Relationships between soil properties and tree species diversity in selected miombo woodland ecosystems, Tanzania
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Date
2016
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Publisher
Sokoine University of Agriculture
Abstract
This study aimed to assess relationships between selected edaphic properties with tree
species diversity and amount of soil organic carbon at Kitulang'halo (Morogoro district)
and Kibutuka (Liwale district) Miombo woodland ecosystems in Tanzania. Ten and eleven
clusters were studied in Kitulang’halo and Kibutuka, respectively. Some of these clusters
were those established by National Forest Resource Monitoring and Assessment
(NAFORMA) while others were imbedded in order to increase reliability of data. Each
cluster had ten circular plots of 15 m radius set al 250 in intervals. Three plots (4. 7 and
10) from each cluster were chosen systematically for soil and tree data collection making a
total of 63 plots. AH tree species with DBH > 5 cm were measured and identified by their
botanical names. Soil sampling was done by digging a soil mini-pit to 30 cm depth
(NAFORMA approach) at intervals of 10 cm and angering to 100 cm depth (World
Agroforestry Centre (1CRAF) approach) at 20 cm depth interval. Tree species diversity
was determined using Shannon-Wiener diversity index (H’). Soil chemical properties (soil
organic carbon (SOC). total nitrogen, exchangeable bases, cation exchange capacity,
available phosphorus and soil pH) from samples collected by NAFORMA approach were
analyzed by standard methods. SOC from soil samples collected by ICRAF approach was
analyzed by Mid Infrared Radiation (MIR) method. Kitulang’halo had 123 different tree
species (H'= 4.26) while Kibutuka had 102 different tree species (H’= 4.06). SOC. total N,
Ca2+, K+, Na+ and CEC were higher at Kibutuka than at Kitulang’halo, while Mg2+,
available P and pH were higher at Kitulang'halo. Tree species richness was positively
related to SOC. Though this relationship was weak, it was significant at P<0.05,
suggesting that SOC was high at higher tree species diversity. Tree species richness was
not related to other soil chemical properties. The amount of SOC at 0-30 cm depth was
about 42% of the total contained at 100 cm depth with about 58% of SOC in layer 30-100 cm depth in both sites. There was a consistent decrease in SOC storage with increasing
soil depth in Kitulang’halo while at Kibutuka the maximum of SOC was found at 20-40
cm (40 t/ha), and then decreased with depth to 100 cm. The amount of SOC estimated by
MIR method (ICRAF approach) and Walkley-Black method (NAFORMA approach)
differed significantly (P<0.05), whereby the NAFORMA approach estimated more SOC
than ICRAF approach. Kitulang’halo and Kibutuka Miombo woodland ecosystems require
promoting conservation activities to increase a wide range of ecosystem processes and
functions.
Description
Dissertation
Keywords
Kitulang'halo, Kibutuka, Miombo woodland, Edaphic properties, FORESTRY, AGRICULTURAL SCIENCES and LANDSCAPE PLANNING::Plant production::Forestry