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Interactive influence of rainfall manipulation and livestock grazing on species diversity of the herbaceous layer community in a humid savannah in Kenya

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Plant Diversity 2019年第3期41卷 198-205页

作者： Joseph o.ondier Daniel o.okach John C.onyango Dennis O.Otieno Department of Botany Maseno University Private Bag Maseno Kenya Department of Biological Sciences Jaramogi Oginga Odinga University of Science and Technology P.O Box 210-40601 Bondo Kenya Department of Plant Ecology University of Bayreuth D-95440 Bayreuth Germany

Changes in rainfall regime and grazing pressure affect vegetation composition and diversity with ecological implications for savannahs. The savannah in East Africa has experienced increased livestock grazing and rainfall variability but the impacts associated with those changes on the herbaceous layer have rarely been documented. We investigated the effect of livestock grazing, rainfall manipulation and their interaction on the composition and diversity of the herbaceous community in the savannah for two years in Lambwe, Kenya. Rainfall manipulation plots were set up for vegetation sampling;these plots received either 50% more or 50% less rainfall than control plots. Simpson’s diversity and Bergere Parker indices were used to determine diversity changes and dominance respectively. The frequency of species was used to compute their abundance and their life forms as determined from the literature. Grazing significantly increased species diversity through suppression of dominant species. Rainfall manipulation had no significant impact on plant diversity in fenced plots, but rainfall reduction significantly reduced diversity in grazed plots. In contrast, rainfall manipulation had no impact on dominance in either fenced or grazed plots. The interaction of grazing and rainfall manipulation is complex and will require additional survey campaigns to create a complete picture of the implications for savannah structure and composition.

关键词： Plant diversity Grazing Rainfall Moist savannah

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鼎湖山森林演替初期优势种马尾松的树干液流特征

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应用与环境生物学报 2022年第5期28卷 1167-1174页

作者：许天云黄健强曾小平张宜辉孟泽 dennis otieno 李跃林中国科学院华南植物园广州510650 厦门大学环境与生态学院厦门361005 中国科学院大学北京100049 肯尼亚奥丁加科技大学邦多210-40601

采用Granier热消散探针法(thermal dissipation probes,TDP),对鼎湖山南亚热带森林演替初期优势树种马尾松(Pinus massoniana)的树干液流变化进行连续监测,同时监测林分光合有效辐射、空气相对湿度、空气温度等环境因子,以探究演替初期... 详细信息

采用Granier热消散探针法(thermal dissipation probes,TDP),对鼎湖山南亚热带森林演替初期优势树种马尾松(Pinus massoniana)的树干液流变化进行连续监测,同时监测林分光合有效辐射、空气相对湿度、空气温度等环境因子,以探究演替初期马尾松树干液流特征、耗水量与其对环境的响应.结果表明:(1)日尺度上针叶林马尾松不同个体树干液流日变化趋势一致,晴天日变化为典型昼高夜低的单峰型曲线,峰值一般出现在中午12:00-14:00;雨天树干液流日变化呈单峰或多峰趋势,液流速率显著低于晴天,峰值出现在降雨后1-2 h内.在干季与湿季,马尾松的液流速率在各方面存在显著差异,干季(10月)马尾松的夜间液流速率显著小于湿季(8月)(P 0.05).日尺度上针叶林马尾松晴天树干液流主要受光合有效辐射、水汽压亏缺的影响(P <0.01);雨天主要受水汽压亏缺、相对湿度、温度的影响.在湿季(8月)与干季(10月)日尺度上马尾松的树干液流特征均首要受到水汽压亏缺的调控.本研究的马尾松林处于演替初期,其优势种马尾松蒸腾量高于同地带演替中期的马尾松,但相比其他地区针叶林,该演替初期马尾松蒸腾量处于较低水平,这有利于其适应季节性干旱环境.

