The hoary-throated spinetail and Rio Branco antbird are two bird species endemic to the Rio Branco drainage of Brazil and Guyana, currently listed as Critically Endangered on the IUCN Red List. Previous assessments of both species’ global populations focused on the Brazilian state of Roraima but did not include most of its border with Guyana, where significant areas of suitable habitat remain along the Ireng (Maú) and Takutu (Tacutu) Rivers. In July and August 2021, we conducted a survey to determine the extent of each species’ geographic range along the two rivers, and to estimate population sizes. We used playback surveys along 219 km of river to ascertain each species’ distribution and intensively sampled three forest blocks to determine densities. Both species were locally abundant on both sides of the international border. Rio Branco antbird occurred over a greater geographic range than hoary-throated spinetail, particularly along the Takutu River, but was confined to a narrower zone along the river edges. Both species appear to have retreated from habitat along the Ireng River that was occupied in the past, possibly due to habitat degradation from increasingly frequent fires. Nevertheless, our minimum estimates of 1147 antbirds and 851 spinetails in the study area represent, respectively, 7.5% and 17.8 % increases over current estimates of global population sizes, and indicate that the Guyana-Brazil border region may become a critical stronghold for both species if effective conservation measures are implemented. We propose establishment of a Key Biodiversity Area encompassing the core of both species’ distributions along the border; extensive follow-up work including stakeholder engagement to explore possibilities for habitat management and protection; and further field study to increase general ecological knowledge of these two bird species.

Describing and understanding growth patterns in tropical forests is crucial to assessing their role in carbon balance. Growth and vital rates of a protected gallery forest in central Brazil were estimated, based on six measurement intervals between 1985 and 2009. The sample consisted of all stems ≥ 10 cm diameter at breast height measured in 151 permanent plots (10 × 20 m), distributed in 10 transects perpendicular to the watercourse and 100 m apart from each other. Statistical significance of changes in density, basal area, growth and vital rates were tested using Wilcoxon signed-rank tests. Vital rates oscillated during the study period. Growth, recruitment and turnover rates fluctuated, but had a net decrease over the whole study period, whereas mortality seemed to be affected by a high disturbance event during the 1994–1999 period. The oscillatory behaviour of growth suggests that the forest is pulsating around a stable state (dynamic equilibrium). Nonetheless, persistence of decelerating growth trends may force the site's carrying capacity to a lower density or biomass state.

The correlation between the biomass of forest primates and a chemical index of the average nutritional quality of leaves in tropical forests has been repeatedly documented since 1990. We tested the role played by protein : fibre on lemur biomass in a gallery forest in southern Madagascar. Plant species abundance was determined based on transect censuses. We calculated an average ratio of protein-to-fibre in leaves and an abundance-weighted ratio, i.e. the mean weighted by the basal area of tree species, to be compared with the figures available for other forest ecosystems in Madagascar and a number of anthropoid habitats. Lemur densities were evaluated through compilation of previous studies made from prior to 1975 and up until 2011 based on strip censuses and/or identification of all groups supplemented with new censuses. A high mean ratio of protein to fibre (> 0.4) supports high folivore biomass at 390 kg km−2 (reaching 630 kg km−2 in the closed-canopy forest area) compared with primate communities in other Malagasy forests (protein : fibre: < 0.5; folivore biomass: < 440 kg km−2), as predicted. However, the data corroborate the finding that the total biomass of lemur communities as well as the biomass of folivorous lemur species are low compared with those of African and Asian primate communities for a given protein : fibre ratio. Tree diversity and leaf production do not consistently explain this pattern. In contrast, the extinction of large folivorous lemurs during the past two millennia presumably allowed too little time for smaller-sized species to evolve equally effective morphological and physiological specializations for processing a large range of fibrous foods.

