scholarly journals Integrating global patterns and drivers of tree diversity across a continuum of spatial grains

2018 ◽  
Author(s):  
Petr Keil ◽  
Jonathan M. Chase
Keyword(s):  
Species Richness ◽  
Species Turnover ◽  
Heterogeneous Data ◽  
Coarse Grain ◽  
Regional Effect ◽  
Scale Models ◽  
Efficient Integration ◽  
Biogeographic Regions ◽  
Global Patterns ◽  
Global Data

What drives biodiversity and where are the most biodiverse places on Earth? The answer critically depends on spatial scale (grain), and is obscured by lack of data and mismatches in their grain. We resolve this with cross-scale models integrating global data on tree species richness (S) from 1338 local forest surveys and 287 regional checklists, enabling estimation of drivers and patterns of biodiversity at any desired grain. We uncover grain-dependent effects of both environment and biogeographic regions on S, with a positive regional effect of Southeast Asia at coarse grain that disappears at fine grains. We show that, globally, biodiversity cannot be attributed to purely environmental or regional drivers, since regions are environmentally distinct. Finally, we predict global maps of biodiversity at two grains, identifying areas of exceptional species turnover in China, East Africa, and North America. Our cross-scale approach unifies disparate results from previous studies regarding environmental versus biogeographic predictors of biodiversity, and enables efficient integration of heterogeneous data.

scholarly journals Inferring global species richness from megatransect data and undetected species estimates

2019 ◽  
Vol 88 (1) ◽  
pp. 42-53 ◽  
Author(s):  
Bernhard A. Huber ◽  
Anne Chao
Keyword(s):  
Species Richness ◽  
New Species ◽  
Confidence Interval ◽  
Incidence Data ◽  
Total Species Richness ◽  
Species Incidence ◽  
Biogeographic Regions ◽  
Global Patterns ◽  
The Impact ◽  
Total Species

Ratio-like approaches for estimating global species richness have been criticised for their unjustified extrapolation from regional to global patterns. Here we explore the use of cumulative percentages of ‘new’ (i.e., not formally described) species over large geographic areas (‘megatransects’) as a means to overcome this problem. In addition, we take into account undetected species and illustrate these combined methods by applying them to a family of spiders (Pholcidae) that currently contains some 1,700 described species. The raw global cumulative percentage of new species (‘new’ as of the end of 2008, when 1,001 species were formally described) is 75.1%, and is relatively constant across large biogeographic regions. Undetected species are estimated using the Chao2 estimator based on species incidence data (date by species and locality by species matrices). The estimated percentage of new species based on the date by species matrices is 76.0% with an estimated standard error (s.e.) of 2.6%. This leads to an estimated global species richness of about 4,200 with a 95% confidence interval of (3,300, 5,000). The corresponding values based on locality by species matrices are 84.2% (s.e. 3.0%) and 6,300 with a 95% confidence interval of (4,000, 8,600). Our results suggest that the currently known 1,700 species of Pholcidae may represent no more than about 25–40% of the total species richness. The impact of further biasing factors like geography, species size and distribution, cryptic species, and model assumptions needs to be explored.

Biogeographical regionalisation of Colombia: a revised area taxonomy

Phytotaxa ◽  
2021 ◽  
Vol 484 (3) ◽  
pp. 247-260
Author(s):  
CARLOS E. GONZÁLEZ-OROZCO
Keyword(s):  
Cluster Analysis ◽  
Species Richness ◽  
Plant Species ◽  
Spatial Patterns ◽  
Species Turnover ◽  
Land Plants ◽  
Geospatial Analyses ◽  
Areas Of Endemism ◽  
Biogeographic Regions ◽  
Definition Of

