Karen Hahn

Karen Hahn
Goethe-Universität Frankfurt am Main · Faculty of Biological Sciences

Dr.

About

144
Publications
62,833
Reads
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2,117
Citations
Citations since 2017
26 Research Items
1369 Citations
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2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
Introduction
Skills and Expertise

Publications

Publications (144)
Poster
Full-text available
Studies on possible plant food and its availability for different groups of early humans so far usually consider only a pre-selected set of plant species often based on the scarce archaeobotanical record. In contrast, the database PlantBITES is a tool to consider the full range of potentially available, dominant plant species in vegetation units. I...
Chapter
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West African savannas undergo severe changes due to climate change and land use pressure, resulting in degradation and biodiversity loss. These changes directly impact local rural livelihoods, as many cash poor rural communities depend on the provisioning ecosystem services of their environments. In a case study of the interdisciplinary research pr...
Article
Full-text available
Background The W National Park and its two hunting zones represent a unique ecosystem in Burkina Faso for biodiversity conservation. This study aims at providing a detailed view of the current state of the floristic diversity as a baseline for future projects aiming at protecting and managing its resources. We combined intensive inventories and di...
Article
Knowledge about the herbaceous layer in relation to environmental factors in West African savannas is still scarce. Early life-cycle events like germination of the herbaceous species are of special interest, as these stages can play critical roles in establishing of the plants and determine population and community dynamics. We aim to assess intras...
Article
Questions: West African savanna ecosystems are affected by increasing land use intensity (e.g., agriculture and livestock herds) due to a growing human population. To understand the impact of land use intensification on savanna vegetation, we aim to answer the following questions: How do savanna species composition, diversity and structure change w...
Article
Full-text available
Edible wild plants are an important supplement to the diets and livelihoods of rural households in West Africa. Despite their role in improving diets, mitigating famine periods and generating income there is a lack of extensive information on their uses for broader areas. Based on ethnobotanical records, we investigated wild food plants on the nati...
Article
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Background Atakora mountains in Benin are a unique but fragile ecosystem, harboring many endemic plant species. The ecosystem is undergoing degradation, and the woody vegetation is dramatically declining due to high anthropogenic actions and recurrent drought. This study aimed to (i) assess the diversity of threatened woody species and (ii) identif...
Article
Full-text available
Non-timber forest product (NTFP) providing species constitute substantial components of West African agroforestry systems and contribute considerably to local livelihoods. The aim of our study was to measure the annual economic contribution of NTFPs to local livelihoods in two villages of south-eastern Burkina Faso, focusing on the following specif...
Article
Full-text available
Rural populations are closely dependent on plant resources for their daily needs. Fruit productivity of these species is an indicator of their economic potential and their capacity to regenerate. This is also fundamental to define sustainable management strategies of species. The present study assessed the fruits and seeds productivity of four fore...
Article
Full-text available
In the face of the current changes in land use and climate as well as habitat destruction, it is important to study herbaceous vegetation as an indicator of changes occurring in savanna ecosystems. We investigated the effects of climate, land use and habitat, both alone and in combination, on the diversity and occurrence of West African savanna her...
Article
Herbaceous plants account for more than three-fourths of the total biomass in savanna ecosystems. However, which environmental factors mainly drive the biodiversity of herbaceous species is still under debate. In this study, we investigated the influence of climate, habitat and land use on species richness and cover in the West African savanna ecos...
Article
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According to environmental predictions, West Africa is becoming vulnerable to the adverse effects of climate change and land use disturbance. Herbaceous vegetation is the most sensitive to these effects. To assess the potential of species to cope with these changes, this study investigated the dispersal potential of different herbaceous species. Da...
Presentation
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Presentation of the automated, EOO- and AOO-based threat assessment of Burkina Faso’s flora, as published in Schmidt, Zizka et al. 2017 Phytotaxa
Article
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West Africa is a floristically understudied region that is facing severe environmental changes in the 21st century. Basic distribution data and information on the conservation status for most plant species of the region are scarce, and good information only exists for small areas of interest or for key species. This lack of knowledge seriously hamp...
Article
Full-text available
West Africa is a floristically understudied region that is facing severe environmental changes in the 21st century. Basic distribution data and information on the conservation status for most plant species of the region are scarce, and good information only exists for small areas of interest or for key species. This lack of knowledge seriously hamp...
