The influence of man-made fires on large wild herbivores in Lake Burungi area in northern Tanzania

The effect of fire on the distribution of large wild herbivores during the late dry season was studied in northern Tanzania during October 1987. All species were attracted to burnt-over areas with 1–10 cm regrowth of grass. Recently burnt areas with no regrowth and areas not burnt during the dry season were avoided.
By the end of the dry season the study area was left as a fire mosaic, with different areas burnt at different times during the dry season. Thirty two percent was unburnt. The fires were mainly man-made but for purposes other than wildlife management. Such a fire mosaic has a positive effect on the larger herbivores by supplying protein-rich food during the dry season.

Résumé

On a étudié en octobre 1987, durant la deuxième saison sèche l'effet du feu sur la distribution de grands herbivores dans le nord de la Tanzanie.
Toutes les espèces sont attirées par les surfaces brûlées où les repousses sont de 1 à 10 cm. Les surfaces sans repousses et les zones non brúéees sont évitées. A la fin de la saison sèche, la zone étudiée ressemblait à une mosaïque due au feu, avec des endroits brûlés a des moments différents durant la saison sèche. Trente-deux pour-cents n'avaient pas brûlé. La plupart des feux avaient été allumes par l'homme, mais dans d'autres buts que la gestion de la faune. Une telle mosaïque a un effet positif sur les grands herbivores car elle fournit un complément de nourriture riche en protéines au cours de la saison sèche.     

Revision of Trigonostomum Schmidt, 1852 (Platyhelminthes, Typhloplanoida, Trigonostomidae) with the description of seven new species

A morphological and taxonomic account of the genus Trigonostomum is provided. All known species are discussed and briefly re-described where necessary. Seven new species are described: T. franki from Curaçao, Florida (USA), the East African Coast and New Caledonia, T. nataschae from the French sub-Antarctic island Kerguelen, T. spinigerum from New Caledonia and T. watsoni from the Australian East Coast and New Caledonia. T. tori and T. galapagoensis , both formerly enclosed in T. setigerum , are considered new species, while T. australis also belongs to the same species group. Proxenetes denhartogi is transferred to Trigonostomum . Based on a comparison of old and new material, T. marki is synonymized with T. penicillatum , while T. prytherchi and T. divae are regarded as junior synonyms of T. lilliei ; T. intermedium and T. quadrifolium are considered synonyms of T. coronatum . Three species are considered species inquirendae : T. brunchorsti , T. piriforme and Marinellia lingulifera . Similarities and differences of the 17 valid species are discussed and summarized in an identification key.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 141 , 271–296.     

Regional and local (road verge) effects on size and fecundity in Banksia menziesii

Abstract Banksia menziesii is a tree at the mesic end (Swan Coastal Plain) of its range and a shrub at the xeric end (Eneabba Plain). Plants at the xeric end produced, on average, as many cones, set 2.3 times as many seeds and stored 8.8 times as many viable seeds in the crown, as those at the mesic end. Plants on road verges had, on average, 2.5 times larger crowns than those at least 50 m further from the road. Road edge plants produced, on average, 2.5 times as many cones, set 3.1 times as many seeds and stored 3.7 times as many viable seeds as non-edge plants. Greater fecundity at the xeric end, including the road verges, could help offset the greater incidence of adult deaths and the reduced likelihood of seedling recruitment after fire at Eneabba.     

A New Development of the Temperature-Gradient Tunnel

The temperature-gradient tunnel provides a range of constanttemperatures simultaneously within one chamber while maintainingother environmental variables at levels which adequately matchmost of the standards which are current in modern plant growthcabinets. The development described in this paper provides (1) an extensionof the temperature range down to 5 C; (2) an enlargement ofthe growing space to increase the work output and allow factorialcombinations of temperature with other environmental variables:(3) an improvement of access to the growing space; (4) an improvementof the humidification system; and (5) the introduction of controlby computer program, allowing, in particular, the provisionof controlled diurnal fluctuations of temperature. A radicallynew system of steam injection provides both heating and humidification,if required, and also satisfies the criteria for improved access. A specimen experiment involving two levels of light intensityand five constant day-temperatures was conducted in the newtunnel. Data are presented for two of the six contrasted specieswhich were grown simultaneously. The response to the uniformlydebilitating effects of severe shade seemed to be dependentupon the species' partitioning ability with respect to the productionof leaf weight and area. This was linked, in turn, to innategrowth potential. The expression of partitioning ability wassubstantially reduced by departures from optimal temperatureregimes. Controlled environment, temperature, computer control, temperature optima, screening, growth analysis, shade response     

The ecology and conservation status of Madagascar's endemic freshwater crayfish (Parastacidae; Astacoides)

