Browsing by Author "Kaseke, Kudzai F."

Now showing 1 - 7 of 7
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    Data Descriptor: Daily observations of stable isotope ratios of rainfall in the tropics
    (Nature Research, 2019-10-08) Munksgaard, Niels C.; Kurita, Naoyuki; Sánchez-Murillo, Ricardo; Ahmed, Nasir; Araguas, Luis; Balachew, Dagnachew L. Balachew; Bird, Michael I.; Chakraborty, Supriyo; Chinh, Nguyen Kien; Cobb, Kim M.; Ellis, Shelby A.; Esquivel-Hernández, Germain; Ganyaglo, Samuel Y.; Gao, Jing; Gastmans, Didier; Kaseke, Kudzai F.; Kebede, Seifu; Morales, Marcelo R.; Mueller, Moritz; Poh, Seng Chee; dos Santos, Vinícius; Shaoneng, He; Wang, Lixin; Yacobaccio, Hugo; Zwart, Costijn; Earth Sciences, School of Science
    We present precipitation isotope data (δ2H and δ18O values) from 19 stations across the tropics collected from 2012 to 2017 under the Coordinated Research Project F31004 sponsored by the International Atomic Energy Agency. Rainfall samples were collected daily and analysed for stable isotopic ratios of oxygen and hydrogen by participating laboratories following a common analytical framework. We also calculated daily mean stratiform rainfall area fractions around each station over an area of 5° x 5° longitude/latitude based on TRMM/GPM satellite data. Isotope time series, along with information on rainfall amount and stratiform/convective proportions provide a valuable tool for rainfall characterisation and to improve the ability of isotope-enabled Global Circulation Models to predict variability and availability of inputs to fresh water resources across the tropics.
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    Drivers of woody dominance across global drylands
    (American Association for the Advancement of Science, 2024-10-11) Biancari, Lucio; Aguiar, Martín R.; Eldridge, David J.; Oñatibia, Gastón R.; Le Bagousse-Pinguet, Yoann; Saiz, Hugo; Gross, Nicolas; Austin, Amy T.; Ochoa, Victoria; Gozalo, Beatriz; Asensio, Sergio; Guirado, Emilio; Valencia, Enrique; Berdugo, Miguel; Plaza, César; Martínez-Valderrama, Jaime; Mendoza, Betty J.; García-Gómez, Miguel; Abedi, Mehdi; Ahumada, Rodrigo J.; Alcántara, Julio M.; Amghar, Fateh; Anadón, José D.; Aramayo, Valeria; Arredondo, Tulio; Bader, Maaike Y.; Bahalkeh, Khadijeh; Ben Salem, Farah; Blaum, Niels; Boldgiv, Bazartseren; Bowker, Matthew; Branquinho, Cristina; Bu, Chongfeng; Byambatsogt, Batbold; Calvo, Dianela A.; Castillo Monroy, Andrea P.; Castro, Helena; Castro-Quezada, Patricio; Chibani, Roukaya; Conceição, Abel A.; Currier, Courtney M.; Donoso, David A.; Dougill, Andrew; Ejtehadi, Hamid; Espinosa, Carlos I.; Fajardo, Alex; Farzam, Mohammad; Ferrante, Daniela; Fraser, Lauchlan H.; Gaitán, Juan J.; Gherardi, Laureano A.; Gusmán-Montalván, Elizabeth; Hernández-Hernández, Rosa M.; Hölzel, Norbert; Huber-Sannwald, Elisabeth; Hughes, Frederic M.; Jadán, Oswaldo; Jeltsch, Florian; Jentsch, Anke; Ju, Mengchen; Kaseke, Kudzai F.; Kindermann, Liana; Köbel, Melanie; le Roux, Peter C.; Liancourt, Pierre; Linstädter, Anja; Liu, Jushan; Louw, Michelle A.; Maggs-Kölling, Gillian; Malam Issa, Oumarou; Marais, Eugene; Margerie, Pierre; Messeder, João Vitor S.; Mora, Juan P.; Moreno, Gerardo; Munson, Seth M.; Oliva, Gabriel; Pueyo, Yolanda; Quiroga, R. Emiliano; Reed, Sasha C.; Rey, Pedro J.; Rodríguez, Alexandra; Rodríguez, Laura B.; Rolo, Víctor; Ruppert, Jan C.; Sala, Osvaldo; Salah, Ayman; Stavi, Ilan; Stephens, Colton R. A.; Swemmer, Anthony M.; Teixido, Alberto L.; Thomas, Andrew D.; Throop, Heather L.; Tielbörger, Katja; Travers, Samantha K.; van den Brink, Liesbeth; Wagner, Viktoria; Wamiti, Wanyoike; Wang, Deli; Wang, Lixin; Wolff, Peter; Yahdjian, Laura; Zaady, Eli; Maestre, Fernando T.; Earth and Environmental Sciences, School of Science
