Species Diversity
Species Diversity
Species diversity describes the variety of species within a biological community and the way individuals are distributed among those species. It is broader than species richness, which simply counts the number of species present. Measures of species diversity commonly incorporate both richness and evenness, allowing ecologists to distinguish between communities containing similar numbers of species but very different patterns of abundance. Species diversity is one of the major dimensions of biodiversity, alongside genetic and ecosystem diversity. :contentReference[oaicite:0]{index=0}
Species Richness and Evenness
Two fundamental components of species diversity are species richness and species evenness. Richness measures how many species occur in a community, while evenness describes how uniformly individuals are distributed among those species. A community dominated by one or two species may therefore have the same richness as a community in which individuals are distributed relatively evenly, while having substantially lower diversity.
Research demonstrates that richness and evenness can respond differently to ecological conditions. Environmental productivity, succession, disturbance, habitat characteristics, and other ecological processes can alter one component without producing an equivalent change in the other. Consequently, species counts alone may conceal important changes in community structure. :contentReference[oaicite:1]{index=1}
Measuring Species Diversity
Ecologists use several approaches to quantify species diversity. Common measures include species richness, the Shannon index, Simpson-type indices, evenness measures, and Hill numbers. These metrics emphasize different characteristics of communities: some are particularly sensitive to rare species, while others place greater weight on common or dominant species. :contentReference[oaicite:2]{index=2}
Hill numbers provide a framework for expressing diversity as an effective number of species and can facilitate comparisons among ecological communities. Rarefaction and extrapolation methods can further improve comparisons when sampling effort differs among sites or when communities have been incompletely sampled. Because no single diversity index captures every dimension of biological variation, the choice of metric should reflect the ecological question being investigated. :contentReference[oaicite:3]{index=3}
Species Abundance and Community Composition
The ecological significance of species diversity depends on more than the total number of species. Relative abundance and species identity can strongly influence ecosystem processes. Communities containing the same number of species can function differently when their abundance distributions or dominant species differ.
Recent research emphasizes this distinction by showing that species abundance patterns may sometimes have stronger effects on ecosystem functioning than richness alone. This reinforces the importance of evaluating community composition, abundance, richness, and evenness together rather than treating biodiversity simply as a species count. :contentReference[oaicite:4]{index=4}
Geographic Patterns of Species Diversity
Species diversity varies greatly across the planet. One of ecology's most prominent geographical patterns is the latitudinal diversity gradient, in which many groups contain substantially more species in tropical regions than at higher latitudes.
Multiple explanations have been proposed for these patterns, including climate, productivity, evolutionary history, geographical area, speciation and extinction rates, ecological opportunity, and environmental stability. The relative importance of these mechanisms can differ among taxonomic groups and ecological systems.
Spatial scale also matters. Patterns observed within individual communities may differ from those appearing across landscapes, regions, or continents. Habitat diversity, environmental heterogeneity, dispersal, and species turnover can all affect how species diversity changes with spatial scale. :contentReference[oaicite:5]{index=5}
Environmental Drivers and Habitat Connectivity
Climate, soil, elevation, rainfall, habitat structure, land use, productivity, and disturbance can all influence species richness and community composition. Environmental gradients therefore frequently produce recognizable changes in biological diversity.
Habitat fragmentation is especially important because isolated populations may become smaller and ecological movement among habitats can decline. Maintaining habitat connectivity can help preserve populations and local species diversity. Wildlife corridors and connected protected landscapes are consequently important conservation tools, particularly as development and environmental change increasingly fragment natural ecosystems. :contentReference[oaicite:6]{index=6}
Species Diversity and Ecosystem Functioning
A major field of ecological research examines the relationship between biodiversity and ecosystem functioning. Experimental and observational studies have repeatedly investigated whether communities containing more species differ in productivity, nutrient cycling, carbon storage, resource use, stability, and other ecosystem properties.
Research has demonstrated that increasing plant species diversity can substantially increase ecosystem productivity, while other studies show that species richness can influence ecosystem carbon storage and ecosystem services. :contentReference[oaicite:7]{index=7} :contentReference[oaicite:8]{index=8}
These effects can arise because species use resources differently, occupy different ecological niches, interact with one another, or respond differently to environmental conditions. Biodiversity–ecosystem-function relationships can also become more complicated when multiple trophic levels, spatial scales, and ecological functions are considered simultaneously.
