The regeneration of miombo woodlands in charcoal production areas in kilosa district, Tanzania
Loading...
Date
2021
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
SUA
Abstract
Miombo woodlands covers 90% of the forested area in Tanzania and 10% of the African
landmass. Therefore, any deforestation or forest degradation of these forests have the
national and continental significance. The ability of miombo to regenerate naturally
functions as the survival mechanism amongst multiple disturbances. The majority of
disturbances to miombo woodlands have been imposed by humans in meeting their
demands for survival. This includes the disturbance generated in obtaining the fuelwood.
Charcoal is used as an important fuelwood to both urban and rural populations. However,
charcoal production is considered as the massive cause of deforestation and forest
degradation in Tanzania and across the continent. Regarding the importance of charcoal
to the society, Sustainable Forest Management (SFM) to ensure the sustained production
of charcoal is requisite. The present study aimed to provide a better understanding of
regeneration of miombo trees through the assessment of the area deliberately harvested
for charcoal production. The study was conducted in eight Village Land Forest Reserves
(VLFRs) in Kilosa district under Community Based Forest Management (CBFM).
Specifically, the study aimed to (i) review literature on regeneration dynamics of miombo
trees, (ii) assess the regeneration status of miombo trees in the charcoal kiln scars, (iii)
assess the forest standing structure and above-ground biomass in harvested blocks and
(iv) determine the optimum stump height and diameter for maximum coppicing in
harvested miombo.
Data collection utilized different methods and sampling approaches. For the first
objective, a standard literature search for documents related to miombo regeneration was
performed using multiple electronic databases. More than 60 peer-reviewed published papers on the subject matter were obtained and critically reviewed. The data for the
second objective was obtained by assessing the kiln scars in charcoal production blocks.
The assessed blocks were only those with 4, 5 and 6 years from cessation of charcoal
production where 154 kiln scars were assessed. The third objective aimed to assess the
standing structure and above-ground biomass, where 106 circular plots with a radius of 15
m were assessed in the areas where charcoal production has ceased for 6 years. In the
fourth objective which aimed on establishing the optimum stump height and diameter for
maximization of coppicing regeneration in the areas harvested for charcoal production,
the assessment was done to stumps within the plot of 50 m x 50 m. A total of 925 stumps,
representing 43 species were measured in the area with 4 (2015-2019), 5 (2014 - 2019)
and 6 (2013 - 2019) years from cessation of charcoal production. The stump height,
stump diameter, regenerants counts and size (basal diameter and height) were measured,
alongside identifying species for individual stumps.
The results revealed that vegetative propagation through coppice and root suckers are the
most feasible and prominent regeneration method in miombo woodlands managed for
charcoal production. Kiln scar results revealed that kiln scars occupy 1.5% of the total
harvested area. The study also confirmed that trees can naturally regenerate in kiln scars
to which the number of tree regenerants increases significantly (F (2,151) = 7.1, p <
0.05) with the addition of time from cessation of charcoal production. Assessment of
standing structure and composition of 6 years post charcoal production cessation recorded
stand dominated by re-growing trees with the basal area, volume and above-ground
biomass of 3.77 ± 1.27m 2 ha -1 , 31.71 ± 10.79m 3 ha -1 and 21.5 ± 7.24t ha -1 , respectively. Also
in the harvested area, about 68% of trees were established from seedlings with remaining
individuals established vegetatively as they were limited to the number of stumps
remained. The assessment of stumps for coppicing revealed that number of living stumps decreased significantly (p < 0.05) with the increase in time where 73, 68 and 51% of
stumps were alive in the area terminated harvesting for 4, 5 and 6 years, respectively.
Also, there is a positive relationship between the stump mortality and the increase of the
stump diameter while no clear pattern for stump height. The coppicing effectiveness of
the stump increases with both diameter (r 2 = 0.31) and height (r 2 = 0.18). The optimum
harvesting diameter and height ranges is from 20 to 40 cm and 45 to 60 cm, respectively.
Generally, it is concluded that trees in harvested charcoal production areas are
regenerating naturally and growing relatively well. Also, vegetative propagation through
stump coppices and root suckers is the most feasible and suitable regeneration method in
management of forest harvested for charcoal production. The coppicing effectiveness is
determined by stump height, stump diameter and the time lapsed from harvesting.
Harvested large diameter trees are associated with high mortality compared to small-
diameter trees. The high stump survival was recorded for stumps with height between 46
and 60 compared to higher mortality of shorter and longer stumps. To reduce the recovery
time of the harvested stand, it is recommended that the minimum harvesting dimensions
should be revised to stump diameter between 20 and 40cm and height between 45 an
60cm. Also, the protection of regenerating areas against disturbances is highly
recommended since its recovery largely depends on the seedlings which are highly
vulnerable to the effects of disturbances such as fire and overgrazing.
Description
Keywords
Woodlands, Sustainable Forest Management, Village Land Forest Reserves, Charcoal production