    Increases in the abundance of woody species have been reported to affect the provisioning of ecosystem services in drylands worldwide. However, it is virtually unknown how multiple biotic and abiotic drivers, such as climate, grazing, and fire, interact to determine woody dominance across global drylands. We conducted a standardized field survey in 304 plots across 25 countries to assess how climatic features, soil properties, grazing, and fire affect woody dominance in dryland rangelands. Precipitation, temperature, and grazing were key determinants of tree and shrub dominance. The effects of grazing were determined not solely by grazing pressure but also by the dominant livestock species. Interactions between soil, climate, and grazing and differences in responses to these factors between trees and shrubs were key to understanding changes in woody dominance. Our findings suggest that projected changes in climate and grazing pressure may increase woody dominance in drylands, altering their structure and functioning.
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    Fog and Dew as Potable Water Resources: Maximizing Harvesting Potential and Water Quality Concerns
    (Wiley, 2018) Kaseke, Kudzai F.; Wang, Lixin; Earth Sciences, School of Science
    Fog and dew are often viewed as economic nuisances causing significant financial losses in the transportation industry and agricultural sector. However, they are also critical components of the hydrological cycle, especially in water scarce environments. Water scarcity is one of the major threats to mankind in the 21st century, and this can be due to development pressures, pollution, and/or expanding populations. In water scarce environments, fog and dew represent potentially exploitable ancillary water resources that could ameliorate the water scarce situation, if efficiently harvested. However, two important issues are often overlooked in relation to fog and dew harvesting and potability. First, current fog and dew harvesting technologies are low yielding with great potential for improvements. Second and more importantly, the potability of these water resources is often based on simple analyses that often omit trace metal and biological analyses. The few studies that report trace metal or biological measurements suggest elevated trace metal concentrations or biological contamination that could be of concern to public health. We discuss the potential for fog and dew harvesting technologies and the need for trace metal and biological analyses of these waters before use.
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    Grazing and ecosystem service delivery in global drylands
    (American Association for the Advancement of Science, 2022-11-24) Maestre, Fernando T.; Bagousse-Pinguet, Yoann Le; Delgado-Baquerizo, Manuel; Eldridge , David J.; Saiz, Hugo; Berdugo, Miguel; Gozalo, Beatriz; Ochoa, Victoria; Guirado, Emilio; García-Gómez, Miguel; Valencia, Enrique; Gaitán, Juan J.; Asensio, Sergio; Mendoza, Betty J.; Plaza, César; Díaz-Martínez, Paloma; Rey, Ana; Hu, Hang-Wei; He, Ji-Zheng; Wang, Jun-Tao; Lehmann, Anika; Rillig, Matthias C.; Cesarz, Simone; Esenhauer, Nico; Martínez-Valderrama, Jaime; Moreno-Jiménez, Eduardo; Sala, Osvaldo; Abedi, Mehdi; Ahmadian, Negar; Alados, Concepción L.; Aramayo, Valeria; Amghar, Fateh; Arredondo, Tulio; Ahumada, Rodrigo J.; Bahalkeh, Khadijeh; Ben Salem , Farah; Blaum, Niels; Boldgiv, Bazartseren; Bowker, Matthew A.; Bran, Donaldo; Bu, Chongfeng; Canessa, Rafaella; Castillo-Monroy, Andrea P.; Castro, Helena; Castro, Ignacio; Castro-Quezada, Patricio; Chibani, Roukaya; Conceição , Abel A.; Currier, Courtney M.; Darrouzet-Nardi, Anthony; Deák, Balázs; Donoso, David A.; Dougill, Andrew J.; Durán, Jorge; Erdenetsetseg, Batdelger; Espinosa, Carlos I.; Fajardo, Alex; Farzam, Mohammad; Ferrante, Daniela; Frank, Anke S. K.; Fraser, Lauchlan H.; Gherardi, Laureano A.; Greenville, Aaron C.; Guerra, Carlos A.; Gusmán-Montalvan, Elizabeth; Hernández-Hernández, Rosa M.; Hölzel, Norbert; Huber-Sannwald, Elisabeth; Hughes, Frederic M.; Jadán-Maza, Oswaldo; Jeltsch, Florian; Jentsch, Anke; Kaseke, Kudzai F.; Köbel, Melanie; Koopman, Jessica