Catastrophic disturbance, logging and the ecology of mahogany (Swietenia macrophylla King): grounds for listing a major tropical timber species in CITES

Recent debate on whether or not mahogany ( Swietenia macrophylla King) is threatened by the international timber trade has focused on the breadth of its range and estimates of the remaining stock of mahogany trees. These data are inadequate to reveal the status of mahogany populations, both because they are incomplete in areal extent and because they do not reveal population parameters such as the existence or density of young trees smaller than commercial size. However, there is sufficient information on the regeneration ecology of mahogany to indicate that under natural conditions this species regenerates in essentially even-aged stands after catastrophic disturbances destroy many or most trees, and, in the case of fires and flooding, saplings and seedlings as well. Adult mahoganies tend to survive these events, and regenerate by shedding seed onto the resulting gaps or clearings. This ecological strategy makes mahogany vulnerable to logging, first because juvenile mahoganies are not found in the understorey, and secondly because logging operations shortcircuit mahogany regeneration processes by selectively removing almost all mahogany seed sources while leaving standing competing vegetation of other species. Listing of mahogany in CITES Appendix II could provide both a mechanism to fill in gaps in information and an incentive to change current practices in favour of silvicultural management to provide for regeneration of this valuable timber species in forests subjected to logging.     

Parinarioidins A-B,unprecedented flavonoids from the bark of Brosimum parinarioides Ducke

1. Download : Download high-res image (450KB)
2. Download : Download full-size image

     

Ecology of diapausing copepodids of Cyclops kolensis Lill. in reservoirs of the Upper Volga

Cyclops kolensis Lill. forms dense populations in different water-bodies of the Upper Volga basin. In spring, when the other planktonic crustaceans have not yet appeared, C. kolensis is an important food object for fishes. Its active reproduction occurs from April to the beginning of June. A rapid accumulation of stage IV copepodids in the plankton occurs in June and at 12–14° they sink into the pelogene in a diapause stage. During the summer stagnation period the diapausing copepodids are distributed evenly over the bottom; their abundance here is 0.7–0.8 million ind. m^-2 (Rybinsk reservoir). During storms and autumn active water mixing the copepodids together with detritus are disturbed and brought to the deepest, silt rich, part of the water-bodies. After the ice formation and at the beginning of bottom heating the diapausing copepodids are transported by near bottom currents and are concentrated in depressions; their biomass here reaches 60 g m^-3. After the thermo-oxy-cline formation they revive and begin to live actively. Copepodids feed, accumulate adipose matter and in February–March they begin to moult.     

Forest succession in Kibale National Park, Uganda: implications for forest restoration and management

Forest succession was studied in four plots in former grasslands at the Ngogo study area in Kibale National Park, Uganda. The plots were located in areas that had been protected from fire for 0.58, 25, 9 and ≈30 years for plots 1, 2, 3 and 4, respectively. Species richness reflected the length of time that the plot had been protected from fire; it was highest in plot 4 and lowest in plot 1. Species density, stem density and basal area were all highest in plot 4 and lowest in plot 1. The species densities of plots 2 and 3 were not different. Similarly, plots 2 and 4 did not differ with regard to stem density or basal area. Animal seed dispersers played a vital role in the colonization of grasslands by forest tree species.     

Amino acid sources in the adult diet do not affect life span and fecundity in the fruit-feeding butterfly Bicyclus anynana

Abstract.  1. In tropical forests, the adults of many butterfly species feed on fruits rather than nectar from flowers and have long life spans. Rotting fruit and nectar differ from each other in many respects, including sources of amino acids and microbial life. If amino acids in the adult diet can be used for reproduction, this may have facilitated the evolution of extended life spans in this guild.
2. This issue was addressed by investigating effects of banana, yeast, and amino acids in the adult diet of the fruit-feeding butterfly Bicyclus anynana (Lepidoptera) on longevity and female reproductive output in two experiments.
3. Results showed that in the fruit-feeding butterfly B. anynana : (i) banana juice, but not sliced banana or added amino acids extend life span compared with a sugar solution of similar composition; (ii) compared with this sugar solution, other cohorts (banana juice-amino acid enriched) did not have significantly higher reproductive outputs; (iii) yeast does not represent a valuable source of nutrients; (iv) caloric restriction may cause decreased life span and rate of reproduction; and (v) increased rates of reproduction have a life span cost.     

Study of enteric pathogens among children in the tropics and effects of prolonged storage of stool samples

The study was performed to compare real-time PCR after nucleic acid extraction directly from stool samples as well as from samples stored and transported on Whatman papers or flocked swabs at ambient temperature in the tropics. In addition, the possible suitability for a clear determination of likely aetiological relevance of PCR-based pathogen detections based on cycle threshold (Ct) values was assessed. From 632 Tanzanian children <5 years of age with and without gastrointestinal symptoms, 466 samples were subjected to nucleic acid extraction and real-time PCR for gastrointestinal viral, bacterial and protozoan pathogens. Equal or even higher frequencies of pathogen detections from Whatman papers or flocked swabs were achieved compared with nucleic acid extraction directly from stool samples. Comparison of the Ct values showed no significant difference according to the nucleic acid extraction strategy. Also, the Ct values did not allow a decision whether a detected pathogen was associated with gastrointestinal symptoms.     

Avian life-history determinants of local extinction risk in a hyper-fragmented neotropical forest landscape

The fact that species vary in their vulnerability to extinction is well documented, but the reasons for these differences remain poorly understood. Why should some species/families/guilds decline rapidly with increasing anthropogenic disturbance, while others either tolerate or proliferate in disturbed habitats? We investigated the bird species composition in 31 primary forest patches of varying size in a region of the Amazonian 'Arc of Deforestation' and assessed which species life-history traits predisposed individual species to extinction. Medium-sized non-flocking canopy frugivores/ominvores of low primary forest dependence were least likely to go extinct in small patches, while small-bodied flock-following primary-forest-dependent terrestrial insectivores were most fragmentation sensitive. We found highly idiosyncratic relationships between the minimum size of forest patches occupied by different species and their territory size requirements estimated based on other Amazonian studies. This suggests that avian assemblages in forest fragments primarily comprise species that either have good dispersal abilities or are highly tolerant to the non-forest matrix, rather than those whose minimum spatial requirements can be met by the size of available forest fragments.