Soil and climate equally contribute to changes in the species compositions of Brazilian dry forests across 300 km

2020 ◽  
Vol 13 (2) ◽  
pp. 171-176
Author(s):  
Daniel M Arruda ◽  
Luiz F S Magnago ◽  
Ricardo R C Solar ◽  
Reinaldo Duque-Brasil ◽  
Priscyla M S Rodrigues ◽  
...  
Keyword(s):  
Spatial Structure ◽  
Species Composition ◽  
Beta Diversity ◽  
Species Turnover ◽  
Spatial Scales ◽  
Dry Forest ◽  
Conservation Strategies ◽  
Dry Forests ◽  
Forest Patches ◽  
Forest Diversity

Abstract Aims Understanding the factors that control biodiversity distributions at different spatial scales has been a key challenge for conservation efforts. That biodiversity, reflected in differences in species compositions among sites (beta diversity), can be derived from species replacement (turnover) and is driven by multiple factors. Here, we sought to tackle this issue through two questions related to threatened Brazilian seasonally dry forests: (i) what is the contribution of species turnover to beta diversity? and (ii) which factors drive variations in species compositions among forest patches? Methods We sampled tree species and environmental variables (soils and climate) in 17 dry forest patches spaced almost 300 km apart. We used the beta diversity partitioning framework to determine the contribution of turnover. We used redundancy analysis, with properly controlled spatial structure, to assess the contributions of the environmental and spatial factors to the variations of the species composition. Important Findings Beta diversity among the patches was mainly represented by the turnover component (98.2%), with Simpson dissimilarity superior to other regions of the country (means of 0.89 and 0.71 in multiple site and pairwise measures, respectively). The environmental factors measured explained more than space, representing 30.3% of the variation of the species composition, of which 28.1% was nonspatially structured. We suggest that 300 km represents a threshold at which edaphic and climatic predictors have similar effects in determining community turnover (14.9% and 12.6%, respectively, without spatial structure). Thus, conservation strategies should be considered across landscapes to effectively protect tropical forest diversity, as even considering the different climatic aspects covered by the scale, landscaped edaphic varieties are important drivers of species turnover.

scholarly journals Squamata reptiles of a fragment of tropical dry forest in northwestern Venezuela (Lake Maracaibo region)

Check List ◽  
2012 ◽  
Vol 8 (6) ◽  
pp. 1220 ◽  
Author(s):  
Junior T. Larreal ◽  
Gilson A. Rivas ◽  
Carlos Portillo-Quintero ◽  
Tito R. Barros
Keyword(s):  
Species Composition ◽  
San Francisco ◽  
Tropical Dry Forest ◽  
Single Species ◽  
Dry Forest ◽  
Forest Fragment ◽  
Dry Forests ◽  
Maracaibo Basin ◽  
Lake Maracaibo

We present a commented taxonomic list of the reptiles found during herpetological surveys carried out in an isolated fragment of tropical dry forest located in the municipality of San Francisco, Zulia state, northwestern Venezuela between January-December 2011. We report a total of 24 species belonging to the order Squamata, distributed in 12 families and 21 genera. Colubridae is the most diverse family with six species, followed by Dipsadidae (four species), Boidae, Gymnophthalmidae, Phyllodactylidae and Teiidae with two species each, and finally Dactyloidae, Iguanidae, Elapidae, Gekkonidae, Sphaerodactylidae and Viperidae with a single species each. The species composition at this site matches what would be expected in a tropical dry forest in the region. Our study suggests that this isolated tropical dry forest fragment is the last refuge of the herpetofauna that once occupied much of the dry forests of the northern Maracaibo basin and should therefore be considered for conservation purposes.

scholarly journals Beta Diversity Partitioning and Drivers of Variations in Fish Assemblages in a Headwater Stream: Lijiang River, China

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 680 ◽  
Author(s):  
Liangliang Huang ◽  
Jian Huang ◽  
Zhiqiang Wu ◽  
Yuanmin Mo ◽  
Qi Zou ◽  
...  
Keyword(s):  
Species Composition ◽  
Beta Diversity ◽  
Fish Assemblages ◽  
Headwater Streams ◽  
Species Turnover ◽  
Diversity Partitioning ◽  
Spatial Variables ◽  
Lijiang River ◽  
Abiotic Variables ◽  
Hydrological Variables