E.; Leder, Cintia V.; Linstädter, Anja; Le Roux, Peter C.; Li, Xinkai; Liancourt, Pierre; Liu, Jushan; Louw, Michelle A.; Maggs-Kölling, Gillian; Makhalanyane, Thulani P.; Malam Issa, Oumarou; Manzaneda, Antonio J.; Marais, Eugene; Mora, Juan P.; Moreno, Gerardo; Munson, Seth M.; Nunes, Alice; Oliva, Gabriel; Oñatibia, Gastón R.; Peter, Guadalupe; Pivari, Marco O. D.; Pueyo , Yolanda; Quiroga, R. Emiliano; Rahmanian, Soroor; Reed, Sasha C.; Rey, Pedro J.; Richard, Benoit; Rodríguez, Alexandra; Rolo, Víctor; Rubalcaba, Juan G.; Ruppert, Jan C.; Salah, Ayman; Schuchardt, Max A.; Spann, Sedona; Stavi, Ilan; Stephens, Colton R. A.; Swemmer, Anthony M.; Teixido, Alberto L.; Thomas , Andrew D.; Throop, Heather L.; Tielbörger, Katja; Travers, Samantha; Val, James; Valkó, Orsolya; Van Den Brink , Liesbeth; Ayuso, Sergio Valesco; Velbert, Frederike; Wamiti, Wanyoike; Wang, Deli; Wang, Lixin; Wardel, Glenda M.; Yahdjian, Laura; Zaady, Eli; Zhang, Yuanming; Zhou, Xiaobing; Singh, Brajesh K.; Gross, Nicolas; Earth and Environmental Sciences, School of Science
    Grazing represents the most extensive use of land worldwide. Yet its impacts on ecosystem services remain uncertain because pervasive interactions between grazing pressure, climate, soil properties, and biodiversity may occur but have never been addressed simultaneously. Using a standardized survey at 98 sites across six continents, we show that interactions between grazing pressure, climate, soil, and biodiversity are critical to explain the delivery of fundamental ecosystem services across drylands worldwide. Increasing grazing pressure reduced ecosystem service delivery in warmer and species-poor drylands, whereas positive effects of grazing were observed in colder and species-rich areas. Considering interactions between grazing and local abiotic and biotic factors is key for understanding the fate of dryland ecosystems under climate change and increasing human pressure.
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    The impact of fog on soil moisture dynamics in the Namib Desert
    (Elsevier, 2018-03) Li, Bonan; Wang, Lixin; Kaseke, Kudzai F.; Vogt, Roland; Li, Lin; Seely, Mary; Earth Science, School of Science
    Soil moisture is a crucial component supporting vegetation dynamics in drylands. Despite increasing attention on fog in dryland ecosystems, the statistical characterization of fog distribution and how fog affects soil moisture dynamics have not been seen in literature. To this end, daily fog records over two years (Dec 1, 2014–Nov 1, 2016) from three sites within the Namib Desert were used to characterize fog distribution. Two sites were located within the Gobabeb Research and Training Center vicinity, the gravel plains and the sand dunes. The third site was located at the gravel plains, Kleinberg. A subset of the fog data during rainless period was used to investigate the effect of fog on soil moisture. A stochastic modeling framework was used to simulate the effect of fog on soil moisture dynamics. Our results showed that fog distribution can be characterized by a Poisson process with two parameters (arrival rate λ and average depth α (mm)). Fog and soil moisture observations from eighty (Aug 19, 2015–Nov 6, 2015) rainless days indicated a moderate positive relationship between soil moisture and fog in the Gobabeb gravel plains, a weaker relationship in the Gobabeb sand dunes while no relationship was observed at the Kleinberg site. The modeling results suggested that mean and major peaks of soil moisture dynamics can be captured by the fog modeling. Our field observations demonstrated the effects of fog on soil moisture dynamics during rainless periods at some locations, which has important implications on soil biogeochemical processes. The statistical characterization and modeling of fog distribution are of great value to predict fog distribution and investigate the effects of potential changes in fog distribution on soil moisture dynamics.
