Land use changes and its affect to biodiversity
Why LUC is so important to biodivesity?.
Land-use and land-cover Changes were considered the key factors for global environmental change (Turner et al. 1995), affect the global biosphere and climate（William E.R.1994）. For terrestrial ecosystems, land-use change probably will have the largest effect to the biodiversity (Osvaldo E.S et al, 2000). Also it is a major cause of the decline in biodiversity in recent decades (Soulé 1991).
At present, loss of biodiversity, including high rates of extinction and a worldwide depletion of biological diversity at genetic, species and ecosystem levels,can be linked to the destruction of natural habitats as a result of land use change at different scale, and is presently considered one of the most urgent environmental problems( Shao et al. 2005) and losing habitats is the greatest threat to biodiversity. According to the Millennium Ecosystem Assessment, over the past 50 years people have changed ecosystems faster and more extensively than in any period in human history.（http://www.nerc.ac.uk/research/issues/biodiversity/pressures.asp）
How LUC affects the biodiversity?
The types of land use are distinguished as land cover conversion, i.e., the complete replacement of one cover type by another, and land cover modification. Land use change happens at every spatio-temporal scale( Shao et al. 2005). Land use changes are affecting many aspects of the Earth system (Shao et al. 2005). In most landscapes within the region, land-use is a major determinant of composition, spatial patterns and function at the species, community and landscape levels (Pan et al. 2001) Timber harvesting and associated silvicultural practices (e.g., clearcutting, thinning, plantation forestry, and prescribed burning), and road building alter spatial and successional patterns as well as the underlying processes and dynamics of forest ecosystems. The quality of water, soil and air resources, ecosystem processes and function and the climate system itself through greenhouse gas fluxes and surface albedo effects have all undergone important changes in the past century ( Shao et al. 2005). These changes are likely to be even greater in this century.
Land use has also caused declines in biodiversity through the loss, modification, and fragmentation of habitats; degradation of soil and water; and overexploitation of native species. Nowadays,biological species live in increasingly fragmented habitat islands embeded in a matrix of human civilization( Shao et al. 2005). Habitat or forest fragmentation is the result of land converted into farmland from forests,grassland and othere natural habitats, which also is the result of land use and habitat conversion.
What about the dilemma that LUC faces?
Land use occurs in local places, with real-world social and economic benefits, while potentially causing ecological degradation across local, regional, and global scales. Society faces the challenge of developing strategies that reduce the negative environmental impacts of land use across multiple services and scales while maintaining social and economic benefits（Jonathan A. Foley, et al.2005）. Land use thus presents us with a dilemma. On one hand, many land-use practices are absolutely essential for humanity, because they provide critical natural resources and ecosystem services, such as food, fiber, shelter, and freshwater. On the other hand, some forms of land use are degrading the ecosystems and services upon which we depend（Jonathan A. Foley, et al.2005）
Although, some scientists point out that the biodiversity will be not so seserously as predicted by the predicting the decreasing deforestation rates, as well as natural forest regeneration through secondary succession to accelerate and an increase in secondary forest area. But it is undoubtable that the world are facing more and more serious biodiversity loss.
The conclusion
Determining the effects of land use change on the Earth system especially biodiversity depends on an understanding of past land use practices, current land use patterns, and projections of future land use, as affected by human institutions, population size and distribution, economic development, technology, and other factors. ( Shao et al. 2005).
Land use has been received increasing attention in the life cycle assessment. At the same time, the ecological responses of land use change have been paid increasing attention. But the interaction between land use and biodiversity is poorly understood. And it is highly likely that we will fully understand the co nservation value of biodiversity before we have already converted most of the remaining primary forest to other land uses. So great attention still need to be paid on the underlying processes and mechanisms of biodiversity impacts of land use change.
REFERENCE
- Euskirchen E.S., Chen J. and Bi R.C. 2001. Effects of edges on plant communities in a managed landscape in northern Wisconsin Forest Ecology and Management 148: 93–108.
- Jonathan A. Foley, Ruth DeFries, Gregory P. Asner, Carol Barford,1 Gordon Bonan, Stephen R. Carpenter, F. Stuart Chapin, Michael T. Coe,1. Gretchen C. Daily, Holly K. Gibbs, Joseph H. Helkowski, Tracey Holloway, Erica A. Howard, Christopher J. Kucharik, Chad Monfreda,1 Jonathan A. Patz, I. Colin Prentice,8 Navin Ramankutty, Peter K. Snyder. 2005. Global Consequences of Land Use。Science 309, 570-574;
- Osvaldo E. Sala, F. Stuart Chapin , III, Juan J. Armesto, Eric Berlow, Janine Bloomfield, Rodolfo Dirzo, Elisabeth Huber-Sanwald, Laura F. Huenneke,Robert B. Jackson, Ann Kinzig, Rik Leemans, David M. Lodge, Harold A. Mooney, Martín Oesterheld, N. LeRoy Poff, Martin T. Sykes, Brian H. Walker, Marilyn Walker, Diana H. Wall .2000. Global Biodiversity Scenarios for the Year 2100, Science 10,Vol. 287: 1770 – 1774
- Pan D., Domon G., Marceau D. and Bouchard A. 2001. Spatial patterns of coniferous and deciduous forest patches in an Eastern North America agricultural landscape: the influence of land use and physical attributes. Landscape Ecology 16: 99–110.
- Shao Jingan, Ni Jiupai, Wei Chaofu, Xie Deti. 2005.Land use change and its corresponding ecological responses: a review. Journal of Geographical Sciences 15, 3, 305-328
- Soulé, M. E. 1991. Conservation: tactics for a constant crisis. Science 253:744-750.
- Turner II, B. L., Skole, D., Sanderson, S., Fischer, G., Fresco, L. and Leemans, R..1995. Land-use and land-cover change. Science/research plan. IGBP Report: 35/HDP Report 7.
- William E. Riebsame，William B. Meyer and B.L. Turner II. 1994，Modeling Land Use And Cover As Part Of Global Environmental Change，Climatic Change28: 45-64.
Maybe they are not so clear to be saw.
My partner in the field and beside him is mimosa pigra.
and pod or bean 
Mo was dancing on the party for graduate.
Zhuangfang is here!
have to find the Chinese version. Ther are here: