Patterns of Species Richness and Distribution of Pteridophytes in Rwanda (Central Africa): A Numerical Approach

Dzwonko, Zbigniew; Kornaś, Jan

doi:10.2307/2845653

“…These authors noted a strong differentiation in species composition between a restinga and a lowland rain forest, which could be related to physical and chemical characteristics of soil and water dynamics, among other factors. Birks (1976) showed that, in Europe, fern assemblages reflected general phytoecological regions, and a similar result was also found by Dzwonko and Kornas (1994) for Africa. Most likely, this concordance is determined by the humidity of the environment, which determines both the distribution of ferns and general vegetation patterns (e.g.…”

Section: Discussionmentioning

confidence: 64%

“…Most likely, this concordance is determined by the humidity of the environment, which determines both the distribution of ferns and general vegetation patterns (e.g. Dzwonko and Kornas 1994). In our study region, humidity is higher in the rain forest than in SSTF and mixed rain forests, thereby leading to a corresponding floristic differentiation, for both flowering species and ferns.…”

Section: Discussionmentioning

confidence: 71%

“…Some authors have highlighted the role of these factors, such as the influence of soil on terrestrial ferns (Tuomisto and Poulsen 1996;Jones et al 2011), and climatic variables, such as air humidity (Dzwonko and Kornas 1994), precipitation (Cardelús et al 2006), and the length of dry season (Jones et al 2013). Considering the vegetation patterns as a whole, soil appears to play a chief role in the floristic variations over short distances, whereas climatic factors are likely to have an effect on a wider scale (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Climate-related variables and geographic distance affect fern species composition across a vegetation gradient in a shrinking hotspot

Gasper

¹

,

Eisenlohr

²

,

Salino

³

2013

Plant Ecology & Diversity

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Background: The Atlantic Forest biome is a top hotspot for conservation priorities, but the variations in fern species composition and the factors driving these are still poorly known. The vegetation gradient found in the state of Santa Catarina, southern Brazil, constitutes an interesting environmental model for examining such patterns. Aims: We analysed the variation in fern species composition across a vegetation gradient in the southern Atlantic Forest and the variables that might influence it. Methods: We applied cluster analysis (TWINSPAN and WPGMA), ordination (DCA), regression (OLS and GWR) and variance partitioning to species occurrence, environmental and spatial data in 40 sample units (50 × 50 km 2 ), using metadata. Results: Bioclimatic variables, mainly those related to humidity (water being an essential medium for fern reproduction), and geographic distance were related to variation in fern species composition. Dispersal constraints, probably related to neutral processes, could be evoked to explain the significance of the geographic distance. Overall, a great deal of uncertainty remained with regard to the determinants of floristic composition. Conclusions: Our study emphasises, for the first time in the Atlantic Forest, a significant role of environmental determinism and dispersal constraints on the variation of fern species composition.

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“…Although the search for a unique, simple primary determinant of observed richness gradient can be simplistic, productivity or climate related variables, more directly related to plant physiological mechanisms (see Saetersdal, Birks & Peglar, 1998), have frequently been found to be the main explanatory variables of plant species richness on larger scales (Richerson & Lum, 1980;Currie & Paquin, 1987;Currie, 1991;Linder, 1991;Myklestad & Birks, 1993;Wright, Currie & Maurer, 1993;Dzwonko & Kornas, 1994;Birks, 1996;O'Brien, Whittaker & Field, 1998;Wohlgemuth, 1998). On the contrary, climate and productivityrelated variables do not seem very relevant in explaining Iberian plant species richness.…”

Section: Other Significant Variablesmentioning

confidence: 99%

“…In our opinion, this shows that energy availability does not greatly determine current plant species number in the Iberian Peninsula. Climate related variables more probably appear when individual species or homogeneous groups with few species are considered (Myklestad & Birks, 1993;Dzwonko & Kornas, 1994;Austin et al, 1996;Birks, 1996;Wohlgemuth, 1998). Even more important than climate, the type of soil and, therefore, available nutrients could determine the coexistence of a greater number of plant species in the Iberian Peninsula.…”

Section: Other Significant Variablesmentioning

confidence: 99%

Spatial and environmental determinants of vascular plant species richness distribution in the Iberian Peninsula and Balearic Islands

Lobo¹,

Castro²,

Moreno³

2001

Biological Journal of the Linnean Society

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Using an exhaustive data compilation, Iberian vascular plant species richness in 50x50 UTM grid cells was regressed against 24 explanatory variables (spatial, geographical, topographical, geological, climatic, land use and environmental diversity variables) using Generalized Linear Models and partial regression analysis in order to ascertain the relative contribution of primary, heterogeneous and spatially structured variables. The species richness variation accounted for by these variables is reasonably high (65% of total deviance). Little less than half of this variation is accounted for spatially structured variables. A purely spatial component of variation is hardly significant.The most significant variables are those related t o altitude, and particularly maximum altitude, whose cubic response reflects the occurrence of the maximum number of species at the highest altitudes. This result highlighted the importance of Iberian mountains as hotspots of diversity and the relevance of large and small scale historical factors in contemporary plant distribution patterns. Climatic or energy-related variables contributed little, whereas geological (calcareous and acid rocks) and, to a lesser extent, environmental heterogeneity variables (land use diversity and altitude range) seem to be more important. 0 2001 The Linnean Society of London ADDITIONAL KEY WORDS: diversity hotspotsgeographical patternsmodelling species richnessvariance partitioning.

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Spatial and environmental determinants of vascular plant species richness distribution in the Iberian Peninsula and Balearic Islands

Lobo¹

2001

Biological Journal of the Linnean Society

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Using an exhaustive data compilation, Iberian vascular plant species richness in 50x50 UTM grid cells was regressed against 24 explanatory variables (spatial, geographical, topographical, geological, climatic, land use and environmental diversity variables) using Generalized Linear Models and partial regression analysis in order to ascertain the relative contribution of primary, heterogeneous and spatially structured variables. The species richness variation accounted for by these variables is reasonably high (65% of total deviance). Little less than half of this variation is accounted for spatially structured variables. A purely spatial component of variation is hardly significant.The most significant variables are those related t o altitude, and particularly maximum altitude, whose cubic response reflects the occurrence of the maximum number of species at the highest altitudes. This result highlighted the importance of Iberian mountains as hotspots of diversity and the relevance of large and small scale historical factors in contemporary plant distribution patterns. Climatic or energy-related variables contributed little, whereas geological (calcareous and acid rocks) and, to a lesser extent, environmental heterogeneity variables (land use diversity and altitude range) seem to be more important. 0 2001 The Linnean Society of London ADDITIONAL KEY WORDS: diversity hotspotsgeographical patternsmodelling species richnessvariance partitioning.

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Patterns of Species Richness and Distribution of Pteridophytes in Rwanda (Central Africa): A Numerical Approach

Cited by 29 publications

References 5 publications

Climate-related variables and geographic distance affect fern species composition across a vegetation gradient in a shrinking hotspot

Climate-related variables and geographic distance affect fern species composition across a vegetation gradient in a shrinking hotspot

Spatial and environmental determinants of vascular plant species richness distribution in the Iberian Peninsula and Balearic Islands

Spatial and environmental determinants of vascular plant species richness distribution in the Iberian Peninsula and Balearic Islands

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