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In the Westphalian Basin (North-Rhine Westphalia, Germany), 176 relevés of hedgerows first surveyed during the 1970s were reassessed in 2009 and 2010, and the floristic differences between these two time points were compared. The results were used to analyse the impact of exogenous factors on the species community composition using multivariate statistics (non-metric multidimensional scaling). Significant changes were found within all of the communities along the first axis of the ordination, and, in most cases, increasing average temperatures were best correlated with these alterations. However, based on the considerable evidence found, the alterations induced by land-use change and the intensification of agriculture appear to be the inducing factors.
Dynamics of juvenile woody plant communities on termite mounds in a West African savanna landscape
(2014)
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 mounds affect juvenile woody plant and non-woody plant species diversity, community composition, biomass and population dynamics. We repeatedly sampled paired termite mound and savanna plots in Pendjari National Park (Sudanian vegetation zone, North Benin, West Africa) over the course of two years. Despite considerable overlap in their species pools, plant communities of mound and savanna plots were clearly separated in ordinations. Species richness and diversity of juvenile woody plants was consistently higher on termite mounds, while no differences could be detected for non-woody plants. Evenness of juvenile woody plants was generally lower on mounds, whereas density and basal area were higher on mounds. In contrast, we did not detect any influence of the mound microhabitat on colonisation, mortality and turnover of woody juveniles. Therefore, we suggest that differences in the communities on and off mounds should be strongly influenced by directed diaspore dispersal through zoochory.
Miombo woodland is found throughout the Zambezian regional centre of endemism where most of the rural population make use of its wild plant species. This article presents the results of a study on the composition of the woody vegetation and its anthropogenous alteration in northern Malawi with particular respect to the impact caused by the collection of wild plants. The main vegetation type in this area is miombo woodland which is composed of 80 woody species. The collection of wild plants does not show an effect on the plant diversity but effects are visible in the decreasing number of tall trees.
Only a small proportion of introduced plant species become invasive and may eventually create ecological or economic problems. In many species it is still not clear which traits cause biological inva-sions. As a case study we focussed on the fast-spreading Epilobium brachycarpum in Central Europe to investigate the potential of this species to become a transformer or agricultural weed. We (1) documented the spread of the species in Central Europe, (2) modelled its range and (3) seed dispersal, (4) described its phytosociological alignment, (5) analysed the traits of invaded vegetation types, (6) described seed production, population densities and life cycle, (7) did competition and germination tests, and (8) drafted a risk assessment. Relevant traits and characteristics of E. brachycarpum are (i) formation of dense stands under ruderal conditions, (ii) high seed production, (iii) effective seed dispersal, (iv) high competitiveness on bare soils against other ruderal plants, and (v) ecological niche shift com-pared to its native range. We expect E. brachycarpum to settle in the Mediterranean, sub-Mediterranean and many parts of temperate Europe within the next decades in habitats strongly altered by human activities, especially open stands of the alliance Sisymbrion. We predict that E. brachycarpum will become a noxious weed in vineyards, and that it will also colonise vegetation of the alliances Bidention and Carici-Epilobion.
Evidence for increasing homogenization and de-ruralization of the Central European village flora
(2013)
In this study, the spontaneous flora of North Rhine-Westphalian villages (NW Germany) recorded in the periods 1980–1984 and 2004–2005 was analyzed. We asked: (i) Did the similarity of the village flora increase with time and to what extent did non-native species contribute to this? (ii) Is the ongoing trend of urbanization reflected in the village flora? (iii) Regarding the species composition and β-diversity: are there differences between the results of a repeated survey and of a type comparison? In both periods, 200 villages were visited once, using consistent criteria for village selection and floristic investigation. Of these, a subset of 61 villages was investigated in both time periods and the rest were selected randomly for the second survey but with respect to the same criteria as used in the first. Using different β-diversity indices (Sørensen index of dissimilarity, Simpson index of dissimilarity and nestedness resultant index) to disentangle pure species turnover and nestedness of species assemblages, we tested whether the similarity among the villages increased over the years. This was done by calculating all pairwise comparisons among the villages of each time period, i.e. their spatial turnover. Additionally, different ecological groups were defined (e.g. "neophytes", "C-strategists" or "urbanophilous species") using the subgroups of species traits (floristic status, Grime's life strategy and urbanity) to indentify urbanization and compositional changes. Our results show that the traditional village flora (species of the Arction lappae, Bidention tripartitae and Potentillion anserinae) is further blurred towards unspecific ubiquitous assemblages found in the periphery of man and that the floristic urbanization is still ongoing. Supported by nearly all ecological groups regarded, our results corroborate that the species composition of Central European villages underwent a considerable degree of homogenization. To some extent this is caused by structural homogenization of villages. Regarding the considerable increase of common ubiquists and α-diversity in general, however, changes in weeding practices seem to be the main reason. Based on the reinvestigated subset we could show that comparable results can be obtained by a consistent use of criteria for the selection of villages, even if unpaired samples were used.
