Measures Of Biodiversity Research Articles

Biodiversity skepticism and measurement practices

AbstractThis paper challenges “biodiversity skepticism:” an inferential move that acknowledges the proliferation, heterogeneity, and lack of covariance of biodiversity measurements, and concludes that we should doubt the scientific validity of the biodiversity concept. As a way out of skepticism, philosophers have advocated for eliminating “biodiversity” from scientific inquiry, revising it, or deflating its meaning into a single measurable dimension. I present a counterargument to the inferential move of the skeptic by revealing how it stands on two unstated premises, namely a reflective view of measurements and the unidirectional dynamics between definitional and measurement practices, and corollary assumptions. These premises and assumptions are misaligned with a richer theoretical understanding of measurement and are sometimes inconsistent with how science operates. A more nuanced view of measurement could better explain measurement proliferation while being consistent with new ways in which the general biodiversity concept could be useful. To conclude, I urge philosophers of measurement and conceptual engineers to collaborate in tackling the interplay between conceptual change and measurement practices.

Satellite remote sensing reveals the footprint of biodiversity on multiple ecosystem functions across the NEON eddy covariance network

Abstract Biodiversity relates to ecosystem functioning by modulating biogeochemical cycles of carbon, water, energy, and nutrients within and between multiple biotic and abiotic components of the ecosystems. However, large-scale, systematic measurements of plant biodiversity are still lacking, and the effects of biodiversity on measured biogeochemical processes are understudied. Here, we combined alpha (α) and beta (β) taxonomic measurements, spectral diversity from satellite observations, structural properties of the vegetation, and climatic drivers to assess the effect of biodiversity on ecosystem functional properties. Ecosystem functional properties were computed from eddy-covariance fluxes at 44 sites of the National Ecological Observatory Network. Based on the spectral variation hypothesis, we used the near-infrared reflectance of vegetation (NIRv) derived from Sentinel-2 satellite imagery to compute Rao’s quadratic entropy (Rao Q), a distance metric related to spatial heterogeneity. Using an automatic model averaging technique, we found that biodiversity proxies hold substantial explanatory power when predicting several ecosystem functions related to carbon and water exchange. In particular, NIRv-based Rao Q (RaoQNIRv) reflected positive biodiversity effects on productivity, as expected from the literature. In contrast, traditional taxonomic α-diversity indices were generally not selected as relevant predictors of the ecosystem functional properties. Yet, β-diversity strongly contributed to the prediction of carbon use efficiency, surface conductance, and water use efficiency. We also found that the RaoQNIRv is less affected by issues of saturation and bare soil contribution compared to RaoQNDVI. We show that spectral heterogeneity based on remotely sensed NIRv holds the potential for globally characterizing the biodiversity-ecosystem functioning relationship (BEF). While systematic measurements of taxonomic diversity co-located at biogeochemical measurement stations could reduce the uncertainty surrounding the BEF relationship at whole-ecosystem scale, remotely- sensed metrics characterizing important functional and structural diversity aspects of the landscape will be crucial for continuous spatiotemporal monitoring of biodiversity with relevant implications for ecosystem services to humankind.

Biodiversity measures of a grassland plant-pollinator community are resilient to the introduction of honey bees (Apis mellifera).

The prairies of Canada support a diversity of insect pollinators that contribute pollination services to flowering crops and wild plants. Habitat loss and use of managed pollinators has increased conservation concerns for wild pollinators, as mounting evidence suggests that honey bees (Apis mellifera) may reduce their diversity and abundance. Plant-pollinator community analyses often omit non-bee pollinators, which can be valuable contributors to pollination services. Here, we experimentally introduced honey bees to examine how their abundance affects the species richness, diversity, abundance, species composition, interaction richness, and interaction diversity of all wild pollinators, and of four higher taxa separately. We identified all insect pollinators and analyzed how honey bee abundance affected the above biodiversity metrics, controlling for flower abundance and flower species richness. Even with high honey bee densities, there was no change to any of these variables, except that beetle species diversity increased. All other taxa had no significant relationship to honey bee abundance. Considering the widespread use of managed honey bees, the effect they have on wild pollinators should be firmly established. Our results suggest that honey bees have little to no short-term impact on the wild pollinator community or its interactions with plants in this native grassland.

