Diversity Patterns of Woody Species on a Latitudinal Transect From the Monsoon Tropics to Desert in the Northern Territory, Australia

1996 ◽  
Vol 44 (5) ◽  
pp. 571 ◽  
Author(s):  
DMJS Bowman
Keyword(s):  
Beta Diversity ◽  
Alpha Diversity ◽  
Woody Species ◽  
Northern Territory ◽  
Annual Rainfall ◽  
North Coast ◽  
Diversity Patterns ◽  
Latitudinal Transect ◽  
The Mean ◽  
Central Australia

A belt transect, made up of 15 contiguous cells (width, 3.5° of longitude; length, 1° of latitude), was established from the monsoon tropics on the central north coast of the Northern Temtory (11°S) to the central Australian desert on the South Australian border (26°S). On this transect, mean annual rainfall was found to have a negative exponential decay with latitude, with arid conditions commencing at around 18"s-the limit of the monsoonal rains. The mean elevation of each cell steadily increased from the north coast to reach a maximum average elevation of 700 m at around 23°S. The mean alphadiversity (quadrat species richness), and mean beta-diversity (turnover of species along an environmental gradient) was determined for each of the 15 cells by sub-sampling a large 20 × 20 m quadrat data set (N > 2000) collected during the course of the Northern Territory 1:106 vegetation mapping program. It was found that there was little within-cell variation of beta-diversity of woody species which occurred in at least five quadrats, as approximated by the first axis of a detrended correspondence analysis (DCA) of these data. The mean first axis DCA scores were strongly correlated with latitude (r = 0.99); thus, there is no evidence for a floristic disjunction in the composition of common woody species between the monsoon tropics and desert. Mean alpha-diversity had a bimodal distribution on the latitudinal transect, with the maximum mean quadrat richness in the monsoon tropics and a second smaller peak occurred in central Australia, with the lowest levels of alpha-diversity to the south of the limit of the monsoon rains. This pattern was mirrored by the mean number and mean Shannon-Wiener diversity of 1:106 vegetation map units on the transect. It was found that 81% of the variance of mean alpha-diversity was explained by mean annual rainfall and mean elevation for the 15 cells. The increase in mean alpha-diversity in central Australia appears to be related to environmental heterogeneity associated with mountainous terrain. It is possible that the central Australian mountains are a refuge for plants that were more widespread during the last ice-age. It is unknown whether the woody species diversity patterns are in equilibrium with the prevailing climate. More data on the palaeo-environments of the Northern Territory are required to answer this question.

Environmental correlates of herpetofaunal diversity in Costa Rica

2010 ◽  
Vol 26 (5) ◽  
pp. 521-531 ◽  
Author(s):  
David Laurencio ◽  
Lee A. Fitzgerald
Keyword(s):  
Costa Rica ◽  
Species Diversity ◽  
Beta Diversity ◽  
Geographic Distance ◽  
Alpha Diversity ◽  
High Elevation ◽  
Diversity Patterns ◽  
Regional Diversity ◽  
Environmental Correlates ◽  
High Elevation Site

Abstract:Disentangling local and historical factors that determine species diversity patterns at multiple spatial scales is fundamental to elucidating processes that govern ecological communities. Here we investigated how environmental correlates may influence diversity at local and regional scales. Primarily utilizing published species lists, amphibian and reptile alpha and beta diversity were assessed at 17 well-surveyed sites distributed among ecoregions throughout Costa Rica. The degree to which regional species diversity patterns were related to environmental variables and geographic distance was determined using Canonical Correspondence Analysis and Mantel tests. Amphibian alpha diversity was highest in lowland Pacific sites (mean = 43.3 species) and lowest at the high elevation site (9 species). Reptile alpha diversity values were high for both lowland Atlantic (mean = 69.5 species) and lowland Pacific (mean = 67 species) sites and lowest for the high elevation site (8 species). We found high species turnover between local sites and ecoregions, demonstrating the importance of beta diversity in the determination of regional diversity. For both amphibians and reptiles, beta diversity was highest between the high-elevation site and all others, and lowest among lowland sites within the same ecoregion. The effect of geographic distance on beta diversity was minor. Ecologically significant climatic variables related to rain, temperature, sunshine and insolation were found to be important determinants of local and regional diversity for both amphibians and reptiles in Costa Rica.