1. Freshwater crayfish of the genus Astacoides are endemic to the highlands of eastern Madagascar. Very little is known about their ecology and how this affects their vulnerability to threats. Working in the Fianarantsoa forest corridor, we used a combination of ecological research (>29 000 crayfish caught and released) and interviews (>130 interviews in 38 villages) to investigate the ecology and status of four of the seven described species. 2. Astacoides species studied showed very slow growth, with growth rates of Astacoides granulimanus and Astacoides crosnieri among the slowest known in any species of crayfish. We found individuals of all three species for which we had growth data which we estimate at more than 20‐years old. The size at which females became ovigerous varied among species. Astacoides betsileoensis withheld reproduction until a large size (only 30% of females were gravid at 60‐mm carapace length, compared with 90% for A. granulimanus). This is likely to make A. betsileoensis particularly vulnerable to overexploitation and we found that only 10% of individuals measured in a market (n = 909) would have reproduced before being caught compared with 35% of the more common A. granulimanus (n = 30 561). 3. Habitat loss is a serious threat to the genus; even A. granulimanus, the most widespread species, was only found in rivers or streams flanked by natural vegetation. Astacoides caldwelli, the rarest species in this study, was found only at low altitudes (<800 m) in rivers draining forested catchments. Habitat loss is particularly rapid in low elevation forest. A. crosnieri was restricted to swampy land that is rapidly being converted to rice fields. Introduced Asian snakehead fish (Channa maculata) may pose a hitherto unrecognised threat to some species, particularly A. betsileoensis. 4. Madagascar's freshwater habitats have great significance for global biodiversity yet conservation effort, as in much of the world, has focused on terrestrial ecosystems. Until recently almost nothing was known about the ecology of Astacoides crayfish, a diverse and economically important genus. Here, we show that members of the genus vary markedly in their reproductive biology, growth rates, habitat requirements and the threats they face. We suggest that habitat loss is an urgent threat, especially to A. caldwelli and A. crosnieri, while overharvesting is probably the most immediate threat to the larger A. betsileoensis. We call for more attention to be paid to Madagascar's exceptional, yet understudied, freshwater biodiversity.     

Long‐term effect of forest fragmentation on the Amazonian gekkonid lizards,Coleodactylus amazonicus and Gonatodes humeralis

Abstract We investigated the effect of forest fragmentation on the abundance of the gekkonid lizards Coleodactylus amazonicus and Gonatodes humeralis in fragments associated with Amazonian savanna near Alter do Chão, Pará, Brazil. These fragments have been isolated for at least 150 years and probably more. Abundance of lizards, tree density and food availability were estimated in 1000‐m transects in eight sites in continuous forest and 21 forest fragments, ranging in size from 3.6 to 360 ha and distant from ～150–10 000 m from continuous forests. Coleodactylus amazonicus was at least an order of magnitude more adundant than G. humeralis in continuous forest, and both species were negatively affected by fragmentation. Coleodactylus amazonicus was encountered only in continuous forest, the largest fragment, and one fragment adjacent to continuous forest. Gonatodes humeralis occurred in the majority of fragments, but was more common in continuous forest, and occurred in lower densities in fragments more distant from continous forest. The species with lowest recorded densities in continuous forest was the most resistant to fragmentation, contrary to what would be predicted from neutral models, such as island‐biogeography theory, possibly because other factors are more important than initial population size in long‐term fragmented landscapes.     

The roles of dispersal limitation and environmental conditions in controlling caddisfly (Trichoptera) assemblages

1. Many recent studies have quantified the relative importance of environmental variables and dispersal limitations in shaping the structure of stream communities. However, the relative importance of these factors at different spatial extents has been seldom evaluated. 2. We analysed the distribution of caddisfly species in 89 Amazonian streams in relation to stream characteristics and spatial variables representing overland dispersal routes. The streams occur in three regions that differ in spatial extent and environmental characteristics. We analysed the data using partial redundancy analysis with two predictor data sets, one environmental and one spatial, to evaluate the variation in assemblage composition. We also separated caddisflies into ‘good’ and ‘poor’ dispersers to evaluate possible differences in the responses of these two groups. 3. The environmental component explained a higher proportion of variance in assemblage composition than did the spatial component. Spatial effects were evident only when data from all three regions were analysed together, although the exclusive spatial fraction was quite low. Good dispersers responded similarly to the community as a whole, while poor dispersers were related to environmental variables only in one region and also were not related to spatial variables. 4. Caddisflies were most affected by environmental factors. The large environmental effect and small spatial effect are in accord with the use of these stream insects as good indicators of site properties and disturbances in monitoring programmes.