Diversity and Ecosystem Stability
Species diversity may contribute to ecosystem stability by allowing different species to respond differently to environmental fluctuations. The ecological "insurance hypothesis" proposes that diverse communities can maintain ecosystem processes when environmental conditions change because declines in some species may be compensated for by others. :contentReference[oaicite:9]{index=9}
Diversity can therefore influence resistance to disturbance, ecological recovery, productivity, and the reliability of ecosystem functions through time. However, stability depends not only on richness but also on species composition, ecological interactions, abundance patterns, and environmental conditions.
Functional and Phylogenetic Diversity
Taxonomic species diversity represents only one dimension of biodiversity. Functional diversity describes variation in ecological traits and roles, while phylogenetic diversity incorporates evolutionary relationships among organisms.
These dimensions do not necessarily change together. A community may contain many species that perform similar ecological functions, while another community with fewer species may contain unusually distinct functional or evolutionary lineages. Conservation strategies based exclusively on species counts can therefore overlook important dimensions of biological diversity.
Research increasingly argues for integrating taxonomic, functional, and phylogenetic information when evaluating biodiversity and establishing conservation priorities. :contentReference[oaicite:10]{index=10}
Species Turnover and Biodiversity Change
Stable species richness does not necessarily mean that biodiversity is stable. Species can disappear from a community while other species colonize it, leaving the total species count approximately unchanged. Abundance distributions and community composition may also change substantially without producing large changes in richness.
This distinction is important for biodiversity monitoring. Studies of ecological change increasingly evaluate species identities, abundances, evenness, turnover, and composition alongside conventional measures of richness. :contentReference[oaicite:11]{index=11}
Threats to Species Diversity
Species diversity is threatened by habitat destruction and fragmentation, climate change, invasive organisms, pollution, overexploitation, and other forms of environmental degradation. These pressures can reduce local populations, alter species distributions, simplify ecological communities, and ultimately contribute to extinction. :contentReference[oaicite:12]{index=12}
Climate change presents a particularly large and increasingly important challenge. Changes in temperature, precipitation, extreme events, and habitat suitability can shift species distributions and reorganize ecological communities. Modeling of tens of thousands of vascular plant species, for example, indicates that many species could lose substantial amounts of suitable habitat as climate conditions change. :contentReference[oaicite:13]{index=13}
Conservation of Species Diversity
Protecting species diversity requires conserving not only individual species but also habitats, ecological interactions, genetic resources, environmental gradients, and the processes that maintain biological communities.
Protected areas, wildlife corridors, habitat restoration, ecological monitoring, control of invasive species, sustainable land management, and climate adaptation can all contribute to maintaining diverse communities. Conservation planning increasingly recognizes that species-rich areas should not be the sole priority: ecologically distinctive communities and species with unusual functional or evolutionary characteristics may also warrant protection.
Long-term biodiversity monitoring is particularly important because changes in abundance or species composition may occur before substantial declines in total species richness become apparent.
Why Species Diversity Matters
Species diversity contributes to ecosystem productivity, resilience, stability, nutrient cycling, carbon storage, food webs, and numerous ecosystem services. Diverse ecosystems also support resources and processes important to people, including food, medicines, clean water, recreation, cultural values, and disease regulation. :contentReference[oaicite:14]{index=14}
The importance of diversity is therefore both ecological and societal. Losses of species can alter ecosystem processes and may produce disproportionately large declines in the economic value generated by functioning ecosystems. :contentReference[oaicite:15]{index=15}
Conclusion
Species diversity is a multidimensional property of ecological communities encompassing species richness, relative abundance, evenness, composition, and the ecological relationships among organisms. Although richness remains one of the most intuitive biodiversity measures, modern ecological research demonstrates that species counts alone cannot adequately describe how biological communities are structured or how they change.
Diversity patterns emerge through interactions among evolution, climate, habitat, geography, ecological processes, disturbance, and species interactions. In turn, species diversity can influence ecosystem productivity, stability, resilience, carbon storage, and ecosystem services.
Understanding and conserving species diversity therefore requires multiple measures and multiple spatial and ecological perspectives. Protecting biological diversity ultimately means preserving not simply large numbers of species, but the abundance structures, ecological functions, evolutionary histories, habitats, and interactions that allow diverse communities to persist.