scholarly journals Robust, data-driven bioregionalizations emerge from diversity concordance

2021 ◽  
Author(s):  
Cristian S. Montalvo-Mancheno ◽  
Jessie Buettel ◽  
Stefania Ondei ◽  
Barry W. Brook
Keyword(s):  
Species Diversity ◽  
Beta Diversity ◽  
Alpha Diversity ◽  
Data Driven ◽  
Conservation Units ◽  
Conservation Action ◽  
Diversity Patterns ◽  
Alpha And Beta Diversity ◽  
Terrestrial Vertebrates ◽  
Site Diversity

Aim: Despite the increasing interest in developing new bioregionalizations and assessing the most widely accepted biogeographic frameworks, no study to date has sought to systematically define a system of small bioregions nested within larger ones that better reflect the distribution and patterns of biodiversity. Here, we examine how an algorithmic, data-driven model of diversity patterns can lead to an ecologically interpretable hierarchy of bioregions. Location: Australia. Time period: Present. Major taxa studied: Terrestrial vertebrates and vascular plants. Methods: We compiled information on the biophysical characteristics and species occupancy of Australia′s geographic conservation units (bioregions). Then, using cluster analysis to identify groupings of bioregions representing optimal discrete-species areas, we evaluated what a hierarchical bioregionalization system would look like when based empirically on the within- and between-site diversity patterns across taxa. Within an information-analytical framework, we then assessed the degree to which the World Wildlife Fund′s (WWF) biomes and ecoregions and our suite of discrete-species areas are spatially associated and compared those results among bioregionalization scenarios. Results: Information on biodiversity patterns captured was moderate for WWF′s biomes (50–58% for birds′ beta, and plants′ alpha and beta diversity, of optimal discrete areas, respectively) and ecoregions (additional 4–25%). Our plants and vertebrate optimal areas retained more information on alpha and beta diversity across taxa, with the two algorithmically derived biogeographic scenarios sharing 86.5% of their within- and between-site diversity information. Notably, discrete-species areas for beta diversity were parsimonious with respect to those for alpha diversity. Main conclusions: Nested systems of bioregions must systematically account for the variation of species diversity across taxa if biodiversity research and conservation action are to be most effective across multiple spatial or temporal planning scales. By demonstrating an algorithmic rather than subjective method for defining bioregionalizations using species-diversity concordances, which reliably reflects the distributional patterns of multiple taxa, this work offers a valuable new tool for systematic conservation planning.

scholarly journals Diversity of epiphyte ferns along an elevational gradient in El Triunfo Biosphere Reserve, southern Mexico

2020 ◽  
Vol 153 (1) ◽  
pp. 12-21
Author(s):  
Derio A. Jiménez-López ◽  
Rubén Martínez-Camilo ◽  
Nayely Martínez-Meléndez ◽  
Michael Kessler
Keyword(s):  
Linear Regression ◽  
Beta Diversity ◽  
Species Turnover ◽  
Cloud Forest ◽  
Alpha Diversity ◽  
Elevational Gradient ◽  
Mountain Range ◽  
Southern Mexico ◽  
Diversity Patterns ◽  
Individual Trees