关键词：马尾松针叶林演替初期树干液流鼎湖山

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Leaf and Ecosystem Gas Exchange Responses of Buffel Grass-Dominated Grassland to Summer Precipitation

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Pedosphere 2015年第1期25卷 112-123页

作者： Mir Zaman HUSSAIN Gnaana SARASWATHI Chhakchhuak LALRAMMAWIA dennis otieno Kailash PALIWAL John TENHUNEN Department of Plant Ecology University of Bayreuth Institute for Genomic Biology University of Illinois Department of Plant Sciences Madurai Kamaraj University

Sporadic rain events that occur during summer play an important role in the initiation of biological activity of semi-arid grasslands.To understand how ecosystem processes of a buffel grass(Cenchrus ciliaris L.)-dominated grassland respond to summer rain events,an LI 6 400 gas exchange system was used to measure the leaf gas exchange and plant canopy chambers were used to measure net ecosystem Co2exchange(NEE) and ecosystem respiration(Reco), which were made sequentially during periods before rain(dry) and after rain(wet). Gross ecosystem photosynthesis(GEP) was estimated from NEE and Reco fluxes, and light use efficiency parameters were estimated using a rectangular hyperbola model. Prior to the monsoon rain, grassland biomass was non-green and dry exhibiting positive NEE(carbon source) and low GEP values during which the soil water became increasingly scarce. An initial rain pulse(60 mm) increased the NEE from pre-monsoon levels to negative NEE(carbon gain) with markedly higher GEP and increased green biomass. The leaf photosynthesis and leaf stomatal conductance were also improved substantially. The maximum net Co2uptake(i.e.,negative NEE) was sustained in the subsequent period due to multiple rain events. As a result, the grassland acted as a net carbon sink for 20 d after first rain. With cessation of rain(drying cycle), net Co2 uptake was reduced to lower values. High sensitivity of this grassland to rain suggests that any decrease in precipitation in summer may likely affect the carbon sequestration of the semiarid ecosystem.

关键词：生态系统过程叶片气体交换半干旱草原夏季降水叶片光合作用半干旱生态系统草地生物量生态系统呼吸

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鼎湖山针阔叶混交林优势种树干液流特征及其与环境因子的关系

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应用生态学报 2012年第5期23卷 1159-1166页

作者：黄德卫张德强周国逸刘世忠 otieno dennis 李跃林中国科学院华南植物园广州510650 中国科学院研究生院北京100049

运用Granier热扩散式探针法,于2010年干湿季对鼎湖山自然保护区针阔混交林4种优势树种马尾松、锥栗、木荷和广东润楠的树干液流密度进行连续监测,并同步观测气温、相对湿度和光合有效辐射等环境因子的变化,研究其树干液流特征及其对环... 详细信息

运用Granier热扩散式探针法,于2010年干湿季对鼎湖山自然保护区针阔混交林4种优势树种马尾松、锥栗、木荷和广东润楠的树干液流密度进行连续监测,并同步观测气温、相对湿度和光合有效辐射等环境因子的变化,研究其树干液流特征及其对环境因子的响应.结果表明:在干湿季,4种优势树种的树干液流速率日变化均呈"昼高夜低"的典型单峰曲线,阔叶树锥栗、木荷和广东润楠的平均液流速率和峰值以及日液流量均显著大于针叶树马尾松;马尾松、锥栗、木荷和广东润楠的最大树干液流密度分别为29.48、38.54、51.67、58.32gH2o.m-2.s-1.优势树种树干液流速率的变化与环境因子的昼夜变化存在时滞;液流速率变化与光合有效辐射、水汽压亏缺和气温等环境因子的变化呈显著正相关,其中湿季以光合有效辐射为主导因子,干季以气温为主导因子.

