Biodiversity Threats

E-mail Print PDF
Article Index
Biodiversity Threats
2
All Pages

 

Threats to Biodiversity and causes of Biodiversity loss
The main threats to biodiversity in Uganda include habitat loss, modification and alteration along with unsustainable harvesting, pollution and introduction of alien species, among others. The historical loss of species has been great in Uganda, and the negative trends are continuing. Many major mammal species, such as rhinos, cheetahs, and oryx were extirpated during Uganda's decades of internal turmoil between 1970 and 1990. Birds and fish species continue to decline in numbers and distribution throughout the country. Most of the remaining large animals are confined to protected areas, where their numbers are small but stable or decreasing still. However, in a few cases (e.g. the mountain gorillas, elephants and kob), the trends show some increase partly because of increased attention (Pomeroy and Tushabe 2004). The major threats to biodiversity in Uganda include the following:

 

Over-harvesting and Exploitation of Biological Resources
The uncontrolled harvesting or removal without replacement affects regeneration of the species. Over-exploitation depletes Uganda stock of animal and plant resources, lowering populations, affecting the genetic diversity and increasing the risk of local extirpation and subsequent extinction. Over-exploitation usually occur from commercial operations, like fishing or hunting and in some cases the species are targeted because of their food value or due their commercial value or because they are used in popular medicines, due to the pet and skin trade, whether to private or public collections.

 

Fish have been extensively exploited for food in Uganda today and illegal fishing through the use of wrong fishing gear is reported to be a threat to fish population. It has a devastating effect on the fish stocks by interfering with the breeding cycle when immature fish and mature fish are caught before spawning. Poaching and over-hunting have, in the past, contributed to the loss of the country species richness. During the 1970s, elephant and buffalo populations declined drastically due to massive poaching (Aleper and Moe 2006). In the late 1980s, with improved management and the reactivation of anti-poaching patrols in Queen Elizabeth National Park (QENP), a number of species primarily kob, buffalo and waterbuck  increased rapidly as a result of a ban in wildlife hunting.


 


Population Pressure and Habitat Conversion/Degradation


Despite the high incidence of disease, including HIV/AIDS, Uganda  population is growing fast and is over 80% rural. Human population growth rates for Uganda exceed 3% per annum, while the average world population growth rate being somewhere around 1.3%. Annually, more land must be brought under cultivation to feed the increased number of people. In places such as Kabale and Kisoro, which are located within the region of the Albertine Rift, the increased demand for agricultural land has led to land fragmentation, which is a generalized pattern, observed across all of Uganda. Fragmentation eliminates connectivity between natural habitats negatively impacting on wildlife movements.
The deforestation rate in Uganda is estimated to be around 55,000 ha per year, based on habitat change from 1990-1995. This causes severe loss of habitat and biodiversity annually. Bushfires are also a major contributing factor to habitat destruction. Some species are eliminated while others proliferate. The domination of savannah woodland by fire-resistant Acacia spp is one example. In Lake Mburo National Park, the proliferation of Acacia hockii is considered a threat to the population of herbivorous animals.

 

Encroachment and changes in land use (including degazzettement)
There is a growing demand for change of land use of PAs to agriculture or industrial expansion. Economic valuation of PAs would help in justifying, in economic terms, the importance of maintaining the PAs.

Soil Erosion
One of the indicators of land degradation is soil erosion. It has been estimated (Yaron et al. 2003) that the annual cost of soil nutrient loss due to soil erosion in Uganda is about $625 million per year. Notwithstanding the accuracy of the data used in the two studies, the evidence is clear: the problem of soil erosion is increasing with every passing year and this calls for urgent action. The draft national soils policy when finalized will a framework for addressing this problem.
Poor agricultural practices, such as over-stocking of rangelands and cultivation on steep slopes, contribute to erosion and siltation of water bodies, thereby altering ecosystems and species composition. Inappropriate policies, such as the agriculture policy of modernization, implicitly encourage monocultural and agrochemical-intensive farming systems that contribute to loss of genetic diversity through over-specialization and pollution of sub-soil ecosystems. The introduction of high-yielding maize varieties and promotion of clonal coffee are current examples.


Invasive Alien Species (IAS)
The introduction of exotic species into natural systems can affect biodiversity in many ways. Exotic species can out-compete native species and replace them in the system, thus reducing the species diversity, lowering genetic diversity, and increasing the homogeneity of the landscape. A preliminary list of IAS for Uganda (NARO 2002) includes species such as Lantana camara, Broussonetia papyrifera, Mimosa pigra and Senna spp. whose threat on native species has increased considerably. For example, Senna spectabilis has invaded over 1,000 ha of the Budongo Forest Reserve and vast areas of the Matiri Forest Reserve (Kyenjojo District) while Broussonetia papyrifera has covered vast areas of the Mabira Forest Reserve. Control strategies for these species are still being investigated (NARO, 2009).


