A floristic and ecological study of epiphytic bryophytes and lichens on standing mature Eperua trees was carried out in dry evergreen (walaba) forest in Guyana, South America. The trees were sampled from their base up to the highest canopy twigs, using mountaineering techniques. Clear vertical distribution patterns of epiphytic species and life-forms were found. Many species, particularly foliose lichens, appear to be preferential or exclusive to either Eperua grandiflora or E. falcata (Leguminosae), which are the dominant trees in the walaba forest. Special attention is given to the species-rich epiphyte vegetation on the upper canopy twigs, which include two categories of species: the sun epiphytes and the pioneers (facultative epiphylls).

The density of arboreal arthropods in a dry evergreen forest in Northeastern Thailand was investigated by the insecticide fogging (knockdown) method. Arthropod densities of 256.4 and 140.4 m-2 were recorded in the dry season and 195.2 and 123.1 m-2 in the rainy season. The main orders were Collembola, Thysanoptera, Hymenoptera (mainly Formicidae) and Hemiptera. Distinct differences were not found in the arthropod faunal structure and density between the dry and rainy seasons. However, this fauna is completely eliminated by the clearing and burning of forest for shifting cultivation.

The results of an experiment investigating the rate of arthropod fall after application of insecticide are presented and problems concerning the efficiency of the estimation methods used in this study are discussed.

Throughout the latter part of the dry season (January-April) of 1985 and 1986, we studied the demography of mature adults in a small population of Argia chelata along a stream at Monteverde, Costa Rica. Males defended sunlit spots along the stream between 1030 h and 1400 h central standard time each day and females visiting these sunlit spots were soon mated. By individually marking all mature adults in the population we found that there was no significant difference between the sexes in daily survival rates (0.85 for males and 0.86 for females). Lifetime mating success was positively correlated with longevitiy in both males and females but the ability of males to obtain a mate appeared to be independent of age.

Although the sex ratio at emergence was 1:1, that of mature adults at the stream was strongly male-biased (87% male), perhaps as a result of a longer or more risky prereproductive period in females related to the costs of egg formation. We argue that the strongly male-biased sex ratio has important effects on the mating system of this species in that the male contact-guards the female for the entire oviposition period each day. Although this limits each male to mating with one female per day, it probably ensures that the male will fertilize most of the eggs laid by the female that day.

Patterns of edge-related environmental changes and plant water relations were investigated in the isolated forest reserves of the INPA-WWF Minimum Critical Size of Eco-systems project near Manaus, Brazil early in the wet season.

Air temperature was elevated and humidity reduced in the understorey within 40 m of the reserve margins, and air temperature and vapour pressure deficit (VPD) were higher in the interiors of 1 ha reserves than in 100 ha reserves. There was increased photosynthetically active radiation penetration to understorey level up to 40 m into a 100 ha reserve.

Soil moisture was depleted in the outer 20 m of both small and large reserves, and surface soil water potentials fell below – 1.5 MPa at the margin of a 1 ha reserve.

Studies of leaf relative water contents (RWCs) in understorey shrubs revealed no appreciable saturation deficits, though RWCs were sometimes lower at the reserve margins. Studies of leaf conductances revealed no evidence of restriction of water loss in these plants, and conductances of plants near the edges were significantly higher and higher for longer.

The implications of these results for reserve design and for local and regional water budgets, as well as the possible role of water stress in increased tree mortality in isolated reserves are discussed.

Padrōes de mudanças ambientais e hídricos de plantas relacionados a bordas de matas isoladas foram investigadas no início da estação seca nas reservas de floresta do Projeto Dinâmica Biológica de Fragmentos Florestais do INPA-WWF, proximo de Manaus, Brasil.

No sub-bosque, até 40 m da borda da mata, a temperatura ambiental estava elevada e a umidade reduzida, e a temperatura do ar e o DPV estavam maiores nas reservas de 1 ha do que nas reservas de 100 ha. A penetração de radiaçao fotosintéticamente ativa no sub-bosque estava aumentada até 40 m da borda em reservas de 100 ha.

A umidade do solo baixou consideravelmente nos 20 m periféricos de reservas grandes a pequenas, e o potencial hídrico na superficie do solo baixou para menos de −1.5 MPa na margem de uma reserva de 1 ha.

Estudos do teor relativo de água (TRA) em folhas de arbustos de sub-bosque nӑo revelaram deficits de saturação apreciaveis apesar de que TRAs foram menores nas bordas das reservas. Estudos da conductancia foliar não revelaram evidência de restrições de perdas hídricas nessas plantas, e as conductancias de plantas próximas a bordas foram significativamente maiores durante um período mais longo.