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 fallows and in a protected area (in total 39 plots), and analyzed the influence of land use on juvenile densities. We further related the influence of land use on juvenile densities to 23 environmental parameters describing soil properties and vegetation structure. Soil acidity, particle size distribution of the soil, and vegetation structure differed between land-cover types. In terms of human impact, we detected five groups of species responding similarly to land use. Although we detected significant differences in soil properties, their direct effects on juvenile densities are less pronounced than their indirect effects. By altering the availability of resources, soil properties affect height and cover of all plants growing in the surrounding of a young woody plant, increasing the competition for light, water and nutrients during the establishment and initial growth. These effects are intensified by human land use and vary between land-cover types.
Bare incrusted soils are a degradation stage often encountered in the Sahel zone. Our study documents the success of restoration (= regreening) experiments using deep ploughing in an experimental site south of Gorom-Gorom in the Oudalan province of Burkina Faso. We used phytosociological relevés and maximum likelihood classifications of digital photography to analyze changes in vegetation. Plant cover in treated plots was found to be about 20 times higher than in control plots, mean species richness more than twice as high. Therefore, this promising restoration method should be tested also in other Sahelian regions. Our approach to combine phytosociological relevés and maximum likelihood classifications of digital photography proved to be very useful.
In spite of enormous climatic differences between Burkina Faso and Germany, 20 species belong to the spontaneous flora of both countries, i.e. 1% of the flora of Burkina Faso and 0.15 % of the German flora. All of them are either ruderal and segetal species (16) or water and reed plants (4). All of the 16 ruderals/segetals are therophytes. From a recent point of view, most of the 20 species can be classified as cosmopolitan, because they cover three and more floristic zones, and/or at least three climatic zones, and/or are represented in at least three continents. Although Burkina Faso has a semi-arid climate, none of the species can be called a sclero- or xerophyte. Therefore, in Burkina Faso, all are more or less bound to habitats at least temporarily flooded or to humid soils. In Germany, however, the concerned ruderals, with one exception, are indicators of medium dry or dry habitats.
Particularly in savannas, termites are ecosystem engineers and a keystone group in ecology. For the understanding of the savanna vegetation, mound building termites are of particular interest. Due to their special soil chemistry and physical structure, termite mounds often host other plants than the surrounding savanna. As our knowledge of the specific contribution of mound-building termites to overall savanna diversity and ecosystem dynamics doubtlessly is not complete, this paper summarises the state of the art in order to stimulate further research. According to the research interest of the authors, focus is laid on the West African savanna and on the genus Macrotermes.
Epoxides and diols of polyunsaturated fatty acids (PUFAs) are bioactive and can influence processes such as tumor cell proliferation and angiogenesis. Studies with inhibitors of the soluble epoxide hydrolase (sEH) in animals overexpressing cytochrome P450 enzymes or following the systemic administration of specific epoxides revealed a markedly increased incidence of tumor metastases. To determine whether PUFA epoxides increased metastases in a model of spontaneous breast cancer, sEH-/- mice were crossed onto the polyoma middle T oncogene (PyMT) background. We found that the deletion of the sEH accelerated the growth of primary tumors and increased both the tumor macrophage count and angiogenesis. There were small differences in the epoxide/diol content of tumors, particularly in epoxyoctadecamonoenic acid versus dihydroxyoctadecenoic acid, and marked changes in the expression of proteins linked with cell proliferation and metabolism. However, there was no consequence of sEH inhibition on the formation of metastases in the lymph node or lung. Taken together, our results confirm previous reports of increased tumor growth in animals lacking sEH but fail to substantiate reports of enhanced lymph node or pulmonary metastases.
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 survey reveals that 71 of the 102 woody species that are found in this area are used for a variety of treatments. These medicinal plants are most commonly applied in obstetrics. The favoured wild plants are frequently found in the area; however, three species are perceived as decreasing in abundance.
The use of woody species of rural populations in Northern Benin was investigated by semi-structured and open interviews. Of the 129 woody species found in the area, 124 (96%) were mentioned to be used as firewood, for house and furniture construction or preparation of tools, for alimentation, in traditional medicine and/or for other purposes. Our study confirms and underlines the high importance of non timber forest products (NTFPs) for the local population.
Most of the grass savannas on lateritic crusts found in the North-Western of Benin are free of trees and a shrub layer is only sparsely developed. The only constant member of the shrub layer is Terminalia laxiflora. Intermediate constancy show Entada africana and Annona senegalensis. With regard to the herbaceous layer two types can be identified: On very shallow soils (<2 cm) Loudetia togoensis is highly constant and often dominating. The same is true for Andropogon pseudapricus on soils of a little bit more than 2 cm. In those types, Lepidagathis anobrya and Spermacoce filifolia show very high constancy (constancy class V) and Cyanotis lanata and Melliniella micrantha occur with high constancy (IV).