Poster
Full-text available
Wild plant species are important nutritious supplements to otherwise nutrient poor diets of rural populations in West Africa. Consequently, a decline of wild food species has a direct negative impact on the nutritional status of local households. Therefore, it is important to investigate how much wild food species contribute to household income and...
Article
Questions Termite mounds are important sources of local‐scale soil heterogeneity and thereby affect savanna vegetation. Studies contrasting mound and savanna vegetation usually neglect variation between savanna types. We aim to answer the following questions: (1) is mound vegetation consistently different from the surrounding savanna vegetation at...
Article
It is common knowledge that plants have been the world-wide most important source of medicines and that they still play this role in developing countries. However, up to now, complete lists of medicinal and aromatic plants (MAP) exist for comparatively few countries. A review of all lists know to the authors reveals the following results: A total o...
Article
In rural Africa, the use of wild plants for medicinal purposes is widespread. Many publications provide regional checklists of medicinal plants, but only a few of these checklists cover Malawi. In the Karongo district, northern Malawi, 30 traditional healers and birth attendants were interviewed regarding their use of woody medicinal plants. This s...
Article
Full-text available
Non-Timber Forest Products (NTFPs) make a major contribution to the livelihoods and diets of rural households in the savanna ecosystems of West Africa. However, land use change and climatic variability might affect their availability in the future. Based on a survey among 227 households in Northern Benin, we investigated local substitution patterns...
Article
Full-text available
Sudanian Savannas are under high agricultural pressure and are therefore changing rapidly. Due to high population densities and an increasing need for food and cash crops, the mosaic of traditional agroforestry systems, fallows and savanna is being transformed into intensively used croplands and savannas only remain in protected areas. The focus of...
Article
In West African savannas, human land use affects the density of woody species seedlings and saplings (juveniles) by altering the state of the physical, chemical, and biological characteristics of the land resulting in different land-cover types. We determined juvenile densities of 25 characteristic woody savanna species on non-arable sites, in fall...
Article
Eine gut entwickelte Grasschicht ist ein typisches Merkmal von Savannen. Viele Gräser der Savanne sind sogenannte C4-Pflanzen. Der Einfluss von Tieren, Menschen oder Feuer hat die „Architektur“ der Savanne über viele Millionen Jahre hinweg geprägt. Pflanzenfresser sowie Gräser der Savanne sind klassische Beispiele für Coevolution. Die gegenseitige...
Article
Full-text available
West African Savanna ecosystems are undergoing severe changes in their vegetation composition due to the impact of human land use and changes in climatic conditions. This study aims to examine the effect of climate, land use, and their interaction on species richness and composition of West African herbaceous vegetation. Plot based vegetation sampl...
Article
Full-text available
Although there is an increasing need for data in ecological studies, many datasets are still lost or not sufficiently visible due to a lack of appropriate data archives. With the West African Data and Metadata Repository, we present a secure long-term archive for a data-poor region allowing detailed documentation by metadata following the EML stand...
Article
Full-text available
Wild plant species are important nutritious supplements to otherwise nutrient poor diets of rural populations in West Africa. Consequently, a decline of wild food species has a direct negative impact on the nutritional status of local households. In this study, we firstly investigated the preferred wild food species in south-east Burkina Faso, thei...
Article
Full-text available
Based on a species inventory and the related distribution dataset, the authors present a quantitative analysis of the vascular plant diversity of Burkina Faso (BFA) and its four phytogeographic zones. We analyzed species richness, higher taxon diversity, life forms, chorological types, introduced species, habitat preferences and the number of rare...
Article
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RESUME Les conséquences de la perte de biodiversité sont entre autres la baisse des services écosystémiques, avec des incidences graves sur la santé des populations, leur alimentation, voire leur habitat. Dans ce contexte, les populations locales ont tendance à adopter des stratégies d'adaptation qu'il importe d'identifier et d'en analyser la durab...
Article
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Sarcocephalus latifolius (Sm.) E. A. Bruce is one of the most useful medicinal plants in many African countries. The root being the part generally used for this purpose. In the context of land degradation and overexploitation of biological resources in many parts of Burkina Faso, a good description of the root system is necessary to better plan for...
Article
Full-text available
Background: The West African country of Burkina Faso (BFA) is an example for the enduring importance of traditional plant use today. A large proportion of its 17 million inhabitants lives in rural communities and strongly depends on local plant products for their livelihood. However, literature on traditional plant use is still scarce and a compreh...
Article
Full-text available
