The Effect of Different Fire Regimes on Soil Properties in Wet Miombo woodlands of Zambia

Miombo woodlands occur on nutrient poor soils and generally experience a warm-to-hot climate with a dry cold season. Wet miombo areas, which receives more than 1,000 mm of average annual rainfall, are distinguished from dry miombo areas receiving less than 1,000 mm of average annual rainfall. Wet miombo woodland occurs over much of eastern Angola, northern Zambia, south western Tanzania and central Malawi in areas receiving more than 1000 mm rainfall per year. Canopy height is usually greater than 15 m, reflecting the generally deeper and moister soils which create favourable conditions for growth. The objective of this study was to investigate the effect of different fire regimes on soil properties in wet Miombo woodlands of Zambia. The study was conducted in Mwekera burning plots located in Mwekera National Forest No. 6 on the outskirts of Kitwe City. This study has uncovered some interesting relationships between fire and soil nutrients, soil chemical and physical properties. The complete fire protected treatment had significantly greater soil bulky density, organic soil carbon, phosphorus (P) and nitrogen (N) than other treatments. The late burning treatment had significantly greater soil pH, soil electrical conductivity, Calcium (Ca) and magnesium (Mg) than other treatments; however, a loss of soil organic matter during late burning fires likely resulted in increased bulk density and strength, and decreased water infiltration rates. Late burning fires also significantly increased soil pH, concentrations of extractable calcium, magnesium and carbon although to a lesser degree than early burning. Early burning fires did not lower soil potassium contents or alter soil chemical and physical properties. Our results indicate that despite differences in fire regimes, soil moisture, calcium and magnesium contents were not significantly different between early burning and late burning treatments. The results suggest that fire management did not affect soil moisture, calcium, and magnesium contents. Keywords: burning plots, fire regimes, soil properties, wet miombo woodlands DOI: 10.7176/JRDM/66-04 Publication date:June 30th 202

