R. M. Laws

Bio: R. M. Laws is an academic researcher. The author has contributed to research in topics: Woodland & Population. The author has an hindex of 1, co-authored 1 publications receiving 100 citations.

Elephants and habitats in north bunyoro, uganda

Abstract: Summary The paper is concerned with the changing relation between elephant populations and vegetation in north Bunyoro, Uganda. The history of the area over the past 100 years is briefly described, particularly in terms of changing human populations and contraction of the elephant range. The main features of the environment, including vegetation types and distribution, annual burning, other species of large mammals (including the results of aerial counts) and birds are described. The main results of investigations on the elephant populations in the area, dealing with numbers, distribution and movements, population density distributions, and social organisation iocluding group size frequencies and structure, are presented. From a population of about 10,000 elephants over 1,000 have been cropped or shot on control in the area since 1965. The results of detailed analyses of material derived from these operations are presented and discussed. Material from the cropping operations represents a cross-section of the population and all animals sampled have been aged from the dentition. It is concluded that the mean daily food intake (wet weight) is 4% of live weight for all classes except lactating females; results of studies of food quality are discussed and a possible explanation for the de-barking of trees presented. The physical condition of elephants in several populations has been compared and appears to be poorer when less browse is available. Growth equations are presented for height and weight; the male shows a post-pubertal growth spurt. Various reproductive parameters are examined including age at puberty, pregnancy rate, and the seasonal cycle. Seasonal conceptions are delayed in North Bunyoro in relation to their timing north of the River Nile and it is suggested that the delay is nutritionally-induced. Recruitment has been falling in this population and this decline is likely to continue in the absence of effective management. Some undesirable consequences of extensive control-shooting are mentioned. The analysis of the elephant populations indicates that they are at densities in excess of the carrying capacities of the habitats, and the continuing changes in these habitats are described. In the grassland and wooded grassland areas the destruction of woodland has progressed radially, a zone of damage about 15–20 km wide having moved outwards through the range. This is consistent with destruction mainly by elephants rather than by fire. The influence of elephants on the forest edge and on the areas of regeneration inside the forest, created by management, is described. Finally specific proposals that have been presented to the National Parks and Forest Department are discussed. These involve rational cropping of over 4,000 elephants over the range and the construction of elephant-proof barriers, the control of fire, and the declaration of a Conservation Area with a statutory Authority on which the various interests concerned would be represented.

The evolution of social behavior

Abstract: For several years the study of social behavior has been undergoing a revolution with far-reaching consequences for the social and biological sciences. Partly responsible are three recent changes in the attitudes of evolutionary biologists. First was growing acceptance of the evidence that the potency of natural selection is overwhelmingly concentrated at levels no higher than that of the individual. Second was revival of the comparative method, especially as applied to behavior and life histories. Third was spread of the realization that not only are all aspects of structure and function of organisms to be understood solely as products of selection, but because of their peculiarly direct relationship to the forces of selection, behavior and life history phenomena, long neglected by the evolutionists, may be among the most predictable of all phenotypic attributes. These ideas have been appreciated by a few biologists for a long time, but they have only recently begun to characterize the science as a whole. Darwin’s discussion of sterility between species as an incidental effect of evolutionary adaptation (41, p. 260) and his refusal to deal with sex ratio selection (42, p. 399) suggest awareness of the difficult problem of determining the levels at which selection is most powerful. Yet significant clarification of this basic issue did not really commence until publication of Wynne-Edwards’ massive volume (179) championing group selection and inadvertently exposing its unlikelihood. As late as 1958, Fisher felt constrained to add to the revised edition of his 1929 classic, The Genetical Theory of Natural Selection, the admonishment (53, p. 49) that his fundamental theorem and its associated considerations, already misused then by decades of population geneticists dealing (as they saw it) with the fitness of populations, refer strictly to "the progressive modification of structure or function only in so far as variations in these are ofadvantage to the individual... [and afford] no corresponding explanation for any properties of animals and plants.., supposed to be of service to the species to which they belong." Williams’ critique (171) provided a significant turning point. Nevertheless, one has only to pick up any biological journal or attend any biological meeting to realize that this question has not yet been settled for all

Biomass and production of large African herbivores in relation to rainfall and primary production

Abstract: Standing crop biomass, energy expenditure and production by large mammalian herbivores in the African savannas show a high degree of correlation with mean annual precipitation and predicted above ground primary production. These relationships possess the potential for predicting carrying capacity and protein production from simple meteorological data.

A Review of Density Dependence in Populations of Large Mammals

Abstract: The study of population regulation has been central to much of the work on the population biology of both animals and plants, as seen in much of the literature (for example, Lack, 1954; Slobodkin, 1961; MacArthur and Connell, 1967; McLaren, 1971; Ricklefs, 1973; Emmel, 1976; Tamarin, 1978). Recent developments in the theoretical aspects of population dynamics have led to a growing union of the concepts of life history analysis with those of population regulation, both in an evolutionary context (for example, Boyce, 1984). Much of the literature dealing with population regulation covers research on fishes and insects, with some work devoted to the study of birds (Nikolskii, 1969; Lack, 1966; Clark et al., 1967; Weatherly, 1972; Varley et al., 1973; Hassel, 1975; Gulland, 1977). Wynne-Edwards (1962) presents information on density dependence for a number of taxonomic categories. Reviews of the literature dealing with density dependence exist for fish (McFadden, 1977) and small mammals (Christian, 1963; Krebs and Myers, 1974). A preliminary review for large mammals was produced by Fowler et al. (1980).