Knowledge about useful plants and their various applications in West Africa is scattered over many publications and often in form of grey literature difficult to access. Several online-databases compile large scale information from these sources and provide comprehensive summarized descriptions of plant usages. Our aim is to additionally build up a...
Article
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Termites are keystone species in savanna ecology, and their mounds are thought to be an important source of habitat heterogeneity and structural complexity of the savanna. Macrotermes termitaria have been shown to allow woody plant colonisation of landscapes otherwise dominated by C4 grasses. In this study, we assess how resource-rich Macrotermes m...
Article
Full-text available
People depend heavily on natural resources for their daily living. In the Sudanian zone of Africa characterized by high population growth and poverty incidence, there is a growing pressure on high value species such as Sarcocephalus latifolius (Sm.) E.A.Bruce. The objectives of this study were to evaluate its diverse uses and to highlight some prac...
Article
Ecosystems are sources of services such as food, water, timber, firewood, health, and spiritual benefits. The unsustainable human use of ecosystems has led to significant declines in the capability of these ecosystems to provide services. In contribution to the preservation of ecosystems, this study aims to assess the potential ecosystem services d...
Poster
Full-text available
We are establishing a West African plant trait database including trees, grasses and herbs. Plant functional traits are useful to link environmental and vegetation data as well as to predict changes in vegetation composition. For the trait database savanna species of the Sub-Sahelian and Sudanian vegetation zone are included.
Poster
Full-text available
Burkina Faso’s protected area network consists of national parks, partial and total faunal reserves and classified forests, including biosphere reserves and Ramsar sites. All of these areas play important roles in biodiversity conservation on the national level. Varying degrees of protection status and size, as well as different climatic zones and...
Poster
Full-text available
Burkina Faso's protected area network consists of national parks, partial and total faunal reserves and classified forests, including biosphere reserves and Ramsar sites. All of these areas represent more than 14% of the total area of the country and play important roles in biodiversity conservation on the national level. Varying degrees of protect...
Poster
Full-text available
Knowledge about useful plants and their various applications in West Africa is scattered over many publications and quite often in form of grey literature difficult to access. Several online-databases (e.g. SEPASAL, PROTA) compile on large scale information from different ethnobotanical literature sources and make the description of plant usages av...
Article
Full-text available
Arbre des savanes et des forêts claires sahélo-soudaniennes à guinéennes, Bombax costatum est une espèce fortement exploitée pour ses calices et menacée dans plusieurs localités au Burkina Faso. Une alternative à la conservation résiderait dans la reconnaissance de l'intérêt économique de l'espèce. Cette étude évalue la valeur monétaire de la produ...
Article
Full-text available
The silk cotton tree Bombax costatum is found in Sahelian-Sudanian and Guinean open woodland and savannah lands. It is heavily used for its calyxes and has come under threat in several areas of Burkina Faso. An alternative conservation approach would be to recognise the economic value of the species. This study produced an assessment in monetary va...
Article
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The West African vegetation zones from the Sahara desert to the Guinean rainforests are shaped by a steep latitudinal precipitation gradient. Their taxonomical and functional composition changes considerably along this gradient. Based on comprehensive distribution data from herbariun collections and relevés this paper presents modelled distribution...
Article
Full-text available
Non-timber forest products (NTFPs) are of high socio-economic value for rural people in West Africa. Main factors determining the status of the populations of socio-economically important tree species providing those NTFPs are human activities. This study assesses the impact of human population density, land use, and NTFP-harvesting (pruning and de...
Article
Full-text available
Browse shrubs and trees, in spite of their significant role in livestock production in arid and semi-arid zones, are often omitted from pasture potential assessments because of the lack of methodology, the difficulty in calculation or method application and because it is usually a long and tedious task. For an accurate estimation of the carrying ca...
Article
Non-timber forest products contribute significantly to rural livelihoods in the West African savannas. This study investigates differences in use preferences for native woody species in six categories of plant use and their economic returns among five ethnic groups in Northern Benin. Ethnobotanical survey data from 230 households revealed that both...
Article
Full-text available
Termites are renowned ecosystem engineers. Their mounds have been described as an important element of savanna vegetation dynamics, but little is known about their large-scale impact on vegetation composition. To investigate the influence of termite-induced heterogeneity in savannas along a climatic gradient in West Africa termite mound vegetation w...
Article
Question In frequently disturbed habitats such as savannas, survival of seedlings and saplings depends on the species-specific ability to persist for a long time and to re-sprout following disturbances that are damaging to individuals. This physiological ability increases with increasing stem diameter, as re-sprouting requires sufficient nutrient r...