Background and aims – In the tropics, some studies have found that the richness of epiphytic ferns present a peak at mountain mid-elevations. However, it is not well understood how transitions from tropical to subtropical conditions affect this peak, and even less is known about beta diversity of epiphytic ferns. Thus, the objective is to understand the effect of climatic gradients on the variation of local richness of ferns and beta diversity patterns along an elevational gradient in a mountain system in southern Mexico.Methods – We sampled 32 trees, each in four elevational bands (100–2200 m). Alpha diversity patterns were analysed using linear regression models. We used the Morisita index to quantify species turnover between bands. An additive partitioning approach was used to analyse the degree to which individual trees, plots, and bands contributed to total species richness. We evaluated the influence of climatic variables on species composition via linear regression models.Key results – A total of 30 species in five families were recorded. Each family contributed in different magnitude to the elevational richness pattern, with Polypodiaceae dominating due to its richness and presence along the entire transect. Alpha diversity at the three scales (αtree, αplot, αband) increased with elevation and rainfall, and with decreasing temperature. Species turnover was high along the gradient, but was scale-dependent, with βtransect (65–75%) and βband (14%) with the greatest contributing to total diversity. Although the contribution of the individual trees was lower, it increased with elevation. Conclusions – We emphasize the importance of including different scale levels in analyses of diversity along elevational gradients. In the region, cloud forest on the mountain peaks harbours the highest diversity of epiphytic fern communities. Due to a limited extent of this mountain range, the epiphyte ferns are susceptible to the effects of climate change.

scholarly journals Historical signatures in the alpha and beta diversity patterns of Atlantic Forest harvestman communities (Arachnida: Opiliones)

2019 ◽  
Vol 97 (7) ◽  
pp. 631-643 ◽  
Author(s):  
A.A. Nogueira ◽  
C. Bragagnolo ◽  
M.B. DaSilva ◽  
T.K. Martins ◽  
E.P. Lorenzo ◽  
...  
Keyword(s):  
Protected Areas ◽  
Atlantic Forest ◽  
Beta Diversity ◽  
Alpha Diversity ◽  
Influential Factor ◽  
Conservation Strategies ◽  
Diversity Patterns ◽  
Alpha And Beta Diversity ◽  
Historical Factors ◽  
Compositional Changes

The integration of ecology and historical biogeography is fostering the investigation of diversity patterns. We studied alpha and beta diversity patterns of Brazilian Atlantic Forest harvestman (Arachnida: Opiliones) communities and related them to environmental and historical factors. Our data bank contains 508 species from 63 sites, encompassing almost the entire latitudinal range of Atlantic Forest. Alpha diversity was higher in coastal sites in the south and southeast regions and decreased in sites inland, as well as in sites in the coastal northeast region, especially in northern Bahia state. Alpha diversity was positively influenced by precipitation and altitudinal range, but the low number of species in northeastern coastal sites seems to be more related to the historical distribution of Neotropical harvestman lineages than to recent environmental factors. Geographic distance was the most influential factor for beta diversity. Compositional changes were also remarkably congruent with areas of endemism delimited for Atlantic Forest harvestmen. The percentage of protected areas for each area of endemism was very unbalanced, and Espírito Santo and Pernambuco states were the least protected areas. The turnover process observed in the compositional changes indicates that conservation strategies should include as many reserves as possible because every community presents a unique set of species.

scholarly journals Testing repeatability, testing repeatability, testing repeatability: harmonization of the DNA metabarcoding protocol for macrobenthos across Europe

2021 ◽  
Vol 4 ◽  
Author(s):  
Laure Van den Bulcke ◽  
Annelies De Backer ◽  
Magdalini Christodoulou ◽  
Sahar Khodami ◽  
Sara Maes ◽  
...  
Keyword(s):  
Beta Diversity ◽  
Pcr Amplification ◽  
Alpha Diversity ◽  
Ring Test ◽  
Diversity Patterns ◽  
Macrobenthic Communities ◽  
Number Of Species ◽  
Dna Metabarcoding ◽  
Low Diversity ◽  
The Impact

