bluuebunny/crossref_metadata_2025_split huggingface dataset:
The rooting patterns of woody and herbaceous plants in a savanna; are they complementary or in competition?
Authors: SEGHIERI J. 
Published: April 2008

SummaryRoot patterns of three woody plants are described in relation to water profiles and average root depth of annual species on three contrasted soil types along a toposequence in a watershed of northern Cameroon. This watershed is in a Sudano‐Sahelian savanna where mean annual precipitation is 800 mm, entirely restricted to the period May‐June to September‐October. Results show great variations of root structure of woody plants according to the distribution of water in the soil during one year. Consequently, under the same climatic conditions, soil depths exploited by woody plants and herbaceous plants can either be the same or not. In the most degraded soils, water does not infiltrate deeply and roots of the two components of savanna are limited to the upper horizons. On the other types of soil, root distribution depends on the soil profile.RésuméLa structure racinaire de trois arbres ou arbustes est décrite, en liaison avec quelques profils hydriques et la profondeur racinaire moyenne des plantes annuelles, sur trois types de sol aux caractéristiques hydriques trés contrastées et situés le long d'une toposéquence d'un bassin versant du Nord‐Cameroun. Le bassin versant est localisé dans une savane soudano‐sahiliénne où la pluviosité annuelle moyenne est de 800 mm répartis entre mai‐juin et septembre‐octobre. Les résultats montrent une forte variation de la structure racinaire des plantes ligneuses en liaison avec la répartition de l'eau dans le sol au cours de l'année. Sous les mêmes conditions climatiques, la profondeur de sol exploitée par les espèces ligneuses et les espèces herbacées peut être ou non la même. Sur les sols les plus dégradés, elle est la même, dans les horizons de surface, à cause de la très faible infiltration de l'eau dans ces sols. Sur les autres types de sol, la répartition des racines dépend du profil pédologique.
Dry season water, female movements and male territoriality in springbok: preliminary evidence of waterhole‐directed sexual selection
Authors: RITTER R. C. , BEDNEKOFF P. A. 
Published: April 2008

SummarySpringbok (Antidorcas marsupialis) breed during the dry season in Nxai Pan N.P., Botswana. Some effects of artificially provisioned water on this springbok population were examined. Although springbok can live for months without water, springbok drank frequently at Nxai Pan and female movements were strongly centred on the single waterhole. Males occupying territories closer to the waterhole had relatively larger horns and thicker necks—two characters important for fighting ability in springbok. By concentrating females in a portion of the habitat, the artificial water source may have increased the skew in male mating success, increased the strength of sexual selection on males, and decreased the effective population size of springbok at Nxai Pan.RésuméLe springbok (Antidorcas marsupialis) se reproduit pendant la saison sèche dans le P. N. de Nxai Pan, au Botswana. On a examiné certains effets de l'approvisionnement d'eau artificiel sur cette population de springboks. Bien que le springbok puisse vivre des mois sans eau, il boit fréquemment à Nxai Pan, et les mouvements des femelles sont fortement centrés sur l'unique point d'eau. Les mâles qui occupent des territoires plus prês du point d'eau ont des cornes relativement plus grandes et un cou plus large—deux caractères importants pour l'aptitude au combat des springboks. En concentrant les femelles sur une partie de l'habitat, le point d'eau artificiel peut avoir biaisé la réussite reproductrice des mâles, augmenté l'impact de la sélection sexuelle qui pése sur les mâles et diminué la taille réelle de la population de springboks á Nxai Pan.
The metazoan ecto‐ and endoparasites of the rabbitfish, Siganus sutor (Cuvier & Valenciennes, 1835) of the Kenyan coast. I
Authors: MARTENS E. , MOENS J. 
Published: April 2008