On the clay plains surrounding Lake Chad (West Africa: northern Sudanian and southern Sahelian zone), certain varieties of pearl millet (Sorghum bicolor), commonly referred to as Masakwa, are cultivated during the dry season. Recently fallowed Masakwa fields support a particular progression of pioneer vegetation. In the first year of fallow, the pioneer vegetation typically belongs to the class Echinochloetea colonae Wittig 2005 and can be classified as Hygrophiletum auriculatae sensu lato. Approximately half of the stands consist of the Hygrophiletum auriculatae Ataholo 2002 sensu stricto, whereas the other half is primarily composed of a Celosia argentea-Hibiscus trionum community. After two years of fallow, the vegetation is typically formed by the Sorghetum arundinacei Ataholo 2002, which, in a few cases, can also occur in the first fallow year.
The year 1989 represents the starting point of the cooperation between botanists of the Goethe-University in Frankfurt (Germany) and of the University of Ouagadougou (Burkina Faso). Some years later, the University of Abomey-Calavi (Benin) joined the cooperation. This paper gives an overview on joint projects, resulting publications and theses, and on other achievements of this fruitful cooperation, which meanwhile also comprises partners of Ivory Coast, Niger and Senegal.
Uses and Management Strategies of the Multipurpose Tree Anogeissus leiocarpa in Eastern Burkina Faso
(2011)
Many people in the semi-arid tropics strongly depend on non-timber forest products (NTFPs) for livelihood. Increasing threats on NTFP-providing tree species, due to land-use intensification and over-harvesting, require ecological studies as well as additional information provided by local people. One important NTFP-providing tree in West Africa is Anogeissus leiocarpa. Even though this species is highly used, ethnobotanical studies on A. leiocarpa are scarce and address mainly qualitative aspects. Our study investigates uses, perceptions of the population development, and management strategies of A. leiocarpa among the Gulimanceba people in eastern Burkina Faso. We conducted a quantitative ethnobotanical survey and investigated distribution of traditional ecological knowledge related to the species on a local scale, i.e. difference in knowledge between villages, genders, and generations. Interviews reveal that A. leiocarpa is harvested by local people for 18 different uses and emphasize its high importance for local people. Ethnobotanical knowledge of A. leiocarpa was mostly evenly spread between genders and generations, while it slightly differed between villages. Although local people did not actively protect A. leiocarpa, current local harvesting modes and management resulted in sustainable use. However, ongoing land-use intensifications require adapted management strategies to guarantee the persistence of this important species. Our results provide, in combination with ecological results of our previous study, appropriate management recommendations. Our study emphasizes the importance of ethnobotanical studies on a local scale level in order to develop management strategies that are reliable in the specific area under the specific circumstances.
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 of 20.7 % of the plant species analyzed by either publications or own research are or were used as MAP. However, regarding single countries, the differences are considerably high. Absolutely leading the list are China (36.2 %), Burkina Faso (35.2 %) and the Korean Republic (34.5 %). Also ahead of other countries or regions are the North of Benin (32.8 %) and the entire Pakistan (30.3 %). Still above average rank Great Britain (26.7 %) and Nepal (23.3 %), while the figures for Bul¬garia (21.0 %), Germany (20.2 %) and France (19.4 %) almost represent the average. Jordan (17.3 %), Vietnam (17.1 %), Sri Lanka (16.6 %), India (16.1 %) and Thailand (15.5 %) rank slightly beneath. Clearly below the average are the percentages of MAP for Hungary (12.2 %) and the USA (11.8 %). The average numbers of MAP in the Philippines (9.5 %) and Malaysia (7.7 %) fall far behind. Calculated on a worldwide scale, every fifth plant can be regarded as MAP. This number matches that from Bulgaria, France and Germany. In northern Benin, Burkina Faso, Korea, China and Pakistan, however, every third plant is or was used as MAP, whereas in Hungary and the USA only every eighth plant can be regarded as MAP. This number drops even further for the Philippines ore Malaysia where only every tenth or thirteenth plant can be attributed to medicinal or aromatic use. These differences might be due to various factors. A geographical component of the results is obvious: in most cases geographically close countries show similar percentages. A correlation between the total number of species and the fraction of those used as MAP cannot be confirmed. The countries with percentage of MAP > 30 % in common show that they belong either entirely (Burkina Faso, Benin) or at least in their rural areas to the poorest countries of the world so that it is (was) impossible for the majority of the people to buy "modern" MAP. In those countries the number of traditional healers outnumbers largely the number of modern doctors. Therefore, the tradition of folk medicine was maintained until today. Additionally, China, Korea and partially Pakistan have a very old and well documented tradition of folk medicine. Due to this documentation even in areas where today "modern MAP" are used, the knowledge was not lost. In neighboring countries or regions, which differ with respect to a more arid or a more humid climate, for the arid country (region) more MAPs are reported than for the humid one. The potential reasons for this phenomenon are discussed in the paper. For many countries the percentage given for MAP in literature is too low. But even these low values represent a striking argument for the importance of a world-wide conservation of biodiversity.