Corrections to the indices of community dissimilarity based on species diversity measures

Oecologia ◽  
1981 ◽  
Vol 48 (2) ◽  
pp. 290-291 ◽  
Author(s):  
Marcel Rejmánek
Keyword(s):  
Species Diversity ◽  
Diversity Measures ◽  
Community Dissimilarity

Effects of thinning-induced changes in structural heterogeneity on growth, ingrowth, and mortality in secondary coastal Douglas-fir forests

2015 ◽  
Vol 45 (11) ◽  
pp. 1448-1461 ◽  
Author(s):  
Christian Kuehne ◽  
Aaron R. Weiskittel ◽  
Shawn Fraver ◽  
Klaus J. Puettmann
Keyword(s):  
Species Diversity ◽  
Prediction Models ◽  
Structural Diversity ◽  
Structural Heterogeneity ◽  
Variable Density ◽  
Douglas Fir ◽  
Tree Level ◽  
Spatially Explicit ◽  
Individual Tree ◽  
Diversity Measures

Thinning is believed to accelerate the development of late-successional attributes, thereby enhancing stand structural heterogeneity in young, secondary forests. By making use of a large-scale experiment implemented in 40- to 60-year-old coastal Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco) forests, we addressed the following objectives: (i) determine the effect of three thinning treatments on the temporal dynamics (first 11 years after thinning) of key forest structure measures, (ii) evaluate the relationships between spatially explicit structural diversity measures and spatially nonexplicit stand metrics, and (iii) test the relationships between stand structure and observed periodic stand volume growth, ingrowth, and mortality. Treatments consisted of high-density, moderate-density, and variable-density thinnings-from-below, as well as a control. Differences in stand structural heterogeneity between treatments were mostly nonsignificant. However, our results suggest that variable-density stands displayed structural enrichment as tree size and tree species diversity increased throughout the study period as a result of continuous ingrowth of species other than Douglas-fir. Simple spatially nonexplicit metrics could not be used to reliably model spatially explicit structural diversity measures. The inclusion of structural and species diversity measures only rarely improved accuracy of sample plot level growth, ingrowth, and mortality prediction models. Despite the short-term nature of this study, we conclude that variable-density thinning shows promise in increasing structural heterogeneity in young even-aged stands. The inclusion of structural diversity measures in growth and mortality models may be beneficial, but further work is needed to clarify the underlying relationships, particularly at the individual-tree level.

Species diversity structure analysis at two sites in the tropical rain forest of Sumatra

2000 ◽  
Vol 16 (2) ◽  
pp. 253-270 ◽  
Author(s):  
Keith Rennolls ◽  
Yves Laumonier
Keyword(s):  
Species Diversity ◽  
Main Tool ◽  
Distinct Species ◽  
Conservation Strategy ◽  
Two Dimensional ◽  
Topographic Gradient ◽  
Diversity Measures ◽  
M 10 ◽  
Α Diversity ◽  
Diversity Structure

Data from a hilly forest study site at Batang Ule, Sumatra, are organized into 30 100-m × 10-m subplots lying perpendicular to the line of maximal topographic gradient, from the valley to the plateau/ridge. The following methodological question is addressed: what species diversity measures are best used in order to reveal the ecologically distinct regions in the site. The main tool used to answer this question is the α-diversity curve (Hα). Graphical examination of tree and species densities, and α-diversity curves identifies an anomalous species diversity behaviour of the ‘ridge above the slope’ subplots which may have implications on land-facet class definitions. Factor analysis of the α-diversity curves indicates that the diversity space is two-dimensional: i.e. two diversity measures are sufficient to characterize the site; the species density (H0), and the Berger-Parker index (H∞). In thetwo-dimensional diversity-space three distinct species diversity groups are found which relate to the topographic gradient at the Batang Ule site. The results are compared with those for a flat homogeneous site at Pasirmayang, Sumatra. The implications of the results on land-classifications in species-diversity mapping and conservation strategy are discussed.

scholarly journals Differential effects of farming practice on cuckoo bumblebee communities in relation to their hosts

2019 ◽  
Author(s):  
Charlotte E. Howard ◽  
Alexander J. Austin ◽  
James D. J. Gilbert
Keyword(s):  
Species Diversity ◽  
Management Practice ◽  
Host Community ◽  
List Type ◽  
Farming Practices ◽  
Farming Practice ◽  
Farm Type ◽  
Conventional Farms ◽  
Community Metrics ◽  
Community Dissimilarity