SummaryIn a survey of the metazoan ecto‐ and endoparasites of Siganus sutor (Cuvier & Valenciennes, 1835), a commercially important herbivorous fish from the Kenyan coast, sixteen species of parasites are found. The gill parasites include Monogenea (Tetrancistrum sigani Goto & Kikuchi, 1917; Microcotyle mouwoi Ishii & Sawada, 1938; Pseudohaliotrema sp. 1 and sp. 2, and an unidentified Microcotylidae species); Copepoda (Caligus sp. and Hatschekia sp.); and Isopoda (one Gnathiidae species). The intestinal parasites found are Digenea (Opisthogonoporoides cf. hanumanthai Madhavi, 1912; Gyliauchen papillatus Goto & Matsudaira, 1918; Hexangium sigani Goto & Ozaki, 1929; and three other unidentified digeneans); Acanthocephala (Sclerocollum rubrimaris Schmidt & Paperna, 1978); and Nematoda (Procamallanus sigani Yamaguti, 1935). The species listed are first records for the Kenyan coast.Infection prevalence, mean intensity and site specificity are determined for the different parasite species. The parasites have an aggregated frequency distribution in the host population: some individuals of the siganid population are more heavily infected than expected in a random distribution, while others are very little or not at all infected.RésuméOn a découvert seize espèces de parasites lors d'une étude des métazoaires ecto‐et endoparasites de Siganus sutor (Cuvier & Valenciennes, 1985), un Poisson herbivore commercialement important de la côte kéyane. Les parasites des branchies comprennent des Monogeneae (Tetrancistrum sigani Goto & Kikuchi, 1917; Microcotyle mouwoi Ishii & Sawada, 1938; Pseudohaliotrema sp.1 & sp.2, et une espèce non identifiée de Microcotylideae); des Copépodes (Caligus sp. et Hatschekia sp.) et un Icopode (une espèce de Gnathiideae). Les parasites intestinaux trouvés appartenaient aux Digeneae (Opisthogonoporoides cf. hanumanthai Madhavi, 1972; Gyliauchen papillatus Goto & Matsudaira, 1918; Hexangium sigani Goto & Ozaki, 1929; et trois autres Digenaeae non identifiés); aux Acanthocephaleae (Sclerocollum rubrimaris Schmidt & Paperna, 1978), et aux Nématodes (Procamallanus sigani Yamaguti 1935). Ces espèces sont rapportées pour la première fois sur la côte kényane. Le degré, l'intensité
Home ranges and social organization of female elephants in northern Kenya
Authors: THOULESS C. R. 
Published: April 2008

SummaryHome ranges and social organization of African elephantsLoxodonta africana(Blumenbach) from the Laikipia‐Samburu population of northern Kenya were studied. Twenty female elephants from this population were fitted with radio collars and monitored for up to 25 months. Home range sizes of radio‐collared elephants varied from 102 to 5527 km2, the widest variation that is known for a single population. Several subpopulations could be distinguished. The ranges of elephants from one subpopulation overlapped with those from other sub‐populations, and elephants from different subpopulations were occasionally seen in the same groups, although they had different movement patterns and home range sizes, and tended to occur in groups of different sizes. Members of the same subpopulation were often close together if they were in the same area, whereas members of different subpopulations seldom came closer than 2 km. There was no evidence for the existence of ‘clans’ within subpopulations, and it is suggested that this difference from other studied elephant populations is related to the much greater distances over which the Laikipia‐Samburu elephants move.RésuméOn a étudié l'espace vital et l'organisation sociale des éléphants africains,Loxodonta africana(Blumenbach), de la population de Laikipia‐Samburu, au nor du Kenya. On a pourvu vingt femelles de cette population de colliers radio et on les a suivies pendant 25 mois. La taille de l'espace vital des éléphants pourvus de colliers radio variait de 102 à 5527 km2, la plus forte variation connue pour une seule population. On a pu distinguer plusieurs sous‐populations. Les territoires d'une sous‐population recouvraient ceux des autres sous‐populations, et l'on pouvait à l'occasion voir dans le même groupe des éléphants de différentes sous‐populations, même si leurs déplacements suivaient un schema different, que la taille de leur territoire était différente et qu'on les rencontrait dans des groupes de taille différente. Les membres de la même sous‐population étaient souvent prés l'un de l'autre s'iis étaient dans la même région, alors que les membres de sous‐populations différentes se rapprochaient rarement à moins de deux kilomètres. II n'y avait pas de preuves de l'existence de clans à l'intérieur des sous‐populations, et l'on suggère que la différence par rapport aux autres populations d'eléphants qui ont étéétudiées est liée aux plus grandes distances parcourues par les éléphants de Laikipia‐Samburu.
Morphometries and reproduction in a population of springbok Antidorcas marsupialis in the semi‐arid southern Kalahari
Authors: SKINNER J. D. , AARDE R. J. VAN , KNIGHT M. H. , DOTT H. M. 
Published: April 2008

