Dataverse World Agroforestry (ICRAF)
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Replication Data for Quantifying the effects of abiotic and biotic factors in determining leaf litter decomposition rates along a disturbance gradient in a tropical montane landscape
No full textDeforestation and forest degradation are driving unprecedented declines in biodiversity across the tropics, and understanding the consequences of these changes for ecosystem functioning is essential for human well-being. Forest degradation and loss alter ecosystem functioning through changes in species composition and abiotic conditions. However, the consequences of these changes for heterospecific processes are often poorly understood. Leaf litter decomposition is a major source of atmospheric carbon and critical for carbon and nutrient cycling. Through a highly replicated litter-bag experiment (3360 bags), we quantified the effects of litter quality, decomposer functional diversity and seasonal precipitation regime on litter decomposition along a tropical disturbance gradient in SW China. In addition, using soil and litter from sites selected from across the disturbance gradient, we established replicated litter-bed treatments and exposed these to a gradient of simulated canopy cover in a shade-house. Across the landscape, mass loss from litter-bags after 12 mo varied from 7-98%. Even after 12 mo, litter-bags installed at the beginning of the dry season had much lower mass loss than those installed at the beginning of the wet season. As expected, litter quality and faunal exclusion had substantial effects on decomposition rates. Decomposition rates declined along the disturbance gradient from mature forest, through regenerating forest to open land, although the effect size was strongly dependent on installation season. The effect of excluding meso- and macro-invertebrates increased with increasing forest degradation, whereas the effect of litter quality declined. Results from the shade-house experiment strongly suggested that forest degradation effects were driven predominantly by changes in micro-climatic conditions resulting from increased canopy openness. To better model the impacts of anthropogenic global change on litter decomposition rates, it will be important to consider landscape scale processes, such as forest degradation.
Key words: carbon cycle; decomposition; disturbance gradient; landscape; leaf litter; litter fauna; litter-bags; mass loss; mesocosm; seasonality; soil properties; tropical forest
Baseline assessment of farmer groups in Manafwa and Kapchorwa Uganda
No full textThe data collection aimed at understanding the characteristics of the different farmer groups in project sites and to determine the strategy options for farmers groups available in the area for improved capacities. The census also acted as a baseline before interventions to strengthening farmer groups so as to monitor any changes after project interventions
Replication data for: Influence of leaf area and nursery substrate on the rootinG aptitude of Theobroma cacao cutting
No full textThis study was conducted to find out the influence of leaf area and nursery substrate on the rooting aptitude of Theobroma cacao. The experimental design was a randomized 3 blocks using substrate such as sawdust+ sand, sand and sawdust
ICRAF-ISRIC Soil VNIR Spectral Library
No full textThe ICRAF-ISRIC Soil VNIR Spectral Library contains visible near infrared spectra of 785 soil profiles (4,438 samples) soils selected from the Soil Information System of the International Soil Reference and Information Centre (ISRIC). The samples consist of all physically archived samples at ISRIC in 2004 for which soil attribute data was available. The spectra were measured at the World Agroforestry Center (ICRAF) Soil and Plant Spectral Diagnostic Laboratory. The samples are from 58 countries spanning Africa, Asia, Europe, North America, and South America. Associated attribute data, such as geographical coordinates, horizon (depth), and physical and chemical properties, are provided as separate tables. Using different methods for linking related files as explained in the pdf document accompanying this dataset (0ICRAF-ISRICSoilVNIRSpectralLibrary.pdf), the visNIR spectra can be linked with all tables holding both physical and chemical properties
Replication Data for: An assessment of the variation of soil properties with landscape attributes in the highlands of Cameroon