ABSTRACTBees are important for vital pollination of wild and crop plants, but are in decline worldwide. Intensification of agriculture is a major driver of bee decline. Organic farming practices are designed to limit environmental impacts of agriculture and can increase bee abundance and species diversity. However, studies have been heavily focused towards some guilds of bees, overlooking others. This includes social brood parasites, cuckoo bumblebees, an understudied bee lineage. Little is known about bumblebee host and cuckoo population dynamics, and the effects of farming practice on cuckoo bumblebees have never previously been evaluated.To compare the effects of farming practice (organic vs conventional) on the abundance, species diversity, and community dissimilarity of cuckoo bumblebees and their hosts, we compared host and cuckoo community metrics across ten matched pairs of organic and conventional farms in Yorkshire, UK.As found by many previous studies, host bumblebees were more abundant on organic farms than on conventional farms. Despite this, cuckoo bumblebees were equally abundant on both farm types. Contrary to prediction, community dissimilarity and species diversity were unaffected by farm type for both host and cuckoo communities.Synthesis and applications: Results suggest that cuckoo bumblebee community metrics are not solely driven by host community metrics, and that cuckoos may respond differently from their hosts to differences among farming practices. This could, in turn, indicate that a unified management practice is not sufficient to conserve all bumblebee species.

Spatial Correlations among Total, Endemic, and Threatened Plant Diversity in Northwest Yunnan, China

2014 ◽  
Vol 955-959 ◽  
pp. 814-820
Author(s):  
Jian Meng Feng
Keyword(s):  
Species Diversity ◽  
Spatial Patterns ◽  
Plant Diversity ◽  
Endemic Species ◽  
Seed Plants ◽  
Spatial Correlations ◽  
Altitudinal Range ◽  
Threatened Plant ◽  
Diversity Measures ◽  
Northwest Yunnan

Located in Southwest China, Northwest Yunnan has drawn much attention around the world because of its high plant richness. However, spatial associations among different diversity measures of seed plants in this region remain elusive. We compiled a database of spatial distribution of total, endemic, and threatened seed plants at county scale in Northwest Yunnan, and examined spatial associations among the three diversity measures and altitudinal range. We found similar spatial patterns of the three diversity measures, which were highest in the northern part of the region. Moreover, strong correlations among the three diversity measures were observed. Altitudinal range was positively correlated with total and endemic species diversity, while endemic species diversity explained more spatial variation of threatened species diversity. The spatial patterns of all three diversity measures were directly or indirectly correlated with altitudinal range, suggesting strong associations among controlling factors of the three diversity measures. Overall, our results showed strong spatial correlations among total, endemic, and threatened plant diversity in Northwest Yunnan, which should help land managers design cost-effective conservation plans in this region.

scholarly journals Effects of land-use on herbaceous vegetation in a semi-arid Mopaneveld savanna

Bothalia ◽  
2021 ◽  
Vol 51 (1) ◽  
Author(s):  
F. Siebert ◽  
N. Van Staden ◽  
D.M. Komape ◽  
A.M. Swemmer ◽  
S.J. Siebert
Keyword(s):  
Land Use ◽  
Species Diversity ◽  
Land Use Change ◽  
Anthropogenic Disturbances ◽  
Community Diversity ◽  
Strip Mining ◽  
Mining Activities ◽  
Data Set ◽  
Diversity Measures ◽  
Effects Of Land Use

Background: Low altitude Mopaneveld savanna in the northeastern parts of South Africa is generally well conserved. However, extensive copper mining, agricultural practices and urbanisation in the Phalaborwa region prompted research on the possible effects of land-use change on plant community diversity and function. Species diversity measures are usually considered adequate to assess disturbance effects to inform conservation efforts and management practices. However, diversity measures based on species level accounts often limit the outcomes of these studies as this approach fails to quantify how disturbances affect ecosystem functioning when community assembly, and not species diversity alone, is altered by land-use change.Objectives: The aim of this study was to apply both species and functional diversity measures to a data set derived from various land-use types (i.e. areas exposed to strip mining activities, communal farming practices and conservation) in the Phalaborwa region to examine the effects of land-use change on the community ecology of the herbaceous layer.Results: Land-use change, particularly severe top-soil disturbances through strip mining activities, had a significant filtering effect on all measures of species diversity, though functional evenness was maintained across land-use types.Conclusion: These results suggest that, despite initial species loss, this particular savanna ecosystem is buffered against anthropogenic disturbances through functional stability. Indicator species analyses, as well as relationships between plant functional types and land-use change, revealed that forb species are largely responsible for ecosystem stability in areas exposed to  anthropogenic disturbances.