Species Diversity: Concepts and Current Research
| David Zelený | Analysis of Community Ecology Data in R | 2026-05-24
Explains Hill numbers, Shannon diversity, Simpson diversity, and species richness, showing how different indices emphasize rare, common, or dominant species differently.
| Will Dunham | Reuters | 2026-05-23
Climate-change modeling of more than 67,000 vascular plant species finds that many could lose most of their suitable habitat by the end of the century, illustrating how climate change can restructure global plant species diversity.
| Associated Press | AP News | 2026-04-10
Examines how conservation genomics is being used to identify climate-resilient organisms and preserve biological diversity as environmental change outpaces natural adaptation.
| Samuel M. Scheiner | Ecological Monographs | 2025-05-13
Examines the fundamental units used to quantify biodiversity and explains relationships among species richness, evenness, Hill numbers, and other diversity measures.
| Y. Shen | Nature Reviews Biodiversity | 2025-04-07
Reviews the concept and mathematical quantification of biological diversity, emphasizing that diversity cannot always be represented adequately by species counts alone.
| Associated Press | AP News | 2025-03-03
Explores wildlife corridors in Kenya as a strategy for maintaining animal populations, habitat connectivity, and species diversity in increasingly fragmented landscapes.
| H. F. Yan et al. | Nature Communications | 2025
Investigates how species abundance and richness contribute differently to ecosystem functioning and argues that abundance patterns can sometimes outweigh richness alone.
| M. Liang et al. | Science | 2025
Develops spatial scaling laws linking biodiversity with ecosystem functioning and stability across ecological scales.
| Joseph A. Tobias et al. | Proceedings of the National Academy of Sciences | 2025
Argues that effective biodiversity conservation requires integrating taxonomic species diversity with functional diversity and ecological roles.
| M. Lorcery et al. | Biological Reviews | 2025
Reviews the deep-time evolution of the latitudinal diversity gradient and examines why species richness has repeatedly become concentrated in tropical regions.
Measuring Species Diversity: Richness, Evenness, and Indices
| Various Authors | Ecological Applications | 2024-12-05
Presents a framework for quantifying biodiversity change across landscapes while accounting for richness, diversity, habitat amount, and spatial configuration.
| Carlo Ricotta | Ecological Indicators | 2024
Evaluates the growing ecological use of Hill numbers and asks when transforming conventional diversity indices into effective numbers of species produces meaningful comparisons.
| M. J. Bollarapu et al. | Ecological Indicators | 2024
Reviews changing approaches to biodiversity quantification, including Shannon, Simpson, richness, evenness, and other measures used to characterize ecological communities.
| Tarald O. Kvålseth | Ecology and Evolution | 2024
Examines the relationship and tradeoff between richness and evenness, the two central components underlying many measures of species diversity.
| Anna L. Hargreaves et al. | Annual Review of Ecology, Evolution, and Systematics | 2024
Reviews mechanisms proposed to explain large-scale latitudinal patterns in species diversity and identifies ways ecological experiments can test those mechanisms.
| Fernando T. Maestre et al. | npj Biodiversity | 2024
Reviews research needs in biodiversity–ecosystem functioning science, including how species richness and functional diversity influence productivity and other ecosystem processes.
| L. Meng et al. | Frontiers in Plant Science | 2024
Investigates variation in plant species diversity and community structure, illustrating how environmental gradients shape species richness and composition.
| L. Sandal et al. | Journal of Animal Ecology | 2024
Shows that species richness and evenness in European bird communities can respond differently to environmental productivity.
| Hong Qian et al. | Current Research in Ecological and Social Psychology | 2024
Provides evidence for a strong latitudinal species-richness gradient in mosses and contributes to the broader debate over geographical patterns of diversity.
| Ian A. Hatton et al. | Science | 2024
Examines the long-standing hypothesis that high species diversity increases ecological stability through compensating dynamics among species.
| Kuczynski et al. | Nature Ecology & Evolution | 2023
Examines methodological biases affecting biodiversity time-series datasets. Changes in local species richness can involve simultaneous colonizations, extinctions, and shifts in abundance, meaning simple species counts may fail to capture important ecological changes.
| Liu et al. | Frontiers in Ecology and Evolution | 2023
Investigates relationships between several dimensions of biodiversity and ecosystem functioning rather than relying exclusively on species richness. The research illustrates why abundance, composition, complementarity, and other community properties are important for evaluating biodiversity effects.