Beta diversity partitioning has currently received much attention in research of fish assemblages. However, the main drivers, especially the contribution of spatial and hydrological variables for species composition and beta diversity of fish assemblages are less well studied. To link species composition to multiple abiotic variables (i.e., local environmental variables, hydrological variables, and spatial variables), the relative roles of abiotic variables in shaping fish species composition and beta diversity (i.e., overall turnover, replacement, and nestedness) were investigated in the upstream Lijiang River. Species composition showed significant correlations with environmental, hydrological, and spatial variables, and variation partitioning revealed that the local environmental and spatial variables outperformed hydrological variables, and especially abiotic variables explained a substantial part of the variation in the fish composition (43.2%). The overall species turnover was driven mostly by replacement (87.9% and 93.7% for Sørensen and Jaccard indices, respectively) rather than nestedness. Mantel tests indicated that the overall species turnover (ßSOR and ßJAC) and replacement (ßSIM and ßJTU) were significantly related to hydrological, environmental, and spatial heterogeneity, whereas nestedness (ßSNE or ßJNE) was insignificantly correlated with abiotic variables (P > 0.05). Moreover, the pure effect of spatial variables on overall species turnover (ßSOR and ßJAC) and replacement (ßSIM and ßJTU), and the pure effect of hydrological variables on replacement (ßSIM and ßJTU), were not important (P > 0.05). Our findings demonstrated the relative importance of interactions among environmental, hydrological, and spatial variables in structuring fish assemblages in headwater streams; these fish assemblages tend to be compositionally distinct, rather than nested derivatives of one another. Our results, therefore, indicate that maintaining natural flow dynamics and habitat continuity are of vital importance for conservation of fish assemblages and diversity in headwater streams.

scholarly journals Livestock grazing-induced large-scale biotic homogenization in arid Mediterranean steppe rangelands

2021 ◽  
Author(s):  
Merdas Saifi ◽  
Yacine Kouba ◽  
Tewfik Mostephaoui ◽  
Yassine Farhi ◽  
Haroun Chenchouni
Keyword(s):  
Species Composition ◽  
Spatial Scale ◽  
Plant Communities ◽  
Beta Diversity ◽  
Large Scale ◽  
Management Practices ◽  
Species Turnover ◽  
Livestock Grazing ◽  
Biotic Homogenization ◽  
Arid Steppe

Despite many studies explored the effect of livestock grazing on plant communities, the response of species composition and diversity to livestock grazing in arid rangelands remain ambiguous. This study examined the effects of livestock grazing on plant communities in arid steppe rangelands of North Africa. Plant diversity of annual species, perennial species and all species combined was measured and compared between grazed and grazing-excluded areas. We also examined the relative importance of species turnover and community nestedness. Moreover, the effects of livestock grazing on beta diversity at local among transects and landscape among sites scales were examined using the multiplicative diversity partitioning. Results revealed that livestock grazing significantly decreased the alpha diversity of all species combined and the diversity of annual plants. Livestock grazing induced a shift in plant community composition where most of species composition variation (~74%) was due to infrequent species replacement ‘turnover’ between the two management types rather than nestedness (~26%). Results revealed also that among transects, beta diversity was higher in grazed steppes than in grazing-excluded steppes. Whereas, among sites, beta diversity was lower in grazed steppes compared to grazing-excluded steppes. These findings suggest that livestock grazing in arid steppe rangelands increases the variation in plant species composition at a local spatial scale and engenders vegetation homogeneity at landscape spatial scale. Therefore, the implementation of appropriate management practices such as short-term grazing exclusion is mandatory to prevent these ecosystems from large scale biotic homogenization.

scholarly journals Environmental DNA reveals the fine-grained and hierarchical spatial structure of kelp forest fish communities

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thomas Lamy ◽  
Kathleen J. Pitz ◽  
Francisco P. Chavez ◽  
Christie E. Yorke ◽  
Robert J. Miller
Keyword(s):  
Beta Diversity ◽  
Aquatic Ecosystems ◽  
Species Turnover ◽  
Spatial Scales ◽  
Regional Scale ◽  
Kelp Forest ◽  
Fish Communities ◽  
Environmental Dna ◽  
Underwater Visual Census ◽  
Rocky Reefs