关键词：针阔叶混交林树干液流环境因子干湿季鼎湖山

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Association between Respirable Dust Exposure and Respiratory Health Concerns among Workers in Apparel Processing Companies in Export Processing Zone (EPZ) in Machakos County, Kenya

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occupational Diseases and Environmental Medicine 2022年第4期10卷 271-291页

作者： owino A. otieno Paul M. Njogu dennis Magu Institute of Energy and Environmental Technology Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya Department of Environmental Health and Disease Control Jomo Kenyatta University of Agriculture and Technology (JKUAT) Nairobi Kenya

Apparel processing is an essential industry in providing clothing needs for the population. The Export Processing Zone (EPZ) in Kenya employs many employees. Garment processing releases respirable dust particles, thus exposing workers to risks to the respiratory system. The study determined the respirable dust health concerns among workers in Apparel Processing Companies (APCs) in EPZ in Machakos County, Kenya. A cross-sectional descriptive design was employed where four companies were studied. Three hundred and sixty-seven participants were selected through systematic random sampling. Data was collected using questionnaires and Interview guides. The study established that workers were exposed to respirable dust PM2.5 ranging from 40.89 ± 24.0 μg·m−3 to 87.49 ± 45.2 μg·m−3 with a mean of 65.61 ± 31.5 μg·m−3. While PM2.5 ranged from 63.59 ± 21.2 μg·m−3 to 313.41 ± 468.0 μg·m−3. With a mean of 104.02 ± 26.0 μg·m−3. Workers complained of different respirable dust-related diseases. The most prevalent conditions were sneezing and coughing (86.4%), chest pains (41.1%), blocked chests (36.8%), and allergic reactions to dust (18.3%). The APC should develop an oSH management system that includes;a dust management policy, dust monitoring, Risk Assessments, Engineering controls installations, medical examination, Training on dust management, PPE provision, and use enforcement.

关键词： Apparel Respirable Dust Health Concerns occupational Safety and Health

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Eco-Climatic Factors Influencing the Distribution of Black Ants (Carebara vidua) in Western Kenya

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Advances in Entomology 2022年第3期10卷 233-251页

作者： Davine Atieno ondede dennis otieno ochuodho Monica A. Ayieko Department of Plant Animal and Food Sciences Jaramogi Oginga Odinga University of Science and Technology Bondo Kenya Jaramogi oginga odinga University of Science and Technology Bondo Kenya

Black ant, Carebara vidua (Smith) is an edible insect of critical value in nutrition. The population abundance of black ants has reduced drastically and they have become scarce in all the agro ecological zones in Western Kenya. Understanding factors influencing the distribution and abundance of C. vidua remains a challenge as C. vidua is an endangered species in many parts of Country Kenya. The decline in the insect population is worrying since black ants are an important source of food across the world. our study aimed at determining the eco-climatic conditions influencing the distribution of black ants. Several factors and conditions have contributed to the decline in the population of black ants. The study was carried out in different agro ecological zones of Kisumu, Siaya, and Homabay Counties. The research presumed a cross-sectional approach to community representation. The purposive sampling technique was used to select the population for the qualitative study. Data was collected through Focused Group Discussion and Key Informant Interviews to get in-depth knowledge on the factors contributing to the change in the distribution of back ants. Verbatim transcription was done to the audio recorded data then data was translated into English. Thematic analysis was done using ATLAS.ti software version 7.5. The results showed various factors that led to the change in distribution and reduction of the population of black ants emerging across the lower midland zones, the factors include;climate change, advancement in agricultural equipment, land degradation, and habitat destruction. These factors made the emergence of the insect unpredictable. over the years across the Lower midland zones, there have been changes in the distribution of C. vidua and the population of insects emerging has reduced hence the insect is disappearing.

关键词： Black Ant Ecological Zones Distribution Population

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Time to consider the potential role of alternative resistance training methods in cancer management?

