Browsing by Author "Brabers, Leon"

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The effect of soil physical properties and soil microclimate on rodent burrows’ abundance and their characteristics in Western Usambara Mountains, Tanzania
(ournal of Agriculture and Ecology Research International, 2014-12-16) Meliyo, Joel, L.; Brabers, Leon; Massawe, Boniface H. J.; Msanya, B. M.; Kimaro, D. N.; Mulungu, L. S.; Kihupi, N. I.; Deckers, Jozef, A.; Gulinck, Hubert; Leirs, Herwig
The present study was carried out between September 2009 and June 2013 in Western Usambara Mountains plague focus with the aim of establishing the influence of selected soil physical properties and soil microclimate on rodent burrows’ abundance, portal orientation and use. Two landscapes with high and medium plague frequencies in Lokome and Lukozi villages were studied. In the two landscapes data were collected from 117 and 200 observation sites respectively, using 100 m x 200 m quadrats. At each quadrat crossing, a sample quadrat of 20 m x 20 m was demarcated for scanning rodent burrows whereby burrows encountered were counted and their portal orientation and burrow use described. Within each sample quadrat, selected soil physical properties including thickness of the soil genetic horizons and soil dry consistence were determined. Soil samples were collected from each horizon for laboratory texture analysis. Temperature (surface and subsurface to a depth 10 cm) and relative humidity at a depth of 10 and 30 cm were collected using infrared, thermo-couple thermometers and i-Buttons. Descriptive statistics, ANOVA and logistic regression were used to analyse the data by R-software. There were significant (P=.0001) differences between the two landscapes regarding topsoil depth, infrared temperature, relative humidity and rodent burrows’ abundance. In the high plague frequency landscape there was a significant influence (P=.05) of topsoil horizon thickness on rodent burrows’ abundance and use. Results also indicate that soil temperature to a depth of 10 cm was significantly (P=.05) correlated with rodent burrow use. Likewise, in the medium plague frequency landscape, soil physical properties and soil microclimate significantly (P=.0001) discouraged rodent burrowing. It was concluded that soil physical and soil microclimate encouraged and discouraged burrowing in the high and the medium plague frequency landscapes, respectively. The landscape with high rodent burrows’ abundance corresponded with high plague frequency records.
Status and variability of soil micronutrients with landforms in the plague focus of Western Usambara Mountains, Tanzania
(International Journal of Plant & Soil Science, 2014-11-13) Meliyo, Joel L.; Massawe, Boniface H. J.; Brabers, Leon; Msanya, B. M.; Kimaro, D. N.; Kihupi, N. I.; Deckers, Jozef A.; Gulinck, Hubert; Leirs, Herwig
A study was carried out in Western Usambara, Tanzania to assess the status of soil micronutrients across three geomorphic units viz., plain, escarpment and plateau in order to provide essential information for on-going studies on plague epidemiology. Nineteen soil profiles were opened, described and 54 samples collected for laboratory analysis. Standard methods were employed to analyse soil physical and chemical properties. Micronutrients Fe, Mn, Cu and Zn were extracted by DTPA and quantities estimated spectrophotometrically. Spatial distribution of micronutrients along the geomorphic units and within pedons was studied using descriptive statistics, correlation, ANOVA and means separation was done by Tukey’s test at 95 % confidence interval in Minitab 14 software. Relationships between small mammal and flea abundance and micronutrients were established by regression analysis using R-software. Results showed that DTPA extractable Fe, Mn, Cu and Zn were variable. Fe ranged from 2.13 to 399.4 mg/kg soil, with a mean of 65.3 mg Fe/kg soil across the geomorphic units. Mn ranged from 0.59 to 266.28 mg Mn/kg soil while Cu ranged from 0.25 to 8.19 mg/kg soil with a mean of 2.98 mg Cu/kg soil. Results show that Zn ranged from 0.08 to 19.6 mg Zn/kg soil, with a mean of 1.16 mg Zn/kg soil. Generally, micronutrients declined with soil depth. The micronutrient levels were high in the geomorphic units with the trend: plateau > escarpment > plain. Iron was found to significantly P<.01 and P<.05 influence plague hosts and vectors. The study concludes that micronutrients vary with soils and geomorphic units. Iron had positive influence on plague hosts and vectors. Further research on the relationships between micronutrients, and plague hosts and vectors in different plague foci in the country is recommended.