Increased diversity of macroinvertebrates, but not fish, near wastewater outfalls in the Red River Basin, Oklahoma

The reuse of wastewater for beneficial purposes (e.g. irrigation) can boost water sustainability, but may have positive or negative impacts on the environment. In some drought-prone or over-allocated river basins, wastewater is an important component of stream flows and may buffer river ecosystems from drought. In these locations, wastewater may have a net positive impact on river ecosystems and its capture and reuse would be harmful to these ecosystems. In other locations, wastewater may have a net negative impact if the quality of the wastewater (i.e. concentrations of contaminants and nutrients) is lower than that of the receiving water body. In this study, we quantified the effects of wastewater on fish and macroinvertebrate communities in the Red River, Oklahoma. We investigated two competing hypotheses. First, we hypothesized that if wastewater flows buffer aquatic communities from drought, then measures of biodiversity should be higher at sampling sites near wastewater outfalls than at sites not near wastewater outfalls. Second, we hypothesized that if wastewater outfalls negatively impact water quality or homogenize the flow regime, then measures of biodiversity should be lower at sites near wastewater outfalls. To test these competing hypotheses, we calculated a suite of biodiversity indices at 320 biological sampling sites in the Red River Basin and analyzed for significant differences in communities based on proximity to wastewater outfalls. We found that proximity to upstream wastewater outfalls had significant positive impacts on macroinvertebrate community biodiversity, but we did not find any significant relationships with fish community diversity. Findings from this study provide insight to management decisions on wastewater reuse initiatives in beneficial subbasins while minimizing harmful ecological impacts.

Surprisingly good fit of pressure-based cropland condition map and bird census data at the national scale

As the world is struggling to halt the rapid decline of biodiversity, the assessment and mapping of ecosystem condition is getting ever increasing attention. Croplands are artificial ecosystems, but as they occupy a large portion of land, they significantly influence biodiversity. Yet, there is a knowledge gap about their suitability to support and maintain wildlife on a national scale. Large-scale condition mapping is meant to address this gap; the good condition of croplands includes their ability to support biodiversity. However, the lack of suitable databases is often a challenge when creating such maps. As there is a strong causal relation between pressures on the ecosystem and its condition, pressure indicators can be used as proxies to approximate condition when more direct indicators are lacking. The validation of condition maps based on pressure proxies is a key but challenging step. In this study, we tested a previously designed pressure-based cropland condition map for Hungary using bird census data. Besides validating the composite condition indicator, we also tested some key elements of the mapping process, such as the choice of variables and thresholds.Using multiple comparisons of means by Tukey’s contrast and Random Forest modelling, we examined the relationship of (1) the continuous pressure-based cropland condition variables, (2) their rescaled, ordinal version (called sub-indicators), and (3) the composite cropland condition indicator (sum of the sub-indicators) with a biodiversity measure, the standardised relative richness of characteristic farmland bird species (rRRCS). To get a picture of the spatial patterns of the examined relationships across Hungary, individual Random Forest models were constructed for all the spatial units of the bird census database, using focal analysis with a 30 km radius moving window.We found significant differences in the mean rRRCS for nearly all sub-indicator categories, signifying that the literature-derived thresholds were mostly sound. Categories with higher (better) condition scores had higher mean rRRCS; the differences are significant in the mid-range but not in the extreme categories, indicating a need for a meaningful simplification of the categories. The goodness-of-fit (R2) of the Random Forest models was found to be high, but it is spatially heterogeneous (ranged from 0.69 to 0.89, with a median value of 0.81), similarly to the variable importance. The proportion of semi-natural areas proved to be the most important condition variable. The proportion of maize and alfalfa were more important than parcel size. Our results show that condition maps based on pressure proxies can reflect patterns of biodiversity surprisingly well. They also highlight the spatial context dependence of the uncertainty of condition maps.