AbstractBiodiversity is changing at an accelerating rate at both local and regional scales. Beta diversity, which quantifies species turnover between these two scales, is emerging as a key driver of ecosystem function that can inform spatial conservation. Yet measuring biodiversity remains a major challenge, especially in aquatic ecosystems. Decoding environmental DNA (eDNA) left behind by organisms offers the possibility of detecting species sans direct observation, a Rosetta Stone for biodiversity. While eDNA has proven useful to illuminate diversity in aquatic ecosystems, its utility for measuring beta diversity over spatial scales small enough to be relevant to conservation purposes is poorly known. Here we tested how eDNA performs relative to underwater visual census (UVC) to evaluate beta diversity of marine communities. We paired UVC with 12S eDNA metabarcoding and used a spatially structured hierarchical sampling design to assess key spatial metrics of fish communities on temperate rocky reefs in southern California. eDNA provided a more-detailed picture of the main sources of spatial variation in both taxonomic richness and community turnover, which primarily arose due to strong species filtering within and among rocky reefs. As expected, eDNA detected more taxa at the regional scale (69 vs. 38) which accumulated quickly with space and plateaued at only ~ 11 samples. Conversely, the discovery rate of new taxa was slower with no sign of saturation for UVC. Based on historical records in the region (2000–2018) we found that 6.9 times more UVC samples would be required to detect 50 taxa compared to eDNA. Our results show that eDNA metabarcoding can outperform diver counts to capture the spatial patterns in biodiversity at fine scales with less field effort and more power than traditional methods, supporting the notion that eDNA is a critical scientific tool for detecting biodiversity changes in aquatic ecosystems.

scholarly journals Beta diversity and knowledge gaps of Colombia’s dry forests: implications for their conservation

Caldasia ◽  
2019 ◽  
Vol 41 (1) ◽  
pp. 1-11
Author(s):  
Gustavo H. Kattan ◽  
Camilo E. Sánchez ◽  
Catalina Vélez ◽  
Laura Ramírez ◽  
Marcela Celis
Keyword(s):  
Seed Dispersal ◽  
Beta Diversity ◽  
Secondary Succession ◽  
Research Effort ◽  
Dry Forest ◽  
Caribbean Region ◽  
Dry Forests ◽  
Ecological Processes ◽  
Frugivorous Birds ◽  
Continental Scale

On a continental scale, Neotropical dry forests exhibit high plant beta diversity, forming twelve unique floristic provinces. Conserving this diversity requires plans to protect areas in each province, based on an understanding of their particular ecological conditions. In Colombia dry forest occurs in seven regions. We explored some challenges for conserving beta diversity at the country scale by downscaling the analysis and framing it in the context of the general knowledge status of the country’s dry forests, and particularly of seed dispersal. Our literature review revealed 178 studies, with an increase in publication rate in recent years. The Cauca Valley and the Caribbean region had the most publications. More than half of studies were species inventories of plants, birds, and bats, whereas only ten studies dealt with plant-animal interactions and five with secondary succession. Analyses on plants, birds, and bats revealed high levels of dissimilarity among regions. One-half of plant species in Colombia´s dry forests are dispersed by birds and mammals. Large-sized frugivorous birds and mammals are absent from remaining forest patches, which may negatively affect patterns of seed dispersal and secondary succession. Understanding the ecological and biogeographic factors at several scales, supported by local knowledge of the ecological processes that contribute to forest integrity, is key for the conservation of the unique and distinctive species composition of regional assemblages. A coordinated research effort that integrates knowledge of ecological processes at local to national scales is a priority.

scholarly journals Aspergillus and Penicillium (Eurotiales: Trichocomaceae) in soils of the Brazilian tropical dry forest: diversity in an area of environmental preservation

2016 ◽  
Vol 64 (1) ◽  
pp. 45 ◽  
Author(s):  
Renan Do Nascimento Barbosa ◽  
Jadson Diogo Pereira Bezerra ◽  
Phelipe Manoel Oller Costa ◽  
Nelson Correia de Lima-Júnior ◽  
Ivana Roberta Gomes Alves de Souza Galvão ◽  
...  
Keyword(s):  
Tropical Dry Forest ◽  
Culture Collection ◽  
Soil Samples ◽  
Dry Forest ◽  
Dry Forests ◽  
Complex Biological System ◽  
Environmental Preservation ◽  
Forest Diversity ◽  
Sabouraud Agar ◽  
Evenness Indices

