Variation in soil properties under different land use types managed by smallholder farmers along the toposequence in southern Ethiopia
Negasa, T; Ketema, H; Legesse, A; Sisay, M; Temesgen, H. (2017). GEODERMA, 290 40-50; 10.1016/j.geoderma.2016.11.021 MAR 15 2017
Abstract: Understanding soil properties under different land use types along toposequences is vital in determining the types of soil management practices that could be implemented by smallholder farmers for improving the soil health as well as soil productivity. It is also important in addressing the issues, of agricultural sustainability . With the objectives of investigating variation in soil properties under different land use types managed by smallholder farmers along the toposequences, three land use types: agroforestry land (AG), cultivated land (CL) and grazing land (GL) under three slope categories (upper, middle and lower slope) were selected in southern Ethiopia , Deko watershed. A total of 108 composite soil samples [3 treatments ( land use types) 3 replications 3 slope categories (upper, middle and lower) 4 soil depth layers: 0-20 cm, 20-40 cm, 40-60 cm and >60 cm] were collected for laboratory analyses. In addition, undisturbed soil samples were taken using core sampler from each soil depth for the determination of soil bulk density. To infer the biological properties of the soils naked eye soil macro-fauna (NEMF) was counted. The results showed that among the soil properties sand (p < 0.001), clay (p = 0.002), soil bulk density (p< 0.001), soil reactio (pH, p < 0.001), Electrical conductivity (EC, p <0.001), Soil organic carbon (SOC %, p < 0.001), Total nitrogen (TN %, p = 0.001) and NEMF (p < 0.001) have shown a significant variation among the land use types while sand (p = 0.027), silt (p = 0.001), clay (p <0.001), SOC (p < 0.001) and TN (p = 0.002) exhibiting significant variation among the slope categories. Similarly, variation of soil bulk density (p < 0.001), soil pH (p < 0.001), SOC (p < 0.001), TN (p =0.002) and NNEMF (p < 0.001) were also statistically significant along the soil depth. Clay was the dominant soil textural fraction showing an increasing trend along the toposequence. Agroforestry land use type has the higher SOC, TN, pH values and EC while cultivated land use type having relatively low amount of SOC, TN, pH and EC. The lower values on cultivated land use types were due to the effects of continuous tillage practices by the smallholder farmers in the area. Slope had minimum effect on soil pH, EC, soil bulk density and the number of observable macro-faunas in the area. Moreover, SOC and TN were increased down the slope on the cultivated land use types of the area.The role of erosion is magnificent in removing SOC and TN from upper slope to lower slope as the area is more vulnerable to erosion due rugged topography. Thus, applying soil and water conservation measures on cultivated land use types play a vital role in minimizing the removal of soils down the slope.
The frankincense tree Boswellia neglecta reveals high potential for restoration of woodlands in the Horn of Africa
Mokria, M; Tolera, M; Sterck, FJ; Gebrekirstos, A; Bongers, F; Decuyper,M; Sass-Klaassen, U. (2017). FOREST ECOLOGY AND MANAGEMENT, 385 16-24; 10.1016/j.foreco.2016.11.020 FEB 1 2017
Abstract: Boswellia neglecta S. Moore is a frankincense-producing tree species dominantly found in the dry woodlands of southeastern Ethiopia . Currently, the population of this socio- economically and ecologically important species is threatened by complex anthropogenic and climate change related factors. Evaluation of tree age and its radial growth dynamics in relation to climate variables helps to understand the response of the species to climate change . It is also crucial for sustainable forest resource management and utilization. Dendrochronological and remote -sensing techniques were used to study periodicity of wood formation and leaf phenology and to assess the growth dynamics of B. neglecta. The results show that B. neglecta forms two growth rings per year in the study area. The growth ring structure is characterized by larger vessels at the beginning of each growing season and smaller vessels formed later in the growing season, suggesting adaptation to decreasing soil moisture deficits at the end of the growing season. Seasonality in cambial activity matches with a bimodal leaf phenological pattern. The mean annual radial growth rate of B. neglecta trees is 2.5 mm. Tree age varied between 16 and 28 years, with an average age of 22 years. The young age of these trees indicates recent colonization of B. neglecta in the study region. The growth rate and seasonal canopy greenness (expressed by Normalized Difference Vegetation Index - NDVI) were positively correlated with rainfall, suggesting that rainfall is the main climatic factor controlling growth of B. neglecta. The observed temporal changes in leaf phenology and vessel size across the growth rings indicate that the species is drought tolerant. Therefore, it can be regarded as a key tree species for restoration of moisture-related limited areas across the Horn of Africa.
