Biodiversity along a Altitudinal Gradient at SPECTRE

The complexity of the Lesser Antilles vegetation must be linked to the variety of topographic features that influence the structure of some climatic parameters, particularly the rainfall. The above mentioned environmental factors influence a plurality of biotopes colonized by specific phytocenoses. Using survey transects of different minimal areas, we highlighted the specific, biocenotic, structural and architectural heterogeneity of the survey stations. This spatio-temporal differentiation of plant groupings is strongly guided by the activities of the successive human societies. These elements show that the anthropized vegetation of the Lesser Antilles represents a true laboratory for the study of plant succession using the synchronic approach.

The correlation between vegetation patterns (species distribution and richness) and altitudinal variation has been widely reported for tropical forests, thereby providing theoretical basis for biodiversity conservation. However, this relationship may have been oversimplified, as many other factors may influence vegetation patterns, such as disturbances, topography and geographic distance. Considering these other factors, our primary question was: is there a vegetation pattern associated with substantial altitudinal variation (10-1,093 m a.s.l.) in the Atlantic Rainforest-a top hotspot for biodiversity conservation-and, if so, what are the main factors driving this pattern? We addressed this question by sampling 11 1-ha plots, applying multivariate methods, correlations and variance partitioning. The Restinga (forest on sandbanks along the coastal plains of Brazil) and a lowland area that was selectively logged 40 years ago were floristically isolated from the other plots. The maximum species richness ([200 spp. per hectare) occurred at approximately 350 m a.s.l. (submontane forest). Gaps, multiple stemmed trees, average elevation and the standard deviation of the slope significantly affected the vegetation pattern. Spatial proximity also influenced the vegetation pattern as a structuring environmental variable or via dispersal constraints. Our results clarify, for the first time, the key variables that drive species distribution and richness across a large altitudinal range within the Atlantic Rainforest.

2008

As ilhas atlânticas dos Açores, Madeira, Selvagens, Canárias e Cabo Verde constituem uma das regiões da Europa mais ricas em diversidade de fungos, plantas e animais. Desde 2004 que a inventariação detalhada da diversidade destas ilhas tem sido um dos principais objectivos dos projectos ATLÂNTICO e BIONATURA (incluídos no projecto EU INTERREG IIIB). Este livro é a mais recente contribuição destes projectos, apresentando uma lista de todos os fungos, flora e fauna terrestre conhecida, incluindo a dulçaquícola, para dois arquipélagos atlânticos (Madeira e Selvagens). A lista abrange o arquipélago da Madeira, constituído por duas ilhas de maiores dimensões (Madeira e Porto Santo) e três pequenas, cujo conjunto constitui as Desertas (Ilhéu Chão, Deserta Grande e Bugio), e ainda o arquipélago das Selvagens, formado por duas pequenas ilhas (Selvagem Grande e Selvagem Pequena) e um ilhéu (Ilhéu de Fora).ABSTRACT: The Azores, Madeira, Selvagens, Canary Islands and Cape Verde are among the r...

Ecography, 2003

K. 2003. Unique elevation diversity patterns of geometrid moths in an Andean montane rainforest. -Ecography 26: 456-466.

The granitic Seychelles are the only mid-oceanic islands of continental origin. Botanists have long focused on taxonomy, and plant communities were described in a qualitative way, based on simple observation. Therefore the altitudinal belts, their fl oristic characteristics and distribution are still poorly understood and conservation efforts focus mainly on species-centred actions. Here we describe a quantitative study of plant communities and indicator species differentiated along the altitudinal gradient on Silhouette, the most pristine and second highest (740 m) island of this archipelago.

Journal of Ecology, 1998

0 Data on the composition\ structure and diversity of plant communities were gath! ered along a 0999!m altitudinal transect from tropical seasonal dry forest to cloud forest on calcareous Cerro Grande in Jalisco\ Me xico[ 1 A total of 369 species\ 181 genera and 092 families of vascular plants occurred in 32 samples of 9[0 ha\ strati_ed at 099!m elevational intervals between 0499 and 1499 m a[s[0[ There were 86 tree species\ 65 shrubs\ 69 vines\ 070 terrestrial herbs\ 28 epiphytes\ 2 hemiparasites\ 2 succulent rosette shrubs and 0 saprophyte[ 2 Forest composition varied continuously with altitude\ based on the Shipley + Keddy "0876# test\ ordination via reciprocal averaging\ and elevational trends in the Sorenson similarities of samples at adjacent altitudes[ supporting the individualistic hypothesis of plant community organization[ 3 Understorey herbs\ shrubs and vines showed the greatest decline in species number with increasing altitude[ This pattern is hypothesized to result from the more open\ more frequently disturbed\ and more completely deciduous canopies at lower\ drier elevations[ The proportion of evergreen woody plants was greater at higher altitudes\ re~ecting less seasonal aridity and greater soil leaching[ The proportion of endo! zoochorous species increased with altitude\ while the proportion of pterochorous and ectozoochorous species decreased\ re~ecting trends in the hypothesized e.cacy of these mechanisms of seed dispersal[ 4 Total basal area of woody plants × 1[4 cm d[b[h[ and basal area per tree both increased roughly fourfold between 0499 and 1499 m[ 5 Species richness decreased sharply with altitude\ due mainly to decreases in ter! restrial herbs\ and "to a lesser extent# shrubs and vines[ The average number of species per 9[0 ha declined from 023 at 0499 m to 32 at 1499 m[ The numbers of species\ genera and families per sample declined linearly with elevation[ Species composition of samples within an altitudinal band showed greater horizontal turnover "b diversity# at lower elevations\ showing that low!elevation forests are not only locally more diverse\ but spatially more patchy[ Community composition varies roughly six times as rapidly with elevation as with the same distance horizontally[ 6 A cascading series of e}ects of elevation on soil fertility\ anti!herbivore defences\ and the level of density!dependent mortality may account for the observed drop in diversity with elevation\ and would be consistent with lower b diversity and greater basal area at higher elevations[

Interciencia, 2012

SUMMARY Both the biodiversity and the landscapes of the Caribbean have been greatly modified as a consequence of human activity. In this essay we provide an overview of the natural landscapes and biodiversity of the Caribbean and discuss how human activity has affected both. Our Caribbean geographic focus is on the insular Caribbean and the biodiversity focus is on the flora, forests, and built up land. Recent land cover changes from agricultural to urban cover have allowed for the proliferation of novel forests, where introduced plant species have naturalized and play important ecological roles that appear compatible with native and endemic flora.

Ecography, 2004

. Elevational gradients, area and tropical island diversity: an example from the palms of New Guinea. Á/ Ecography 27: 299 Á/310. The factors causing spatial variation in species richness remain poorly known. In this study, factors affecting species richness of palms (Palmae/Arecaceae) were studied along the elevational gradient of New Guinea. Interpolated elevational ranges were calculated from a database of all known collections for 145 species in 32 genera. The amount of land area at different elevations greatly affects the species richness gradient. If assessed in equal-elevation bands species richness appears to decline monotonically, but when assessed in equal-area bands species richness shows a pronounced midelevation peak, due to the large proportion of lowlands in New Guinea. By randomising species ranges within the total elevational gradient for palms and accounting for area, we found the mid-elevation peak to be consistent with a middomain effect caused by the upper and lower limits to palm distribution. Our study illustrates the importance of accounting for area in macroecological studies of richness gradients and introduces a novel yet simple method for doing this through the use of equal-area bands. Together, the effect of area and the mid-domain effect explain the majority of variation in species richness of New Guinea palms. We support calls for the multivariate assessment of the mid-domain effect on an equal footing with other potential explanations of species richness.