A method of assessing rain forest structure by ranking relative abundance of 41 habitat variables was used to describe habitat differences among six trapping sites (324 subsites). Variables included aspects of all vegetation layers but concentrated on those considered to be important to small mammal distribution. Ordination and classification methods resulted in similar analyses of the data. Differences in habitat structure were primarily related to the moisture conditions of the trapping sites and secondarily to their successional age (regenerating versus primary forest). The most important habitat variables for differentiating between sites were LITTER, CLEARING, SOILS, PIG DAMAGE, FLOODING, FAN PALM, EMERGENTS, CANOPY SURFACE and SEEDLINGS. Habitat structure also varied within sites with some suggestion of small-scale patterning.

Small mammal captures were more likely in drier sites and subsites, but there was no difference in trap success between regenerating sites and primary forest sites. Greater numbers of species were captured in sites containing a variety of habitats, a discrete layering of vegetation and an extensive understorey. Small mammal captures were positively associated with five habitat variables (EMERGENTS, LITTER, ROTTING LOGS, SEEDLINGS, ROUGH BARK) and negatively associated with five others (LAYERS, BERTAM, SEDGES, PIG DAMAGE, FLOODING). The destruction caused by pigs is thought to be a major factor since it reduces litter and food availability over wide areas. Leopoldamys sabanus was the most abundant small mammal captured (40/68 individuals) and trap success differences among sites (0.4–1.9%) reflect its preference for higher, well-drained habitats.

The study demonstrates the usefulness of a simple method of ranking habitat features according to importance/abundance thus eliminating the all but impossible task of direct measurements in this complex system. This simple method of habitat description provides a basis for studying variables influencing faunal distribution patterns.

Earth mounds are important determinants of vegetation pattern in savannas, acting as foci for establishment of woody plants. In the Kenya highlands, mounds formerly attributed to termites have recently been found to be Mima mounds produced by rhizomyid mole rats. We investigated Mima mounds on black cotton soils near Kenyatta International Airport and on brown clay soils between Nairobi and Thika. At Kenyatta Airport, mounds had loamier, more granular soils than intermounds, and contained small rocks that mole rats can move. At the site between Nairobi and Thika, mound soils were more friable, higher in pH, and lower in carbon than intermound soils. Data from this and other studies indicate that Mima mound soils are more favourable for plant growth than those of true termite mounds. Mound vegetation exhibited lower coverage of grasses and greater coverage by forbs, shrubs, and bare ground, a pattern indicative of intense grazing and soil disturbance. Acacias, absent from most mounds, were abundant in the zone bordering the mound. This pattern may reflect the favourability of mound soils, combined with the effects of high grazing pressure. Future studies of savanna vegetation should distinguish between termite mounds and Mima mounds.

Chemical baits corresponding to natural orchid fragrance chemicals were used to attract and sample male orchid bees in terra firme and flood plain forest sites on the Tambo-pata Reserve in south-eastern Perú. The study was conducted monthly for two years. A total of 38 species of bees was collected at these chemical baits, and although most species were collected from both habitats, 11 species were significantly more common in one habitat than the other. There was considerable variation in the number and types of chemicals to which each of the orchid bee species was attracted.

Two cycles of seasonal abundance occurred annually in the number of orchid bee individuals and species collected at the chemical baits. A major peak occurred a month following onset of the wet season, and a minor peak occurred during the dry season. Species body size was related to seasonal activity, but additional factors such as flowering phenology and nest parasites were also probably involved.

The number of orchid bee species found on the Tambopata Reserve was similar to the number found in forest sites of eastern and central Brazil, Costa Rica, and Panamá. This homogeneity in species richness is in marked contrast to other insect groups such as Odonata, Lepi-doptera, Asilidae (Diptera), Tabanidae (Diptera), and Cicindelidae (Coleoptera), for which the species numbers recorded on the Tambopata Reserve are the highest for any similar sized area in the world.

An investigation of seasonal rates of litter production in a mixed forest, Hong Kong Island, was undertaken from October 1982 to January 1984. Total annual litterfall amounted to 1218.96 g m−2 yr−1, comprising 68.6% leaves, 18.9% woody material, and 12.5% fruits, seeds and insect frass. 398.70 g m−2 of litter was recorded immediately after a severe typhoon (9 September 1983). Rates of leaf-fall and organic debris production were correlated with prevailing temperature and rainfall. Leaf-fall peaked in January 1983, March to July 1983, and in September 1983 after the typhoon, while large amounts of insect faeces were collected in May and June. Woody litter production rates were correlated with temperature and rainfall recorded in previous months. Woody litterfall exhibited no obvious periodicity but was slightly increased during March and April. The seasonal distribution of litterfall is discussed in relation to climatic factors and habitat nutrient economy.

A land use survey involving land typing and vegetation classification was conducted within the Luuq District Refugee Area (200,000 ha) in south-western Somalia. Average rainfall and annual temperature of the area are 310 mm and 30.5° C. The area is composed of limestone and basalt uplands, gypsiferous and alluvial interplains, and ancient and recent alluvial terraces of the Juba River.

Land types were identified by aerial photo survey and ground observation and mapped on a 1:100,000 scale LandSat Satellite (colour) Image. Soil types were classified according to the method used by the US Department of Agriculture, Soil Conservation Service. Vegetation was sampled according to the Braun-Blanquet approach in 52 releves located within previously mapped land types, and analysed using the traditional phytosociological methods and the DECORANA and TWINSPAN computer programs. The results of these methods are compatible with one another. Most community types identify distinct land types: basalt and limestone uplands, gypsum and alluvial interplains, and depressions and gentle rises of the Juba River terrace.

Commiphora and Acacia species dominate the open thorny bushland. They are mostly medium-sized shrubs and trees, 1 to 4 m in height. There is little herbaceous ground cover except in depressions and drainageways. Total shrub and tree cover averages 34%. Due to the large influx of refugees, there has been excessive cutting for fuelwood and construction material and notable bushland converted to cropland. Degradation of the vegetation and soils is prominent and is most evident on the upper and lower terraces of the Juba River.