SummaryThe timing and duration of the male rut were monitored in a population of springbok in the Kalahari from 1984. Timing was random and could not be related to any proximate factor; the duration varied from 5 to 23 days. Springbok rams were shot or captured in the hot‐wet, cold‐dry and hot‐dry seasons from 1988 to 1992. Body condition and testicular exocrine and endocrine functions were measured. Territorial and non‐territorial rams were treated in the same way. All body measurements were lower for non‐territorial than for territorial rams, but only neck girth differed significantly. Captured animals were stimulated with GnRH and plasma testosterone concentrations were measured over 90 min. Overall, non‐territorials showed a greater response than territorial rams. The response of territorial rams to GnRH at the beginning of a rut was significantly less than the response 1 week later. Ewes came into oestrus shortly after the beginning of the male rut; in four of the past five years lambing peaked in the hot‐wet season. Rams appeared to be physiologically capable of reproductive activity throughout the year, and responded to various stimuli by exhibiting rutting and/or mating behaviour. The possible stimuli are discussed.RésuméOn a surveillé l'occurence et la durée du rut des mâles dans une population de springboks du Kalahari depuis 1984. L'occurence semblait se faire au hasard et ne répondre à aucun facteur évident; la durée allait de 5 à 23 jours. On a tué des springboks mâles en saison chaude et humide, froide et séche, et chaude et sèche, de 1988 à 1992. On a mesuré la condition physique ainsi que les fonctions testiculaires exocrines et endocrines. Les mâles ont tous été traités de la même fa¸on, qu'ils soient territoriaux ou non. Toutes les mensurations corporelles étaient plus petites pour les mâles non territoriaux que pour les mâles territoriaux, mais seul le tour de cou différait significativement. On a stimulé des animaux capturés avec du GnRH et mesuré les concentrations de testostérone dans le plasma au bout de 90 minutes. En général, les mâles non territoriaux montraient une réponse plus forte que les mâles territoriaux. La réponse des mâles territoriaux au GnRH administré au début du rut était significativement moindre qu'une semaine plus tard. Les femelles entraient en chaleur peu après le début du rut des mâles, et pour quatre des cinq dernières années, la mise‐bas a culminé pendant la saison chaude et humide. Les mâles semblaient physiologiquement capables d'avoir une activité reproductrice tout au long de l'annee et répondaient à différente stimuli en exhibant un comportement de rut ou d'accouplement. On discute des stimuli possibles.
Effects of 20 years of grazing exclusion in an area of the Queen Elizabeth National Park, Uganda
Authors: LENZI‐GRILLINI CARLO R. , VISKANIC PAOLO , MAPESA MOSES 
Published: April 2008

SummaryThe floristic and structural changes resulting from the long‐term exclusion of large herbivores from an experimental area set up in 1971 have been analysed, comparing it to two plots in the surrounding grazed and trampled area.The vegetation of the area is grassland with thicket clumps, with Sporobolus pyramidalis P. Beauv. dominating the grassland and Capparis tomentosa Lam. dominating the thicket layer. The survey showed that long‐term exclusion of herbivores results in: (i) higher density and cover in the grass and thicket layer, (ii) lower biodiversity in the grass layer and in the isolated shrubs, (iii) higher root biomass, probably due to the absence of trampling. Despite the difference in area, no difference was noted between the biodiversity of the thicket clumps of the ungrazed area and the grazed and trampled plots.RésuméOn a analysé les changements floristiques et structurels résultant de l'exclusion à long terme des grands herbivores d'une zone expérimentale établic en 1971, en la comparant à deux zones situées dans la région voisine, pâturée et piétinée. La végétation de la région est une prairie avec des massifs de buissons, avec Sporobolus pyramidalis P. Beauv. dominant la prairie et Capparis tomentosa Lam. dans les buissons. L'étude a montré que l'exclusion à long terme des herbivores aboutit à: (i) une densité et une couverture plus grandes de l'herbe et des buissons, (ii) une biodiversité plus faible dans la couche herbeuse et dans les fourrés isolés et (iii) une plus forte biomasse des racines, due probablement à l'absence de piétinement. Malgré la région beaucoup plus élevée, on n'a noté aucune différence de biodiversité dans les agglomérats de buissons dans la zone non pâturée.
Diversity of ground‐living spiders at Ngome State Forest, Kwazulu/Natal: a comparative survey in indigenous forest and pine plantations
Authors: MERWE M. VAN DER , DIPPENAAR‐SCHOEMAN A. S. , SCHOLTZ C. H. 
Published: April 2008