| English et al. | Ecology and Evolution / NOAA Repository | 2022
Examines how urbanization affects plant diversity and whether developed environments increase or decrease biodiversity relative to rural landscapes. The study also considers the role of non-native species in shaping urban species assemblages.
| National Park Service | U.S. National Park Service | 2022
Describes the exceptional species richness of Great Smoky Mountains National Park. Thousands of documented plant, animal, fungal, and microbial species make the region one of North America's major temperate biodiversity centers.
| National Park Service | U.S. National Park Service | 2022
Introduces biodiversity through the work and legacy of biologist E. O. Wilson. It emphasizes that biological diversity occurs at genetic, species, and ecosystem levels and underpins ecological systems upon which humans depend.
| Michael Roswell, Jonathan Dushoff & Rachael Winfree | Oikos | 2021
Provides a conceptual guide to measuring species diversity and recommends Hill numbers as an intuitive framework for comparing richness and relative abundance.
| S. Hosokawa et al. | Scientific Reports | 2021
Evaluates diversity indices for marine ecological assessment and discusses how richness and evenness can indicate changes in benthic communities.
| D. J. McGlinn et al. | Ecology | 2021
Presents a multiscale method for distinguishing the roles of abundance, evenness, and spatial aggregation in observed species-richness patterns.
| E. Bestion et al. | Proceedings of the National Academy of Sciences | 2021
Demonstrates experimentally that phytoplankton biodiversity can become increasingly important to ecosystem functioning under fluctuating temperatures.
| James B. Grace, Michel Loreau & Bernhard Schmid | Ecology | 2021
Discusses methods for separating species-identity effects from general biodiversity effects in biodiversity–ecosystem-function studies.
| Various Authors | Proceedings of the Royal Society B | 2020-11-25
Finds that greater plant species richness can increase ecosystem carbon storage, illustrating a major functional consequence of species diversity.
| Various Authors | Proceedings of the Royal Society B | 2020-03-04
Examines how local species diversity, beta diversity, and climate jointly influence ecological communities and ecosystem properties.
| C. Paul et al. | Science Advances | 2020
Investigates the functional relationship between biodiversity and ecosystem processes and explores mathematical descriptions of diversity effects.
| M. R. Felipe-Lucia et al. | Proceedings of the National Academy of Sciences | 2020
Uses data from multiple trophic groups to show how land-use intensity alters relationships among species richness, ecosystem functions, and ecosystem services.
| Andrew Gonzalez et al. | Ecology Letters | 2020
Reviews how biodiversity–ecosystem-function research can be expanded from local experiments to landscapes, regions, and larger spatial scales.
| Sean M. Hoban et al. | Biological Conservation | 2020
Discusses biodiversity targets and indicators and clarifies the relationship among genetic, species, and ecosystem diversity.
Community Structure, Richness, Abundance, and Composition
| N. Anzai et al. | Ecosphere | 2023
Tracks long-term changes in species richness and evenness during forest succession and shows that the two dimensions of diversity can follow different trajectories.
| A. M. Herrera et al. | Ecological Indicators | 2023
Compares alpha species-diversity indicators and explains why species richness alone can obscure differences in evenness among ecological communities.
| M. T. Shilereyo et al. | Frontiers in Conservation Science | 2023
Examines how land use, habitat, and rainfall seasonality influence small-mammal richness, abundance, evenness, and species composition.
| H. Yan et al. | Frontiers in Ecology and Evolution | 2023
Investigates relationships among plant diversity measures and environmental factors, showing that different components of biodiversity respond in distinct ways.
| H. Liang et al. | Ecological Indicators | 2023
Compares measured biodiversity with people's perceptions and recreational preferences in urban green spaces.
| Various Authors | Ecology | 2022-07-23
Shows that local biodiversity change results from interactions among abundance, richness, and evenness rather than changes in species counts alone.
| National Park Service | U.S. National Park Service | 2022-04-12
Explains how habitat fragmentation and connectivity influence amphibian distributions and can cause losses of local species diversity.
| Various Authors | Ecology | 2022-02-14
Examines biodiversity–ecosystem-function relationships while treating both species richness and evenness as important dimensions of taxonomic diversity.
| Y. Zhang et al. | Diversity | 2022
Reviews the latitudinal diversity gradient and evaluates how climate and global environmental change may alter one of ecology's most prominent species-richness patterns.