Plant populations can respond to temporal environmental heterogeneity caused by natural disturbances, such as herbivory. Palm individuals of several species are preyed upon by mammals, but the effects of such herbivory events on population dynamics remain poorly known. To evaluate the effects of environmental stochasticity on a Geonoma schottiana (Arecaceae) population, we surveyed annually 40 permanent 20 × 10-m plots in a riparian tropical forest over 5 y (2000–2004) and results were analysed using matrix models. The population growth rate (λ) was in equilibrium during the study period and only one bad year was identified (2002–2003), which had a higher mortality of juvenile individuals due to herbivory. Additionally, the bad year had a higher mortality of reproductive individuals than the other periods. The stasis matrix elements of the later life stages were the vital rates with highest elasticities. The mortality of juvenile and reproductive individuals had a negative contribution to λ in the bad year. Conversely, the growth of infant and juvenile individuals and the clonal growth of juveniles were the vital rates with highest contribution to stability maintenance of λ in the bad year in a life-table response experiment. The palm population had a high individual density, high proportion of the initial life stages, clonal growth, high fertility, abundant seed bank and high seedling recruitment. Despite these traits, if stochastic herbivory events occur frequently over a long period of time, the population will have a negative growth rate and the probability of local extinction will be very high.

Diameter increments, recruitment and mortality were studied over a six-year period in a 3.02 ha sample in an area of 64 ha of undisturbed gallery forest alongside the Gama stream. The study site is located in Fazenda Água Limpa in Brasília, Federal District, Brazil. Trees ≥ 31 cm gbh (10 cm dbh) were measured every three years from 1985 in 151 (10 m × 20 m) permanent plots in Gama forest.

The mean annual diameter increment for trees ≥ 10 cm dbh was 0.25 cm y-1. Variability was high with coefficients of variation c. 100% or more. Light-demanding and large upper storey species tended to grow faster than shade-tolerant and lower storey species. Mean increments for the community increased with increasing diameter classes.

The mean annual mortality rate for the community was 3.5% y−1 while the recruitment was 2.7%. The community was dynamic with 86% of all species either suffering mortality or gaining recruits or both during the six years. The net difference between recruitment and mortality was zero for 55 species. The recruitment compensated for the mortality of most of the abundant species.

A field experiment was conducted to test the effects of simulated folivory on leaf production, plant growth rate and mortality of small individuals of Metrodorea pubescens in an evergreen gallery forest in central Brazil. Although complete defoliation decreased annual growth rate, both in absolute and relative values, it also stimulated leaf production. Mortality was observed only in individuals in the smallest size class, but was not statistically related to percentage defoliation. Recovery of completely defoliated individuals was rapid and after one year over 70% of their initial number of leaves was present. It is probable that insect folivory is not a direct cause of mortality of juveniles of this species.

Community structure, macrohabitat selection, and patterns of species co-occurrence were examined during a 14-month study of small mammals in the Cerrado Province of central Brazil. Data were collected from mark-recapture grids in brejo and gallery forest, and from live-trapping and specimen collection in all habitat types within cerrado (campo limpo, campo sujo, cerrado [s.s.], cerradão, brejo, valley-side wet campo, and gallery forest). Gallery forest supported the highest species richness, most complex vertical distribution of species, highest level of trophic diversity, and highest macroniche diversity. Degree of habitat selection varied widely. All habitat types supported both rodents and marsupials, although marsupials tended to be much less common in the grasslands (campos) than in woodlands (cerrado) and forests (cerradão, gallery forest). Some species, such as Didelphis albiventris, occurred in all habitat types, while others were much more restricted. Oryzomys bicolor, for example, ocur-red only in gallery forest. No habitat type had a completely distinct fauna: overlap in species composition always occurred with at least one other habitat type. Because of the great variability of habitats, and the fact that subsets of the mammal fauna were frequently habitat specific, the overall species richness of any portion of mixed cerrado vegetation is remarkably high.

