Képzés és Gyakorlat 17.

A soil carbon assessment was performed comparing agricultural cropping systems with natural vegetation along a sampling transect spanning different agro-ecologies on the eastern foot slopes of Mount Kenya in Embu county, 125 km from Nairobi, Kenya. The aim was to determine differences in soil carbon stocks and carbon recalcitrance and relate these to soil textural class, altitude, climatic parameters and land use. Soils from main agricultural systems as tea, coffee and maize-based intercropping, as well as from natural vegetation cover were sampled in triplicates, in five layers from 0 to 30 cm in depth and processed for total carbon analysis. The whole soil samples were also analysed using Laser-Induced Fluorescence Spectroscopy (LIFS) to assess carbon humification. Prototype portable equipment intended for future in situ analysis was used in the lab to ascertain the structure of the most recalcitrant and stable carbon present in different agro-ecosystems. In addition, Near Infrared Spectroscopy (NIRS) was tested for the quantitative analysis of soil carbon, showing that it is a reproducible and low-cost method that provided satisfactory results under the processing conditions of the samples. Results showed wide variation in the level and quality of carbon stored in the soils, depending on soil texture, land use, elevation, climate, agricultural practices and land use history. Considering the heterogeneous nature of sampled soils and the performance of NIRS and LIFS, these results can be used as a basis for the development of fully portable systems able to provide rapid, clean and potentially cost-effective relevant information for soil management

Climate Change and Cereal Production Evolution Trend in the Sahel: Case Study in Mali from 1951 to 2010

Mali is a Sahelian country with a large climatic contrast from North to South. The current climatic and production evolutionary study is focused on the six major agro-climatic cereal production zones ranging from Kayes (400 mm) to Sikasso (>1000 mm) of rainfalls. Climatic data are rainfall records, daily maximum and minimum temperatures from 60 years of the six major synoptic weather observation stations. Data were analyzed on comparing average decades of the two normal periods of 30 years (1951-1980) and (1981-2010). Annual agronomic production data for millet, sorghum, maize and rice are derived from Mali's agricultural statistics base from 1984 to 2013. Main climatic results analyses indicate that climate change resulted in a decrease of 100 mm isohyets between the 2 periods of 30 years. The structure of the rainy season was little changed between these two periods since the average start of the season was delayed by 6 days and the average end date of the season became earlier by 4 days. Maximum temperatures increased significantly from + 0.44°C to + 1.53°C and minimum temperatures significantly increased from + 1.05°C to + 1.93°C in varying way depending on the sites. Statistics of major agronomic food crop production in Mali from 1984 to 2013 indicate an average increase of 985 to 4492 thousand tones, or 22% increase per year. There is a positive upward in saw tooth trend in Malian production from 1984 to 2013. This positive trend is the result of a combination of agricultural extension, agronomic research application and the management of small farmer holder in the Sahel. This evolution needs better study for drawing necessary right conclusions