| J. A. Pilowsky et al. | Science Advances | 2022
Uses process-based ecological models to examine how species coexistence, ecological interactions, and environmental conditions generate biodiversity patterns.
| NOAA Fisheries | National Oceanic and Atmospheric Administration | 2021
Explains how diversity within species affects population survival and adaptation. Although focused on genetic diversity, the article demonstrates how genetic variation interacts with population persistence and therefore influences the long-term maintenance of species diversity.
| Fukaya et al. | Nature Communications | 2020
Develops methods for estimating large-scale patterns of species abundance. Because diversity reflects not only how many species occur but also their relative abundance, these methods improve understanding of regional biodiversity, rarity, community assembly, and extinction risk.
| NOAA Science On a Sphere | NOAA | 2020
Maps global bird species richness using distribution information for thousands of bird species. Tropical regions generally contain the greatest numbers of species, providing a clear illustration of geographic gradients in species diversity.
| National Park Service | U.S. National Park Service | 2020
Explains biodiversity as the variety of life, habitats, and ecological relationships on Earth. Diverse communities provide ecological processes and resources that contribute to ecosystem resilience and the ability of organisms to respond to environmental change.
| National Park Service | U.S. National Park Service | 2019
Introduces biological diversity as the variety of living organisms found across terrestrial, freshwater, marine, subterranean, and other environments. Species diversity forms one major component alongside genetic and ecosystem diversity.
| Convention on Biological Diversity | CBD | 2018
Highlights the extraordinary biological richness of marine ecosystems. Some ocean environments contain extremely high concentrations of species, while continuing exploration of deep-sea habitats regularly reveals organisms previously unknown to science.
| National Park Service | U.S. National Park Service | 2018
Provides an accessible introduction to biodiversity and distinguishes variety of organisms, genetic diversity, ecosystem diversity, and frequency of occurrence. It also discusses threats to biodiversity and reasons for protecting diverse biological communities.
| Various Authors | Royal Society Open Science | 2015-03-01
Separates the effects of species richness from functional diversity to determine which aspects of tree diversity are most closely associated with ecosystem functioning.
| Dolph Schluter | The American Naturalist | 2015
Evaluates evolutionary explanations for higher tropical species richness, including ecological opportunity, speciation, extinction, age, and geographical area.
| Anne Chao et al. | Ecological Monographs | 2014
Develops a rarefaction and extrapolation framework using Hill numbers that allows more rigorous comparisons of species diversity among incompletely sampled communities.
| Joseph R. Pasari et al. | Proceedings of the National Academy of Sciences | 2013
Demonstrates that biodiversity operating at local and larger spatial scales contributes to ecosystem multifunctionality.
| Various Authors | Proceedings of the Royal Society B | 2012-03-28
Shows that species richness can affect not just the quantity but also the quality and reliability of ecosystem services.
| Moriaki Yasuhara et al. | Global Ecology and Biogeography | 2012
Describes large-scale patterns of Arctic benthic species diversity and investigates environmental variables responsible for those patterns.
| Various Authors | Philosophical Transactions of the Royal Society B | 2011-08-27
Reviews conceptual and statistical difficulties involved in using species-diversity measures to evaluate biodiversity patterns and ecological processes.
| Various Authors | Ecosphere | 2011-04-28
Examines how relationships between taxonomic species diversity and functional diversity vary among ecosystems and depend on both richness and evenness.
| Anne Chao, Chun-Huo Chiu & Lou Jost | Philosophical Transactions of the Royal Society B | 2010
Extends Hill-number approaches to phylogenetic diversity, allowing ecological diversity measures to incorporate evolutionary relationships among species.
| Ethan P. White et al. | Ecology | 2010
Integrates spatial and temporal approaches to species richness and highlights the importance of habitat diversity and environmental heterogeneity.