This study proposes a biogeographical regionalisation of Colombia based on geospatial analyses of plant species turnover and a revised area taxonomy. The spatial patterns of species turnover are calculated for 20,342 plant species in continental Colombia with distributions estimated from 271,568 georeferenced records aggregated to 414 (~50 km) grid cells across Colombia. The proposed biogeographic regions are defined by applying an agglomerative cluster analysis using a matrix of pairwise Simpson’s beta (bsim) dissimilarity values. Three main centres of species richness and 25 areas of endemism were identified across Colombia, complementing the definition of regionalisation. Biogeographical regionalisation comprises two dominions (Pacific and Boreal Brazilian), six provinces (Chocó-Darién, Guajira, Magdalena, Paramo, Sabana and Imerí) and thirty-five districts. The revised area taxonomy provides an updated and objective biogeographical classification for Colombia and is the first biogeographic regionalisation exclusively based on the taxic distributional overlap of Colombia´s land plants.

scholarly journals Do carabids (Coleoptera: Carabidae) and chironomids (Diptera: Chironomidae) exhibit similar diversity and distributional patterns along a spatio-temporal gradient on a glacier foreland?

2018 ◽  
Author(s):  
Mauro Gobbi ◽  
Valeria Lencioni
Keyword(s):  
Species Richness ◽  
Species Turnover ◽  
Aquatic Insect ◽  
Taxonomic Diversity ◽  
Carabid Beetles ◽  
Species Assemblages ◽  
Glacier Foreland ◽  
Distributional Patterns ◽  
Glacier Front ◽  
Spatio Temporal

Carabid beetles and chironomid midges are two dominant cold-adapted taxa, respectively on glacier forefiel terrains and in glacial-stream rivers. Although their sensitivity to high altitude climate warming is well known, no studies compare the species assemblages exhibited in glacial systems. Our study compares diversity and distributional patterns of carabids and chironomids in the foreland of the receding Amola glacier in central-eastern Italian Alps. Carabids were sampled by pitfall traps; chironomids by kick sampling in sites located at the same distance from the glacier as the terrestrial ones. The distance from the glacier front was considered as a proxy for time since deglaciation since these variables are positively correlated. We tested if the distance from the glacier front affects: i) the species richness; ii) taxonomic diversity; and iii) species turnover. Carabid species richness and taxonomic diversity increased positively from recently deglaciated sites (those c. 160 m from the glacier front) to sites deglaciated more than 160yrs ago (those located >1300 m from glacier front). Species distributions along the glacier foreland were characterized by mutually exclusive species. Conversely, no pattern in chironomid species richness and turnover was observed. Interestingly, taxonomic diversity increased significantly: closely related species were found near the glacier front, while the most taxonomically diverse species assemblages were found distant from the glacier front. Increasing glacial retreat differently affect epigeic and aquatic insect taxa: carabids respond faster to glacier retreat than do chironomids, at least in species richness and species turnover patterns.

Community characteristics of forest understory birds along an elevational gradient in the Horn of Africa: A multi-year baseline

The Condor ◽  
2021 ◽  
Author(s):  
Kyle D Kittelberger ◽  
Montague H C Neate-Clegg ◽  
Evan R Buechley ◽  
Çağan Hakkı Şekercioğlu
Keyword(s):  
Species Richness ◽  
Species Turnover ◽  
Survival Rates ◽  
Elevational Gradient ◽  
Forest Understory ◽  
Bird Abundance ◽  
Tropical Mountains ◽  
Demographic Rates ◽  
Understory Birds ◽  
Over Time