Gallery and floodplain forests in monsoonal northern Australia are mostly sclerophyllous and dominated by five closely related species of Melaleuca (Myrtaceae) amongst which niche differentiation is unclear. We present a floristic and environmental analysis of ‘the flooded forest’ using data from 340 plots distributed across 450 000 km2 of the Top End of the Northern Territory. Melaleuca argentea was confined to streams and occurred on sandier substrates, whereas M. cajuputi mostly occurred in the near-coastal lowlands on clay soils. The greater basal area of M. cajuputi suggests an association with productive sites. Melaleuca dealbata, M. viridiflora and M. leucadendra occurred on a wide range of soils. More deeply floodprone sites were occupied by M. argentea and M. leucadendra along streams and by M. leucadendra and M. cajuputi on floodplains and in swamps. A general deficiency but occasional abundance of Melaleuca seedlings suggests that regeneration is episodic. Seedlings were more frequent in recently burnt areas and especially where fires had been severe. We propose that Melaleuca forests occur where disturbance by fire and/or floodwater is too great for rain forest to persist, rendering them the wetland analogue to the eucalypts that dominate well-drained portions of the north Australian environment.

ABSTRACT. Factors contributing to the resistance of gallery forests in savannas to the entry of fire were investigated using field observations and manipulation experiments. Mass of savanna fuels did not decrease close to forest boundaries, and in some instances increased, while savanna fuels adjacent to forests were moister than in the savanna beyond for only 1 d after rainfall. A fuel drying experiment conducted in both forest and savanna microclimates indicated that both fuel type and microclimate contributed to the resistance of forests to fire entry, although the former played a larger role. While savanna fuels in a savanna microclimate became ignitable in c. 1 d after rain, forest fuels in a forest microclimate required 4 wk to achieve ignitability. A further experiment juxtaposing forest fuels to burning savanna indicated that fire entry into forests was faciliated by deep root mats and the presence of a superficial litter layer, both of which become attenuated at the forest/savanna contact. It is concluded that fuels in these forests can reach an ignitable state late in the dry season, but that frequent fire entry is probably precluded by the tendency of savanna fires to occur earlier in the dry season and by discontinuities in fuels at the savanna/forest contact.

RESUMEN. Se investigaron los factores que contribuyen a la resistencia de la entrada del fuego a los bosques en galería de las savanas mediante observaciones de campo y experimentos de manipulación. La masa de los combustibles de la savana no decrecieron cerca de los bordes del bosque; por el contrario, en algunos casos se incrementaron, mientras que los combustibles de la savana cercanos al bosque eran mas húmedos que en la savana restante, solamente por un día despues de un evento de lluvia. Un experimento de secado de combustible, que fue conducido en los microclimas de bosque y de savana, indica que tanto el tipo de combustible como el microclima contribuyen a la resistencia de los bosques a la entrada del fuego, aunque el primer factor tuvo un papel de mayor importancia. Mientras que los combustibles de la savana en el microclima de la savana se volvieron ‘encendibles’ cerca de un día despues de lluvia, los combustibles del bosque dentro del microlima del bosque tomaron cuatro semanas para llegar a dicho estado. Un experimento que sobrepuso combustibles del bosque a la savana ardiente indicó que la entrada del fuego a los bosques se facilitó por la presencia de mantillos orgánicos profundos y de una capa superficial de hojarasca, presencia que se ve atenuada en la zona de contacto bosque/savana. Se concluye que los combustibles en estos bosques pueden alcanzar un estado de ignición tarde en la estación de sequía, pero que la entrada frecuente del fuego es probablemente evitada por la tendencia que tienen los fuegos de savana a presentarse temprano en la estación seca y por las discontinuidades de combustibles en la zona de contacto savana/bosque.

Phyllostomide bats are the most important consumers of Piper fruits in the Neotropics (Heithaus et al. 1975) and, in particular, Carollia perspicillata and Glossophaga soricina are the species which demonstrate distinct preferences for these fruits (Charles-Dominique 1991, Fleming 1981, Fleming et al. 1977, Marinho-Filho 1991, Palmeirim el al. 1989). This is also true of Piper arboreum Aubl. (Piperaceae) in the gallery forests of Central Brazil (Bizerril & Raw 1997).

