The total of all non-migratory wildlife species in the Masai Mara ecosystem has declined by 58% in the last 20 years. This decline ranges from 49% in small brown antelopes to 72% in medium brown antelopes. In individual wildlife species, the decline ranges from 52% in Grant's gazelle to 88% in the warthog. Declines of over 70% have been recorded in bu¡alo, gira¡e, eland and waterbuck. Only elephant, impala and ostrich have not shown any signi¢cant decline or increase. Overall, there has not been any signi¢cant di¡erence in decline of all wildlife population sizes inside and outside the reserve, except for Thomson's gazelle and warthog. Livestock have not signi¢cantly declined over the entire analysis period. However, livestock and cattle populations signi¢cantly declined during the 1983^88 period. Donkey declined by 67%, while shoats (goats and sheep) remained stable. In the case of wildlife, land use and vegetation changes, drought e¡ects and poaching are considered to be among the potential factors that may have been responsible for the decline; the decline in livestock during the 1983^84 period was probably due to drought e¡ects. wildlife Les aª nes ont diminue¨de 67%, tandis que che© vres et moutons restaient stables. Dans le cas de la faune sauvage, les changements d'utilisation des terres et de la ve¨ge¨tation, les e¡ets de la se¨cheresse et du braconnage sont a© compter parmi les facteurs qui peuvent avoir e¨ter esponsables du de¨clin; le de¨clin du cheptel en 19831 984 e¨tait probablement duª a© la se¨cheresse.
Summary The goal of this vegetation classification is to facilitate consistent field description of Kenyan vegetation communities and to convey in simple terms an impression of the site. It employs clearly defined rules of usage and easily measured vegetation characteristics. A hierarchical approach to classification was chosen to reflect the varying detail of information available from both remote sensing and ground survey methods. Four levels of classification are proposed. Level 1 names are descriptive of the primary vegetation lifeform found at the site. A modifier is included to indicate the canopy cover of that primary lifeform. Level 2 names provide a description of lifeforms of secondary importance. Level 3 names are descriptive of the height of the primary lifeform while Level 4 names indicate characteristic plant species found in the vegetation community Résumé Le but de cette classification végétale est de faciliter une description de terrain logique des communautés végétales au Kenya et de donner, en termes simples, une premiere description du site. Elle met en oeuvre des règies claires d'utilisation et des caractéristiques végétales facilement relevées. On a choisi une approche de classification hiérarchique pour illustrer la variation de détails disponible aussi bien pour une évaluation à distance que pour des méthodes d'investigation au sol. On propoe quatre niveaux de classification. Le niveau 1: des noms décrivent les formes de végétation primaire de l'endroirt. Un modificateur indique ce qui compose la canop ée de cette végétation primaire. Les noms du niveau 2 décrivent les formes d'importance secondaire. Au niveau 3, les noms indiquent la hauteur des formes d'importance primaire, tandis que le niveau 4 donne les especès végétales caractéristiques de la communauté considérée.
SUMMARY Stable carbon and nitrogen isotope ratios of bone collagen from elephants that died in the Tsavo National Park, Kenya, between 1975 and 1980, were determined in an attempt to establish possible changes in past diets. Individuals ranged from one to fifty years old at the time of death, and possessed a mean δ13C value of ‐ 18‐4 ± 018 and a mean δ15N value of 13‐8±018. These values for carbon were independent of age at the time of death, which suggests that these elephants assimilated similar proportions of C3 (shrub and tree) and C4 (grass) vegetation during the sixty‐year period covered by these specimens. Faecal analyses showed high interindividual variation in the proportion of C3/C4 food eaten, but the mean intake was similar (around 75% trees and shrubs) to that estimated from the isotopic composition of bone collagen. These data suggest that in the Tsavo National Park, elephants have maintained similar proportions of C3 and C4 vegetation in their diet over the past fifty years even though woodlands were being converted to grasslands. We suggest that this resulted from the high mobility of elephants or immigrations of individuals from similar woodland areas. Résumé On a déterminé le taux d'isotopes de carbone et d'azote dans le collagéne osseux des éléphants morts au Pare National du Tsavo (Kenya) entre 1975 et 1980 pour relever d'éventuels changements dans les régimes alimentaires entérieurs. Les individus furent classés de un à cinquante ans selon l'âge de leur mort et possédaient un delta 13C moyen de ‐18‐4 ± 0–18, etun δ15Nde 13.8 ± 0–18. Pour le carbone, ces valeurs étaient indépendantes de l'âge au moment de la mort, laissant supposer que ces éléphants ont absorbé des proportions semblables de végétation de type C3 (arbres et arbustes) et C4 (plantes herbacées) durant toute la période de soixante ans où ont vécu ces individus. L'analyse des excréments montrait de grandes variations individuelles dans la rapport C3/C4 mais la consommation moyenne était similaire (environ 75% d'arbres et arbustes) à celle qui avait été estimée à partir de la composition en isotopes du collagène osseux. Ces données suggèrent qu'au Tsavo, les éléphants ont conserveé un régime alimentaire de composition similaire en type C3 et C4 durant les cinquante dernières années, même lorsque les régions boisees se sont transformées en savanes herbeuses. Nous suggérons que ceci est le résultat soit d'une grande mobilityé des éléphants, soit de l'immigration d'individus provenant de régions boisées semblables.
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