Biodiversity comprises the great variety of living things, including plants, animals, fungi, and micro-organisms. It can be considered at various levels of complexity: genes, species, communities, and ecosystems. Biodiversity has evolved, and interacts with, the natural processes that sustain life. It is intricately connected with moderation of the climate, the purification of air and water, the fertility of soils, and the decomposition of wastes.
Biodiversity provides many resources for human consumption. It supplies many foods, fibres, fuels, and medicines, and research is uncovering new uses for natural products. We also benefit psychologically and physiologically from contact with nature. For example, such contact has proven beneficial in health care. Further, biodiversity is essential in adaptation to environmental change. Variability within species allows their populations to respond to change, with evolutionary processes favouring individuals that are most suited to new conditions.
Anthropogenic changes to the environment are threatening biodiversity. According to the World Conservation Union, over 16 000 species of plants and animals are currently in danger of becoming extinct. The greatest pressures on biodiversity are from habitat loss, largely due to agricultural and urban development. The global expansion of human populations has led to the pollution and deforestation of many biodiverse habitats.
In Australia, threats to biodiversity include the introduction of exotic pest species like Paterson’s curse (Echium plantagineum), foxes (Vulpes vulpes), and rabbits(Oryctolagus cuniculus), the introduction of commercially bred exotic species like sheep (Ovis aries), and changes in water and food sources, which favour some species, like the overabundant eastern grey kangaroo (Macropus giganteus), and create problems for others, like the platypus (Ornithorhynchus anatinus). As noted above, changes in animal and plant communities affect the physical environment. For example, the mangrove woodlands at Port Gawler are changing the coastline as they advance southward, by promoting the build up of sediments and modifying tidal flows.
There is increasing political resolve to improve the conservation of biodiversity, including urban biodiversity. The United Nations Environment Programme was established in 1972 to foster cooperation in environmental research and education to improve the environmental standards of international development. The focus on biodiversity was intensified when, in 1992 at the Rio Earth Summit, the Convention on Biological Diversity was signed by delegates from 150 countries. This convention calls for conservation, sustainable use, and sharing of biological resources. Then, in 2007, the Curitiba Declaration on Cities and Biodiversity was signed, expressing the importance of the contribution that urban areas can make in conserving biodiversity.
Urban biodiversity
There are many advantages to incorporating biodiversity into urban areas. However, typically, as city populations increase, so does the amount of paved and built areas within them, decreasing the space available for urban greenspace and biodiversity. For example, many European cities have very few trees and concentrations of greenspace are limited. Small areas of habitat that are not connected are of limited value to urban wildlife as they are not able to move between them. Yet urban consolidation can incorporate much biodiversity.
While urban environments are highly modified for human habitation, they still include important remnants of native vegetation, wildlife corridors along waterways, and habitat in recreational parks, along streets, and in residential gardens. Notably, both public and private spaces provide places for nature. Further, while it is fundamental to conserve native plant species, exotic plants can also play an important part in the conservation of local animals. Well chosen exotic plants can provide habitat where native plants are lacking, sometimes perform better in urban environments, and some drought-resistant exotics can reduce water use.
Green cities need citizens with positive environmental attitudes. Importantly, urban areas are where many people experience the natural environment and develop a relationship with nature, necessary to generate positive environmental attitudes. Such attitudes provoke awareness and support of local environmental issues, like catchment health, and for conservation more broadly, including endangered species and non-urban conservation areas. Tourism also plays an important role in advancing environmental awareness in and around cities. Biological and geological features, like migrating birds and mountain ranges, can be drawcards for local, national, and international tourists.
Cities can be centres for conservation efforts. The concentration of human and material resources in cities enable research and practical conservation to be carried out in universities, zoological and botanical gardens, government agencies, and private organisations. For example, The Adelaide Zoo is involved in captive breeding programs for endangered and vulnerable animals. In one such program, brush-tail rock-wallabies (Petrogale penicillata penicillata) were cross-fostered by yellow-footed rock-wallabies (Petrogale xanthopus xanthopus) to increase their captive population and enable some re-introduction into the wild.
Natural and built environments in close proximity can be problematic. Large trees can create structural damage to buildings through moving soils and falling branches. Large groups of animals can also be a problem, like flocks of Australian white ibis (Threskiornis molucca) near airports that damage aircraft and delay flights. There are also health concerns when natural and urban environments coexist. Wild animals can catch diseases from domesticated pets, such as toxoplasmosis spread by cats (Felis catus). Conversely, people are susceptible to zoonoses, animal diseases that can infect humans, such as Q-fever. However, understanding these concerns and ensuring sensible planning mitigates these problems. Further, the risks posed by not incorporating biodiversity into urban environments far outweigh any concerns it presents.
BioCity@UniSA research includes the fields of biology, zoology, and ecology in conjunction with urban and regional planning, spatial sciences, geomorphology, and hydrology. Biodiversity research is focussed on reconstructing past events to understand change, and the conservation of flora and fauna in the Adelaide and Mount Lofty Ranges region. Urban biodiversity research informs, and is informed by, research into all of the BioCity@UniSA research themes: water, green cities, land use, hazards, and communities. BioCity@UniSA is exploring methods to educate, and learn from, a biodiverse, green city.
