A group of researchers have been burning the midnight oil
are using data collected over more than fifty years to determine the
factors that result in positive and negative land use change through
understanding how soil, water and biodiversity are maintained in some
areas thus managing ecosystems.
East African landscape has been changing
with agricultural production impacting on the biodiversity on one of
the world's most diverse ecosystems and affecting areas traditionally
used by pastoralists and wildlife. Understanding the factors behind land
use changes in East Africa has been the objective of a network of
international researchers, known as LUCID (Land Use Change, Impacts and
Dynamics), who are using data collected over more than fifty years to
determine the factors that result in positive and negative land use
change. Understanding how soil, water and biodiversity are maintained in
some areas and not others is of interest not only to the LUCID
scientists but to environmental projects elsewhere in Africa and Asia.
The impact of socioeconomic changes on
the environment is often ignored in land use and biodiversity research,
says Jennifer Olson, network co-coordinator, even though it is critical
to understanding how land use can be improved. Working in Kenya, Uganda
and Tanzania, LUCID researchers compare old and new data, using aerial
photographs and satellite images to see changes over time in land use.
Distinct from other projects, five decades of data identifying changes
in land use is then integrated with ecological data (from soil sampling
and wildlife/plant surveys) and socioeconomic data (from personal
interviews and population counts).
Whether an area is maintained or
degraded in terms of soil, water and biodiversity is dependent on a
number of factors including inherent soil quality, local climate,
population and political stability. Migration is also "a really
important reason for the conversion of land from more natural vegetation
to crops," stresses Olson. It is happening especially in densely
populated areas and where young people have insufficient land for their
families, she adds. Consequently, a greater number of people are moving
out into the more marginal areas, leading after a few years to severe
soil degradation which is difficult to reverse.
This is a particular problem in Kenya,
says Olson, where the good land is already cultivated. People move into
the drier areas and manage to get some food from the land while
supplementing their income with off-farm work, but usually at the
expense of the natural environment.
In Uganda, where it is generally not as
dry, Olson reports that some areas, such as the former cattle corridor
in the central and southern regions, which have yet to be put under
cultivation, are at risk; LUCID projections suggest it is only a matter
of time. In Tanzania, two predominant land use changes are the rapid
conversion of pastoral areas to crop land, and large areas of the miombo
woodland being cleared for tobacco and other crops.
In some areas of East Africa, however,
environmental resources have been improved by people engaging in
extensive agriculture. In all three countries, Olson and her team found
that in areas that are more 'hooked up' to markets and where the soil
quality and rainfall is adequate, farmers can derive enough income from
their farms to invest the time and resources needed to institute soil
erosion prevention practices, apply chemical fertilisers and/or use
manure.
As a result, says Olson, soil fertility
in some areas has started improving. Soil fertility has also been
boosted when, in the past, governments stepped in to subsidise chemical
fertiliser. However, Olson points out that "to start to use manure in a
systematic way that makes a difference is quite an effort."
After some years of neglect, governments
and NGO's in East Africa are beginning to pay more attention to
agriculture. And in areas where the land is marginal, Olson sees
agricultural extension programmes and off-farm jobs as critical to
providing farmers with the means to replenish soil fertility. Olson also
lists community land use planning - which involves preservation of some
forest and pasture land for community use - poverty reduction, and
family planning programmes as keys to halting land degradation.
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