Modelling landslide dynamics in forested landscapes

The research resulting in this thesis covers the geological, geomorphological and landscape ecology related themes of the project 'Podzolisation under Kauri (Agathis australis): for better or worse?' supported by theNetherlands Organisation for Scientific Research (NWO). The general objective of this thesis is to investigate landscape, soil and vegetation dynamics in theWaitakereRangesRegionalParkon the North Island of New Zealand, where also all the fieldwork was carried out. The main core of the thesis consists of the development of a dynamic landscape process model to simulate soil redistribution by shallow landsliding. Resulting spatial patterns of erosion and deposition, changes in landslide susceptibility over time and the relation of spatially explicit landscape attributes with vegetation patterns are further explored.·Chapter 1 is a general introduction elaborating on the geology, climate and socio-economic setting of the study area and explains the main objectives and research questions. The contents and overall structure of the thesis are also illustrated. Following this introductory chapter, the thesis is composed of 5 chapters based on scientific papers published in or submitted to peer reviewed journals. ·Chapter 2 deals with the general tectonic setting of the study area. Quaternary coastal and fluvial terrace morphology and chronology are explored to reconstruct the tectonic history of the south-west coast of the Northland region inNew Zealand. This chapter is situated on the geological timescale (1.8 Ma BP till present) and places the subsequent chapters dealing with the landscape process model and its applications, acting on a timescale of years to decades, in a broader spatio-temporal perspective. Field surveys and the analysis of aerial photography yield an inventory of 13 fluvial and 12 marine terrace levels. Due to poor exposure of clear field evidence in the form of e.g. wave-cut platforms or distinct river sediments, planar landscape morphology forms the main criterion for terrace remnant identification. Based on the record of terrace height spacings, sparse tephra age control and correlation with global paleoclimatic records, an attempt is made to reconstruct the regional Quaternary uplift rates. Because no hard chronostratigraphic marker is present within the fluvial terrace sequence, fluvial terrace levels are linked to the marine sequence by using the mean uplift rates calculated from the marine terraces (0.35 mm yr -1 from 0- 0.1 Ma and 0.26 mm yr -1 from 0.1-0.3 Ma). Both sets of terraces are then correlated with oxygen isotope fluctuations and the astronomically tuned timescale from ODP Site 677 and the Vostok ice core paleoclimatic records. Oldest marine and fluvial terrace levels are estimated 1.21 Ma and 0.242 Ma respectively. Although there seems to be some form of controversy about the uplift history and especially the preservation of terraces in the study area, a general regional uplift, superimposed on glacio-eustatic sea-level changes, is substantiated as the only possible mechanism leading to the maintenance of a considerable relief and active denudation processes inland.·Chapter 3 deals with the development and application of the LAPSUS-LS landscape process model. The model is constructed as a component of the LAPSUS modelling framework ( L andsc A pe P roces S modelling at m U lti dimensions and scale S ; -LS:L and S lide,refers to the process specific model component). LAPSUS-LS delineates the location of shallow landslide initiation sites and simulates the effects on spatial patterns of soil redistribution and resulting landslide hazard for a large watershed within the study area. Processes that need to be incorporated in the model are reviewed followed by the proposed modelling framework. The model predicts the spatial pattern of landslide susceptibility within the simulated catchment and subsequently applies a spatial algorithm for the redistribution of failed material on the basis of a scenario of triggering rainfall events, relative landslide hazard and trajectories with runout criteria for failed slope material. The model forms a spatially explicit method to address the effects of shallow landslide erosion and sedimentation because digital elevation data are adapted between timesteps and on- and off-site effects over the years can be simulated in this way. By visualisation of the modelling results in a GIS environment, the shifting pattern of upslope and downslope (in)stability, triggering of new landslides and the resulting slope retreat by soil material redistribution due to former mass movements is simulated and assessed.·Chapter 4 zooms in on a more theoretical aspect of the LAPSUS-LS model and evaluates digital elevation model (DEM) resolution effects on model results. The focus is on influences of grid size on landslide soil redistribution quantities and resulting spatial patterns and feedback mechanisms. Distributions of slope, specific catchment area and relative hazard for shallow landsliding are analysed for four different DEM resolutions (grid sizes of 10, 25, 50 and 100 m) for a 12 km 2 study catchment in theWaitakereRanges. The effect of DEM resolution proves to be especially pronounced for the boundary conditions determining a valid landslide hazard calculation. For coarse resolutions, the smoothing effect results in a larger area becoming classified as unconditionally stable or unstable. Simple empirical soil redistribution algorithms are applied for scenarios in which all sites with a certain landslide hazard fail and generate debris flow. The lower initial number of failing cells but also the inclusion of slope (limit) in those algorithms becomes apparent with coarser resolutions. For finer resolutions, much larger amounts of soil redistribution are found, which is attributed to the more detailed landscape representation. Looking at spatial patterns of landslide erosion and sedimentation, the size of the area affected by these processes also increases with finer resolutions. In general, landslide erosion occupies larger parts of the area than deposition, although the total amounts of soil material eroded and deposited are the same. Analysis of feedback mechanisms between soil failures over time shows that finer resolutions show higher percentages of the area with an increased or decreased landslide hazard. When the extent of sites with lower and higher hazards are compared, finer grid sizes and higher landslide hazard threshold scenarios tend to increase the total extent of areas becoming more stable relative to the less stable ones. It is concluded that extreme care should be taken when quantifying landslide basin sediment yield by applying simple soil redistribution formulas to DEMs with different resolutions. Rather, quantities should be interpreted as relative amounts. For studying shallow landsliding over a longer timeframe, the 'perfect' DEM resolution may not exist, because no resolution can possibly represent the dimensions of all different slope failures scattered in space and time. It is emphasised that the choice of DEM resolution, possibly restricted by data availability in the first place, should always be adapted to the context of a particular type of analysis.·Chapter 5 and 6 describe two distinct applications of the LAPSUS-LS model: in Chapter 5 , a sediment record is used, in combination with the LAPSUS-LS model, to reconstruct the incidence of high-magnitude/low-frequency landslide events in the upper part of theWaitakereRivercatchment and the history of the Te Henga wetland at the outlet. Sediment stratigraphy and chronology are interpreted by radiocarbon dating, foraminiferal analysis, andprovisionaltephrochronology. Gradual impoundment of the wetland began c. 6000 cal yr BP, coinciding with the start of a gentle sea-level fall, but complete damming and initial sedimentation did not begin until c. 1000 cal yr BP. After damming, four well-defined sediment pulses occurred and these are preserved in the form of distinct clay layers in most of the sediment cores. For interpreting the sediment pulses, the LAPSUS-LS modelisapplied to determine spatially distributed relative landslide hazard, applicable at the catchment scale. An empirical landslide soil redistribution componentisadded to determine sediment delivery ratio and the impact on total catchment sediment yield. Sediment volumesarecalculated from the wetland cores and corresponding landslide scenarios are defined through back-analysis of modelled sediment yield output. In general, at least four major high-magnitude landslide events, both natural and intensified by forest clearance activities, occurred in the catchment upstream of Te Henga wetland during the last c. 1000 years. Their magnitude can be expressed by a range of critical rainfall thresholds representing a LAPSUS-LS scenario.·Chapter 6 is a more ecologically focused application of the model and links digital terrain analysis and landslide modelling with the spatial distribution of mature kauri trees. The use of topographical attributes for the analysis of the spatial distribution and ecological cycle of kauri ( Agathis australis ), a canopy emergent conifer tree from northernNew Zealand, is studied. Several primary and secondary topographic attributes are derived from a DEM for theWaitakereRivercatchment and the contribution of these variables in explaining presence or absence of mature kauri is assessed with logistic regression and Receiver Operating Characteristic (ROC) plots. The topographically based landslide hazard index calculated with the LAPSUS-LS model appears to be very useful in explaining the occurrence and ecological dynamics of kauri. It is shown that the combination of topographic -, soil physical - and hydrological parameters in the calculation of this single landslide hazard index, performs better in explaining presence of mature kauri than using topographic attributes calculated from the DEM properties alone. Moreover, this example demonstrates the possibilities of using terrain attributes for representing geomorphological processes and disturbance mechanisms, often indispensable in explaining a species' ecological cycle and forest stand dynamics. The results of this analysis support the 'temporal stand replacement model', involving disturbance as a dominant ecological process in forest regeneration, as an interpretation of the community dynamics of kauri. Furthermore, a certain threshold maturity stage, in which trees become able to stabilise landslide prone sites and postpone a possible disturbance by this process, together with great longevity are seen as major factors making kauri a 'landscape engineer'.·Synthesising, Chapter 7 reflects on the most important conclusions from the research resulting in this thesis and discusses the achievement of the main objectives and answers to the research questions postulated in Chapter 1. Three general themes are put forward covering the previous chapters. Finally some ideas for future research are suggested

