Species primarily dependent on habitats outside protected areas have to cope with the direct pressure of human utilization or harassment, and the indirect pressure of habitat modification. In Uganda, wetlands mainly used by cranes occur mostly outside protected areas. The country's wetlands are however under heavy modification, and this and other pressures are thought to have reduced crane populations to 10–30% of the number in the early 1970s. From January 2005 to January 2006, we assessed the status of crane breeding and distribution in the country. Breeding and foraging sites were assessed through a nationwide newspaper survey, and visits to wetlands. We established occurrence of 21 nests during the study period, and crane use of 27 out of 30 districts surveyed. Crane harassment and trapping were common during breeding, as was crop damage by cranes. This is the first attempt to show the distribution of crane breeding outside protected areas throughout the country. In addition to maintaining suitable breeding habitat, survival of cranes in Uganda lies in part in community engagement and punishing crimes related to hunting and destruction of nests. 相似文献
We conducted a comprehensive census of the vascular epiphytes in a lowland forest in Panama by means of a canopy crane. In
0.4 ha of ca. 40-m tall forest, 103 species of vascular epiphytes with 13,099 individuals were found. The orchids were the
most important family both in species and individual numbers, accounting alone for >40% of all species and >50% of all individuals.
There was a clear vertical segregation of species with a concentration at intermediate heights: more than 50% of all individuals
were found between 15 m and 25 m above ground. Tree species identity, tree size and the position of a tree in the forest (“space”)
all influenced species composition. However, none of the two environmental variables nor space alone explained more than 10%
of the total variation in epiphyte assemblages in several canonical correspondence analyses. By far the largest proportion
of the observed variation remained unexplained and is arguably due to mere chance. In the future, our results will be used
as a baseline data-set for the direct observation of the long-term dynamics in a diverse epiphyte community. 相似文献
Abstract. 1. The enormous diversity of phytophagous insects in forest canopies is hypothesised to be supported by the number of herbivorous species per host tree species or host specificity. It is therefore necessary to examine the effect of host plant species on compositional changes in the herbivore communities. 2. The lepidopteran larval communities were examined in the canopies of 10 tree species in a temperate deciduous forest of Japan. The phylogeny and leaf flush phenology of host plant species were taken into account as factors affecting the herbivore community assembly. 3. Examination of seasonal changes in the larval community structures on each tree species showed that larval species richness, abundance, and evenness decreased significantly from spring to summer. Larval species richness and abundance were characterised by family-level phylogenetic differences among tree species, whereas evenness was determined at a higher taxonomic level. 4. Compositional changes in the larval communities among tree species showed a remarkable pattern, with a phylogenetic effect at a high taxonomic level in spring, similar to evenness, but a phenological effect in summer. This suggests that host specificity could support the lepidopteran larval diversity in spring. 5. These results suggest that the differences in host utilisation of the herbivore, which reflects the phylogenetic effect of the host plants, can be important as a factor affecting the diversity of lepidopteran larval communities in temperate forests. 相似文献
Stable carbon isotope analysis has become a key tool in functional ecology, yet considerable natural variability often limits the interpretations. In this study we document the spatial, taxonomic, temporal and tissue-specific δ13C variability in 10 tree species of a temperate European forest. The Swiss Canopy Crane provided access to the three dimensional space within 55 trees 30–35 m high representing the genera Acer, Carpinus, Fagus, Prunus, Quercus, Tilia, Abies, Larix, Picea and Pinus. The results from six broad-leaved and four conifer species (seven deciduous, three evergreen) documented that the species effect was not significant in contrast to tissue-specific and spatial differences in the canopy. Year-to-year differences were not large but still significant.
Our analysis confirmed a significant difference between δ13C of foliage collected in the upper and lower canopy, but revealed no systematic differences with respect to azimuthal directions in tree crowns of the broad-leaved trees, as opposed to the conifers, which show clear differences between the sun-exposed and the shaded side. Tissue-specific differences were significant, despite surprisingly similar mean values for most tissue types. Such tissue effect was largely due to young branch xylem, which exhibited a systematic less negative deviation from the other tissue types. These findings were consistent across the species tested and provided some guidelines towards a representative sampling strategy for 13C analysis. 相似文献