A comparison of fine‐scale distribution patterns of four plant groups in an Amazonian rainforest (original) (raw)
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Edaphic and Floristic Variation within a 1-ha Plot of Lowland Amazonian Rain Forest1
Biotropica, 2006
Several studies in lowland tropical rain forests have documented effects of local-scale topographic variation on plant species distribution and abundance patterns. Few studies have compared the distribution patterns of more than one plant group, however, and even fewer have related these to measured physical and chemical soil characteristics. Here, we document such soil characteristics within a square 1-ha plot in Amazonian Ecuador, and compare them to the distribution patterns of terrestrial pteridophytes, angiosperm ground herbs, and palms. Substantial variation in soil properties was found within the plot. The three plant groups showed highly correlated floristic patterns within the 1-ha plot even after the effect of geographical distances had been taken into account. Mantel tests yielded significant correlations between edaphic patterns, as measured by distances in various soil and topographic characteristics, and floristic patterns. For all three plant groups, differences in elevation within the plot were highly correlated with floristic distances, and for terrestrial pteridophytes and palms, distances in soil calcium content and sand content were also important. Our results resembled those obtained at wider spatial scales with the same plant groups, which indicates that soil factors may play an important role for distribution and beta diversity of plants, even at the local scale.
Journal of Tropical Ecology, 2007
Studies in western Amazonian forests have found that similarities in soil cation concentration and texture explain floristic similarities between sites, when these are measured using trees, pteridophytes or Melastomataceae. However, it is not known to what extent the three plant groups react to the same soil characteristics, because tree studies have almost always been conducted in different areas than studies on the understorey plant groups. We made inventories in 23 sites representing non-inundated rain forests on clayey to loamy soil in three regions of western Amazonia. Significant Mantel correlations between the floristic patterns of trees and pteridophytes were found in all three regions when floristic differences were measured with species presence-absence data. When species abundance data were used, and when the floristic patterns of trees and Melastomataceae were compared, significant correlations were found in one or two regions. Mantel correlations between plant groups were highest in the two regions where the observed variation in soil characteristics was largest. In all regions, the same soil variables emerged with significant Mantel correlations with trees, pteridophytes and Melastomataceae. Soil calcium and magnesium were most frequently retained in the models of multiple regression on distance matrices. On average, soil differences explained 50% of the variation in floristic differences (range = 14-84%), and geographical distances explained 16% (range = 0-64%). Our results demonstrate that beta diversities of the three plant groups are highly correlated, and that much of this congruence is explained by similar reactions to soil variation. These results support the idea that pteridophytes, and to a lesser degree Melastomataceae, can be used as indicators of general floristic and edaphic patterns in Amazonian rain forests. Since understorey plants are much quicker to inventory than trees, this would make it possible to recognize and map floristic patterns over huge areas of lowland Amazonia within a reasonable time.
Floristic patterns along a 43‐km long transect in an Amazonian rain forest
Journal of …, 2003
1 The floristic variation in Amazonian lowland forests is poorly understood, especially in the large areas of non-inundated (tierra firme) rain forest. Species composition may be either unpredictable as abundances fluctuate in a random walk, more-or-less uniform, or it may correspond to environmental heterogeneity. 2 We tested the three hypotheses by studying the floristic variation of two phylogenetically distant plant groups along a continuous 43-km long line transect that crossed tierra firme rain forest in northern Peru. 3 The observed floristic patterns were compared to patterns in the spectral reflectance characteristics of the forest as recorded in a Landsat TM satellite image. The topography of the transect was measured in the field, and surface soil samples were collected to document edaphic conditions. The two plant groups, pteridophytes and the Melastomataceae, were assessed in 2-m wide and 500-m long sampling units. 4 Floristic similarity (Jaccard index) between sampling units ranged from 0.01 to 0.71 (mean = 0.27), showing that some units were almost completely dissimilar while others were very alike. 5 Spatially constrained clustering produced very similar subdivisions of the transect when based separately on satellite image data, pteriophytes, and Melastomataceae, and the subdivisions were also related to topography and soil characteristics. Mantel tests showed that floristic similarity patterns of the two plant groups were highly correlated with each other and with similarities in reflectance patterns of the satellite image, and somewhat less correlated with geographical distance. 6 Our results lend no support to the uniformity hypothesis, but they partially support the random walk model, and are consistent with the hypothesis that species segregate edaphically at the landscape scale within the uniform-looking forest.