Standards‐based evaluation inform ecological restoration outcomes for a major mining activity in a global biodiversity hotspot

The International Principles and Standars for the Ecological Restoration and Recovery of Mine Sites were used to assess the restoration quality of one of the world's largest mines, located in the world's most biodiverse temperate forest. Quantitative analysis of longitudinal data spanning 35 years scored restoration quality at 2‐stars against a 5‐star forest ecosystem restoration target, with little indication of improvements from adaptive management. Two‐thirds of indicator plants were significantly under‐represented in early‐stage restoration and declined with age. Most plant species were effectively absent, including key structural species. Invasive plants and native legumes were persistently overabundant. Time required for the maturation of tree species will prevent the production of fundamental ecosystem features for well over a century (e.g. hollows and fallen logs), inhibiting functional fauna return (reptiles, bats, and conservation priority cockatoos in particular). The significantly different outcome compared with previous assessments is due to the age of restoration assessed and previous assumptions that early‐stage success indicate that restoration is on the correct, prolonged trajectory toward full ecological restoration. However, previous assessment methods did not consider many key metrics of the standards, nor accurately predict future restoration trajectory. In particluar, initial plant species richness (the only measure of biodiversity in the company's restoration completion criteria) did not reflect future restoration quality. These substandard restoration outcomes may result from removing the deep, multi‐layered bauxitic substrate on which the ecosystem evolved and establishing restoration on shallow topsoil over a more homogenized, impervious substrate. This study demonstrates the value of a robust, adaptable multi‐factor framework and methodology to evaluate restoration outcomes.

Incorporating seasonality, predictability, and modularity into the optimization of biodiversity conservation for ecological networks

Improving the connectivity of ecological networks (ENs) is a proven strategy for biological conservation. However, without a clear understanding of animal movement, research on ENs may not provide a sufficient reference for maintaining biodiversity. To address this gap, we embraced central concepts of movement ecology and conducted a study in the Qilian Mountains. The predictability and seasonality of environmental conditions were combined to identify ecological sources with rich temporal niches and improve the informed preference character of resistance surface. Then, we constructed ENs with six dispersal thresholds. Further, integrating modularity and circuit theory, we pinpointed priority areas for restoration within the ENs. Our findings indicated that the eastern part of the Qilian Mountains showed higher biodiversity suitability, with terrain being the primary factor limiting dispersal. Additionally, comparative analyses demonstrate that the new method for measuring biodiversity from the perspective of temporal niche is reliable and better aligns with the needs of biodiversity conservation. In light of emerging challenges within the study area, where apex predators seriously suppress the populations of some smaller predators, we propose a novel conservation idea that emphasizes the strategic retention and removal of barriers to maintain biological balance. This study enriches methodologies for biodiversity measurement, provides forward-looking conservation strategies, and offers practical contributions toward mitigating biodiversity loss.

A technological biodiversity monitoring toolkit for biocredits

Abstract Biodiversity is in crisis globally, and we consistently fail to hit global targets to stem its loss. Inspired by the Kunming‐Montreal Global Biodiversity Framework, the biodiversity credit market offers an avenue for vital funding for biodiversity conservation projects around the world. Various biodiversity credit methodologies and standards are becoming available, and most will require the measurement and monitoring of biodiversity at scale. Private investment in conservation through biodiversity credits entails specific needs for biodiversity data collection, including the need for biodiversity claims to be verifiable. We conceptualise these requirements around ‘SAGED’ criteria: Scalable, Accessible, Granular (data of appropriate spatial, taxonomic and temporal resolution), Evidenceable and Directly measured (where possible). Measuring and monitoring biodiversity across ecosystems, ecoregions and taxa is expensive and time‐consuming with traditional survey methods. These methods often rely on access to experts with sufficient taxonomic and survey expertise, which is challenging in many parts of the world. Accordingly, we review biodiversity monitoring technologies and assess their readiness to fulfil key requirements of assessments for the purpose of nature accounting for biodiversity credits (particularly SAGED criteria). We focus on monitoring technologies that are commonly cited by biodiversity credit methodologies, including (e)DNA metabarcoding, passive acoustic monitoring and various other remote sensing methods. We also explore the current limits of these techniques in obtaining appropriate biodiversity measures and metrics for biodiversity finance. Synthesis and applications. Technological solutions for biodiversity monitoring are not (yet) a panacea but are key for evidenceable monitoring at scale. For current use in biocredit markets, we advise these are combined with ground validation and human‐collected ecological data. Developments in automation and machine learning will rapidly make these technologies more accessible and efficient.

