Germination and seedling resprouting capacity of the very large-seeded tree species Prioria copaifera Griseb. (Fabaceae) was studied in the seasonally moist forest of Barro Colorado Island, Panamá. Seeds with 60% of their cotyledonary mass removed did not suffer a reduced probability of germination compared to unmanipulated seeds and seeds infested with up to eight insect larvae germinated as well as uninfested seeds. Unmanipulated seeds were able to consecutively produce up to four functional resprout shoots after excision of the initial, and subsequent, fully expanded shoots. Even seeds with up to 60% of their reserves removed showed some capacity to resprout. Less than 10% of seeds we encountered in the field 2 mo after the end of the fruiting season were in a viable state, with the majority (55%) of mortality attributable to insect or pathogen damage. Of the 46 seeds that were viable, 30% had suffered partial removal of seed reserves similar to our manipulation treatments. These results indicate that P. copaifera seeds are capable of tolerating severe seed and shoot damage. The selective advantage conferred by damage tolerance may in part have contributed to the evolution of large seed size in this species.

Nests of a fungus-growing termite Macrotermes jeanneli discharge all their metabolic gases through a single outlet to the atmosphere. This made it possible to measure the production of metabolic gases, and the rates of water loss, for intact nests in the field. Rates of production of carbon dioxide and methane from isolated nest components (different termite castes and intact fungus combs) were measured. Using previously published nest population data and fungus comb weights in relation to nest size, the expected gas production rates for intact nests were calculated. These estimates were compared with direct observations of the gaseous outflow from intact nests. The rates were in reasonable agreement, but some nests emitted excess carbon dioxide, probably produced by respiration of tree roots and non-termite soil organisms. Large nests may have a total gas outflow of 100,000 to 400,000 1 d–1 including 800 to 1500 1 d–1 of CO2 and 0.5 to 1.3 1 d–1 of CH4. Nests lose water at the rate of up, to 13 1 d–1 gross, but allowing for ambient humidity the net water loss was up to about 5 1 d–1. Some of this is metabolic water, but the larger proportion comes from the soil. Area-based estimates of gas production were made for this and two other species of Macrotermes, but they are not accurate because the field distribution and mound density are not adequately known.

The demographic history of a flower-cohort of the tropical tree Dicymbe altsonii (Caesalpiniaceae) was studied by collecting litter from flowers, fruits and seeds, and by monitoring seedling survival. Flower production was estimated at 137 to 172 m−2 in a plot of 1 ha. Four percent of the flowers yielded a pod, which contained an average of 2.0 seeds. Post-dispersal mortality over 3 mo was 39% of the initial number of dispersed seeds. Most flowers and fruits were aborted. Insect and vertebrate predation in the tree and on the ground was very low. Reproductive litter production of this species was estimated to be equal to leaf litter production. The amount of phosphorus lost in litter from fruits and flowers was much larger than in leaf litter. This implies that the impact of the biennial flowering events on the nutrient dynamics of the trees and of the ecosystem may be large. It is argued that the reproductive cycle and the pre-dispersal demography of Dicymbe seem to be determined by a scarcity of nutrient resources, and possibly by pollinator limitation.

The abundance and diversity of soil macrofauna were assessed in a range of vegetation types in northern Botswana. Hand-sorting of soil was used to extract all fauna greater than 2 mm body length from sandy soils in both the dry season (June) and towards the end of the single rainy season (February). Abundance varied significantly between samples from within a sampling location, within a vegetation type and occasionally between seasons. Greater densities were found in wet season samples from locations within closed canopy woodland except where permanent water was a significant feature of the habitat. Overall abundance was comparable to published estimates from more moist tropical and temperate habitats suggesting an important role for soil macrofauna in semi-arid systems. Ordinal level diversity also varied significantly within vegetation types and with season.

Damage to Hawaiian Acacia koa forest by Hurricane Iniki was assessed by comparison with our previous measures of stand structure and leaf area index (LAI) at sites along a precipitation/elevation gradient on western Kauai. Reductions in LAI ranged from 29 to 80% and were correlated with pre-hurricane LAI and canopy height. The canopy damage resulted in a large pulse of litter, ranging from 4 to 19 t ha-1 across our study sites. In the first year post-hurricane, LAI recovery and relative increase in stand basal area were negatively correlated with the fraction of canopy LAI lost. The two major overstorey species, A. koa and Metrosiderous polymorpha, were damaged less than the sub-canopy species, Dodonaea viscosa and Psidium guajava. Although D. viscosa and P. guajava were both severely damaged in the hurricane, the alien species P. guajava had much higher survival than the native D. viscosa, both as adults and as seedlings. However, seedling density of P. guajava was limited by low recruitment. At these sites, there was no drastic change in species composition following hurricane disturbance, and forest structure and productivity had recovered to a great degree within 2 y.