Nature Conservation in Uganda's Tropical Forest Reserves

Abstract: This report arises from a three-year survey of the status of Uganda's twelve principal tropical high forest reserves, carried out between 1985 and 1988 for the Uganda Forest Department (FD), with financial support from the World Wide Fund for Nature (WWWF-International), and the New York Zoological Society (NYZS). It presents the results of this survey, and attempts to: describe the present status of the principal forest reserves in terms of the type and extent of recent human disturbance;review their importance as a renewable natural resource, and the ways in which present management practices may affect their long-term ability to provide mankind with a range of useful goods and services: describe the wildlife communities that are characteristic of these forest reserves; and show how they are important to national and international species conservation efforts;review the need to set aside areas of relatively undisturbed natural forest as strict nature reserves, and provide guidelines for the selection of appropriate areas; and provide specific recommendations on forest management aimed at ensuring sustainable methods of exploitation. The project began as a one-year survey of six forests in Western Uganda, but was extended at the request of the Minister of Environment Protection to include major forests elsewhere, so that ultimately all of Uganda's closed canopy forests exceeding 100 km squared were included (11 forests), together with one smaller forest (Itwara) which had been included in the orginal project proposal.

Rainfall, soil nutrient status and biomass of large African savanna mammals

Abstract: ummary Published estimates of population densities of large savanna herbivores are used to relate biomass to rainfall, and soil nutrient status as determined by geomorphology (after Bell, 1982). This reveals that the positive correlation between total large herbivore biomass and rainfall in arid/eutrophic savannas (Coe, Cumming & Phillipson, 1976) also applies for nineteen out of twenty-three individual herbivore species. Herbivores are divided into two groups, arid and moist savanna species, on the basis of the rainfall at which their peak population densities occur on soils of low nutrient status (< 820 and ≥ 1000 mm, respectively). These groups reflect the division between arid/eutrophic) and moist/dystrophic) savannas. Arid savanna herbivores, which dominate total herbivore biomass, include grazers, mixed feeders and browsers and are less selective feeders. Their biomass tends to decline at higher levels of rainfall on low nutrient status soils and only the larger species, such as elephant, buffalo and hippopotamus, are widespread in moist/dystrophic savannas where mean annual rainfall exceeds 1000 mm. Moist savanna species are mainly highly selective grazers and occur widely in moist/dystrophic) savannas. Their biomasses are usually low and show a positive correlation with rainfall on soils of low nutrient status. Large carnivore biomass is positively correlated with rainfall in arid/eutrophic) savannas, reflecting a positive relationship to prey biomass. The biomass of individual carnivore species is most closely correlated with the biomass of the preferred size class of prey. These relationships suggest that natural populations of large savanna mammals tend to be close to the limits set by their food resources. Resume Les estimations publiees de densites de population des grands herbivores de savane sont utilisees pour mettre en relation la biomasse avec les chutes de pluie et la composition du sol en nutriments, telle qu'elle est determinee par la geomorphologie (d'apres Bell, 1982). Ceci revele que la correlation positive entre la biomasse totale de grands herbivores et la chute de pluie dans les savanes arides/ eutrophiques (Coe, Cumming & Phillipson, 1976) s'applique egalement pour dix-neuf des vingt-trois especes d'herbivores. Les herbivores sont divises en deux groupes–especes de savanes arides ou humides–selon le niveau de chutes de pluie auquel correspond leur densite de population maximale sur des sols pauvres en nutriments (< 820 et ≥ 1000 mm respectivement). Ces groupes refletent la division entre les savanes arides/eutrophiques) et humides/dystrophiques). Les herbivores de savane aride, qui dominent la biomasse totale des herbivores, comprennent des brouteurs d'herbe, des brouteurs mixtes, des brouteurs de feuilles et des brouteurs moins selectifs. Leur biomasse tend a diminuer aux plus hauts niveaux de pluies sur sols pauvres et seules quelques grandes especes comme l'elephant, le buffle et l'hippopotame sont repandus dans les savanes humides/dystrophiques) ou la quantite de pluie depasse 1000 mm. Les especes de savane humide sont principalement des brouteurs d'herte tres selectifs. Leurs biomasses sont generalement faibles et presentent une correlation positive avec les chutes de pluie sur sols pauvres en nutriments. La biomasse des grands carnivores est en correlation positive avec les chutes de pluie en savanes arides/eutrophiques, illustrant la relation positive avec la biomasse de leurs proies. La biomasse de chaque espece de carnivore est beaucoup plus intimement liee a celle de son type de proie. Ces relations suggerent que les populations naturelles de grands mammiferes de savane tendent aetre proches des limites fixees par leurs ressources alimentaires.