Congruence between floristic patterns of trees and lianas in a southwest Amazonian rain forest
Ecography, 2007
The congruence in floristic patterns between different life-forms of woody plants remains poorly understood in tropical rain forests. We explored whether the floristic patterns of woody plants, divided into small trees 2.5 Á 10 cm dbh, large trees ]10 cm dbh, and lianas ]2.5 cm dbh were associated with each other or with patterns in soil properties, elevation, and geographical distances between sample plots. We also tested whether ecological amplitudes in relation to environmental variables differed among the plant groups. Trees and lianas were inventoried in 44 0.1-ha plots, distributed among three lowland and two submontane sites in the Madidi National Park, Bolivia. Soil samples were analysed for physico-chemical properties. Floristic differences between sites (as measured with each plant group separately) yielded significant Mantel correlations with each other, and with pH, Ca, Mg, elevation and geographical distance. Mantel correlations with edaphic distances were higher for large trees than small trees, but for Mantel correlations with geographical distance the situation was reversed. Environmental and geographical distances explained 31% of the variation in floristic differences for large trees, 22% for small trees, and 10% for lianas. The ecological amplitudes of lianas were wider than those of all trees for pH, Mg and elevation. The amplitudes of the two size classes of trees did not differ. In principal coordinates ordination, the three plant groups produced similar overall floristic patterns that were explainable by environmental factors.
Different floristic patterns of woody understorey and canopy plants in Colombian Amazonia
Journal of Tropical Ecology, 2002
Distribution patterns of vascular plants with diameter at breast height (dbh) ≥ 2.5 cm were studied on the basis of compositional data from 30 small plots located in a rain-forest area in Colombian Amazonia. The research questions were: How are distribution patterns of species in relation to local abundance in plots? Do understorey species (defined as species with individuals that never attained dbh ≥ 10 cm anywhere) show better correlations with soils and environment than canopy species (defined as species with individuals that attained dbh ≥ 10 cm)? Are patterns found in the entire range of landscape units comparable to those found in well-drained uplands alone? Species that occurred in more than one plot showed higher local abundances. This pattern was consistent among environmental generalists and specialists. Locally rare species (with only one individual in a plot) occurred mostly in well-drained uplands. Considering all landscape units, Mantel tests showed substantial correla...
Discovering floristic and geoecological gradients across Amazonia
Journal of Biogeography, 2019
Aim: To map and interpret floristic and geoecological patterns across the Amazon basin by combining extensive field data with basin-wide Landsat imagery and climatic data. Location: Amazonia. Taxon: Ground truth data on ferns and lycophytes; remote sensing results reflect forest canopy properties. Methods: We used field plot data to assess main ecological gradients across Amazonia and to relate floristic ordination axes to soil base cation concentration, Climatologies at High Resolution for the Earth's Land Surface Areas (CHELSA) climatic variables and reflectance values from a basin-wide Landsat image composite with generalized linear models. Ordination axes were then predicted across all Amazonia using Landsat and CHELSA, and a regional subdivision was obtained using k-medoid classification. Results: The primary floristic gradient was strongly related to base cation concentration in the soil, and the secondary gradient to climatic variables. The Landsat image composite revealed a tapestry of broad-scale variation in canopy reflectance characteristics across Amazonia. Ordination axis scores predicted using Landsat and CHELSA variables produced spatial patterns consistent with existing knowledge on soils, geology and vegetation, but also suggested new floristic patterns. The clearest dichotomy was between central Amazonia and the peripheral areas, and the available data supported a classification into at least eight subregions. Main conclusions: Landsat data are capable of predicting soil-related species compositional patterns of understorey ferns and lycophytes across the Amazon basin with surprisingly high accuracy. Although the exact floristic relationships may differ B I OS K E TCH Hanna Tuomisto, Kalle Ruokolainen, Gabriela Zuquim and most of the other authors are biologists interested in how species are distributed in Amazonia, what the determinants of species occurrences are and how these relate to the broader context of geological history and evolutionary processes. Jasper Van doninck is a geographer specialized on using remote sensing for biodiversity mapping.
Plant Ecology, 2011
A quantitative inventory of trees and lianas was conducted (1) to compare floristic composition, diversity and stem density variation between three different forest types (tierra firme, floodplain and swamp), and (2) to analyse the relationships between floristic similarity and forest structure in two regions ~60 km apart in Yasuní National Park, Amazonian Ecuador. A total of 1,087 species with a diameter at breast height ≥ 2.5 cm were recorded in 25 0.1-ha plots. Tierra firme was the habitat with the highest number of species and stem density for trees and lianas, followed by floodplain and swamp in both regions. Two hypotheses that have been independently proposed to describe plant distribution in tropical rain forests, together explain species spatial distribution in this study. The fact that the 30 most important species per forest type (totalling 119 species) accounted for 48.2% of total individuals supports the oligarchy hypothesis. Likewise, 28 out of these 119 species are reported as restricted to a single forest type, which supports the environmental-determinism hypothesis. In general, both canopy and understorey trees and lianas showed rather similar floristic patterns across different forest types and regions.