Groundnut

Abstract The document attempts to distil what is currently known about the likely impacts of climate change on the commodities and natural resources that comprise the mandate of CGIAR and its 15 Centres. It was designed as one background document for a review carried out by the High Level Panel of Experts on Food Security and Nutrition (HLPE) at the behest of the UN Committee on World Food Security (CFS) on what is known about the likely effects of climate change on food security and nutrition, with a focus on the most affected and vulnerable regions and populations. A total of 25 summaries covering 22 agricultural commodities, agroforestry, forests and water resources, present information on the importance of each commodity for food and nutrition security globally, the biological vulnerability of the commodity or natural resource to climate change, and what is known about the likely socio- economic vulnerability of populations dependent partially or wholly on the commodity or natural resource. With a few exceptions, the likely impacts of climate change on key staples and natural resources in developing countries in the coming decades are not understood in any great depth. There are many uncertainties as to how changes in temperature, rainfall and atmospheric carbon dioxide concentrations will interact in relation to agricultural productivity; the resultant changes in the incidence, intensity and spatial distribution of important weeds, pests and diseases are largely unknown; and the impacts of climate change and increases in climate variability on agricultural systems and natural-resource-dependent households, as well as on food security and the future vulnerability of already hungry people in the tropics and subtropics, are still largely a closed book. CGIAR along with many other partners is involved in a considerable amount of research activity to throw light on these issues