Tropical tree growth driven by dry-season climate variability

Interannual variability in the global land carbon sink is strongly related to variations in tropical temperature and rainfall. This association suggests an important role for moisture-driven fluctuations in tropical vegetation productivity, but empirical evidence to quantify the responsible ecological processes is missing. Such evidence can be obtained from tree-ring data that quantify variability in a major vegetation productivity component: woody biomass growth. Here we compile a pantropical tree-ring network to show that annual woody biomass growth increases primarily with dry-season precipitation and decreases with dry-season maximum temperature. The strength of these dry-season climate responses varies among sites, as reflected in four robust and distinct climate response groups of tropical tree growth derived from clustering. Using cluster and regression analyses, we find that dry-season climate responses are amplified in regions that are drier, hotter and more climatically variable. These amplification patterns suggest that projected global warming will probably aggravate drought-induced declines in annual tropical vegetation productivity. Our study reveals a previously underappreciated role of dry-season climate variability in driving the dynamics of tropical vegetation productivity and consequently in influencing the land carbon sink.We acknowledge financial support to the co-authors provided by Agencia Nacional de Promoción Científica y Tecnológica, Argentina (PICT 2014-2797) to M.E.F.; Alberta Mennega Stichting to P.G.; BBVA Foundation to H.A.M. and J.J.C.; Belspo BRAIN project: BR/143/A3/HERBAXYLAREDD to H.B.; Confederação da Agricultura e Pecuária do Brasil - CNA to C.F.; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES, Brazil (PDSE 15011/13-5 to M.A.P.; 88881.135931/2016-01 to C.F.; 88887.199858/2018-00 to G.A.-P.; Finance Code 001 for all Brazilian collaborators); Conselho Nacional de Desenvolvimento Científico e Tecnológico - CNPq, Brazil (ENV 42 to O.D.; 1009/4785031-2 to G.C.; 311874/2017-7 to J.S.); CONACYT-CB-2016-283134 to J.V.-D.; CONICET to F.A.R.; CUOMO FOUNDATION (IPCC scholarship) to M.M.; Deutsche Forschungsgemeinschaft - DFG (BR 1895/15-1 to A.B.; BR 1895/23-1 to A.B.; BR 1895/29-1 to A.B.; BR 1895/24-1 to M.M.); DGD-RMCA PilotMAB to B.T.; Dirección General de Asuntos del Personal Académico of the UNAM (Mexico) to R.B.; Elsa-Neumann-Scholarship of the Federal State of Berlin to F.S.; EMBRAPA Brazilian Agricultural Research Corporation to C.F.; Equatorian Dirección de Investigación UNL (21-DI-FARNR-2019) to D.P.-C.; São Paulo Research Foundation FAPESP (2009/53951-7 to M.T.-F.; 2012/50457-4 to G.C.; 2018/01847‐0 to P.G.; 2018/24514-7 to J.R.V.A.; 2019/08783-0 to G.M.L.; 2019/27110-7 to C.F.); FAPESP-NERC 18/50080-4 to G.C.; FAPITEC/SE/FUNTEC no. 01/2011 to M.A.P.; Fulbright Fellowship to B.J.E.; German Academic Exchange Service (DAAD) to M.I. and M.R.; German Ministry of Education, Science, Research, and Technology (FRG 0339638) to O.D.; ICRAF through the Forests, Trees, and Agroforestry research programme of the CGIAR to M.M.; Inter-American Institute for Global Change Research (IAI-SGP-CRA 2047) to J.V.-D.; International Foundation for Science (D/5466-1) to M.I.; Lamont Climate Center to B.M.B.; Miquelfonds to P.G.; National Geographic Global Exploration Fund (GEFNE80-13) to I.R.; USA’s National Science Foundation NSF (IBN-9801287 to A.J.L.; GER 9553623 and a postdoctoral fellowship to B.J.E.); NSF P2C2 (AGS-1501321) to A.C.B., D.G.-S. and G.A.-P.; NSF-FAPESP PIRE 2017/50085-3 to M.T.-F., G.C. and G.M.L.; NUFFIC-NICHE programme (HEART project) to B.K., E.M., J.H.S., J.N. and R. Vinya; Peru ‘s CONCYTEC and World Bank (043-2019-FONDECYT-BM-INC.INV.) to J.G.I.; Peru’s Fondo Nacional de Desarrollo Científico, Tecnológico y de Innovación Tecnológica (FONDECYT-BM-INC.INV 039-2019) to E.J.R.-R. and M.E.F.; Programa Bosques Andinos - HELVETAS Swiss Intercooperation to M.E.F.; Programa Nacional de Becas y Crédito Educativo - PRONABEC to J.G.I.; Schlumberger Foundation Faculty for the Future to J.N.; Sigma Xi to A.J.L.; Smithsonian Tropical Research Institute to R. Alfaro-Sánchez.; Spanish Ministry of Foreign Affairs AECID (11-CAP2-1730) to H.A.M. and J.J.C.; UK NERC grant NE/K01353X/1 to E.G.Peer reviewe

Stem hydraulic architecture and xylem vulnerability to cavitation for miombo woodlands canopy tree species