Soil is a complex biological system that plays a key role for plants and animals, especially in dry forests such as the Caatinga. Fungi from soils, such as Aspergillus and Penicillium, can be used as bioindicators for biodiversity conservation. The aim of this study was to isolate and identify species of Aspergillus and Penicillium in soil, from the municipalities of Tupanatinga and Ibimirim, with dry forests, in the Catimbau National Park. Five collections were performed in each area during the drought season of 2012, totaling 25 soil samples per area. Fungi were isolated by suspending soil samples in sterile distilled water and plating on Sabouraud Agar media plus Chloramphenicol and Rose Bengal, and Glycerol Dicloran Agar. Isolates were identified by morphological taxonomy in the Culture Collection Laboratory and confirmed by sequencing of the Internal Transcribed Spacer of rDNA. A total of 42 species were identified, of which 22 belong to the genus Aspergillus and 20 to Penicillium. Penicillium isolates showed uniform distribution from the collecting area in Tupanatinga, and the evenness indices found were 0.92 and 0.88 in Tupanatinga and Ibimirim, respectively. Among isolates of Aspergillus evenness, the value found in Tupanatinga (0.85) was very close to that found in Ibimirim (0.86). High diversity and low dominance of fungi in soil samples was observed. These results contributed to the estimation of fungal diversity in dry environments of the Caatinga, where diversity is decreasing in soils that have undergone disturbance.

Abundance of Panamanian dry-forest birds along gradients of forest cover at multiple scales

2009 ◽  
Vol 26 (1) ◽  
pp. 67-78 ◽  
Author(s):  
Jesse R. Lasky ◽  
Timothy H. Keitt
Keyword(s):  
Forest Cover ◽  
Multiple Scales ◽  
Spatial Scales ◽  
Habitat Associations ◽  
Forest Birds ◽  
Dry Forest ◽  
Forest Species ◽  
Dry Forests ◽  
Open Habitat ◽  
Forest Coverage

Abstract:Community structure and species’ abundances may be strongly correlated to patterns of forest cover, although such patterns are poorly known for tropical dry-forest birds, especially for those in Panamanian dry forests. Birds were distance-sampled during point counts in five dry-forest fragments in Panama. Distance from point count to forest edge and forest coverage at three spatial scales (500, 1000 and 2000-m radius) were compared as covariate predictors of the abundance of avian species and guilds. Each covariate was selected in at least two models of species or guild abundance. Abundance patterns were consistent with previously reported habitat associations for only two of seven open-habitat or forest-preferring species that showed forest cover-abundance relationships. Null models best described the abundance of all forest species and the subset of uncommon forest species. Thus many of these species appear insensitive to the forest-cover gradients studied. Total abundance of open-habitat-preferring species increased in dry forests with increasing forest coverage within 500 m, suggesting that the relationship between their abundance and vegetation structure are spatial-scale and habitat dependent. Nectarivores had lower abundance as forest cover within 1000 m increased, supporting previous claims that this group is tolerant of forest edges.

Partitioning beta diversity to unravel mechanisms underlying the distributions of nonvolant small mammls in Brazil’s Cerrado

2020 ◽  
Author(s):  
Raquel Ribeiro ◽  
Robert E Ricklefs ◽  
Jader Marinho-Filho
Keyword(s):  
Small Mammals ◽  
Beta Diversity ◽  
Large Scale ◽  
Spatial Configuration ◽  
Species Turnover ◽  
Spatial Scales ◽  
Species Distributions ◽  
Habitat Specificity ◽  
Species Sorting ◽  
Cerrado Biome

Abstract Species distributions and the mechanisms that produce patterns in the occupation space are recurrent themes in community ecology. Here, we examine beta diversity among assemblages of small mammals in the Cerrado domain of Brazil to partition the effects of turnover and nestedness on species distributions. Our objective was to evaluate whether balanced spatial variation in abundance (β bal) and abundance gradients (β gra) are congruent within and among habitats and localities of the Brazilian Cerrado. In addition, we wanted to understand whether ecological mechanisms, such as dispersal limitation, habitat filtering, and species sorting, drive the distribution patterns of the Cerrado small mammals. We analyzed the occurrence and abundances of small mammals from 16 localities widely distributed across the Cerrado biome, and grouped our data with respect to two distinct spatial scales. Baselga’s Bray–Curtis index of dissimilarity and its respective partitions, i.e., balanced variation in abundance (β bal) and abundance gradients (β gra), were estimated between sampling units at the two spatial scales. Thus, we used exponential models to search for distance decay in species similarity between pairs of localities and between similar habitats. Our results show that differences between small mammal assemblages in the Cerrado are driven mainly by species replacement rather than independent gain or loss of species, both at small and large scales. The spatial turnover patterns of small mammals in the Cerrado biome are determined by a combination of large scale (biogeographic, spatial) and local mechanisms (low dispersal and habitat specificity). However, processes occurring at small scales seem to be more important in species sorting than processes occurring at large scales. The spatial configuration of the landscape and the extent and quality of habitats strongly influence the rate of species turnover in Cerrado. Thus, protecting the different types of habitats should be of prime importance to conserving the diversity of Cerrado small mammals.