Macrobenthos is a good indicator to evaluate the potential effects of human activities on the marine benthic ecosystem. In environmental impact assessments (EIAs), macrobenthic species identification is typically based on morphological characteristics, a time-consuming and labor-intensive process for which specific taxonomic knowledge and experts are needed. DNA metabarcoding can circumvent most of these shortcomings. However, to be applicable in EIAs and to be adapted by policy, a standardized protocol that allows for reproducible and reliable DNA metabarcoding results is a prerequisite. Here, three research questions were investigated as part of the international Interreg NSR project GEANS: 1) “How many replicates of DNA extractions and PCR products are needed to capture most of the macrobenthic species in a sample?”, 2) “Is a ‘fixed’ DNA metabarcoding protocol repeatable across different institutes?” and 3) “What is the impact of small changes in this DNA metabarcoding protocol on alpha diversity?”. These are important steps to convince stakeholders that this efficient and quick method generates reliable and comparable results. First, variation in macrobenthic species across technical replicates was investigated in three biological replicates from three macrobenthic communities in the Belgian Part of the North Sea (BPNS) with high, medium and low diversity. For each biological replicate, six DNA replicates were taken and one of these DNA replicates was used to assess variation between three replicates for PCR amplification. Three DNA replicates were needed in locations with a high and medium diversity to pick up at least 80% of the species diversity present in the six replicates, while four DNA replicates were needed in the location with low diversity. Variation in the detected species between PCR replicates was high, illustrating the importance of including at least three PCR replicates in the lab protocol. Second, we conducted a ring test where subsamples of 12 bulk macrobenthos samples, originating from four different macrobenthic communities in the BPNS (differing in species density and diversity), were distributed to four institutes located in Belgium, the Netherlands, Germany and Denmark. Samples were processed using the same standardized lab protocol and the resulting datasets were processed bioinformatically by one institute. The number of ASVs and the number of species reflected the morphological diversity patterns, i.e. highest values for the replicates from the highly diverse macrobenthic community, lowest numbers in the low diversity replicates and intermediate values in the samples from the medium diversity community. These patterns were identical between the four institutes, showing high repeatability for alpha diversity when using the same protocol. In total, 100 macrobenthic species were detected through DNA metabarcoding, of which 60 species were picked up by all four institutes, while 0-14 species were recorded by only one of the four institutes. Beta diversity patterns were also comparable between the four institutes, as the nMDS plot clearly showed clustering based on the macrobenthic communities, independent of the institute that conducted the work. Finally, small changes to the lab protocol (different DNA extraction kit, different high fidelity polymerases for PCR amplification, different reagents for clean-up) resulted in only minor changes in alpha diversity: similar number of species were detected as with the fixed protocol in all samples and 70% - 75% of the species were shared between the ‘fixed’ and adjusted protocols. This study shows for the first time that DNA metabarcoding offers a highly repeatable assessment of alpha and beta diversity patterns, which supports the suitability of DNA metabarcoding for monitoring of marine macrobenthos. These results are highly valuable to establish a harmonized and uniform DNA metabarcoding protocol, to be used by all institutions in Europe when implemented as a new standard method in EIAs of the benthic ecosystem.

Alpha- and beta- diversity of woody species across environmental gradients in African and Australian tropical savannas

2020 ◽  
Author(s):  
Felix Trotter ◽  
Caroline Lehmann ◽  
Keyword(s):  
Beta Diversity ◽  
Woody Plant ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Geographic Distance ◽  
Alpha Diversity ◽  
Woody Species ◽  
Mean Annual Temperature ◽  
Alpha And Beta Diversity ◽  
Rainfall Seasonality

