Climate Change and Land Use - Batch 1

Soil Respiration across predominant Land-uses in the Vea catchment in the Sudan savannah zone, North-east Ghana

2015-04-01T00:00:00Z

Soil Respiration across predominant Land-uses in the Vea catchment in the Sudan savannah zone, North-east Ghana Owusu Prempeh, Nat A study to quantify soil respiration (SR) across predominant land-uses in the Vea catchment, a semi-arid Savannah ecosystem of Ghana, was carried out using the closed static chamber method and CO2 transmitter (GMD 20, Vaisala). The goal was to determine the magnitude of the contribution of soil CO2 flux from predominant land-uses to the global carbon budget. The annual soil CO2 fluxes determined from the predominant land-uses were related to the soil organic carbon (SOC) stocks under the land-uses. Additionally, the impact of cropping systems, field management practices, topography, soil temperature and moisture as well as their seasonal and spatial variability on soil CO2 fluxes were determined. The mean annual soil CO2 fluxes for the major land-uses, were significantly different (p=0.00); these were 12.79 ± 0.89, 9.10 ± 0.42 and 5.61 ± 0.29 t CO2 C ha-1 y-1 for woodland, graze-land and cropland respectively and these correlated strongly with SOC stock density of 37.91 ± 1.29 (woodland), 29.31 ± 1.74 (graze-land) and 27.36 ± 1.70 Mg C ha-1 (cropland). The overall mean annual soil CO2 flux from the catchment was 9.23 ± 0.53 t CO2 C ha-1 y-1. Carbon losses from land-use conversions of woodland to other land-uses were more pronounced in the cropland than in graze-land, which is poorly-managed native vegetation. Using the current (2013) SOC as the base year and assuming business as usual scenario, the IPCC SOC tool was used to estimate the decadal SOC dynamics of the land- uses for next 60 years. The mean soil CO2 flux under mixed cropping system was highest (114.67 ± 3.51) followed by rice monoculture (108.08 ± 2.82) whilst groundnut monoculture had the least (83.17 ± 2.85 [mgCO2 C m-2 h-1]). Fisher’s multiple tests revealed that mean soil CO2 fluxes were significantly different (p<0.05). The Soil CO2 fluxes were more sensitive to soil moisture stress than soil temperature at temperatures above 35 °C. Topography had significant impact on soil CO2 flux; lowland mean soil CO2 flux (86.3 [gCO2 C m-2month-1]) was over 30 percent higher than up-land mean soil CO2 flux (64.8 [gCO2 C m-2 month-1]) for all the land-uses and statistically, the CO2 fluxes were different (p<0.05) across the study field. There were marked seasonal and spatial variations in soil CO2 flux due to variations in local climate and soil attributes as influenced by the different land-uses. The mean C emission across the study field ranged between 8- 32 g m-2 week-1 depending on land-use type. The study concluded that land-uses and cropping systems, topography, porosity and soil moisture and temperature variations influence SR dynamics, SOC stocks and soil CO2 flux exchanges between land and atmosphere. A Thesis submitted to the West African Science Service Centre on Climate Change and Adapted Land Use and the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use

Effect of Climate Change and Variability on Pearl Millet (Pennisetum glaucum (L.) R. Br.) Production in the Sudanian and Sahelian Agro-Ecological Zones in Mali

