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Serengeti National Park (serengeti + national_park)
Selected AbstractsSpatial and temporal hotspots of termite-driven decomposition in the SerengetiECOGRAPHY, Issue 3 2010Bernd P. Freymann Ecosystem engineers are organisms that directly or indirectly control the availability of resources to other organisms by causing physical state changes in biotic or abiotic materials. Termites (Insecta, Isoptera) are among the most important ecosystem engineers in tropical ecosystems. We used a field experiment in the tall grasslands of Serengeti National Park, Tanzania, to investigate 1) the consumption by termites of grass litter and dung baits along the landscape gradient of catena position, and 2) seasonal variation in litter and dung removal. Our maps of termitaria and patterns of bait removal revealed clear spatial and temporal hotspots of termite activity. In the dry season termites removed more baits at the top-catena positions than at the bottom positions, but there was no effect of catena position in the wet season. Spatial hotspots of termite activity overlapped with those of both mammalian herbivores and predators. Within the framework of ecosystem engineering, this study suggests that intraspecific aspects of spatial heterogeneity and temporal variability deserve much greater consideration. [source] Relationship between road dust and ungulate density in Serengeti National Park, TanzaniaAFRICAN JOURNAL OF ECOLOGY, Issue 4 2008Vedasto G. Ndibalema Abstract We measured the responses of ungulate grazers to roads by recording the density of dust on grasses and compared distance sampling of ungulates in Serengeti National Park (SNP), Tanzania. Data were collected on the east and west side of the Ngorongoro,Seronera main gravel road to test if road traffic and dust were important factors determining distribution patterns amongst grazers. Results indicate that dust increased progressively with traffic speed and volume during dry season. More dust was intercepted on the west than on the east side of the road mainly because of wind effects. Dust deposition (measured as density g grass g,1 dust) was higher on short grasses than on long grasses during the dry and late-dry seasons than during the wet season, when paired perpendicular distances up to 300 m were compared. Mean number of observed grazer species indicated that most fed further from the west side of the road than from the east perhaps to minimize higher density of dust commonly spread on foliage up to 200 m away from the road. Despite that most grazers avoided road side grass shoulders, supporting the ,dust aversion hypothesis', the test predictions from the ,road disturbance' and the ,road attraction' hypotheses did not support the responsive behaviours of grazers toward roads. Résumé Nous avons mesuré la réponse d'ongulés brouteurs à la présence de routes en enregistrant la densité de poussière sur les herbes et en comparant la distance des ongulés dans le Parc National du Serengeti, en Tanzanie. Les données ont été récoltées à l'est et à l'ouest de la principale route en gravier du Ngorongoro Seronera pour voir si le trafic routier et la poussière étaient des facteurs importants qui déterminaient les schémas de distribution des animaux brouteurs. Les résultats indiquent que la poussière augmente progressivement avec la vitesse et le volume du trafic pendant la saison sèche. On a recueilli plus de poussière du côté ouest de la route, surtout à cause des effets du vent. Les dépôts de poussière (mesurés comme la densité g d'herbe/g de poussière) étaient plus abondants sur les herbes courtes que sur les longues pendant la saison sèche et en fin de saison sèche qu'en saison des pluies lorsqu'on comparait deux à deux des distances perpendiculaires allant jusqu'à 300 mètres. Le nombre moyen d'espèces d'animaux brouteurs observées indiquait que la plupart se nourrissaient plus loin du côté ouest de la route que du côté est, peut-être pour minimiser la forte densité de poussière qui se dépose régulièrement sur le feuillage jusqu'à 200 mètres de la route. Bien que la plupart des brouteurs évitent les accotements herbeux de la route, ce qui vient soutenir l'hypothèse de l'aversion pour la poussière, les tests de prédiction concernant les hypothèses de « perturbations par la route » ou d'« attraction par la route » ne supportent pas le comportement réactif des ongulés brouteurs vis-à-vis de la route. [source] Illegal meat hunting in serengeti: dynamics in consumption and preferencesAFRICAN JOURNAL OF ECOLOGY, Issue 3 2008Vedasto G. Ndibalema Abstract Although wild meat is an important source of protein across Africa, patterns and reasons for its demand are poorly defined. A study was conducted on consumption by inhabitants of ten villages in five districts to the west of Serengeti National Park, Tanzania. The first sample of 600 villagers was