Africa's miombo woodlands constitute one of the most important dry tropical forests on earth, yet the hydraulic function of these woodlands remains poorly researched. Given the current predictions of increased aridity by the end of this century in the miombo ecoregion, understanding the likely response of miombo woodlands tree species to water stress is crucial in planning adaptation strategies. Predicting the response of miombo woodlands to future climate trends is hampered by a lack of knowledge on the physiology of the common miombo woodlands tree species. In particular, plant-water relations for this woodlands type are not well understood.An understanding of plant-water relations for this woodlands type will provide insights into how water limits tree species distribution in this ecosystem. This will also improve our prediction model on the likely response of this ecosystem to predicted climate change. For this reason, the overall objective of this research was to evaluate the hydraulic architecture and xylem vulnerability to cavitation for nine principal miombo woodlands tree species differing in drought tolerance ability and habitat preference. This was achieved by; examining the hydraulic properties and evaluating the extent to which each hydraulic design was vulnerable to water stress-induced xylem cavitation; investigating how seasonal changes in plant-water relations influences seasonal patterns of leaf display and; analyzing the relationship between stem hydraulic supply and leaf functional traits related to drought tolerance ability.This research has found that drought-intolerant tree species with mesic specialization have more efficient stem hydraulic systems than co-occurring habitat broad ranging species. Broad ranging tree species attain wider habitat distribution by adjusting their hydraulic supply in response to changing ecosystem water availability. The finding that hydraulic properties differ significantly between tree species with contrasting habitat preference suggests that tree hydraulic design may have some adaptive ecological role in influencing species habitat preferences in miombo woodlands.The evaluation of xylem vulnerability to cavitation revealed that mesic specialized tree species were more vulnerable to water stress-induced cavitation than habitat broad ranging tree species. Vulnerability to cavitation in individuals from the same broad-ranging species growing in contrasting habitats showed only marginal and statistically insignificant (P &gt; 0.05) differences between wet and dry sites.In the investigation of the influence of seasonal changes in stem water relations on seasonal leaf display, seasonal rhythms in stem water status were found to exert significant controls on leaf phenology. Mesic specialists had strong stem water controls throughout the year in comparison to broad ranging tree species.An analysis of the relationship between stem hydraulic supply and leaf functional traits suggests that stem hydraulic supply constrains leaf biomass allocation patterns among miombo tree species. Mesic specialists tend to invest more in leaf longevity than broad ranging tree species.This thesis has uncovered some interesting relationships between plant-water-relations and the distribution of miombo woodlands tree species. These results lead to the conclusion that in an event of increased ecosystem drying under future climate trends, tree species with mesic specialisation are at a greater risk of experiencing cavitation related species mortality than broad ranging ones.</p

Impacts of Public-Private Partnership on Local Livelihoods and Natural Resource Dynamics: Perceptions from Eastern Zambia

This study evaluated the long-term implications of a Public-Private Partnership (PPP) on livelihoods and natural resource (NR) dynamics under a market-oriented approach to conservation. Drawing examples from the Luangwa Valley in eastern Zambia, the study sought to answer questions on two closely interrelated aspects. These included the contribution of PPP to sustainable livelihoods in and around Protected Areas (PAs) and its impacts on natural resources in Game Management Areas (GMAs). Quantitative data were collected from PPP participating and non-PPP households using standardized structured interviews, while qualitative data were obtained from three chiefdoms using semi-structured interviews and focus group discussions. Taking the case of Community Markets for Conservation (COMACO) in eastern Zambia, results of this study showed that PPP contributed to sustainable livelihoods and overall natural resources management through varied ways. These include promotion of conservation farming, agroforestry, poacher transformation (individuals who have given up poaching due to PPP interventions) and provision of markets for the produce of participating households. Further, impacts of PPP on soil fertility, crop, and honey yields were statistically significant (p ˂ 0.05). A combination of increased crop productivity and household incomes has seen a 40-fold increase in poacher transformation. The results of this study suggest that PPPs, if well-structured, have the potential to address both livelihoods and enterprise needs with an ultimate benefit of promoting both sustainable livelihoods and natural resources management around PAs in tropical Africa

Stem hydraulic architecture and xylem vulnerability to cavitation for miombo woodlands canopy tree species