Abstract Tropical mountains are global hotspots for birdlife. However, there is a dearth of baseline avifaunal data along elevational gradients, particularly in Africa, limiting our ability to observe and assess changes over time in tropical montane avian communities. In this study, we undertook a multi-year assessment of understory birds along a 1,750 m elevational gradient (1,430–3,186 m) in an Afrotropical moist evergreen montane forest within Ethiopia’s Bale Mountains. Analyzing 6 years of systematic bird-banding data from 5 sites, we describe the patterns of species richness, abundance, community composition, and demographic rates over space and time. We found bimodal patterns in observed and estimated species richness across the elevational gradient (peaking at 1,430 and 2,388 m), although no sites reached asymptotic species richness throughout the study. Species turnover was high across the gradient, though forested sites at mid-elevations resembled each other in species composition. We found significant variation across sites in bird abundance in some of the dietary and habitat guilds. However, we did not find any significant trends in species richness or guild abundances over time. For the majority of analyzed species, capture rates did not change over time and there were no changes in species’ mean elevations. Population growth rates, recruitment rates, and apparent survival rates averaged 1.02, 0.52, and 0.51 respectively, and there were no elevational patterns in demographic rates. This study establishes a multi-year baseline for Afrotropical birds along an elevational gradient in an under-studied international biodiversity hotspot. These data will be critical in assessing the long-term responses of tropical montane birdlife to climate change and habitat degradation.

scholarly journals Global patterns and drivers of alpine plant species richness

2021 ◽  
Author(s):  
Riccardo Testolin ◽  
Fabio Attorre ◽  
Peter Borchardt ◽  
Robert F. Brand ◽  
Helge Bruelheide ◽  
...  
Keyword(s):  
Species Richness ◽  
Plant Species ◽  
Plant Species Richness ◽  
Alpine Plant ◽  
Global Patterns

Diversity metrics, species turnovers and nestedness of bird assemblages in a deep karst sinkhole

2017 ◽  
Vol 63 (2) ◽  
pp. 8-16 ◽  
Author(s):  
Corrado Battisti ◽  
Marco Giardini ◽  
Francesca Marini ◽  
Lorena Di Rocco ◽  
Giuseppe Dodaro ◽  
...  
Keyword(s):  
Species Richness ◽  
Random Distribution ◽  
Diversity Index ◽  
Species Turnover ◽  
Floristic Composition ◽  
Bird Assemblages ◽  
Β Diversity ◽  
Stick Model ◽  
Karst Sinkhole

We reported a study on breeding birds occurring inside an 80 m-deep karst sinkhole, with the characterization of the assemblages recorded along its semi-vertical slopes from the upper edge until the bottom. The internal sides of the sinkhole have been vertically subdivided in four belts about 20 m high. The highest belt (at the upper edge of the cenote) showed the highest values in mean number of bird detections, mean and normalized species richness, and Shannon diversity index. The averaged values of number of detections and species richness significantly differ among belts. Species turnover (Cody’s β-diversity) was maximum between the highest belts. Whittaker plots showed a marked difference among assemblages shaping from broken-stick model to geometric series, and explicited a spatial progressive stress with a disruption in evenness towards the deepest belts. Bird assemblages evidenced a nested subset structure with deeper belts containing successive subsets of the species occurring in the upper belts. We hypothesize that, at least during the daytime in breeding season, the observed non-random distribution of species along the vertical stratification is likely due to (i) the progressive simplification both of the floristic composition and vegetation structure, and (ii) the paucity of sunlight as resources from the upper edge to the inner side of the cenote.

scholarly journals The conservation value of South East Asia's highly degraded forests: evidence from leaf-litter ants

2011 ◽  
Vol 366 (1582) ◽  
pp. 3256-3264 ◽  
Author(s):  
Paul Woodcock ◽  
David P. Edwards ◽  
Tom M. Fayle ◽  
Rob J. Newton ◽  
Chey Vun Khen ◽  
...  
Keyword(s):  
Species Richness ◽  
Leaf Litter ◽  
Oil Palm ◽  
Species Turnover ◽  
Spatial Scales ◽  
Forest Conversion ◽  
Conservation Value ◽  
Natural Forests ◽  
Ant Communities ◽  
Logged Forest