systematically selected from village registers and surveyed using a questionnaire. The second sample consisted of 341 arrested illegal meat hunters. Nine species dominated by eland (Taurotragus oryx) and wildebeest (Connachaetes taurinus) in terms of meat taste and hunting vulnerability respectively were found to be most preferred or consumed. There were remarkable variations in consumption and preferences for each species amongst ethnic groups and localities. The economics of protein consumption indicates that wild meat is consistently cheaper and hence consumed more frequently than other meats. Respondents' topmost tasty meat , eland and topi (Damaliscus lunatus) , were rare; consequently, common species e.g. buffalo (Syncerus caffer) and wildebeest were the substitutes mostly consumed to supplement beef and fish. Presence of carnivore species on the menu clearly demonstrates survival techniques when availability changes. Wildlife managers should, therefore, bestow attention to the conservation of all species for a balanced ecosystem and species survival. Résumé Bien que la viande de brousse soit une importante source de protéines dans toute l'Afrique, le schéma et les raisons de cette demande sont mal définis. On a réalisé une étude sur la consommation des habitants de dix villages dans cinq districts situés à l'ouest du Parc National de Serengeti, en Tanzanie. Le premier échantillon de 600 villageois fut systématiquement sélectionné sur les registres du village et suivi au moyen d'un questionnaire. Le second échantillon se composait de 341 chasseurs illégaux qui avaient été arrêtés. On a découvert que neuf espèces, dominées par l'éland (Taurotragus oryx) et le gnou (Connochaetes taurinus) en ce qui concerne le goût et la vulnérabilitéà la chasse, avaient la préférence et étaient plus consommées. Il y avait de remarquables variations de consommation et de préférences pour chaque espèce selon les groupes ethniques et les localités. L'économie de la consommation de protéines indique que la viande de brousse est notablement moins chère et donc consommée plus fréquemment que les autres viandes. La viande la plus appréciée des répondants, l'éland et le topi (Damaliscus lunatus) était rare. Par conséquent, les espèces communes comme le buffle (Syncerus caffer) et le gnou étaient les substituts les plus consommées pour compléter le b,uf et le poisson. La présence de carnivores au menu montre bien les techniques de survie lorsque la disponibilitéévolue. Les gestionnaires de la faune sauvage devraient donc accorder leur attention à la conservation de toutes les espèces pour la survie des espèces elles-mêmes et d'un écosystème équilibré. [source] The role of rainfall and predators in determining synchrony in reproduction of savanna trees in Serengeti National Park, TanzaniaJOURNAL OF ECOLOGY, Issue 1 2007SIMON A. R. MDUMA Summary 1We examined the factors determining synchrony in reproduction in nine Acacia and six other tree species in the Serengeti ecosystem. 2We test two hypotheses: (i) an abiotic hypothesis where the primary determinant of synchrony is an adaptation to water availability; and (ii) biotic hypotheses where these adaptations to water can be further refined by additional adaptations to avoid predators, or attract seed and fruit dispersers. 3Flowering and fruiting were recorded monthly for individually marked trees during 1997,2004. Flowering in different species occurs semi-annually, annually or, in the case of one species, once every 2 years. For most species synchrony of flowering was correlated with seasonal rainfall, with lags related to the mean height of the species; small species flowered during the rains while larger species flowered in the dry season. Fruiting seasons occurred at the end of the rains irrespective of the flowering season. 4Most species showed flowering synchrony greater than expected from the distribution of rainfall. This may be related to avoidance of insect seed predators through predator satiation. Two Acacias showed multi-annual fruiting (masting), possibly as a predator avoidance mechanism. Acacia tortilis has two flowering seasons: a dry season flowering with early abortion of pods and a wet season flowering producing successful fruits. 5Two species of Commiphora appeared to be synchronized so as to attract birds that disperse seeds. Acacia tortilis produced indehiscent pods attractive to ungulates, possibly to kill bruchid beetles during digestion and so increase seed viability. 6Our results suggest that synchrony in these trees is caused by a strong interaction between abiotic and biotic factors. Closely related species have different reproductive patterns of synchrony that seem to be adapted to different combinations of rainfall, predators and dispersers. Rainfall is the primary determinant but the activities of predators and dispersers increase the degree of synchrony. [source] | ||||||||||