Floristic composition and similarity of 15 hectares in Central Amazon, Brazil
Revista de biología tropical, 2011
The Amazon region is one of the most diverse areas in the world. Research on high tropical forest diversity brings up relevant contributions to understand the mechanisms that result and support such diversity. In the present study we describe the species composition and diversity of 15 one-ha plots in the Amazonian terra firme dense forest in Brazil, and compare the floristic similarity of these plots with other nine one-ha plots. The 15 plots studied were randomly selected from permanent plots at the Embrapa Experimental site, Amazonas State in 2005. The diversity was analysed by using species richness and Shannon's index, and by applying the Sorensen's index for similarity and unweighted pair-group average (UPGMA) as clustering method. Mantel test was performed to study whether the differences in species composition between sites could be explained by the geographic distance between them. Overall, we identified 8 771 individuals, 264 species and 51 plant families. Most of ...
Biodiversity and Conservation, 1998
Four hectares were inventoried for all trees with diameter at breast height (DBH) of 10 cm or greater in a terra ®rme forest 200 km Northeast of Manaus, Central Amazonia. The number of species varied from 137 to 168, the number of individuals from 639 to 713, total basal area from 32.8 to 40.2 and total biomass from 405 to 560 tons per hectare. The majority of trees, 90%, had a DBH between 10 and 30 cm. Leguminosae, Lauraceae, Sapotaceae, Chrysobalanaceae and Moraceae were the most rich families (number of species) in all sampled hectares. The most abundant families in all sampled hectares (number of trees) were Leguminosae, Burseraceae, Myristicaceae, Moraceae and Chrysobalanaceae. The most dominant families in all sampled hectares (basal area and biomass) were Leguminosae, Lecythidaceae, Chrysobalanaceae, Bombacaceae and Moraceae. Similarity indexes at family level varied from 67 to 86% between the four hectares sampled. Alexa grandi¯ora (Leguminosae) was the most abundant species in the hectares one and three, while Scleronema micranthum (Bombacaceae), and Oenocarpus bacaba (Palmae) were the most abundant species in hectares two and four. S. micranthum was the most dominant species (basal area) in hectares one and two, while Bertholletia excelsa (Lecythidaceae) and Goupia glabra (Celastraceae) were the most dominant species in hectares three and four. S. micranthum (Bombacaceae), Buchenavia sp. 2 (Combretaceae), B. excelsa (Lecythidaceae) Couepia obovata (Chrysobalanaceae) were the most dominant species (biomass) in hectares one to four, respectively. Similarity indexes at species level varied from 26 to 44% between the four sampled hectares. This inventory is compared with previous studies and it was found that, in our study area, there was a greater proportion of trees of 60 cm diameter or more and consequently a considerably higher total basal area. It is concluded that there are still an inadequate number of inventories of Amazonian terra ®rme forests to elucidate the major oristic pattern a both regional and local levels. Since the area is a mosaic of distinct¯oristic communities it is essential to obtain further standardized inventory data in order to set adequate conservation policies for the region.
2019
Background Ecotone has been defined as "a multi-dimensional environmentally stochastic interaction zone between ecological systems with characteristics defined in space and time, and by the strength of the interaction" (Hufkens et al. 2009). This is a known concept to define transitional zones between two or more ecological communities, ecosystems or biotic regions. Ecotone forests, dispersed in northern Brazilian Amazonia, are natural formations which have been largely affected by anthropogenic impacts, such as deforestation and fire. Maracá Ecological Station, State of Roraima, Brazil, is a protected area with extensive representations of ecotone forests in this region of the Amazonia. Forest inventories and floristic surveys are important as they extend our knowledge (1) of forest structure and tree species composition and (2) of tree and palm species ecology in this region of the Amazonia. Both improve our ability to predict changes in plant diversity, considering the ‡ § | ‡ ‡ ¶ # ¶ © Silva W et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. future scenarios of climate change in comparison with previous surveys performed in Maracá. New information We present a forest inventory carried out in 129 plots (10 m x 50 m; 6.45 ha in total) dispersed in a grid (5 km x 5 km) located in a forest zone ecotone in the eastern part of Maracá Ecological Station. All stems (tree + palm) with diameter at breast height ≥ 10 cm were recorded, identified and measured. A total of 3040 stems were recorded (tree = 2815; palm = 225), corresponding to 42 botanic families and 140 identified species. Seven families and 20 genera contained unidentified taxa (12.2%). Sapotaceae (735 stems; 10 species), Leguminosae (409; 24) and Rubiaceae (289; 12) were the most abundant families. Peltogyne gracilipes Ducke (Leguminosae), Pradosia surinamensis (Eyma) T.D.Penn. (Sapotaceae) and Ecclinusa guianensis Eyma (Sapotaceae) were the species with the highest importance value index (~ 25%). The dominance (m ha) of these species corresponds to > 36% of the total value observed in the forest inventory. Our dataset provides complementary floristic and structure information on tree and palm in Maracá, improving our knowledge of this Amazonian ecotone forest.