South East Asia is widely regarded as a centre of threatened biodiversity owing to extensive logging and forest conversion to agriculture. In particular, forests degraded by repeated rounds of intensive logging are viewed as having little conservation value and are afforded meagre protection from conversion to oil palm. Here, we determine the biological value of such heavily degraded forests by comparing leaf-litter ant communities in unlogged (natural) and twice-logged forests in Sabah, Borneo. We accounted for impacts of logging on habitat heterogeneity by comparing species richness and composition at four nested spatial scales, and examining how species richness was partitioned across the landscape in each habitat. We found that twice-logged forest had fewer species occurrences, lower species richness at small spatial scales and altered species composition compared with natural forests. However, over 80 per cent of species found in unlogged forest were detected within twice-logged forest. Moreover, greater species turnover among sites in twice-logged forest resulted in identical species richness between habitats at the largest spatial scale. While two intensive logging cycles have negative impacts on ant communities, these degraded forests clearly provide important habitat for numerous species and preventing their conversion to oil palm and other crops should be a conservation priority.

scholarly journals Flower‐visitor communities of an arcto‐alpine plant—Global patterns in species richness, phylogenetic diversity and ecological functioning

2018 ◽  
Vol 28 (2) ◽  
pp. 318-335 ◽  
Author(s):  
Mikko Tiusanen ◽  
Tea Huotari ◽  
Paul D. N. Hebert ◽  
Tommi Andersson ◽  
Ashley Asmus ◽  
...  
Keyword(s):  
Species Richness ◽  
Phylogenetic Diversity ◽  
Alpine Plant ◽  
Flower Visitor ◽  
Global Patterns ◽  
Ecological Functioning

scholarly journals Changes of arthropod diversity across an altitudinal ecoregional zonation in Northwestern Argentina

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e4117 ◽  
Author(s):  
Andrea X. González-Reyes ◽  
Jose A. Corronca ◽  
Sandra M. Rodriguez-Artigas
Keyword(s):  
Species Richness ◽  
Polynomial Regression ◽  
Species Turnover ◽  
Predictor Variable ◽  
Elevational Gradient ◽  
Pitfall Trap ◽  
Northwestern Argentina ◽  
Higher Taxa ◽  
Total Species Richness ◽  
Wide Range

This study examined arthropod community patterns over an altitudinal ecoregional zonation that extended through three ecoregions (Yungas, Monte de Sierras y Bolsones, and Puna) and two ecotones (Yungas-Monte and Prepuna) of Northwestern Argentina (altitudinal range of 2,500 m), and evaluated the abiotic and biotic factors and the geographical distance that could influence them. Pitfall trap and suction samples were taken seasonally in 15 sampling sites (1,500–4,000 m a.s.l) during one year. In addition to climatic variables, several soil and vegetation variables were measured in the field. Values obtained for species richness between ecoregions and ecotones and by sampling sites were compared statistically and by interpolation–extrapolation analysis based on individuals at the same sample coverage level. Effects of predictor variables and the similarity of arthropods were shown using non-metric multidimensional scaling, and the resulting groups were evaluated using a multi-response permutation procedure. Polynomial regression was used to evaluate the relationship between altitude with total species richness and those of hyperdiverse/abundant higher taxa and the latter taxa with each predictor variable. The species richness pattern displayed a decrease in species diversity as the elevation increased at the bottom wet part (Yungas) of our altitudinal zonation until the Monte, and a unimodal pattern of diversity in the top dry part (Monte, Puna). Each ecoregion and ecotonal zone evidenced a particular species richness and assemblage of arthropods, but the latter ones displayed a high percentage of species shared with the adjacent ecoregions. The arthropod elevational pattern and the changes of the assemblages were explained by the environmental gradient (especially the climate) in addition to a geographic gradient (the distance of decay of similarity), demonstrating that the species turnover is important to explain the beta diversity along the elevational gradient. This suggests that patterns of diversity and distribution of arthropods are regulated by the dissimilarity of ecoregional environments that establish a wide range of geographic and environmental barriers, coupled with a limitation of species dispersal. Therefore, the arthropods of higher taxa respond differently to the altitudinal ecoregional zonation.

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