Spatial distribution and habitats of useful plants: an initial assessment for conservation on an indigenous territory, Panama

In order to examine the spatial distribution of forest resources on local territories and to understand the factors controlling such distributions, we studied the spatial patterns of a group of 23 useful plant species on the territory of a Kuna community in the province of Darien, Panama. A stratified random sampling scheme was used to survey the distribution and abundance of the species across a 3500 ha area around the village. Data on the physical environment as well as the geographic coordinates of the sample plots were also obtained. A series of canonical analyses was conducted to evaluate the species–environment relationships and to identify spatial structures in the species distributions left unexplained by the environmental variables. Four distinct distribution patterns were identified among the species; these were most strongly explained by land-use, the degree of canopy closure and topography. Significant spatial structures, independent of the measured environmental variables, were related to anthropogenic pressure and an edaphic gradient, and the habitat associations of the individual species were described. The results obtained from this case study suggest that land-use dynamics may play a predominant role in structuring inhabited landscapes, and that diversity in distribution patterns and habitat associations will require a combination of spatially explicit management strategies to ensure the local resource base.     

Evaluation of a conservation strategy: a spawning aggregation closure for red hind, Epinephelus guttatus, in the U.S. Virgin Islands

Many tropical reef fishes spawn in large aggregations, which are readily targeted by fishers. By the 1980s, at least two grouper spawning aggregations were eliminated by intensive fishing off the island of St. Thomas, U.S. Virgin Islands, and another aggregating species, red hind, was intensively targeted. By 1988, the average length of red hind had greatly decreased to 295 mm, and the sex ratio was extremely skewed to 15 females per male, suggesting a heavily fished stock. Since this species is a protogynous hermaphrodite, the loss of large individuals (primarily males) could potentially result in sperm limitation in spawning aggregations. In 1990, a spawning aggregation closure was implemented. By 1997, average size of red hind had increased to 395 mm and sex ratio had shifted to 4 females per male. Fish were observed aggregating only in structurally complex habitat along the insular shelf edge. This habitat type is apparently not common along most of the shelf edge off St. Thomas and may provide shelter while reducing risk of predation during aggregation periods. These data suggest that protection of spawning aggregations is a sound management strategy with considerable potential for aiding the sustainable use of reef fish resources.     

Effects of tidewater on the feeding ecology of hooded crane (<Emphasis Type="Italic">Grus monacha</Emphasis>) and conservation of their wintering habitats at Chongming Dongtan,China

Dongtan (or East Tideland) on Chongming Island in China is an important wintering site of Grus monacha (hooded crane). Field observations were conducted in Dongtan in the wintering season of 2000–2001 to determine how tidal fluctuation affects the habitat use and behavior of G.monacha. Scirpus mariqueter (sea-bulrush) was the dominant species in the tidal vegetation; and its corms were the major food source for G.monacha. The corms in the outer zone (far from the dyke) were buried underground shallower than those in the inner zone (near the dyke) because of erosion by tidewater. For easy access to food, G.monacha tended to select the outer zone and the edge of tidal creeks as its foraging sites for the majority of time spent on the tideland. Regression analysis revealed that distance of the foraging sites to the dyke was correlated with tidal height. The cranes did not appear to show territorial behavior, and tended to form large-sized flocks, especially at high tide, because of the effect of the tidewater and the non-uniform distribution of food. Thus, the height of the tide is an important factor responsible for the habitat selection of G.monacha, which was also the major cause of the cranes selecting only the natural tideland at Dongtan on Chongming Island. Unfortunately, the habitats of G.monacha are limited, and even threatened, at Dongtan because the tideland is frequently reclaimed. Appropriate measures should be taken to prevent the tideland being further reclaimed, otherwise the natural wintering grounds of G.monacha will soon disappear.     