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Journal of Sport and Health Science 2023年第6期12卷 715-725页

作者： Francesco Bettariga Chris Bishop dennis R.Taaffe Daniel A.Galvão Luca Maestroni Robert U.Newton Exercise Medicine Research Institute Edith Cowan UniversityJoondalupWA 6027Australia School of Medical and Health Sciences Edith Cowan UniversityJoondalupWA 6027Australia London Sport Institute School of Science and TechnologyMiddlesex UniversityLondonNW44BTUK School of Human Movement and Nutrition Sciences University of QueenslandSt.LuciaQLD 4067Australia

Exercise has emerged as fundamental therapeutic medicine in the management of cancer.Exercise improves health-related outcomes,including quality of life,neuromuscular strength,physical function,and body composition,and it is associated with a lower risk of disease recurrence and increased survival.Moreover,exercise during or post cancer treatments is safe,can ameliorate treatment-related side effects,and may enhance the effectiveness of chemotherapy and radiation therapy.To date,traditional resistance training(RT)is the most used RT modality in exercise oncology.However,alternative training modes,such as eccentric,cluster set,and blood flow restriction are gaining increased attention.These training modalities have been extensively investigated in both athletic and clinical populations(e.g.,age-related frailty,cardiovascular disease,type 2 diabetes),showing considerable benefits in terms of neuromuscular strength,hypertrophy,body composition,and physical function.However,these training modes have only been partially or not at all investigated in cancer populations.Thus,this study outlines the benefits of these alternative RT methods in patients with cancer.Where evidence in cancer populations is sparse,we provide a robust rationale for the possible implementation of certain RT methods that have shown positive results in other clinical populations.Finally,we provide clinical insights for research that may guide future RT investigations in patients with cancer and suggest clear practical applications for targeted cancer populations and related benefits.

关键词： Blood flow restriction Cluster set Eccentric training Resistance trainingTagedAPTARAEnd

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Carbon dioxide exchange and biomass productivity of the herbaceous layer of a managed tropical humid savanna ecosystem in western Kenya

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Journal of Plant Ecology 2013年第4期6卷 286-297页

作者： G.o.K’otuto D.o.otieno B.Seo H.o.ogindo J.C.onyango Department of Applied Plant Sciences Maseno UniversityPrivate Bag MasenoKenya Department of Plant Ecology University of Bayreuth95440 BayreuthGermany Department of Botany Maseno UniversityPrivate Bag MasenoKenya

Aims Humid savannas,as a result of high precipitation amounts,are highly productive.they are also hotspots for land use change and potential sources of carbon dioxide(Co_(2))due to the large soil carbon(C)stocks.understanding how ecosystem Co_(2) exchange is influenced by changes arising from agricultural land use is vital in future management of these ecosystems and in responding to the ongoing shifts in manage-ment and climate.the aim of this study was to identify how ecosystem Co_(2) exchange and biomass productivity of the herbaceous layer of a humid savanna in Kenya respond to current management practices.Methods We used flux chambers to quantify Co_(2) fluxes,while monthly harvests were undertaken to determine biomass development of the herba-ceous layer of three sites that were(i)fenced to exclude livestock graz-ing,(ii)subjected to grazing by livestock and(iii)abandoned after being cultivated for maize production and also open to grazing by livestock.Important findingsthe peak aboveground biomass ranged between 380 and 1449 g m−2 and biomass production was significantly(Power in the grazed and abandoned plots.the maximum gross primary production(gPP)and net ecosystem Co_(2) exchange(NEE)ranged between 21.8±1.3 to 32.5±2.7 and−9.6±0.7 to−17.9±4.8μmol m−2 s−1,respectively.seasonal NEE fluctuations ranged between 10 and 21μmol m−2s−1,while spatial(among sites)differences ranged between 2 and 10μmol m−2 s−1.Ecosystem respiration(Reco)fluc-tuated between 5 and 10μmol m−2 s−1 during the growing sea-son.Reco was,however,not significantly different among the sites.unlike in other similar ecosystems where ecosystem respiration is determined by the ambient temperature,we did not find any rela-tionship between Reco and temperature in this savanna.Instead,soil moisture accounted for 38-88%of the spatial and seasonal fluc-tuations in ecosystem Co_(2) fluxes and aboveground biomass pro-duction.management influenced the maximum gPP and NEE rates through modification of soil moisture,plant species composition and