Species Diversity and Ecosystem Functioning
| Various Authors | Biology Letters | 2019-10-30
Tests ecological theories of biodiversity using geographical patterns in reef-fish species richness.
| Various Authors | Proceedings of the Royal Society B | 2019-07-10
Tests biodiversity–ecosystem-function relationships in fish communities using species richness and other measures of community structure.
| Nico Eisenhauer et al. | Advances in Ecological Research | 2019
Reviews biodiversity–ecosystem-function relationships from a multitrophic perspective and emphasizes interactions among plants, animals, microbes, and food webs.
| Yoann Le Bagousse-Pinguet et al. | Proceedings of the National Academy of Sciences | 2019
Compares taxonomic, functional, and phylogenetic richness and demonstrates that the different dimensions of biodiversity can respond differently to environmental stress.
| J. Rybicki et al. | Ecology Letters | 2019
Models how habitat amount and fragmentation interact to alter species diversity in competitive ecological communities.
| S. M. Durán et al. | Science Advances | 2019
Shows how remotely sensed functional diversity can contribute to understanding biodiversity patterns and ecosystem functioning.
| U.S. Geological Survey | USGS | 2018-08-02
Reports research showing that declines in species diversity can produce disproportionately large losses in the economic value of ecosystem functioning.
| Various Authors | National Park Service | 2018-03-07
Finds greater tree species richness, evenness, rare-species representation, and alpha diversity in eastern U.S. national parks than in surrounding forest landscapes.
| Niv DeMalach et al. | Global Ecology and Biogeography | 2018
Shows that plant species-accumulation curves in drylands are strongly affected by evenness and spatial aggregation.
| Various Authors | Proceedings of the Royal Society B | 2017-11-15
Examines how evolutionary history and contemporary environmental processes combine to produce global gradients in reef-fish species richness.
| Smithsonian Environmental Research Center | Smithsonian Institution | 2017
Reports research showing that biodiversity can strongly influence ecosystem productivity and ecological functioning. Loss of species can therefore alter ecosystem processes at magnitudes comparable to other major environmental pressures.
| Hillebrand et al. | Journal of Applied Ecology / NOAA Repository | 2017
Demonstrates that stable local species richness does not necessarily mean biodiversity is unchanged. Species identities and abundances may undergo substantial turnover even when the total number of species remains approximately constant.
| Nicole Ornelas | U.S. National Park Service | 2017
Introduces biodiversity as the variety of species and ecosystems and discusses efforts to document biological diversity within Cabrillo National Monument. The article emphasizes the ecological roles organisms play within functioning communities.
| Felix Gugerli et al. | Basic and Applied Ecology | 2008
Examines relationships among genetic diversity, species diversity, and ecosystem-level biodiversity and discusses whether different levels of biodiversity covary.
| Pedro Flombaum & Osvaldo E. Sala | Proceedings of the National Academy of Sciences | 2008
Demonstrates experimentally that increasing plant species diversity can strongly increase ecosystem productivity.
| Various Authors | Ecology | 2007-05-01
Investigates empirical relationships among species richness, evenness, and other components of biological diversity.
| X. Hu, F. He & Stephen P. Hubbell | The American Naturalist | 2007
Develops neutral models of local species diversity in communities embedded within larger metacommunities.
| Various Authors | Science | 2006-05-12
Discusses evidence concerning the relationship between species diversity and ecosystem functioning in highly diverse ecological communities.
| Various Authors | Ecology | 2005-05-01
Compares ecological diversity indices and emphasizes richness, evenness, dominance, and rarity as conceptually different dimensions of species diversity.
Finds that species richness and evenness can be controlled by different ecological processes and therefore should not automatically be treated as interchangeable measures.
Develops neutral-theory predictions for relative species abundance and explains how immigration and extinction influence local species diversity.
| S. Kathleen Lyons & Michael R. Willig | Ecology | 2002
Shows that estimates of latitudinal species-richness gradients depend strongly on the spatial scale at which communities are analyzed.
| John J. Stachowicz et al. | Ecology | 2002
Finds relationships between native species richness and resistance to biological invasion, helping establish links between diversity and community stability.
Habitat, Geography, Environmental Gradients, and Biogeography
| Chen et al. | Nature Communications | 2026
Species richness and ecological uniqueness represent different dimensions of biodiversity and do not necessarily occur in the same places. The study examines their global relationship and shows why conservation planning should consider both species-rich areas and locations containing unusually distinctive biological communities.
| Wei et al. | Frontiers in Ecology and Evolution | 2026
Examines the diversity and spatial distribution of ancient trees in urban environments. The research illustrates how species composition, environmental pressures, development, climate, disease, and habitat alteration influence the persistence of diverse tree communities.
| NOAA | National Oceanic and Atmospheric Administration | 2025
Provides an overview of biological diversity encompassing variation within species, among species, and among ecosystems. It connects biodiversity with environmental protection, ecosystem services, conservation, and national and international environmental policy.