Africa's miombo woodlands constitute one of the most important dry tropical forests on earth, yet the hydraulic function of these woodlands remains poorly researched. Given the current predictions of increased aridity by the end of this century in the miombo ecoregion, understanding the likely response of miombo woodlands tree species to water stress is crucial in planning adaptation strategies. Predicting the response of miombo woodlands to future climate trends is hampered by a lack of knowledge on the physiology of the common miombo woodlands tree species. In particular, plant-water relations for this woodlands type are not well understood. An understanding of plant-water relations for this woodlands type will provide insights into how water limits tree species distribution in this ecosystem. This will also improve our prediction model on the likely response of this ecosystem to predicted climate change. For this reason, the overall objective of this research was to evaluate the hydraulic architecture and xylem vulnerability to cavitation for nine principal miombo woodlands tree species differing in drought tolerance ability and habitat preference. This was achieved by; examining the hydraulic properties and evaluating the extent to which each hydraulic design was vulnerable to water stress-induced xylem cavitation; investigating how seasonal changes in plant-water relations influences seasonal patterns of leaf display and; analyzing the relationship between stem hydraulic supply and leaf functional traits related to drought tolerance ability. This research has found that drought-intolerant tree species with mesic specialization have more efficient stem hydraulic systems than co-occurring habitat broad ranging species. Broad ranging tree species attain wider habitat distribution by adjusting their hydraulic supply in response to changing ecosystem water availability. The finding that hydraulic properties differ significantly between tree species with contrasting habitat preference suggests that tree hydraulic design may have some adaptive ecological role in influencing species habitat preferences in miombo woodlands. The evaluation of xylem vulnerability to cavitation revealed that mesic specialized tree species were more vulnerable to water stress-induced cavitation than habitat broad ranging tree species. Vulnerability to cavitation in individuals from the same broad-ranging species growing in contrasting habitats showed only marginal and statistically insignificant (P > 0.05) differences between wet and dry sites. In the investigation of the influence of seasonal changes in stem water relations on seasonal leaf display, seasonal rhythms in stem water status were found to exert significant controls on leaf phenology. Mesic specialists had strong stem water controls throughout the year in comparison to broad ranging tree species. An analysis of the relationship between stem hydraulic supply and leaf functional traits suggests that stem hydraulic supply constrains leaf biomass allocation patterns among miombo tree species. Mesic specialists tend to invest more in leaf longevity than broad ranging tree species. This thesis has uncovered some interesting relationships between plant-water-relations and the distribution of miombo woodlands tree species. These results lead to the conclusion that in an event of increased ecosystem drying under future climate trends, tree species with mesic specialisation are at a greater risk of experiencing cavitation related species mortality than broad ranging ones.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Socio-economic determinants of participating in riverbank cultivation at the household level in the Upper Kafue River basin in Kitwe District, Zambia

Riverbank cultivation is a valuable agricultural practice that performs essential functions including socio-economic along the Upper Kafue River Basin in Kitwe, Zambia. Even though riverbanks are considered the most endangered ecosystems globally, they continue to face degradation through cultivation, putting pressure on land use. This study assessed socioeconomic determinants of participating in riverbank cultivation at the household level. Open-ended questionnaire was administered as the main data collection tool. Questionnaire survey data were collected from 244 households living in thirteen unplanned compounds. This was complemented with transect walks. Data was then analyzed using the logistic regression model to establish socio-economic drivers that significantly drove river and stream bank cultivation. The findings from the study show that riverbank cultivation promoted livelihoods of the poor, household head's age positively influenced riverbank cultivation, unprecedented levels of poverty, unemployment and education level strongly contributed to household's decision to cultivate on riverbanks for them to be food secure and generate income. Larger family households had higher demand for food consumption putting more pressure on riverbank cultivation for food provisions. Unclear land titles stood out as major challenge households faced, whilst male household heads had entitlement to agricultural land. Declining soil fertility led to low agriculture productivity driving households to cultivate riverbanks where soils were more productive throughout the year. The current land-use and agricultural policies are indifferent towards riverbank cultivation in Zambia, with the effect of encouraging the practice. The study recommends strengthening the enforcement of laws governing riverbank cultivation