Tree planting activities of NFA are focused on introduced species (Eucalyptus spp., Pinus spp. and Grevillea robusta). Although useful to meet short terms needs for timber, they could threaten the survival of native species if there are no guidelines for private tree planting. Moreover, the National Agricultural Advisory Services (NAADS) program has a focus on improved varieties in a bid to modernize agriculture in line with the Plan for Modernization of Agriculture (PMA). Native species are ignored by these efforts. However, the integration of natural resource management is becoming important in NAADS programs and offers opportunity for addressing this anomaly.
Lakes and rivers might be the ecosystems most affected by the introduction of exotic species and the consequent ecological changes in species and community composition. For example, the introduction of the Nile perch and water hyacinth has been extremely damaging for biodiversity in Lake Victoria. Lake Victoria is the largest tropical lake in the world, with 68,000 km2 of surface area shared among three countries: Uganda, Kenya and Tanzania. This lake supports Africa most important inland fishery and, until recently, harboured more than 600 species of endemic haplochromine cichlids.


Over the past century, the ecology of Lake Victoria has changed significantly and the fish stocks were subjected to three major events, which included fishing intensification, introduction of exotic species into the lake, and environmental changes. The introduction of the Nile Perch is resulting into approximately 40% of the haplochromine species disappearing. It is estimated that approximately 150 species of the haplochromine cichlids are extinct, 100 of them being from Ugandan waters.


The water hyacinth (Ecihhornia crassipes), also known as the waterweed and arguably the most noxious aquatic weed in the world, was first reported on Lake Victoria in December 1989, having entered the Lake from River Kagera, and then on Lake Kyoga in May 1998. The plant is native to South America where it occurs basically harmlessly in streams and seasonally flooded environments. Given its high proliferation rate, the weed has spread rapidly over the years to the shores of Lake Kyoga, the banks of River Nile and most of the northern tip of Lake Albert impacting negatively on fish and other aquatic species.


Oil and gas exploration in the Albertine Rift
Prospecting for oil in the Albertine Rift is a major threat to biodiversity in the area. Hardman Resources Limited (from Australia) has confirmed that Uganda can produce commercial quantities of oil (up to an estimated 10000 barrels per day). This has raised excitement and other companies such as Heritage Oil (from Canada) and Tullow Oil (from United Kingdom) have been licensed to drill in other parts of the Albertine Graben. There is also prospecting for geothermal energy by the Ministry of Water, Minerals and Energy. Exploration activities such as road construction, drilling and movement of heavy machinery are likely to interfere with the behaviour of wildlife. Habitat loss (to construction of roads and other infrastructure), pollution, population increase and increased pressure of extraction of resources (as more people are attracted to work in oil related activities) are occurring, inevitably.

Although a National Oil Policy is now in place, there is an urgent need to review and harmonise the regulatory frameworks for the petroleum and mining sectors in Uganda and other cross-sectoral laws affecting the sectors e.g. the Land Act, National Environment Act, Uganda Wildlife Act, and Forest Act so as to minimize the negative impacts of oil and mineral exploration on biodiversity in the Albertine region.


Illegal exploitation and cross border trade in Natural Products
Illegal exploitation of resources has been most pronounced on the Uganda-DRC border affecting mostly the timber resources. There is a possibility of such trade also affecting the northern Uganda region targeting products such as Gum Arabic and wildlife through movements between Uganda and Southern Sudan.

Poverty
Relationship between biodiversity management and poverty is measured using indicators of wealth status which include land ownership, ability to hire labour, resources to ensure education, quality of housing, and income levels. People around the protected areas in Uganda are very poor, being some of the poorest in Africa (Plumptre, et al., 2003) .

People around the protected areas make constant demands for resources from within the protected areas because of poverty levels. Resources demanded include fuel wood, timber, non-timber forest products, game meat and water. Because of poverty, there is limited capacity to develop alternatives to resources found within the biodiversity protected areas.

The community priority areas are focused on growing enough food to feed their families and possibly having a bit left for sell. Using their meager resources to grow alternatives to resources which can easily be got from the biodiversity protected areas is not a priority. Thus the demand for natural resources is not likely to diminish in the near future, but rather to increase.


Insecurity and conflicts
There has been insecurity in some parts of the country, notably; the Mt. Ruwenzori (1996-2000), Murchison Falls National park (1992-2005), Bwindi national park (1996), Mgahinga national parks (1989-1994), and this has had a profound effect on wildlife conservation. During the times of insecurity different species of animals for instance the mountain gorillas and elephants have been indiscriminately killed and trade in animal parts. Wildlife habitats has been encroached and heavily degraded.

 

Invasive Species of plants have contributed to degradation of natural habitats and displacement of native biodiversity

This is reported in several forest reserves e.g., in Mabira, Budongo and Matiri forest reserves whereby paper mulberry and acacia species have been recorded (NFA, 2011). Within Wildlife Conservation areas, changes in vegetation due to invasive species of acacia and other pasture grasses have been reported in Lake Mburo and Queen Elizabeth National parks.Nile Perch that was introduced in Lake Victoria in 1960s became invasive and displaced over 300 cichlid species in the lake (NBSAP, 2002).

 

//