| Caldwell et al. | Conservation Research / NOAA Repository | 2024
Finds persistent geographic and taxonomic biases in biodiversity research. Understudied organisms and ecosystems may consequently receive less conservation attention, emphasizing the need for broader monitoring of species diversity across regions and taxonomic groups.
| Eisenhauer et al. | Current Biology | 2024
Discusses translating biodiversity theory into practical ecological applications. The article considers how understanding biological diversity can contribute to ecosystem management, conservation, agriculture, and sustainable food systems.
| Various Authors | Proceedings of the Royal Society B | 2017-05-31
Examines how random ecological drift changes species abundances, reduces within-community diversity, and increases differences among communities.
| Rebecca A. Graves et al. | Proceedings of the National Academy of Sciences | 2017
Shows that species richness by itself does not necessarily predict cultural ecosystem services, illustrating the limitations of using richness as a universal biodiversity proxy.
| V. E. Pennington et al. | Plant Ecology | 2017
Examines climatic and soil controls on forb diversity in sagebrush ecosystems, where forbs account for a large proportion of total plant species richness.
| L. Winter et al. | International Journal of Life Cycle Assessment | 2017
Reviews approaches for incorporating biodiversity and species loss into life-cycle environmental assessment.
| U.S. Geological Survey | USGS | 2016-01-15
Summarizes evidence that species-rich biological communities tend to sustain greater productivity and healthier ecosystem functioning.
| E. K. Karadimou et al. | Scientific Reports | 2016
Shows that relationships between functional diversity, species richness, and evenness vary with ecological scale.
| Various Authors | Philosophical Transactions of the Royal Society B | 2016
Explores biodiversity–ecosystem-function relationships in dynamic and spatially heterogeneous landscapes rather than isolated experimental plots.
| Sebastian T. Meyer et al. | Ecosphere | 2016
Demonstrates that positive effects of plant species richness on ecosystem functions can strengthen as biodiversity experiments continue over time.
| Benjamin A. Gill et al. | Proceedings of the Royal Society B | 2016
Shows that unrecognized cryptic species can alter apparent geographical patterns of species diversity and estimates of latitudinal richness.
| Kathryn Eckert & Glenn Plumb | National Park Service | 2016
Provides a biodiversity glossary distinguishing species richness—the number of species—from species diversity, which also incorporates relative abundance.
Applied Examples, Conservation, and Monitoring
| National Park Service | U.S. National Park Service | 2024-01-12
Explains the use of Shannon species diversity in bird monitoring and illustrates how diversity reflects both the number of bird species and their relative abundances.
| National Park Service | U.S. National Park Service | 2021-05-18
Examines regional variation in Alaskan plant diversity and shows how elevation, vegetation structure, and borealization affect species richness.
| National Park Service | U.S. National Park Service | 2019-12-30
Examines alpine-tundra species richness in subarctic Alaska and the potential effects of warming climate on high-latitude biological communities.
| David M. Leslie Jr. | National Park Service | 2016-04-08
Discusses strategies for biodiversity conservation and argues that preserving species richness and ecological function is essential to maintaining natural heritage.
| Danielle Buttke et al. | National Park Service | 2016
Reviews relationships between biodiversity and human health, including examples in which greater species richness affects disease regulation and other ecosystem services.
| Ryan A. Chisholm et al. | Ecology Letters | 2014
Uses long-term tropical forest data to analyze abundance fluctuations among thousands of tree species and their implications for the maintenance of diversity.
| Smithsonian ForestGEO | Smithsonian Institution | n.d.
Uses globally distributed forest plots to investigate how regional history and environmental conditions influence local tree species diversity.
| Smithsonian ForestGEO | Smithsonian Institution | n.d.
Examines community-based monitoring of highly diverse tropical forests and relationships among canopy structure, species richness, and Shannon diversity.
| Julieta Benítez-Malvido & Miguel Martínez-Ramos | Conservation Biology | n.d.
Finds reduced seedling and understory plant species richness in fragmented tropical forests compared with continuous forest.
| United Nations | United Nations Climate Action | n.d.
Explains how climate change, habitat conversion, and ecosystem degradation threaten species diversity while biodiversity itself can increase ecosystem resilience to environmental change.