Interpreting dragonfly diversity to aid in conservation assessment: lessons from the Odonata assemblage at Middle Creek, north-eastern Victoria, Australia

In order to evaluate single-occasion sampling in compiling inventories for Odonata, larvae were sampled on 20 occasions from 1987–1990 at a site on Middle Creek, north-eastern Victoria, and adults sought also on each visit to more fully evaluate the diversity of the asemblage, and limitations of depending on a single life stage for this purpose. A total of 18 species (7 Zygoptera, 11 Anisoptera) included 15 species collected as larvae and 16 as adults. Few species were common as larvae, and about half the 2806 specimens identified were Austrogomphus cornutus Watson. Orthetrum caledonicum (Brauer) and Ischnura heterosticta (Burmeister) were also abundant, and these three species were also the most common as adults. The number of species obtained ranged from 2–9 on different occasions, and represent different 'habitat groups' within the local fauna. The Middle Creek odonate fauna appears to be much richer than that of a nearby site on the Kiewa River (12 species), and reasons for this are discussed. Seasonal variation in species representation and relative abundances are noted. Any single sample occasion provided insufficient knowledge of the total assemblage to interpret odonate diversity reliably.     

Interpopulation genetic divergence in European grayling (Thymallus thymallus, Salmonidae) at a microgeographic scale: implications for conservation

In order to provide guidelines for conservationand management of the severely declining LakeSaimaa (eastern Finland) European grayling(Thymallus thymallus, Salmonidae), weinvestigated the microgeographic geneticstructure of three populations from the watersystem using 17 microsatellite loci andmitochondrial DNA polymerase chainreaction-restriction fragment lengthpolymorphism analysis. Microsatellites revealedlow levels of intrapopulation genetic diversityand substantial divergence between populationssampled from spawning sites separated by aslittle as 55 kilometers. Mitochondrial analysisindicated the occurrence of two compositehaplotypes within Lake Saimaa. The nucleotidesubstitution estimates between the haplotypessuggested their separation to markedly predatethe late Pleistocene period. The populationsexhibited marked frequency differences for thetwo mitochondrial haplotypes, reinforcing theview of limited interpopulation gene flowwithin Lake Saimaa. An individual basedmicrosatellite Neighbor-Joining dendrogramdemonstrated clustering of all the specimensaccording to their sampling origin. Individualassignment tests revealed 100% assignmentsuccess of individuals into their population oforigin and 100% exclusion (p <0.05) from all alternative referencepopulations. These findings exemplify that T. thymallus populations may be genetically highly structured over small geographical scales and provide a good starting point for the development of appropriate conservation strategies for Lake Saimaa grayling.     

The Large Blue butterfly, Phengaris [Maculinea] arion, as a conservation umbrella on a landscape scale: The case of the Czech Carpathians

Conservation umbrellas are charismatic species, the conservation of which also conserves the high diversity of associated plants and animals. The Large Blue butterfly, Phengaris [Maculinea] arion (Lepidoptera, Lycaenidae), is a textbook example of a charismatic endangered invertebrate, intensively studied throughout Europe and protected by the EU Habitat Directive. While surveying P. arion at the westernmost outskirts of the Carpathians (Javorniky and Vsetinske Mts.), within a stronghold of the species in the Czech Republic, we asked whether occupied sites differed from unoccupied ones in the composition of vascular plants and butterfly assemblages. The occupied sites (n = 65) were small pastures, including abandoned ones, with S to W exposure, located on rugged terrain and displaying a high microtopographic heterogeneity; the unoccupied sites (n = 101) were typically mown or intensively grazed. The vegetation of occupied sites was characteristic for non-intensive submountain pasture, butterfly assemblages were species richer, contained more specialised species, and significantly higher proportion of red-listed species. P. arion thus may act as an umbrella for a high number of species associated with traditional land use in the study area and elsewhere. Its survival will depend on the continuation of small-scale land use varying in space and time, and can be threatened by uniformisation of management, even if practised under the guise of agri-environmental payments.