SummaryA survey of ground‐living spiders was conducted over a one‐year period at Ngome State Forest, Kwazula/Natal. Five different habitat types: grass, open forest, dense forest, ecotone and pine, were sampled with 180 pitfall traps. The grass, open forest and dense forest represented indigenous vegetation while the pine represented exotic vegetation. The ecotone consisted of a mixture of indigenous forest plants and pine trees. Pine had the lowest spider diversity while grass had the highest spider diversity. However, variation in spider diversity within habitat types was considerable and an analysis of variance found no significant difference in mean values of spider diversity between habitat types. Consequently, the results do not unambiguously support the hypothesis that exotic vegetation has lower ground‐living spider diversity than indigenous vegetation.RésuméOn a mené pendant un an une étude sur les araignées vivant sur le sol de la Ngome State Forest, au Kwazulu/Natal. On a testé cinq types d'habitats différents avec des piéges: l'herbe, la forêt ouverte, la forêt dense, l'écotone et la pinède. L'herbe, la forêt ouverte et la forêt dense présentaient une végétation indigène tandis que la pinède représente une végétation exotique. L'écotone consiste en un mélange de plantes forestières indigènes et de pins. La pinède renferme la plus faible diversité d'araignées et l'herbe, la plus haute diversité. Cependant, la variation de diversité des araignées à l'intérieur des types d'habitat était considérable, et une analyse de la variance n'a pas montré de différence significative dans les valeurs moyennes de diversité des araignées entre les types d'habitat. Par conséquent, les résultats ne supportent pas sans ambiguïté l'hypothèse selon laquelle la végétation exotique présente une plus faible diversité d'araignées vivant au sol que la végétation indigène.
Elephant damage and safari hunting in Pterocarpus angolensis woodland in northwestern Matabeleland, Zimbabwe
Authors: CAMPBELL B. M. , BUTLER J. R. A. , MAPAURE I. , VERMEULEN S. J. , MASHOVE P. 
Published: April 2008

SummaryThis study examines the extent of elephant damage in two State Forests and investigates whether wildlife utilization, particularly of elephant (Loxodonta africana), produces economic returns which offset the negative impact of elephant damage on the timber resource. Eight common timber species were studied; 25% of trees >9·5 cm diameter at breast height (dbh) sampled had been damaged by elephants or other herbivores. P. angolensis, one of the most economically important timber species, was the worst affected; 67% of trees >34 cm dbh had been damaged by elephants. The results indicate that elephant can cause mortality of trees, and 13% of P. angolensis sampled had been killed by elephants. Elephant appear to be limiting recruitment into exploitable size classes. Simple economic calculations estimate that the benefits derived from elephant trophy hunting (US$0·35 ha‐1 y‐1) outweigh the timber losses caused by elephant (US$0·15 ha‐1 y‐1). The economic value of hunting in the Forests is shown to be greater than the value of extractable timber.RésuméCette étude examine Pétendue des dégats d'éléphants dans deux Forêts d'Etat et pose la question de savoir si l'utilisation de la faune sauvage, et particulièrement de l'éléphant (Loxodonta africana), génère des retombées économiques qui compensent l'impact négatif des dégats des éléphants sur la ressource en bois. Huit espèces communes d'arbres furent étudiées; 25% des arbres de plus de 9,5 cm de diamètre à hauteur de poitrine (dbh) échantillonnés avaient été endommagés par les éléphants ou d'autres herbivores. P. angolensis, l'une des espèces d'arbre les plus importantes économiquement, était le plus gravement affecté; 67% des arbres de moins de 34 cm dbh avaient été endommagés par les éléphants. Les résutats indiquent que l'éléphant peut causer la mortalité des arbres et que 13% des P. angolensiséchantillonnés avaient été tués par les éléphants. L'éléphant semble limiter le renouvellement parmi les classes de tailles exploitables. De simples calculs économiques suggèrent que les bénéfices dérivés de la chasse sportive à l′éléphant (US$0.35/ha/an) compensent les pertes causées aux arbres par les éléphants (U/0.15/ha/an). La valeur économique de la chasse dans les Forêts s'avère done plus élevée que la valeur du bois exploitable.
Management of Graves’ orbitopathy in Latin America: an international questionnaire study compared with Europe
Authors: Ramos Helton E. , Diehl Leandro A. , Camacho Cleber P. , Perros Petros , Graf Hans ,   for the Latin American Thyroid Society
Published: April 2008