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    The Impact of Rainfall on Soil Moisture Dynamics in a Foggy Desert.
    (PLOS, 2016) Li, Bonan; Wang, Lixin; Kaseke, Kudzai F.; Li, Lin; Seely, Mary K.; Department of Earth Sciences, School of Science
    Soil moisture is a key variable in dryland ecosystems since it determines the occurrence and duration of vegetation water stress and affects the development of weather patterns including rainfall. However, the lack of ground observations of soil moisture and rainfall dynamics in many drylands has long been a major obstacle in understanding ecohydrological processes in these ecosystems. It is also uncertain to what extent rainfall controls soil moisture dynamics in fog dominated dryland systems. To this end, in this study, twelve to nineteen months’ continuous daily records of rainfall and soil moisture (from January 2014 to August 2015) obtained from three sites (one sand dune site and two gravel plain sites) in the Namib Desert are reported. A process-based model simulating the stochastic soil moisture dynamics in water-limited systems was used to study the relationships between soil moisture and rainfall dynamics. Model sensitivity in response to different soil and vegetation parameters under diverse soil textures was also investigated. Our field observations showed that surface soil moisture dynamics generally follow rainfall patterns at the two gravel plain sites, whereas soil moisture dynamics in the sand dune site did not show a significant relationship with rainfall pattern. The modeling results suggested that most of the soil moisture dynamics can be simulated except the daily fluctuations, which may require a modification of the model structure to include non-rainfall components. Sensitivity analyses suggested that soil hygroscopic point (sh) and field capacity (sfc) were two main parameters controlling soil moisture output, though permanent wilting point (sw) was also very sensitive under the parameter setting of sand dune (Gobabeb) and gravel plain (Kleinberg). Overall, the modeling results were not sensitive to the parameters in non-bounded group (e.g., soil hydraulic conductivity (Ks) and soil porosity (n)). Field observations, stochastic modeling results as well as sensitivity analyses provide soil moisture baseline information for future monitoring and the prediction of soil moisture patterns in the Namib Desert.
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    A multi-scale analysis of Namibian rainfall over the recentdecade – comparing TMPA satellite estimates and groundobservations
    (Elsevier, 2016-12) Lu, Xuefei; Wang, Lixin; Pan, Ming; Kaseke, Kudzai F.; Li, Bonan; Department of Earth Sciences, School of Science
    Study region Namibia. Study focus The lack of ground observations has long been a major obstacle in studying rainfall patterns in many dryland regions, particularly in the data scarce African continent. In this study, a continuous 6-year (2008–2013) daily record of ground observations collected from Weltevrede Farm at the edge of the Namib Desert was used to evaluate TRMM Multi-satellite Precipitation Analysis (TMPA, 0.25° resolution) daily rainfall estimates of this area. A Mann-Kendall trend analysis was conducted using all the available annual TMPA satellite data (1998–2015) to examine long-term trends in rainfall amount, intensity, frequency and seasonal variations over four locations across a rainfall gradient. New hydrological insights for the region The agreement between ground and satellite rainfall data was generally good at annual/monthly scales but large variations were observed at the daily scale. Results showed a spatial variability of rainfall trends across the rainfall gradient. We observed significant changes in frequency along with insignificant changes in intensity and no changes in total amount for the driest location, but no changes in any of the rainfall parameters were observed for the three wetter locations. The results also showed increased rainfall variability for the driest location. This study provided a useful approach of using TMPA data associated with trend analysis to extend the data record for ecohydrological studies for similar data scarce conditions. The results of this study will also help constrain IPCC predictions in this region.