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Published:
Feb 27, 2019Keywords:
Cropping frequency Intensification Species diversity Succession Slash-and-burn Soil
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The effect of shortening fallow length on recovery of plant species richness, composition and growth in shifting cultivation landscapes of Kilosa District, Tanzania
Abstract
There is insufficient knowledge on the
effects of shifting cultivation on vegetation
change, especially in situations of land use
intensification. This study investigated the
effects of shortening fallow length on
recovery of small (Dbh < 5 cm) and big
(Dbh ≥ 5 cm) plant species richness,
composition and height growth in a dry
Miombo woodland in East Central Tanzania.
Vegetation sampling was conducted on 40
(10 m x10 m) plots and 80 (5 m x 5 m) subplots
from adjacent sites under fallow for 3,
5, 7 and 15 years and a control secondary
forest. Results showed that shortening
fallow length to not less than 7 years did not
have a significant negative effect on
recovery of plant species richness and height
growth for both small and big sized plant
species. However, there was a remarkable
shift in composition of dominant species
when fallow length was less than 15 years.
Results showed that big size Miombo
woodland defining species such as
Brachystegia bussei, B. boehmii, and B.
spiciformis were deprived in fallows
younger than 15 years but dominant in
secondary forest. Non-Miombo woodland
defining species such as Cassia burtii and
Dombeya shumpangae were instead
dominant in younger fallows. These results
imply that if the fallow length is shortened
to 3 years as required by Village Land Use
plans in Kilosa District, the sustainability of
the shifting cultivation systems will be
threatened, affecting ecosystems services
offered by landscapes under shifting
cultivation. It is therefore recommended that
fallow length be prolonged to at least 7 years
and that communities are encouraged to
retain some of the Miombo woodland
defining species in the fields under
cultivation.
effects of shifting cultivation on vegetation
change, especially in situations of land use
intensification. This study investigated the
effects of shortening fallow length on
recovery of small (Dbh < 5 cm) and big
(Dbh ≥ 5 cm) plant species richness,
composition and height growth in a dry
Miombo woodland in East Central Tanzania.
Vegetation sampling was conducted on 40
(10 m x10 m) plots and 80 (5 m x 5 m) subplots
from adjacent sites under fallow for 3,
5, 7 and 15 years and a control secondary
forest. Results showed that shortening
fallow length to not less than 7 years did not
have a significant negative effect on
recovery of plant species richness and height
growth for both small and big sized plant
species. However, there was a remarkable
shift in composition of dominant species
when fallow length was less than 15 years.
Results showed that big size Miombo
woodland defining species such as
Brachystegia bussei, B. boehmii, and B.
spiciformis were deprived in fallows
younger than 15 years but dominant in
secondary forest. Non-Miombo woodland
defining species such as Cassia burtii and
Dombeya shumpangae were instead
dominant in younger fallows. These results
imply that if the fallow length is shortened
to 3 years as required by Village Land Use
plans in Kilosa District, the sustainability of
the shifting cultivation systems will be
threatened, affecting ecosystems services
offered by landscapes under shifting
cultivation. It is therefore recommended that
fallow length be prolonged to at least 7 years
and that communities are encouraged to
retain some of the Miombo woodland
defining species in the fields under
cultivation.