<p>Patterns of woody plant diversity in the tropical savanna biome has received little research attention but is relevant to understanding the complex vegetation dynamics of a biome that have remained contentious for almost a century. Tropical savannas of Africa and Australia are defined by the co-existence of woody plants and grasses, and the evolution and assembly of the savanna biome trace back 3-10 million years. Here, we explored patterns of local (alpha-) diversity and species turnover (beta-diversity) of woody plant species across African and Australian savannas. We aimed test the relative role of the environmental gradients of rainfall, temperature, fire and soil in shaping the relative abundance of all of woody species, genera, and families. Using generalized additive models (GAMs) and generalised dissimilarity models (GDMs) of field inventory data from vegetation plots across sub-Saharan Africa and Northern Australia we analysed changes in alpha- and beta-diversity. Environmental gradients were characterised as effective rainfall (ER), rainfall seasonality (coefficient of variation of monthly rainfall), mean annual temperature (MAT), temperature seasonality, fire frequency, and cation exchange capacity (CEC) in soils.</p><p>Savannas in Australia are on average drier and hotter than in Africa likely as a product of lower altitude. Crucially, diversity across all taxonomic levels is approximately two to three times greater in Africa compared with Australia. Within each continent, rainfall seasonality was the strongest environmental correlate of both alpha- and beta-diversity. In Africa, there is a strongly negative relationship between alpha-diversity at all taxonomic levels and rainfall seasonality. In contrast, in Australia, the relationship between alpha-diversity and rainfall seasonality while relevant is non-linear. Surprisingly within continents, rainfall, temperature, soils and fire had little bearing in these data on patterns of alpha diversity.</p><p>In terms of beta-diversity, and likely linked to the overall differences in diversity between continents, the geographic distance equalling total species turnover is greater in Australia than in Africa. Effective rainfall was the only additional significant correlate of woody species turnover in Australia, but only in arid regions. In Australia, at higher taxonomic levels the capacity of GDMs to explain variation in the data diminished substantially as a product of low diversity in genera and families. When compared to Australia, species turnover in Africa increases when geographic distance, rainfall seasonality and mean annual temperature are relatively low.</p><p>Our findings highlight that with ongoing climate change specifically with shifts in rainfall distribution that will also affect local drought regimes, rainfall seasonality could substantially alter patterns of diversity, specifically in Africa. There have been persistent attempts to explain ecosystem dynamics in savannas with respect to climate, soils and fire with emphasis often on total rainfall, but our findings suggest that rainfall seasonality can have strong effects on diversity that may interact with other environmental correlates such as fire.</p>

scholarly journals Beta diversity patterns derived from island biogeography theory

2018 ◽  
Author(s):  
Muyang Lu ◽  
David Vasseur ◽  
Walter Jetz
Keyword(s):  
Community Composition ◽  
Beta Diversity ◽  
Island Biogeography ◽  
Species Abundance ◽  
Alpha Diversity ◽  
Species Level ◽  
Neutral Model ◽  
Diversity Patterns ◽  
Species Abundance Distributions ◽  
Species Area

AbstractThe Theory of Island Biogeography (TIB) has been successful in predicting alpha diversity patterns such as species-area relationships and species-abundance distributions. Although beta diversity (i.e. the dissimilarity of community composition) has long been recognized as an important element of the TIB and is crucial for understanding community assembly processes, it has never been formally incorporated into the theory. Here we derive theoretical predictions for the expected pairwise beta diversity values under a species-level neutral scenario where all species have equal colonization and extinction rates. We test these predictions for the avian community composition of 42 islands (and 93 species) in the Thousand Island Lake, China. We find that alpha diversity patterns alone do not distinguish a species-level neutral model from a non-neutral model. In contrast, beta diversity patterns clearly reject a species-level neutral model. We suggest that the presented theoretical integration beta diversity offers a powerful path for testing the presence of neutral processes in ecology and biogeography.

Kyiv park "Nivki" and "Teremki" forests and ecological analysis of their habitats

2014 ◽  
Vol 25 (3-4) ◽  
pp. 53-68
Author(s):  
I. V. Goncharenko ◽  
H. M. Holyk
Keyword(s):  
Standard Deviation ◽  
Species Composition ◽  
Human Impact ◽  
Soil Nitrogen ◽  
Beta Diversity ◽  
Plant Cover ◽  
Alpha Diversity ◽  
Light Regime ◽  
Individual Species ◽  
Anthropogenic Pressure