Drivers of deforestation and potential for carbon trading in miombo woodlands

Africa's Miombo woodlands are vast, of high conservation value and essential for human well-being. This forest type plays a pivotal role in livelihoods of the majority of resource-poor rural communities in southern Africa. Majority of these communities have limited access to sources of employment and domestic income because they have little cash or other resources. It is, however, unfortunate that livelihood factors such as agricultural production and use of fire have constantly altered miombo woodlands. These livelihood factors have all profoundly contributed to degradation and in some cases depletion of the forest resources in southern Africa. Many studies have demonstrated that deforestation in miombo woodlands is one of the major contributors to global climate change. However, the question of what exactly drives woodlands deforestation at the regional scale remains largely unanswered. Over the last three decades, significant amount of evidence has coalesced around the general assumption that factors that drive tropical deforestation interact in a complex way and fluctuate significantly at global, regional and country levels. Not surprising all UNFCCC negotiations and key debates have tended to revolve around forests. This is mainly because of the realization that the objectives of mitigating climate change may not be reached without extensive action on deforestation and forest degradation. Therefore, a review of drivers of deforestation in miombo woodlands will help in deepening our understanding of what drives miombo woodlands deforestation and what the potential for future carbon trade is like

The potential of Zambian copper-cobalt metallophytes for phytoremediation of minerals wastes

The Copper-Cobalt Belt of the Democratic Republic of the Congo and Zambia is one of the most important metallogenic regions in the world. In addition, it hosts the world’s richest metallophyte flora. There are more than 600 metallophytes in the Copper-Cobalt Belt, including many species unique to the area. The phenomenon of abnormal copper-cobalt accumulation in certain plants has been observed since the 1950s in the Copper-Cobalt Belt, with more than thirty hyperaccumulator plants identified. Hyperaccumulator plants might be useful for important phytotechnologies. There is also a wide range of Excluder-type metallophytes in the Copper-Cobalt Belt, especially grasses and sedges, that might be suitable for phytostabilization of minerals wastes

The potential of Zambian copper-cobalt metallophytes for phytoremediation of minerals wastes

The Copper-Cobalt Belt of the Democratic Republic of the Congo and Zambia is one of the most important metallogenic regions in the world. In addition, it hosts the world’s richest metallophyte flora. There are more than 600 metallophytes in the Copper-Cobalt Belt, including many species unique to the area. The phenomenon of abnormal copper-cobalt accumulation in certain plants has been observed since the 1950s in the Copper-Cobalt Belt, with more than thirty hyperaccumulator plants identified. Hyperaccumulator plants might be useful for important phytotechnologies. There is also a wide range of Excluder-type metallophytes in the Copper-Cobalt Belt, especially grasses and sedges, that might be suitable for phytostabilization of minerals wastes

Assessing the spatio-temporal variability of NDVI and VCI as indices of crops productivity in Ethiopia : a remote sensing approach

This study aims at characterizing agricultural drought in Ethiopia and understanding the effects of drought on crop yield. Monthly, seasonal and annual Normalized Difference Vegetation Index (NDVI) and Vegetation Condition Index (VCI) values were calculated using MODIS (MOD13Q1) from the year 2003 to 2017. The relationships between NDVI, VCI, and crop yield were examined to predict the possibility of drought impacts on crop productivity. We found that VCI and NDVI data provides consistent and spatially explicit information for operational drought monitoring in Ethiopia. Results also indicated that the most extreme agricultural drought in recent years occurred in 2003, 2004, 2008, 2009, and 2015. These findings also show that mild to severe droughts have a great chance of occurrence in Ethiopia. However, only severe drought has significant impacts on crops. The food crops yield data used in this study include cereals, legumes, and tubers. It was observed that cereals such as (Zea mays), teff (Eragrostis tef), haricot beans (Phaseolus vulgaris) are more sensitive to agricultural drought when compared to the tubers such as sweet potato (Ipomoea batatas) and taro (Colocasia esculenta). Thus, drought preparedness programs need to pay more attention to the cultivation of these crops under severe drought conditions