2016-05-01T00:00:00Z

Effect of Climate Change and Variability on Pearl Millet (Pennisetum glaucum (L.) R. Br.) Production in the Sudanian and Sahelian Agro-Ecological Zones in Mali Toure, Halimatou Aboubacar Climate change is expected to increase vulnerability in all agro-ecological zones of Mali through rising temperature and more erratic rainfalls, which will have drastic consequences on food security and economic growth. This study aimed at assessing the effect of Climate Change and Variability on Pearl Millet (Pennisetum glaucum (L.) R. Br.) Production in the Sudanian and Sahelian Agro-Ecological Zones in Mali. First, the perception of farmers on climate change variability and their adaptation practices to overcome or reduce the negative impacts of climate change on their farming system as well as their livelihoods were investigated in the Sahelian zone. Therefore, 119 farmers’ household including women and youth were randomly selected and interviewed using structured questionnaire. Next, the changes in trends of daily temperature and precipitation extremes in Sotuba and Cinzana during the period 1961 - 2014 were assessed. In order to investigate extreme precipitation and temperature, daily minimum and maximum records for two stations (Ségou and Bamako) were collected at the Aghrymet Meteorological Centre of Niamey for the period 1961-2014. Finally, the performance of two millet varieties in two agro-ecological zones of Mali was assessed using the DSSAT (The decision support system for agro-technology transfer) model under different climate conditions. Two years’ experiments were therefore conducted at Agricultural Research Station of Sotuba and Cinzana in the randomised complete block design with 4 replications. The fertiliser treatments included Control, MANURE, NPK and NPK+MANURE. DSSAT model were used to simulate crop grain yields under 2 different weather conditions (historical and future). The results showed that farmers perceived a decrease in annual rainfall as the main factors of climate change and variability. Several strategies such as selling of animals, planting improved crop varieties, engaging in new activities (outside agriculture) and credit were the commonly preferred adaptation strategies to deal with climate change and variability. A significant decrease of warming trends in cool days, cool nights, whereas warm extreme nights, day times and warm spells on the contrary showed positive significant increasing warming throughout the Ségou Region. The results of precipitation extremes for Ségou showed significant decrease in consecutive wet and extremely wet day. The study provided evidence that during the last 53 years, Ségou was particularly affected by warm extremes based on night time indices rather than cold extremes based on day time indices. At Sotuba, the average grain yield was 1293 kg ha-1 and 1503 kg ha-1 for the years 2013 and 2014, respectively. In Cinzana, the observed average grain yields in 2013 and 2014 were 1390 and 1530 kg ha-1, respectively. The analyses did show significant differences between the varieties and among the fertilizer treatments. Moreover, millet yield responded to the different historical climatic conditions under all treatments. In line with the experimental data, the highest historical grain yields were achieved when the combination NPK+MANURE was applied. Millet grain yields were higher under the simulations with historical weather data than the simulations with climate change scenarios. Simulation of climate change effects on millet grain yield showed that all scenarios underestimated crop yield compared to the Baseline for all treatments and both varieties. Significant differences (P < 0.05) were revealed among the scenario outputs. All the varieties showed lowest grain yields under the four treatments for ACCESS1-0 (Hot-Wet) among the scenarios. Based on the findings of this study, policy could be developed to enhance farmers’ adaptation strategies in the Sudanian and Sahelian zones of Mali. A Thesis Submitted to the Department of Civil Engineering, College of Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Climate Change and Land Use

Impact of Cashew Expansion on Land Use/ Land Cover Change and Carbon Stocks in the Forest-Savanna Transition Zone, North-East Côte d’Ivoire

2015-04-01T00:00:00Z

Impact of Cashew Expansion on Land Use/ Land Cover Change and Carbon Stocks in the Forest-Savanna Transition Zone, North-East Côte d’Ivoire Akpa, You Lucette An increased production of cashew (Anacardium Occidentale L.) in the forest-savanna transition zone of Côte d’Ivoire calls for an understanding of the biophysical, ecological as well as climate change implications that may be associated with its production. This study aimed to deepen knowledge on how expansive cashew production impacts on land use/ land cover and its consequences on biodiversity and carbon stocks. Using the maximum likelihood classification algorithm and post-classification change detection procedure, the spatial-temporal dynamics of land use/ land cover was assessed based on a series of Landsat images for 1988, 2001 and 2014. Vegetation inventories were carried out to determine the composition and structure of cashew plantations and natural vegetation. From the diameter and species identification as well as soil samples data collected in inventory, the biomass and for that matter carbon stock was calculated. Multiple linear regression analysis was used to examine the main drivers of cashew expansion at household level, and GIS and multicriteria analysis were used to analyse the natural vegetations’ vulnerability to future cashew expansion. The results identified cashew expansion (a rate of 26.78% and 7.24% per annum for the periods 1988-2001 and 2001-2013, respectively) as major land use changes. From 1988 to 2014, 26.4% and 34.1% of forest/woodland and savanna areas respectively were converted to cashew plantations, given a natural vegetation conversion rate of 2.35 to 2.88% per annum. There was a decrease in tree species richness and evenness from natural vegetation to cashew plantations. In terms of vegetation structure however, mature plantation had basal area similar to forest/woodland. The total carbon stocks in Mg C ha-1 t/ha were low in cashew plantations, where mature stands had 21.826 ± 3.23 (Mean ± SE), young iii 25.927 ± 6.53 and juvenile 16.732 ± 2.96 compared with natural vegetation (forest/woodland 64.375 ± 12.43, tree savannas 23.94 ± 3.3 and tree/shrub savannas 21.012 ± 10.12). There was no significant difference in soil organic carbon and total soil carbon stocks under different land use types, except between forest (24.67 ± 5.37 Mg C ha-1) and tree/shrub savanna (8.92 ± 1.57 Mg C ha-1). The long drought episode of the early 1980s was identified as the trigger for cashew plantation establishment, whilst better income and lack of technical support were the main drivers for expansion. Plantation size of households was influenced by two demographic factors of age and gender farmers (P < 0.05 and 0.305 R2-adjusted). Natural vegetation vulnerability to future cashew expansion was in the descending order of forest/woodland (21.43%), tree savanna (11.87%) and tree/shrub savanna (8.27%). This implies that cashew expansion is of higher threat to more woody vegetation which has serious implication in terms of conservation and carbon emissions. There is therefore a need for a more sustainable management approach to cashew agriculture practices to ensure optimum production for farmers, while conserving the forest-savanna ecosystem. A Thesis Submitted to the Department of Civil Engineering, College of Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Climate Change and Land Use