Groundnut

Abstract The document attempts to distil what is currently known about the likely impacts of climate change on the commodities and natural resources that comprise the mandate of CGIAR and its 15 Centres. It was designed as one background document for a review carried out by the High Level Panel of Experts on Food Security and Nutrition (HLPE) at the behest of the UN Committee on World Food Security (CFS) on what is known about the likely effects of climate change on food security and nutrition, with a focus on the most affected and vulnerable regions and populations. A total of 25 summaries covering 22 agricultural commodities, agroforestry, forests and water resources, present information on the importance of each commodity for food and nutrition security globally, the biological vulnerability of the commodity or natural resource to climate change, and what is known about the likely socio- economic vulnerability of populations dependent partially or wholly on the commodity or natural resource. With a few exceptions, the likely impacts of climate change on key staples and natural resources in developing countries in the coming decades are not understood in any great depth. There are many uncertainties as to how changes in temperature, rainfall and atmospheric carbon dioxide concentrations will interact in relation to agricultural productivity; the resultant changes in the incidence, intensity and spatial distribution of important weeds, pests and diseases are largely unknown; and the impacts of climate change and increases in climate variability on agricultural systems and natural-resource-dependent households, as well as on food security and the future vulnerability of already hungry people in the tropics and subtropics, are still largely a closed book. CGIAR along with many other partners is involved in a considerable amount of research activity to throw light on these issues

Exploring the impacts of field interactions on an integrated assessment of terraced crop systems in the Peruvian Andes

This study explores a modelling approach to investigate the interactions between terracing, water availability, and land use decisions and farmers' incomes in a study area in the Peruvian Andes. We tested the hypothesis that these interactions affect the simulated spatial distribution of impacts because of technology changes as well as aggregate impacts. To do this a model simulating water redistribution at the catchment scale is linked to a site-specific model of land use and management, using the trade-off analysis modelling system. The results indicate that the interactions do not affect the aggregate impacts but they do result in different spatial patterns of land use and farm income in the study area. The simulated effects of terraces on productivity are affected by the spatial patterns of terracing. These findings suggest that, although field-level interactions may average out in aggregate analysis, the effects they have on the spatial pattern of land use allocation and income may be relevant for analysis of environmental impact and equity studies in which the spatial distribution of effects is importan

Groundnut

Abstract The document attempts to distil what is currently known about the likely impacts of climate change on the commodities and natural resources that comprise the mandate of CGIAR and its 15 Centres. It was designed as one background document for a review carried out by the High Level Panel of Experts on Food Security and Nutrition (HLPE) at the behest of the UN Committee on World Food Security (CFS) on what is known about the likely effects of climate change on food security and nutrition, with a focus on the most affected and vulnerable regions and populations. A total of 25 summaries covering 22 agricultural commodities, agroforestry, forests and water resources, present information on the importance of each commodity for food and nutrition security globally, the biological vulnerability of the commodity or natural resource to climate change, and what is known about the likely socio- economic vulnerability of populations dependent partially or wholly on the commodity or natural resource. With a few exceptions, the likely impacts of climate change on key staples and natural resources in developing countries in the coming decades are not understood in any great depth. There are many uncertainties as to how changes in temperature, rainfall and atmospheric carbon dioxide concentrations will interact in relation to agricultural productivity; the resultant changes in the incidence, intensity and spatial distribution of important weeds, pests and diseases are largely unknown; and the impacts of climate change and increases in climate variability on agricultural systems and natural-resource-dependent households, as well as on food security and the future vulnerability of already hungry people in the tropics and subtropics, are still largely a closed book. CGIAR along with many other partners is involved in a considerable amount of research activity to throw light on these issues