Foundational Theory and Research
| A. J. Hamilton | Journal of Environmental Management | 2005
Examines the meanings and uses of the terms species diversity and biodiversity. The paper cautions that these concepts are sometimes used interchangeably despite representing different dimensions of biological variation and conservation value.
| L. Borda-de-Água et al. | The American Naturalist | 2002
Connects species-area relationships, species-abundance distributions, and diversity indices within a common mathematical framework.
| Michel Loreau et al. | Science | 2001
Reviews the emerging scientific consensus on biodiversity and ecosystem functioning and distinguishes species diversity from the effects of particular species.
| Brian J. Wilsey & Catherine Potvin | Ecology | 2000
Experimentally separates species richness from species evenness and demonstrates that changes in evenness can influence ecosystem functioning independently of richness.
| Mark W. Schwartz et al. | Oecologia | 2000
Reviews relationships between biodiversity and ecosystem function and emphasizes the importance of species turnover and identity in addition to simple richness.
| Shigeo Yachi & Michel Loreau | Proceedings of the National Academy of Sciences | 1999
Introduces the ecological "insurance hypothesis," proposing that greater species richness stabilizes ecosystem processes because species respond differently to environmental fluctuations.
| Michel Loreau | Proceedings of the National Academy of Sciences | 1998
Develops a mechanistic model explaining why changes in species diversity can alter productivity and other ecosystem functions.
| Stephen P. Hubbell | Coral Reefs | 1997
Develops ideas that later became central to neutral biodiversity theory, linking species richness, relative abundance, immigration, speciation, and community size.
| Nature Education | Nature Scitable | n.d.
Introduces neutral theory as an explanation for patterns of species abundance and diversity. Unlike traditional niche theories, neutral models assume ecological equivalence among species and explore how dispersal, extinction, speciation, and chance shape communities.
| Nature Education | Nature Scitable | n.d.
Reviews major patterns linking species abundance, geographic distribution, rarity, and diversity. Species-abundance distributions help ecologists understand why communities contain a few common species and many relatively uncommon species.
| Smithsonian Ocean | Smithsonian Institution | n.d.
Explains biodiversity through genetic, species, and ecosystem perspectives. It also describes how taxonomy, ecology, evolution, and genetics provide different but complementary approaches to understanding the enormous variety of life.
| Smithsonian Tropical Research Institute | Smithsonian Institution | n.d.
Describes biodiversity research in tropical ecosystems, where exceptional numbers of plants, animals, fungi, and microorganisms coexist. Tropical forests provide important natural laboratories for studying the origins, maintenance, and ecological consequences of high species diversity.
Educational and Reference Sources
| National Park Service | U.S. National Park Service | 2024-05-15
Describes the unusually diverse habitats and plant and animal communities of Acadia National Park and illustrates how environmental transitions promote local species diversity.
| National Park Service | U.S. National Park Service | 2024-01-25
Describes the NPSpecies inventory system and the systematic documentation of species occurrence, distribution, conservation status, and habitat across national parks.
| Smithsonian National Museum of Natural History | Smithsonian Institution | n.d.
Introduces biodiversity as variation among genes, species, and ecosystems and explains why the diversity of species and their interactions matters to functioning ecosystems.
| Nature Education | Nature Scitable | n.d.
Explains how ecologists characterize biological communities using species richness, relative abundance, species diversity, and evenness.
| Shahid Naeem | Nature Scitable | n.d.
Explains relationships between species diversity, species composition, ecosystem functioning, and ecological stability.
| Bradley Cardinale et al. | Nature Scitable | n.d.
Reviews causes of biodiversity decline and explains how richness, evenness, and composition affect ecological processes.
| U.S. Geological Survey | USGS | n.d.
Provides an overview of biodiversity and major threats to species, including habitat destruction, invasive organisms, overexploitation, pollution, and climate change.
| U.S. Geological Survey | USGS Thesaurus | n.d.
Defines species diversity as incorporating both the number of species within an area and the evenness with which individuals are distributed among them.
| Elsevier | ScienceDirect Topics | n.d.
Explains species richness, species-area relationships, geographical richness patterns, and the distinction between local and regional diversity.
| Elsevier | ScienceDirect Topics | n.d.
Explains species evenness and demonstrates why two communities containing the same number of species may nevertheless have very different levels of species diversity.
Total unique sources: 133 Duplicates removed: 11