No full textSoil properties are useful for assessing the potential of landscapes to provide terrestrial ecosystem services, but they are affected by anthropogenic activities and environmental factors including landscape attributes. This study assessed how soil properties are influenced by landscape attributes and their interactions in the highlands of Cameroon using the Land Degradation Surveillance Framework as a data collection tool. Soil properties (soil organic carbon [SOC], clay content, exchangeable bases [ExBas], electric conductivity [EC], boron [B], manganese [Mn], phosphorus [P], pH) were quantified within classes of landscape attributes. Soil samples were collected on 160 (1,000 m2) plots randomly located in a sentinel site of 100 km2 and were analyzed using a combination of conventional laboratory methods and mid‐infrared spectroscopy. Soil properties were highly affected by soil depths, land use types, slope gradients, and topographic positions, but less by their interactions. Significant interactions existed between land use types and topographic positions for SOC, EC, ExBas, and pH, and between slope gradients and topographic positions for pH, whereas Mn was influenced by the interaction between land use types and slope gradients. Most soil properties were higher in low altitude plots and those with higher vegetation cover but decreased in the upslope direction. The pH and clay contents were less affected by slope gradient confirming the inherent nature of the properties. These results are useful for site‐specific implementation of ecological intensification in areas with complex topography such as the highlands of Cameroon, offering a reference for future ecological policies and landscape restoration
Replication data for: Growth and fuelwood properties of five tree and shrub species in the Sahelian and Sudanian ecozones of Mali: relationships with mean annual rainfall and geographical coordinates
No full textIn the Sahelian and Sudanian ecozones of West Africa, the rainy season lasts only 3-4 months per year, there are steep rainfall gradients with latitude and longitude, the climate is becoming increasingly hotter and drier with more variable rainfall, some fuelwood species are disappearing locally, demand for fuelwood is increasing, and we expect that fuelwood production will be increasingly limited to drier sites in the future. We need a methodology, therefore, to identify the best species for fuelwood production in drier sites. We used a methodology that could be used to identify the best fuelwood species for drier and wetter sites in regions where there are steep rainfall gradients. We investigated variation in growth and fuelwood properties of five species (Balanites aegyptiaca, Combretum glutinosum, Guiera senegalensis, Piliostigma reticulatum, Ziziphus mauritiana) along rainfall gradients. Growth parameters (tree height, stem diameter under bar
k, mean ring width) and fuelwood properties (basic density, volatile matter, fixed carbon, ash content, moisture content, gross calorific value, gross calorific value per cubic meter, fuel value index) were adjusted for tree age. For each species, linear regressions were used to determine the effects of mean annual rainfall and geographical coordinates, which were correlated with rainfall, on tree growth and fuelwood properties; and the effects of tree growth on fuelwood properties in lower, intermediate and higher rainfall zones. Geographical coordinates explained more variation than rainfall, and relationships with rainfall differed among species. Larger trees had wood with higher basic density, fixed carbon, ash content, moisture content, gross calorific value and/or gross calorific value per cubic meter, but lower volatile matter and/or fuel value index. Relationships between growth and fuelwood properties were not significant in all species and rainfall zones. Based on this study, we recommend producing fuelwood of C. glutinosum and G. senegalensis
Replication data for: Genetic Variation of Kenyan Populations of Warburgia ugandensis, an Important East African Highlands Medicinal Tree Species
No full textWarburgia ugandensis is an important medicinal tree species in Eastern Africa used to treat several ailments. Wild populations are under great threat due to unsustainable harvesting for medicines and indiscriminate felling of trees for timber and firewood. There is an urgent need for developing and implementing conservation strategies of this species and information on genetic structure is a crucial input. Analysis of molecular variance (AMOVA), which employed 141 AFLP markers revealed most genetic variation to be among individuals within populations (59%, P is less than 0.0001), but variation among populations (41%, P is less than 0.0001) was highly significant as well. Constrained ordination analysis illustrating the relationship among populations showed a clear distinction between W. ugandensis from Uganda and western Kenya and other W.
ugandensis populations. No correspondence was shown in some cases on pair-wise genetic distances and geographic distances among populations. These findings suggested that conservation strategies for the species in Kenya should place relatively more emphasis on the revealed genetic structuring within the country