SummaryContext  Management of Graves’ orbitopathy (GO) and dysthyroid optic neuropathy (DON) continues to be challenging. Other surveys have been successful in elucidating trends in GO management. Knowledge of current practice by members of the Latin American Thyroid Society (LATS) who manage patients with GO was targeted by distribution of a questionnaire. We compared our results with a previously reported European Thyroid Association (ETA) survey.Objectives  To determine how endocrinologists in Latin America access and treat patients with GO and compare the results with the same European survey.Results  One hundred and two responders representing endocrinologists from 10 countries participated in the survey. Most (57%) participate in a multidisciplinary setting for GO management. Access to a surgeon for orbital decompression was available only ‘within months’ according to 48·3% of responders. Despite suspected DON, 32·4% were reluctant to recommend urgent referral to an eyecare physician. Steroids were preferred as the first‐option therapy by 88·2% of responders (by intravenous route by 57·8% of these). The presence of diabetes reduced the use of steroids to 64·7% (P < 0·001) and increased the use of other immunosuppressive agents (from 1% to 9·8%, P < 0·01). Development of cushingoid features resulted in a reduction in steroid use to 40·2% (P < 0·001), with increased preference for irradiation (from 23·5% to 52·9%, P < 0·001) and nonsteroidal immunosuppressive drugs (from 1% to 10·8%, P < 0·01), along with a nonsignificant trend to higher indication of orbital surgery (from 24·5% to 34·3%).Conclusion  Some potential deficiencies in the diagnosis and management of DON and hyperthyroidism were observed in our survey, highlighting the need for improvement in specialist education and the quality of care offered to patients with GO in Latin America.
Multi‐scale patterns of human activity and the incidence of an exotic forest pathogen
Authors: Cushman J. Hall , Meentemeyer Ross K. 
Published: April 2008

Summary

Plant pathogens can have major impacts on diverse taxa and ecological systems world‐wide, and some of the most conspicuous of these are invasive non‐native species. Although many factors are known to influence the distribution and abundance of plant pathogens, the extent to which humans play a role is less well‐known but still critical for understanding the dynamics of invasive pathogens in natural systems.
One invasive pathogen of great concern world‐wide is Phytophthora ramorum, which causes Sudden Oak Death, an emerging forest disease. Here, we examined the influence of humans and a range of environmental factors on the distribution of P. ramorum at three distinct spatial scales in northern and central California.
At the local scale, P. ramorum more commonly occurred in soil on hiking trails used heavily by humans than in soil from adjacent areas off trails. These results support the hypothesis that humans dispersed the pathogen within already infected areas and into areas lacking local sources of inoculum.
At the landscape scale, using a network of 202 randomly located plots across a 275 km2 area, we found that forests on public land open to recreation exhibited higher prevalence of disease in a critical infectious host tree (bay laurel, Umbellularia californica), than forests on private lands. Infection levels were also higher in plots surrounded by large amounts of forest with warm climatic conditions and greater potential soil moisture. Although prevalence of diseased canker hosts (Quercus agrifolia, Q. kelloggii and Lithocarpus densiflora) was positively associated with dominance of bay laurel and rainy season temperatures, it was not significantly related to public access, and we hypothesize that this occurred because our study area was in the early stages of infection.
At the regional scale, the probability of disease occurrence at 165 sites distributed across the geographic range of P. ramorum in California increased significantly as human population density increased in the surrounding area. Chances of infection also increased significantly with precipitation and presence of bay laurel.
Synthesis. Our results suggest that human activity – along with temperature, moisture and host composition – is associated with increased prevalence of an influential exotic forest pathogen. These results indicate that there may be conflicts between humans and disease, and that efforts to address this issue may require aggressive management of human activity.