Geographic distribution, large-scale spatial structure and diversity of parasitoids of the seed-feeding beetleAcanthoscelides macrophthalmus

2016 ◽  
Vol 107 (3) ◽  
pp. 322-331 ◽  
Author(s):  
A. Wood ◽  
E.B. Haga ◽  
V.A. Costa ◽  
M.N. Rossi
Keyword(s):  
Species Richness ◽  
Spatial Structure ◽  
Species Composition ◽  
Geographic Distribution ◽  
Large Scale ◽  
Current Knowledge ◽  
Spatial Scales ◽  
Species Abundance ◽  
Geographic Area ◽  
Parasitoid Species

AbstractBruchine beetles are highly host-specific seed feeders during the larval stage. Although some specific parasitoid families have been recorded attacking bruchine beetles, most studies have been done at small spatial scales. Therefore, the current knowledge about the diversity and the geographic distribution of parasitoid species parasitizing bruchines is scarce, especially at a wide geographic area that extends over large distances through a latitudinal cline (i.e. large-scale spatial structure). The present study determined the species richness and evenness of parasitoids attacking the bruchine beetleAcanthoscelides macrophthalmusfeeding onLeucaena leucocephalaseeds, examined their geographic distribution, and characterized the large-scale spatial structure in parasitoid species composition. A total of 1420 parasitoids (all Hymenoptera) belonging to four families, five subfamilies and eight species were collected (genera:Horismenus, Paracrias, Urosigalphus, Stenocorse, Chryseida, Eupelmus). Most parasitoid species showed wide spatial distribution, high evenness in species abundance and the species richness estimators were close to stabilization (approximately eight species). Overall, greater similarity was observed in the species composition of plant populations near to each other than those farther apart, revealing a large-scale spatial structure in parasitoid species composition.

scholarly journals Environmental heterogeneity explains species turnover but not nestedness in fish assemblages of a Neotropical basin

2017 ◽  
Vol 29 (0) ◽  
Author(s):  
Oscar Eduardo Peláez ◽  
Filipe Manoel Azevedo ◽  
Carla Simone Pavanelli
Keyword(s):  
Species Composition ◽  
Beta Diversity ◽  
Environmental Variables ◽  
Environmental Heterogeneity ◽  
Fish Assemblages ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Paraná River ◽  
Fish Diversity ◽  
Parana River

Abstract Aim: Heterogenous environments can contribute to maintain biodiversity. Traditionally beta diversity studies have focused on determining the effect of environmental variables on the total dissimilarity of species composition. However, decomposing beta diversity in species replacement and nestedness could give new insights on mechanisms affecting spatial patterns of biodiversity. We aimed to answer two main questions about spatial patterns of fish diversity in a Neotropical basin: 1) whether some regions contribute differently to fish diversity, and 2) whether species turnover and nestedness are explained by environmental gradients. Methods Sampling sites in the main channel and tributaries of the Upper Paraná River were sampled between 2013 and 2015. We partitioned beta diversity and tested the relationship of turnover and nestedness with environmental variables. Results 74 species were captured. Some of these species were restricted to different sites, contributing to variation in species composition. Hill numbers showed a trend for higher diversity in the tributaries than in Paraná River sampling sites, and the partition of beta diversity revealed that species replacement drove dissimilarity in species composition. Only total beta diversity and turnover were related to environmental variables, mainly conductivity and turbidity. Conclusions Species diversity and composition of fish assemblages in the Upper Paraná River could be related to environmental gradients. Overall, our results suggest that Paraná River tributaries contribute to increase environmental heterogeneity, and hence to maintain a high diversity and variation in species composition. For that reason, we strongly recommend preserving highly heterogeneous habitats in the region.

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