关键词： tropical humid savanna abandoned croplands biomass production ecosystem Co_(2)exchange livestock grazing soil water content

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Seed dispersal by Tana River mangabeys in fragmented gallery forests

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open Journal of Ecology 2012年第1期2卷 12-20页

作者： Duncan M. Kimuyu Geoffrey M. Wahungu dennis o. otieno Department of Plant Ecology University of Bayreuth Bayreuth Germany School of Natural Resources and Environmental Studies Karatina University College Karatina Kenya

Data collected on a free ranging group of Tana River mangabeys (Cercocebus galeritus) indicates that this endangered primate species, which has previously been regarded as a seed predator, plays an important role in seed dispersal and do contribute to the regeneration of a highly fragmented gallery forest. We observed fruit handling behavior and the post-dispersal fate of seeds ingested by the mangabeys. The two main fruit handling behaviors observed, fruit swallowing and processing fruits in cheek pouches, positively contributed to seed disper- sal. Seed predation was not common during this study, apart from a few particular plant species such as Acacia robusta and Alangium salviifolium with non-fleshy fruits. We found a correlation between seed predation and fruit availability, respectively seasonal differential specific dispersal efficiency. The role of the mangabeys in dispersing seeds and facilitating forest regeneration is enhanced by their movement across forest patches through non-forested matrix, which contributes to the deposition of seeds and regeneration in these habitat gaps.

关键词： Cercocebus Galeritus Seed Dispersal seed Predation Seasonality Dispersal Efficiency Fragmentation Habitat Gaps Tana River Forests

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季节性干旱驱动亚热带森林的碳积累

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Journal of Plant Ecology 2023年第1期16卷 241-256页

作者： Brian Njoroge Yuelin Li dennis otieno Shizhong Liu Simin Wei Ze Meng Qianmei Zhang Deqiang Zhang Juxiu Liu Guowei Chu Fasih Ullah Haider John Tenhunen Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems South China Botanical GardenChinese Academy of SciencesGuangzhou 510650China Guangdong Provincial Key Laboratory of Applied Botany South China Botanical GardenChinese Academy of SciencesGuangzhou 510650China University of Chinese Academy of Sciences Beijing 100039China Department of Botany Jaramogi Oginga Odinga University of Science and TechnologyBondo 210-40601Kenya Department of Plant Ecology University of Bayreuth95440 BayreuthGermany

本研究旨在表明处于南亚热带的鼎湖山生物圈保护区的干旱频率和强度正在增加,并说明季节性干旱对亚热带森林碳积累的影响。这是为了应对全球气候变化导致的干旱加剧所带来的威胁开展的一项研究。我们使干旱指数(标准化降水指数、标准降... 详细信息

本研究旨在表明处于南亚热带的鼎湖山生物圈保护区的干旱频率和强度正在增加,并说明季节性干旱对亚热带森林碳积累的影响。这是为了应对全球气候变化导致的干旱加剧所带来的威胁开展的一项研究。我们使干旱指数(标准化降水指数、标准降水蒸散发指数、降水距平百分率及自校准帕尔默干旱指数)准确确定干旱期和降水量增加期。此后,将2003至2014年(12年)监测采集的实测涡动通量和土壤含水量数据在干旱期和湿润期之间进行比较,以确定干旱对生态系统碳积累的影响。在本研究所选择的12年期间,干旱的发生时间约占比20%,最强干旱事件和严重程度发生于2012至2013年。研究期间的年平均降水量和气温分别为1404.57±43.2 mm和22.65±0.1°C,与30年记录(1990–2020)相比较,年降水量减少量可达523 mm,而气温则增加了2.55°C。与全球针对大多数森林生态系统研究所发表的数据呈相反趋势,处于中国南亚热带区域的鼎湖山生物圈保护区在60%的干旱期内所监测的森林生态系统记录到显著的碳积累趋势,说明季节性干旱驱动了森林的碳积累。

关键词：干旱气候变化碳积累鼎湖山生物圈保护区涡动通量

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