scholarly journals Different diversity measures and genetic traits reveal different speciesgenetic diversity relationships: A case study in forest tree communities

2013 ◽  
Vol 62 (1-6) ◽  
pp. 25-37 ◽  
Author(s):  
F. Bergmann ◽  
H.-R. Gregorius ◽  
D. Kownatzki ◽  
Chr. Wehenkel
Keyword(s):  
Genetic Diversity ◽  
Species Diversity ◽  
Genetic Relationships ◽  
Statistical Significance ◽  
Distinct Species ◽  
Community Genetics ◽  
Genetic Trait ◽  
Genetic Traits ◽  
Diversity Measure ◽  
Diversity Measures

AbstractRelationships between species diversity and genetic diversity, the two most important elements of biodiversity, have recently attracted considerable interest in the field of community genetics. The present study contributes to this issue by addressing three questions that seem to have been ignored so far, namely whether the use of (a) different diversity measures, of (b) different components of diversity, and of (c) different genetic traits may lead to different assessements of speciesgenetic diversity relationships. For this purpose, data on species composition and genetic traits were collected from the natural regeneration of nine forest communities, which consist of three pure and six mixed tree stands located in the Thuringian forest area. The genetic traits comprised one DNA (AFLP) and five isozyme traits all of which were determined in all species. In contrast to other studies, the species diversity was determined for two components, SD (species diversity) and NeS (effective number of genetically distinct species), and the genetic diversity was determined for three components, TSGD (the transspecific genetic diversity taken over all species of a community), ISGD and NGS (each describing a special average of intraspecific genetic diversity). Each component was quantified by measures of diversity representing four orders of the Renyi/Hillfamily. The orders correspond to the degree to which prevalence of types is considered in the diversity measure (at the lowest order, known as richness, prevalence is disregarded, with increasing order, the diversity measure reports prevalent types only). In our data, the diversity measured for each genetic trait separately showed a great range of variation across traits and components of diversity even in the same stand. The choice of the diversity component thus turned out to have a substantial effect on the assessment of the level of genetic diversity within stands. This prompted more detailed studies of the relationships between species and genetic diversity. Relationships were quantified with the help of the coefficient of co-variation, and the statistical significance of the co-variations was verified through permutation tests. The co-variations between SD and TSGD were found to be generally positive and in most cases significant, but the co-variation declined with increasing orders of diversity for most of the genetic traits. In contrast, the co-variation between SD and ISGD was not consistent for the four orders of diversity. In particular, the co-variations for the highest order were found to be negative for all traits. The results of our explorative study thus demonstrate that the assessment of levels of genetic diversity within stands as well as species-genetic interrelations critically depend on the choice of the diversity component, of the order of diversity, and of the genetic trait. These observations lend support to different and even opposing hypotheses on the processes potentially generating species-genetic relationships. Therefore, strategies in the conservation of biodiversity, for example, are suggested to be related more specifically to the components and orders of diversity to be safegarded and to consider the functions of genetic traits in relation to adaptationally relevant environmental factors.

Species diversity, abundance, biomass, size and trophic structure of fish on coral reefs in relation to shark abundance

2017 ◽  
Vol 565 ◽  
pp. 163-179 ◽  
Author(s):  
SC Barley ◽  
MG Meekan ◽  
JJ Meeuwig
Keyword(s):  
Species Diversity ◽  
Coral Reefs ◽  
Trophic Structure

Diatoms in the Early Valdai (Weichselian) sediments in Lake Ladoga basin

2019 ◽  
pp. 225-228
Author(s):  
Anna V. Ludikova
Keyword(s):  
Species Diversity ◽  
High Energy ◽  
Lake Ladoga ◽  
Diatom Assemblages ◽  
Marine Diatoms ◽  
Selective Preservation

The pioneer diatom study of the Early Weichselian (Valdai) sediments in Lake Ladoga basin was performed. The specifics of the diatom assemblages (co-occurrence of ecologically incompatible taxa, poor species diversity, low diatom concentration and selective preservation) suggest that during the Early Weichselian time intense erosion of previously deposited marine Eemian (Mikulino) sediments prevailed, which resulted in re-deposition of marine diatoms. The sedimentation took place in high-energy environments unfavorable for diatom accumulation and preservation.

High community dissimilarity at low productivity causes the productivity-richness relation to vary with observational scale

2010 ◽  
Vol 11 (1) ◽  
pp. 27-34 ◽  
Author(s):  
W. Li ◽  
M. Stevens
Keyword(s):  
Community Dissimilarity
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