The crop’s growing areas of Malawi have been broadly classified
into three agroecological zones (AEZ) based on
the altitude, soil type characteristics and prevailing climatic conditions;
rainfall, temperature.
Mid-Altitude altitude AEZ ranges between 600-1,300
m (above sea level) and dominated ferallitic
and ferruginous soil types, receiving an annual average
rainfall of about 875mm, Examples of areas falling within this zone includes Lilongwe-kasungu plain,
Upper South Rukuru valley, Chitipa Plain, and Shire Highlands.
The agroecosystems of the mid altitude agroecological areas
are dominated by maize monocrop or intercropped with pumpkins, beans and
groundnuts (other legumes), monocrops of Tobacco, Soybean, ground nuts, cassava, sweet potatoes, tomatoes
and many more (Moyo, 2008). Smallholder farmers in the zone usually
practice mixed farming system by tending to keep various types of livestock
such as sheep, chickens, pigeon, cattle, goats, pigs within the agroecosystem (Peters,
2002). To some extent these traditional systems increased and maintained agrobiodiversity.
MAJOR THREATS TO BIODIVERSITY
i.
Population Pressure
High
populations especially on the Lilongwe-Kasungu plain is putting more pressure
on land for settlements and food production. With high percentage of people in
the area attaining marriage age and start fresh families has increased demand
for settlement land. High population coupled with poor land use policies have resulted
more extensive clearing of the existing natural ecosystems and altering
productive arable lands into settlements leading to diminished land holding
size for agricultural production.
In order to expand food production areas, farmers
have started cultivating in marginal areas (i.e. hillsides and river flow
bases), thus increasing soil erosion that are causing siltation of rivers on
the zone and destroying habitats for aquatic species i.e. fish.
ii.
Agriculture Production Methods and inputs aiming to increase
productivity
Farmers have
been adopting some methods of farming and using chemicals to promote
productivity of their crop without the long term effect of their technologies.
Most of the
areas in zone are produce tomato and tobacco both these crops are associated
with high pesticides application. The pesticides lead to killing of non-target
insect species hence results in reduction insects’ diversity.
Transition
from traditional mixed farming to modern monoculture farming systems in order
to maximise yields of most important or cash crop (maize and tobacco) in all
other areas of the agroecosystem is causing significant loss in biodiversity
and resulting in decline of species and genetic diversity (Khumalo et al, 2012).
iii.
Poverty
Most people in the
zone leave below poverty line which forces
people to depend on natural resources for energy (fuelwood), food, and fodder (Environmental
Affairs Department 2006). Livestock’s theft more especially on the
Lilongwe-Kasungu plain has also been high due to poverty, forcing most farmers
to stop keeping livestock like cattle, minimizing livestock diversity in
agroecosystems.
iv.
Introduction of invasive alien species
There
are some exotic species which have been introduced in the agroecological zone
that have negative effects on the existence of other species in agroecosystems
these are known as invasive alien species.
The
major threat of invasive alien species to the biodiversity is through
alteration of the microclimate and displacing the indigenous flora and fauna.
Such kind of species affect biodiversity present in the mid altitude
agroecosystems include Eucalyptus sp (e.g. blue gum), Gmelina arborea, and
Lantana camara (mainly used as hedges) (see
Environmental Affairs Department 2006).
STRATEGIES
OF MAINTAINING AND PROMOTING BIODIVERSITY
i.
Agroforestry
In
simple terms agroforestry is defined broadly as agricultural systems in which
trees are grown together with annual crops and/or livestock, resulting in
enhanced complementary relations between components and increased multiple use
(Bichier 2006). Agroforestry is a more suitable approach is
agroecosystems of all the areas of the zone in maintaining and promoting
numbers of animals and plants species. The system can be implemented by
planting multipurpose leguminous trees in fields’ boundaries or marginal land
(i.e. gliricidia, sesbania, leuceana) or intercropped with maize (i.e. T.
vogelli) (Mercycorps, 2015).
ii.
Mixed farming systems
Farming
systems that diversify planted crops in form of polycultures and integrating
livestock by exploiting complementarity and synergism offers a great
opportunity of promoting biodiversity (Altieri 1999).
Promoting
intercropping of cereal – legume plants, double up legumes helps to promote
diversity at species level while usage of different kinds of varieties of the
crops helps maintain genetic and promote diversity (Altieri 1999). Implementing
these kind of systems will benefit the zone’s agroecosystems more. Diet and
income will be diversified, risks of total crop failure will be minimised, reduced
insect and disease incidence, labour will be utilised efficiently, also returns
will be maximised under low levels technologies.
REFERENCE
Altieri
M.A. 1999. The ecological role of biodiversity in agroecosystems. Agriculture,
Ecosystems and Environment 74 (1999) 19–3. Department of Environmental Science,
Policy and Management, University of California, 201 Wellman, Berkeley, CA
94720, USA.
Bichier P. 2006. Agroforestry and the Maintenance of
Biodiversity. American Institute Of Biological Sciences.
Environmental
Affairs Department 2006. National Biodiversity strategy and action plan. Malawi
government, Ministry of Energy, Mines, and Natural Resources.
FAO.
2004. Building on Gender, Agrobiodiversity and Local knowledge.
Khuma,
S., Chirwa, P.W., Moyo, B.H. and Syampungani, S. 2012. The status of
agrobiodiversity management and conservation in major agroecosystems of
Southern Africa. Bioversity International.
Long,
C.L., Li, H., Ouyang, Z., Yang, X., Li, Q., Trangmar, B., 2003. Strategies for
agrobiodiversity conservation and promotion: a case from Yunnan, China.
Biodiversity & Conservation, Vol 12, Issue 6, pp 1145-1156.
Management
in African Agriculture.CABI publishers,Oxon, pp. 35-50.
MercyCorps.
2015. Discussion paper; Building resilient food systems Through agroecological
principles and practices.
Moyo, B.H.Z., 2009. Indigenous knowledge-based
farming practices: a setting for the contestation of modernity, development and
progress. Scottish Geographical Journal.125 (3-4), 353-360.
Peters, P.E., 2002. The limits of knowledge:Securing
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