Long -Term Vegetation Dynamics over the Bani River Basin as Impacted by Climate Change and Land Use

2015-04-01T00:00:00Z

Long -Term Vegetation Dynamics over the Bani River Basin as Impacted by Climate Change and Land Use Traore, Souleymane Sidi This study investigated the long-term trends in vegetation and rainfall and the extent and rate of vegetation change over the Bani river Basin at multiple spatial and temporal scales in relation to local and regional drivers. Monthly 8-km Normalized Difference Vegetation Index (NDVI) timeseries data from 1982 to 2011 was derived from 10-day Satellite Pour l’Observation de la Terre vegetation product (SPOT-VGT) at 1-km (1998-2011) and 15-day GIMMS (Global Inventories Monitoring and Modelling Systems) at 8-km satellite data (1982-2006). Gridded rainfall data at 8-km grid resolution was created from 40 meteorological stations and complemented with Tropical Rainfall Measurement Mission (TRMM) data. A Mann Kendall (MK) trend analysis was used to determine the trend for each dataset using monthly and annual time-series. This analysis produced some indicators like Kendall’s tau, p-value and Theil-Sen. The p-value estimator (p-value less than 0.07) was used in this study to show the significance of the trend. Trend analysis revealed that within the study area vegetation greening trends are mostly associated with areas where natural vegetation is still well represented. From the results 934 pixels (49% of the study area) showed a positive trend while 155 pixels (8% of the study area) showed a negative trend significant at p-value less than 0.07. During the same period rainfall had increased by about 17 mm, translating into a positive trend for almost the entire study area. Vegetation productivity in the study area is dependent on rainfall which varies greatly temporally and spatially. The linear Pearson correlation was used to estimate the relationship between NDVI and rainfall for every pixel at monthly interval for the growing season data. Comparing their long-term mean the result showed a good correlation between the two datasets with an R value of 0.98. Four (4) reference areas were used to explain and cross verify representative areas that exhibit either entirely negative MK-trends or entirely positive MK-trends over the monitoring period. These reference areas were selected based on their trend in rainfall and NDVI and their NDVI long-term departure. Free 30-meter Landsat images were acquired for the four reference areas for the following three intervals: 1984 and 1986, 1999 and 2000 and 2009 and 2010. Land Use/Land Cover (LULC) change was then quantified and the rate of land conversion was determined. LULC variables included urban, Cropland and natural vegetation (Shrublands, Steppe, Open Trees and Closed Trees). For the entire period, the class ‘Natural Vegetation’ decreased between 22.83% and 63.47% from its initial area for areas (1) and (2), while the iv decrease was 8.35% for area (3) and 13.39% for area (4). The class ‘Cropland’ increased for 564.86% in area (3); 62.17% in area (4); 35.79% in area (2) and 16.22% in area (1). To investigate whether there is a relationship between NDVI, rainfall and LULC change, LULC variables were correlated with long-term trend in rainfall and NDVI. The results showed there is a positive correlation between increases in rainfall and some land cover classes, while some classes such as settlements were negatively correlated with vegetation productivity trends. Croplands and Natural Vegetation were positively correlated (r=0.89) with rainfall while settlements have a negative correlation with NDVI time series trends (r=-0.57). Despite the fact that rainfall is the major determinant of vegetation cover dynamics in the study area, it appears that other human-induced factors such as urbanisation have negatively influenced the change in vegetation cover. The results provide spatially explicit and temporally good and rich information of vegetation productivity dynamics and its drivers at landscape scale. This is an important input for assessing the impact of climate change on vegetation for biophysical modelling. It also improves our knowledge of the drivers of vegetation productivity changes. The study suggests that NDVI can be useful for general vegetation cover monitoring and planning. Future studies need to also look at the effect of vegetation cover change in regard to other landscape components such as specifically population density and soil degradation A Thesis Submitted to the Department of Civil Engineering, College of Engineering in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Climate Change and Land Use