The seed dispersal system of a neotropical tree, Cabralea canjerana (Meliaceae), was studied in two forested areas in southeastern Brazil. The first study site, Parque Estadual Intervales (PEI), is a 49,000-ha reserve composed mostly of old-growth Atlantic rain forest. The second site, Mata de Santa Genebra (MSG), is a 250-ha fragment of old-secondary semideciduous forest whose present bird fauna differs markedly from the original, in part as a consequence of forest fragmentation. At PEI 35 bird species ate the diaspores of C. canjerana. Black-tailed tityra (Tityra cayana, Tyrannidae) was the main seed disperser, but several other species were also important seed dispersers. In contrast, at MSG C. canjerana diaspores were eaten by 14 bird species. At this area, the red-eyed vireo (Vireo olivaceus, Vireonidae) was the most important seed disperser, but it was also a ‘waster’ which dropped seeds beneath parent plants, or carried them to sites unsuitable for germination. At PEI, exposed seeds on the forest floor were heavily preyed upon by rodents and insects. Insects destroyed mainly seeds deposited near to parent plants. Insect predation was less intense at MSG than at PEI. The rodent density at MSG was unusually small, and part of the post-dispersal seed predation may be done by terrestrial birds, such as doves and tinamous, which are especially common at MSG. Some of the differences recorded between the seed dispersal systems of C. canjerana at PEI and MSG may have been the result of the fragmentation and isolation of the latter area.

Green, P. T. (1997)

Red crabs in rain forest on Christmas Island, Indian Ocean: activity patterns, density and biomass. Vol. 13 Part 1: 17–38. On page 29 the phrase: “but a significant correlation existed across sites (r=0.81, n=44, P<0.001).” should read: “but a significant correlation existed across sites (r=-0.69, n=44, P<0.001).”

On page 33 the phrase “but the same correlation accounted for 81% of total variation when all sites were analysed together.” should read: “but the same correlation accounted for 48% of total variation when all sites were analysed together.”

As a consequence of its relatively high productivity in primary successional sites on Mauna Loa, Hawai'i, the mat-forming fern Dicranopteris linearis can influence attributes of soil detrital pools. Decomposition, nutrient release and rates of asymbiotic N fixation in Dicranopteris litter were determined over an elevational range of oligotrophic sites. ‘Hot spots’ of nitrogen fixation occurred in Dicranopteris litter, as evidenced by acetylene reduction rates as high as 22 nmol g−1 h−1. However, potential N fixation rates for the entire litter mass were 0–0.1 g m−2 y−1, less than other N inputs such as rainfall. Dicranopteris' decomposition rates were low compared to other tropical species, even under high temperature and rainfall conditions, with ≥50% of the original leaf and >77%of the stem mass remaining after 2 y of decomposition. Slow decomposition was related to high ligninrnitrogen ratios (56–129) in litter and above-ground positioning of unabscised, decomposing litter. As a result of its slow decomposition rates, Dicranopteris is an major contributor to soil detrital pools. Aggradation of the detrital pool is an important process whereby nutrients are accrued within these ecosystems. Consequently, Dicranopteris exerts an important influence on soil genesis and ecosystem development during primary succession on pahoehoe lava.

Seeds of the Brazilnut tree (Bertholletia excelsa Humb. & Bonpl., Lecythidaceae) sustain one of the most important extractive industries in neotropical forests. Yet little is known about the demography and seed dispersal ecology of Bertholletia, particularly in natural stands which have not been previously harvested. This study presents data on the population density, spatial distribution, and seed dispersal ecology of Brazilnut trees at a pristine stand located within the Kayapó Indian Area of southeastern Amazonia, Pará, Brazil. Brazilnut trees were primarily found within groves (castanhais) of 75 to 149 trees, with a few isolated trees in between. Although the density of trees ≥ 10 cm in diameter at breast height (hereafter, dbh) at two groves was 4.8 to 5.1 trees ha–1, the overall density for the entire study area of c. 950 ha was estimated at 1.3 tree ha–1. Within-grove nearest neighbour distances averaged 21 m and were markedly skewed towards even shorter distances. Seed dispersal experiments using 709 marked seeds indicated that this pattern can be largely explained by the highly restricted seed shadows imparted by the main seed dispersal agents of Bertholletia at this site, the red-rumped agouti (Dasyprocta leporina). Agoutis on average scatterhoard Bertholletia seeds to an average distance of 5 m, and rarely beyond 20 m, from seed stations. We suggest that, once edaphic and climatic conditions are suitable, the highly contagious spatial distribution of Bertholletia trees at the landscape level can be largely accounted for by the quantitatively dominant effect of short-distance dispersal by caviomorph rodents, and rare events of long-distance dispersal provided by other vectors. This mechanism of grove formation need not resort to untested conjectures of human dispersal and intentional planting in prehistoric and historic times as it has often been suggested in the literature.