How to target climate-smart agriculture? Concept and application of the consensus-driven decision support framework "targetCSA"
Brandt, P; Kvakic, M; Butterbach-Bahl, K; Rufino, MC. (2017). AGRICULTURAL SYSTEMS, 151 234-245; 10.1016/j.agsy.2015.12.011 FEB 2017
Abstract: Planning for agricultural adaptation and mitigation has to lean on informed decision-making processes. Stake-holder involvement, consensus building and the integration of comprehensive and reliable information represent crucial, yet challenging, pillars for successful outcomes. The spatially-explicit multi-criteria decision support framework "targetCSA" presented here aims to aid the targeting of climate-smart agriculture (CSA) at the national level. This framework integrates quantitative, spatially-explicit information such as vulnerability indicators (e.g. soil organic matter, literacy rate and market access) and proxies for CSA practices (e.g. soil fertility improvement, water harvesting and agroforesty) as well as qualitative opinions on these targeting criteria from a broad range of stakeholders. The analytic hierarchy process and a goal optimization approach are utilized to quantify collective, consensus-oriented stakeholder preferences on vulnerability indicators and CSA practices. Spatially-explicit vulnerability and CSA data are aggregated and coupled with stakeholder preferences deriving vulnerability and CSA suitability indices. Based on these indices, relevant regions with the potential to implement CSA practices are identified. "targetCSA" was exemplarily applied in Kenya exploring group-specific and overall consensus-based solutions of stakeholder opinions on vulnerability and CSA under different consensus scenarios. In this example, 32 experts from four stakeholder groups who participated in two surveys were included. The subsequent analyses not only revealed consistently regions with high CSA potential but also highlighted different high potential areas depending on the applied consensus scenario. Thus, this framework allows stakeholders to explore the consequences of scenarios that reflect opinions of the majority and minority or are based on a balance between them. "targetCSA" and the application example contribute valuable insights to the development of policy and planning tools to consensually target and implement CSA.
Tree cover in Central Africa : determinants and sensitivity under contrasted scenarios of global change
Aleman, JC; Blarquez, O; Gourlet-Fleury, S; Bremond, L; Favier, C. (2017). Scientific Reports, 7 10.1038/srep41393 JAN 30 2017
Abstract: Tree cover is a key variable for ecosystem functioning, and is widely used to study tropical ecosystems. But its determinants and their relative importance are still a matter of debate, especially because most regional and global analyses have not considered the influence of agricultural practices. More information is urgently needed regarding how human practices influence vegetation structure. Here we focused in Central Africa , a region still subjected to traditional agricultural practices with a clear vegetation gradient. Using remote sensing data and global databases, we calibrated a Random Forest model to correlatively link tree cover with climatic, edaphic, fire and agricultural practices data. We showed that annual rainfall and accumulated water deficit were the main drivers of the distribution of tree cover and vegetation classes (defined by the modes of tree cover density), but agricultural practices, especially pastoralism, were also important in determining tree cover. We simulated future tree cover with our model using different scenarios of climate and land-use (agriculture and population) changes. Our simulations suggest that tree cover may respond differently regarding the type of scenarios, but land-use change was an important driver of vegetation change even able to counterbalance the effect of climate change in Central Africa .
Wildlife Population Dynamics in Human-Dominated Landscapes under Community-Based Conservation: The Example of Nakuru Wildlife Conservancy, Kenya
Ogutu, JO; Kuloba, B; Piepho, HP; Kanga, E. (2017). PLOS ONE, 12 (1):10.1371/journal.pone.0169730 JAN 19 2017
Abstract: Wildlife conservation is facing numerous and mounting challenges on private and communal lands in Africa , including in Kenya . We analyse the population dynamics of 44 common wildlife species in relation to rainfall variation in the Nakuru Wildlife Conservancy (NWC), located in the Nakuru-Naivasha region of Kenya , based on ground total counts carried out twice each year from March 1996 to May 2015. Rainfall in the region was quasi-periodic with cycle periods dependent on the rainfall component and varying from 2.8 years for the dry season to 10.9 years for the wet season. These oscillations are associated with frequent severe droughts and food scarcity for herbivores. The trends for the 44 wildlife species showed five general patterns during 1996-2015. 1) Steinbuck, bushbuck, hartebeest and greater kudu numbers declined persistently and significantly throughout 1996-2015 and thus merit the greatest conservation attention. 2) Klipspringer, mongoose, oribi, porcupine, cheetah, leopard, ostrich and Sykes monkey numbers also decreased noticeably but not significantly between 1996 and 2015.3) Dik dik, eland, African hare, Jackal, duiker, hippo and Thomson's gazelle numbers first increased and then declined between 1996 and 2015 but only significantly for duiker and hippo. 4) Aardvark, serval cat, colobus monkey, bat-eared fox, reedbuck, hyena and baboon numbers first declined and then increased but only the increases in reedbuck and baboon numbers were significant. 5) Grant's gazelle, Grevy's zebra, lion, spring hare, Burchell's zebra, bushpig, white rhino, rock hyrax, topi, oryx, vervet monkey, guinea fowl, giraffe, and wildebeest numbers increased consistently between 1996 and 2015. The increase was significant only for rock hyrax, topi, vervet monkey, guinea fowl, giraffe and wildebeest. 6) Impala, buffalo, warthog, and waterbuck, numbers increased significantly and then seemed to level off between 1996 and 2015. The aggregate biomass of primates and carnivores increased overall whereas that of herbivores first increased from 1996 to 2006 and then levelled off thereafter. Aggregate herbivore biomass increased linearly with increasing cumulative wet season rainfall. The densities of the 30 most abundant species were either strongly positively or negatively correlated with cumulative past rainfall, most commonly with the early wet season component. The collaborative wildlife conservation and management initiatives undertaken on the mosaic of private, communal and public lands were thus associated with increase or no decrease in numbers of 32 and decrease in numbers of 12 of the 44 species. Despite the decline by some species, effective community based conservation is central to the future of wildlife in the NWC and other rangelands of Kenya and beyond and is crucially dependent on the good will, effective engagement and collective action of local communities, working in partnerships with various organizations, which, in NWC, operated under the umbrella of the Nakuru Wildlife Forum.