Cenotic diversity and leading ecological factors of its floristic differentiation were studied on an example of two areas – Kyiv parks "Nivki" and "Teremki". It is shown that in megalopolis the Galeobdoloni-Carpinetum impatientosum parviflorae subassociation is formed under anthropogenic pressure on the typical ecotope of near-Dnieper hornbeam oak forests on fresh gray-forest soils. The degree of anthropogenic transformation of cenofloras can be estimated by the number of species of Robinietea and Galio-Urticetea classes, as well as neophytes and cultivars. Phytoindication for hemeroby index may be also used in calculation. We propose the modified index of biotic dispersion (normalized by alpha-diversity) for the estimation of ecophytocenotic range (beta-diversity) of releves series. We found that alpha-diversity initially increases (due to the invasion of antropophytes) at low level of antropogenic pressure, then it decreases (due to the loss of aboriginal species) secondarily with increasing of human impact. Also we found that beta-diversity (differential diversity) decreases, increasing homogeneity of plant cover, under the influence of anthropogenic factor. Vegetation classification was completed by a new original method of cluster analysis, designated as DRSA («distance-ranked sorting assembling»). The classification quality is suggested to be validated on the "seriation" diagram, which is а distance matrix between objects with gradient filling. Dark diagonal blocks confirm clusters’ density (intracluster compactness), uncolored off-diagonal blocks are evidence in favor of clusters’ isolation (intercluster distinctness). In addition, distinction of clusters (syntaxa) in ordination area suggests their independence. For phytoindication we propose to include only species with more than 10% constancy. Furthermore, for the description of syntaxonomic amplitude we suggest to use 25%-75% interquartile scope instead of mean and standard deviation. It is shown that comparative analysis of syntaxa for each ecofactor is convenient to carry out by using violin (bulb) plots. A new approach to the phytoindication of syntaxa, designated as R-phytoindication, was proposed for our study. In this case, the ecofactor values, calculated for individual releves, are not taken into account, however, the composition of cenoflora with species constancies is used that helps us to minimize for phytoindication the influence of non-typical species. We suggested a syntaxon’s amplitude to be described by more robust statistics: for the optimum of amplitude (central tendency) – by a median (instead of arithmetic mean), and for the range of tolerance – by an interquartile scope (instead of standard deviation). We assesses amplitudes of syntaxa by phytoindication method for moisture (Hd), acidity (Rc), soil nitrogen content (Nt), wetting variability (vHd), light regime (Lc), salt regime (Sl). We revealed no significant differences on these ecofactors among ecotopes of our syntaxa, that proved the variant syntaxonomic rank for all syntaxa. We found that the core of species composition of our phytocenoses consists of plants with moderate requirements for moisture, soil nitrogen, light and salt regime. We prove that the leading factor of syntaxonomic differentiation is hidden anthropogenic, which is not subject to direct measurement. But we detect that hidden factor of "human pressure" was correlated with phytoindication parameters (variables) that can be measured "directly" by species composition of plant communities. The most correlated factors were ecofactors of soil nitrogen, wetting variability, light regime and hemeroby. The last one is the most indicative empirically for the assessment of "human impact". We establish that there is a concept of «hemeroby of phytocenosis» (tolerance to human impact), which can be calculated approximately as the mean or the median of hemeroby scores of individual species which are present in it.

Impact of changing rainfall conditions on surface and groundwater resources in an experimental watershed in Greece

2013 ◽  
Vol 12 (2) ◽  
pp. 119-125
Keyword(s):  
Groundwater Resources ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Rainfall Regime ◽  
Winter Rainfall ◽  
Rainfall Depth ◽  
Rainfall Volume ◽  
The Mean ◽  
Groundwater Reserves ◽  
The Impact

The present study concerns the impact of a change in the rainfall regime on surface and groundwater resources in an experimental watershed. The research is conducted in a gauged mountainous watershed (15.18 km2) that is located on the eastern side of Penteli Mountain, in the prefecture of Attica, Greece and the study period concerns the years from 2003 to 2008. The decrease in the annual rainfall depth during the last two hydrological years 2006-2007, 2007-2008 is 10% and 35%, respectively, in relation to the average of the previous years. In addition, the monthly distribution of rainfall is characterized by a distinct decrease in winter rainfall volume. The field measurements show that this change in rainfall conditions has a direct impact on the surface runoff of the watershed, as well as on the groundwater reserves. The mean annual runoff in the last two hydrological years has decreased by 56% and 75% in relation to the average of the previous years. Moreover, the groundwater level follows a declining trend and has dropped significantly in the last two years.

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