Forest Plant and Bird Communities in the Lau Group, Fiji

We examined species composition of forest and bird communities in relation to environmental and human disturbance gradients on Lakeba (55.9 km²), Nayau (18.4 km²), and Aiwa Levu (1.2 km²), islands in the Lau Group of Fiji, West Polynesia. The unique avifauna of West Polynesia (Fiji, Tonga, Samoa) has been subjected to prehistoric human-caused extinctions but little was previously known about this topic in the Lau Group. We expected that the degree of human disturbance would be a strong determinant of tree species composition and habitat quality for surviving landbirds, while island area would be unrelated to bird diversity.All trees > 5 cm diameter were measured and identified in 23 forest plots of 500 m² each. We recognized four forest species assemblages differentiated by composition and structure: coastal forest, dominated by widely distributed species, and three forest types with differences related more to disturbance history (stages of secondary succession following clearing or selective logging) than to environmental gradients (elevation, slope, rockiness). Our point counts (73 locations in 1 or 2 seasons) recorded 18 of the 24 species of landbirds that exist on the three islands. The relative abundance and species richness of birds were greatest in the forested habitats least disturbed by people. These differences were due mostly to increased numbers of columbid frugivores and passerine insectivores in forests on Lakeba and Aiwa Levu. Considering only forested habitats, the relative abundance and species richness of birds were greater on the small but completely forested (and uninhabited) island of Aiwa Levu than on the much larger island of Lakeba.Forest disturbance history is more important than island area in structuring both tree and landbird communities on remote Pacific islands. Even very small islands may be suitable for conservation reserves if they are protected from human disturbance

Changes in regional ventilation during histamine bronchial challenge in stable asthma

Our objective was to examine the changes in regional ventilation during histamine-induced bronchoconstriction in stable asthma. We measured regional ventilation by a new method which measures regional distribution of inhaled 127Xe during tidal breathing by a gated method and by simultaneously measuring 99mTc counts from labelled macroaggregates, allowed for changes in lung shape during the breathing cycle. We studied 10 asthmatic patients [forced expiratory volume in 1 s (FEV1 2.04-4.37 litres)] and measured, in addition to the regional ventilation, oxygen saturation (SaO2), minute ventilation (V(E)) and tidal volume (V(t)) before and after inhaling enough histamine to lower FEV1 by >20% and/or SaO2 by >4%. Histamine inhalation reduced FEV1 by 0.44-1.15 liters and SaO2 by 0-4%. It increased V(E) and functional residual capacity (FRC) in 8 of the 10 patients. The FEV1 fall did not correlate with the SaO2 fall, V(E) or FRC changes. Histamine inhalation increased apical ventilation in most patients but the changes in regional ventilation in the left and right lungs were asymmetrical in 17 out of the 30 lung regions studied (upper, middle and lower paired regions in 10 patients). These results demonstrate that histamine bronchial challenge causes uneven regional ventilation. 0Any resultant change in ventilation-perfusion balance may be the underlying mechanism of oxygen desaturation seen in this procedure and in spontaneous attacks of asthma.link_to_subscribed_fulltex