Siphoneugena Berg (Myrtaceae, Myrteae) is a small eugenioid genus with eight species ranging from Puerto Rico to Northern Argentina with the centre of diversity in Southeastern Brazil. Keys to the species and varieties are provided, as well as synonyms, descriptions, illustrations and a map of geographical occurrence. Two new taxa are described from Brazil: Siphoneugena guilfoyleiana C. Proença, the only species to occur in sandy maritime vegetation on the Ilha do Cardoso, state of São Paulo and S. densiflora Berg var. cipoensis C. Proença, an endemic of the Serra do Cipó mountain range in the state of Minas Gerais. A new combination S. dussii (Krug & Urban) C. Proença based on Marlierea dussii, is made for a species that grows in Venezuela, Guyana, Surinam and the West Indies. This study confirms current opinions as to the low taxonomic value of open versus closed calyces in establishing natural genera within the Myrtaceae.

A study of the resting site preferences of Glossina palpalis gambiensis in an area of a gallery forest in the Northern Guinea Savanna of Mali, infested exclusively by G. p. gambiensis was conducted in February, 1980 (hot dry season). Five site-types were compared: fallen logs, boles, undergrowth, tree canopies and branches. Distribution of resting flies was as follows: fallen logs (55.62%), boles (35.24%), undergrowth (8.4%), tree canopies (0.61%) and branches (0.00%). Most of the flies were collected during the periods 06.00–09.00 (37.47%) and 09.00–12.00 hr (46.5%). On boles, 86.06% of flies were found below 1.0 m and no flies were collected above 2.0 m. These results are compared to those obtained during simultaneous studies on the resting site preferences of G. p. gambiensis in an area along the same gallery forest, with mixed G. p. gambiensis and G. morsitans submorsitans infestation. Possible reasons for the differences observed are discussed.

Resting site preferences of the tsetse Glossina morsitans submorsitans Newstead were studied in a savanna woodland and gallery forest in the Northern Guinea Savanna of Mali. Five site-types [boles, fallen logs, undergrowth (‘bushes’), branches and tree canopies] were observed. Flies alighting to rest on these site-types were trapped on tanglefoot. Observations were made in the warm rainy, warm dry and hot dry seasons.

Boles were dominant as the preferred resting sites in the savanna woodland in all seasons; fallen logs were the next preferred site-type, while few flies were collected from the undergrowth, branches and tree canopies. Approximately 90% of flies on boles were collected below 1.0 m and none were found above 2.5 m.

During the hot dry season in the gallery forest, the undergrowth was the most preferred site-type; unshaded undergrowth accounted for approximately 98% of all flies on the undergrowth. Fallen logs and boles were the next preferred site-types; branches and tree canopies recorded very few flies. Probable reasons for the results obtained and the importance of these results in tsetse control operations are discussed.

Studies on the resting site preferences of the tsetse, Glossina palpalis gambiensis Vanderplank, were conducted in a gallery forest in the Northern Guinea Savanna in Mali. Tanglefoot was used to trap flies alighting to rest on the various site-types investigated. Five site-types were observed: boles, fallen logs, undergrowth (‘bush’), branches and tree canopies. Observations were made in the warm rainy, warm dry and hot dry seasons.

Distribution of resting flies on site-types was significantly heterogenous in each of the seasons. More than 80% of flies collected in each of the three seasons were found on fallen logs. Generally, there was no significant difference in numbers found on the top or side of fallen logs. Boles were the next best preferred site-type. Approximately 90% of flies on boles were collected below 1.0 m and none was found above 2.0 m. Few flies were collected from the undergrowth (bushes), tree canopies and branches. Similarities and differences between results obtained from the present study with those of other workers are discussed. The importance of the results in ground insecticide control operation against this species is noted.