As impliçõtes desses resultados para o planejamento de reservas e para o balanço hídrico local e regional, assim como as possiveis funçoes de ‘stress’ hídrico na alta mortalidade de árvores em reservas isoladas são discutidas.

The chemical composition of bulk precipitation was studied for a period totalling 18 months between 1975 and 1978 at a high rainfall site in central Java. The following elements were determined: calcium, magnesium, sodium, potassium, nitrate-nitrogen, chlorine, phosphate-phosphorus, silicon, aluminium, iron, manganese and pH. Ammoniacal nitrogen, total nitrogen and sulphate-sulphur were determined, during four weeks in May 1983. Concentrations of all elements rose dramatically during the exceptionally severe dry season of 1977 which may have caused accession rates for some nutrients to be overestimated (i.e. compared to a year with ‘normal’ rainfall) by about 10%. Results are explained in terms of prevailing wind directions and proximity to, or absence of, particular solute sources, such as the ocean, volcanoes or eroding lands.

Most elements exhibited intermediate concentrations when compared with data for other humid tropical locations; sodium and perhaps nitrogen were on the low side and pH on the high side of the spectrum. Annual accession rates at the study site were considerable by pan-tropical standards, mainly as a result of high rainfall totals. Comparing accession rates with 25-year-average nutrient immobilization rates in stemwood of local plantations of Pinus merkusii Jungh. et de Vr. and Agathis dammara Warb. showed atmospheric inputs of magnesium and potassium to be high enough (theoretically) to account for losses of these elements in stemwood removal. Corresponding figures for nitrogen were 90% (Pinus) and 50% (Agathis), and for calcium and phosphorus 60 and 40% respectively (both species).

A survey of small mammals was made in a tree plantation in Sabah, East Malaysia. Transects within pure plantings of Eucalyptus deglupta, Gmelina arborea, Albizia falcataria, and A. falcataria/Theobroma cacao were compared with a similar transect laid through seven-year-old logged forest near the plantation. A total of 16 small mammal species were trapped, with 11 found in the logged forest area, and 15 in the plantation. Values for the Shannon-Wiener Diversity Index (H') and for biomass were highest in logged forest, which also showed a low (<45%) Percent Similarity when compared with any of the plantation areas. Highest diversity and biomass values within the plantation were found in Albizia falcataria plantings, while the lowest were found in A. falcataria underplanted with Theobroma cacao. All plantation areas were dominated by Maxomys whiteheads, whereas A. falcataria plantings had the highest numbers of Tupaia glis and Tupaia tana.

The study shows that although tropical plantations of exotic tree species can support a large number of species of scansorial small mammals, overall diversity and species biomass per hectare is much lower than that found in logged forest.

Brachystegia-Julbernardia (miombo) woodlands inside and outside the Sengwa Wildlife Research Area, Zimbabwe, show major differences in structure, biomass and species composition. The woodlands inside the research area have a lower stem area, tree density and biomass than those outside it. The shrubs inside the research area occur at a higher density than they do outside it, but the biomasses of shrubs in the two woodlands are similar. The woodlands inside the research area are affected by elephants and fire, whereas those outside it are affected mainly by fire. It is postulated that the policy of maintaining the elephant population at 250 in the research area is having a beneficial effect and, provided elephants and fire are kept in check, the woodlands inside the research area will eventually recover.

Litterfall was recorded for one year in Acacia albida woodland in Mana Pools National Park, Zimbabwe. Leaves fell throughout the year, but leaf-fall rate peaked in the wet season. Litterfall was 1.5 t ha−1 year−1, comprising 50% leaves, 20% fruits, 17% ‘fine’ material (mainly frass), 4% flowers and 9% wood and bark. Net above ground production by A. albida trees was 1.7 t ha−1 year−1, including leaf production of 1.0 t ha−1 year−1, twig production of 0.3 t ha-1 year−1 and fruit production of 0.3 t ha−1 year−1. Insects consumed about 26% of leaf production. Net above ground herbaceous production was estimated from rainfall data using regression equations: it was 6.8 t ha−1 year−1 for annual grasses and 2.8 t ha−1 year−1 for forbs. Net above ground primary production in A. albida woodland was 11.3 t ha−1 year−1. The seasonal variations in the nitrogen, phosphorus, potassium, magnesium and calcium concentrations of different A. albida litter components were recorded. The estimated falls of N, P, K, Ca and Mg were 31.1, 2.1, 9.8, 15.0 and 3.4 kg ha−1 year−1 respectively.