Forest Department in the Karnataka part of the Western Ghats.
At the regional and landscape levels, this can be done using past and present land cover and land use maps. The joint development of satellite imagery, image analysis techniques, and GIS has opened avenues for such studies.
At the regional level, such studies are being carried out for the entire Western Ghats of Karnataka, and at the landscape level, it was done for the Agastyamalai area, which is one of the ‘super hotspots’ in the southern Western Ghats.
Ecosystem Uses and Forest Products in Understanding Biodiversity Change
Understanding changes in biodiversity requires the analysis of the processes that are at play. The first major set of processes is constituted by those related to human activities, especially the direct exploitation of the ecosystems and species.
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