Biological Consequences of Ecosystem Fragmentation

Change in land use patterns brought in by development such as road constructions are prominent process of environmental degradation in many regions across the world. Taking away native vegetation and its substitution with other land use (Roads) expose the environment to number of undesirable consequences. Intact natural landscapes such as forest are fragmented in to smaller patches. These patches or remnants are positioned in different location across the landscape and on diverse soil types. They possess different vegetation type and differ in size and shape. Alteration in the microclimate within and surrounding, and isolation of fragments from each other are prime effects of habitat fragmentation.

As a result of landscape fragmentation there are alterations in physical fluxes over the landscape. Changes in radiation, wind, and water can have significant effects on the fragments of native vegetation. Difference in balance of radiation may have effects on number and activity of soil microorganism and invertebrates. It also affects larger fauna through changes in resource availability. Changes in temperature have effects on competition, affecting predator - prey and parasitic interactions, nutrient cycle is affected. The wind can both directly (physical damage) and indirectly (change in vegetation) alter the landscape and its composition. Alterations in water fluxes can have important influence on biota of the area. Erosions alter drainage patterns and lead to plant colonization. It can change the habitat through changes in surface and soil moisture levels. Habitat fragmentation diminishes both habitat size and connectivity among individuals and population.

Many species have difficulty surviving in environments of reduced size, increased isolation and new ecological boundaries. Isolated habitat is likely to have more species than it can manage leading to loss of species. Habitat fragmentation reduces population connectivity and reduces the probability of population persistence. Furthermore, fragmentation creates edge habitat which are susceptible to invasion by invasive species. Invasive species have significant impact on the native communities of the remnants and can affect the whole system of the landscape. Habitat fragmentation of natural landscape has significant impacts on the communities of the remnants.

Bhutan today is experiencing a rapid development with accelerated economic activities. With expansion of population and developmental activities in the country, land use patterns are changing. As a result, pressures on natural resources are ever increasing. Developmental activities include agriculture development, urbanization, industrialization, mining and quarrying, transportation facilities and networks, hydro power and rural electrification. Every year considerable forest area is lost to these activities. Land degradation, biodiversity and habitat loss, and human-wildlife conflicts are some of the environmental challenges in the country.

With all developmental activities and environmental challenges, Bhutan may already be facing many of the biological consequences of ecological fragmentation. Many species also may have gone extinct without notice and many might be on the verge. It is evident that there are number of invasive species of plants present in the country. It is also realized that the numbers of well known species are declining each year. It is certain that the country would have to face almost all the consequences of habitat fragmentation if no proper planning and conservation measures are taken up in the near future.

Source │Biological Consequences of Ecosystem Fragmentation: A Review │Conservation Biology Volume 5, No. 1, March 1991.