Patterns of plant species composition on Amazonian sandstone outcrops in Colombia

Abstract

Vascular plant species compositional patterns of the low forest, scrub, and herbaceous vegetation on white sand soils and sandstone substrates were studied at six sandstone plateaus in Colombian Amazonia, by means of a field survey according to the Braun‐Blanquet relevé method. Canonical Correspondence Analysis (CCA) was applied to separate effects of habitat and spatial configurations of the plateaus on species patterns. Also, information on dispersal ability and phytogeographic affinity of species was used to test explanations for between plateau differences. Low trees, shrubs and herbs were the main species recorded in 212 relevés. The main gradients in the species patterns were linked to the spatial configuration of the plateaus. Spatially controlled species patterns were mainly related to soil depth and soil organic matter. The association between phytogeographic affinity and the habitat controlled spatial link of species pointed at insufficient sampling at one plateau. Dispersal ability did not explain the habitat controlled spatially distributed occurrences of plant species. This might indicate a low frequency of local extinctions at the sandstone plateaus, especially of the poorly dispersed species, possibly because plant populations survive fire or drought disturbances in local sheltered places. Space and habitat controlled species patterns at one plateau were quite distinct from patterns at the other plateaus. This might be due to unmeasured habitat factors (e.g. unrecorded soil variation or human disturbance history) or the preferential, surveyor biased sampling procedure.

Geological Substrates Shape Tree Species and Trait Distributions in African Moist Forests

“…Our results from the Congo basin are consistent with differences in species distribution and community composition among geological substrates reported in Amazonia [6], [7], [50]. The particular role of sandstone has been pointed out in Columbia, where sandstone plateaus are common landscape features [51], [52]. In this study, we focused on abundant and wide-spread species, excluding those with narrow occurrence and potentially more specific environmental requirements.…”

Amazonian White‐Sand Forests Show Strong Floristic Links with Surrounding Oligotrophic Habitats and the Guiana Shield

“…B) which supports results from studies of Colombian white‐sand forests showing strong phytogeographic links with the Guiana Shield flora (Cortés et al . , Giraldo‐Cañas , Arbeláez & Duivenvoorden ). On the other hand, the ecoregions with the highest percentage of shared western Amazon white‐sand specialists, when using only species from loreto.wsf.PE (Peru), and acre.wsf.BT (Brazil), are located in the western Amazon (Iquitos varzea, Napo moist forests, and Southwest Amazon moist forests) (Fig.…”

“…Taxonomic revisions and local floristic studies in Amazonian white‐sand forests have emphasized the existence of plant species and genera disjunctly distributed between the Guiana Shield region and western Amazonian white‐sand forests ( e.g ., Spruce , Gentry & Ortiz , Berry et al . , Cortés & Franco , Silveira , Arbeláez & Duivenvoorden , García‐Villacorta & Hammel , Struwe & Albert , Fine et al . ).…”

Seed Dispersal Modes of the Sandstone Plateau Vegetation of the Middle Caquetá River Region, Colombian Amazonia1

“…Many of these plateaus are built up of horizontally layered sandstone formations of Paleozoic or Mesozoic age, and may rise very high above the lowland landscapes. In most cases, the plateaus form a habitat and substrate for plant communities that are quite different from that of the surrounding tall forest vegetation (Arbeláez & Duivenvoorden 2004). Soils are shallow nutrient‐poor white sands (Cuevas 1992), waterlogged in times of rainfall, but drying out quickly during prolonged dry spells (Duivenvoorden & Lips 1993).…”

“…In addition, the species composition between plateaus is similar, but is distinct from that of the surrounding tall forest (Maguire 1979, Huber 1988, Duivenvoorden & Lips 1993, Prance 1996, Arbeláez 2003). Thus, the widespread distribution of typical sandstone species among the scattered spaced sandstone areas can be the result of the existence of remnant populations (Arbeláez & Duivenvoorden 2004), but it can also be the consequence of an effective long distance dispersal.…”