Fragments maintain similar herpetofauna and small mammal richness and diversity to continuous habitat, but community composition and traits differ

ContextHuman disturbance has transformed ecosystems globally, yet studies of the ecological impact of landscape modification are often confounded. Non-random patterns of land clearing cause differing vegetation types and soil productivity between fragments in modified landscapes and reference areas—like national parks—with which they are compared.ObjectivesWe sought to explore the influence of land modification on herpetofauna and small mammal communities using multiple biodiversity measures—species richness and diversity, individual species abundance, and community composition. We also aimed to investigate the role of traits such as diet, habitat breadth, and litter size in moderating species responses to land modification.MethodsWe established 100 sampling sites to survey herpetofauna and small mammals in 11 fragments in an agricultural landscape compared to 11 ecologically equivalent ‘pseudo-fragments’ in a nearby national park in south-eastern Australia. We selected pairs of fragments and pseudo-fragments of the same size and vegetation type, and used identical survey methods to sample pairs simultaneously, thereby controlling for numerous confounding factors, such as differing vegetation type, weather, and survey effort.ResultsSpecies richness and diversity were similar between fragments and pseudo-fragments. Despite this, we found community composition differed markedly—driven by the varying responses of individual species—indicating a shift in fauna communities associated with land modification. Fossorial habit, omnivorous diet, and broad habitat requirements led to higher abundance in fragments whilst arboreality, carnivorous diet, and narrow habitat requirements led to higher abundance in pseudo-fragments.ConclusionsAlthough fragments hold similar numbers of species to continuous areas, they contain distinct and novel communities, and sustain high abundances of some species. These diverse communities are dominated by native species, including threatened species, and their distinctive composition is shaped by traits conducive to persistence amidst land modification. These novel communities may provide a reservoir of resilience in the face of environmental change and should be viewed as complementary to conservation areas.

Adding a mosaic mowing regime to urban lawns is the key to city biodiversity management for pollinators

City populations are growing rapidly, with built-up areas occupying ever-larger areas within the cities. One of the last green places in a city is urban lawns. Our study aimed to investigate how lawn management changes can contribute to improving insect pollinator biodiversity at the city scale. Over two years, we studied dozens of urban lawns in Prague (Czech Republic) that were partially left unmown, and we selected three major groups of pollinators: Lepidoptera, Coleoptera and Hymenoptera. This study showed that leaving unmown lawn areas has a strong positive effect on insect biodiversity. The high intensity of lawn flowering through the vegetation season was also crucial. Our research showed that leaving unmown parts of urban lawns is one of the key amendments to maintain or even increase pollinator biodiversity in cities. It also appears to be the best way to attract red-listed species. A significant reducing mowing frequency to achieve a higher flowering intensity should be a positive solution. So-called insect gardening by reducing urban lawn mowing frequency or leaving parts of lawns completely unmown can help not only pollinators but also other animals that find food or shelter in them. This management will also enable the propagation of flowering plants. Additionally, biodiversity measures coincide with reducing evapotranspiration and thus cooling urban heat islands.

Assessing the Impact of Urbanization on Medicinal Plant Diversity and Conservation Strategies in Delhi NCR

This study investigates the impact of urbanization on medicinal plant diversity and conservation strategies in Delhi NCR. Using a quantitative approach, data were collected from 419 households through a structured questionnaire. Statistical analyses, including correlation and regression, revealed a significant negative relationship between urbanization and both medicinal plant diversity and conservation efforts. Urban expansion was found to reduce biodiversity and hinder the effectiveness of conservation strategies. The study concludes that urbanization poses a serious threat to the preservation of medicinal plants and recommends strengthening urban planning to incorporate biodiversity measures, raising public awareness, and enhancing green infrastructure. The findings underscore the need for immediate action to mitigate the negative effects of urbanization on medicinal plant diversity.

Poor transferability of richness models: Predicting plot-scale plant diversity in the Waterberg, South Africa

Modelling measures of biodiversity for understudied taxa or regions is one method to address taxonomic and geographic biases in biodiversity data. However, modelling biodiversity metrics, such as species richness, to unsampled areas is only useful if predictions are reliable. As a result, testing the transferability of richness models is necessary for assessing the potential for models to predict to unsampled areas. Here we test the transferability of plant richness models between two reserves to examine if the richness-environment relationship from one reserve can accurately estimate richness patterns in the other reserve, using the vascular plant species richness of the Waterberg region (savanna biome; northern South Africa) as a model system. Six richness response variables (total species, grass species, herb species, woody species, genus, and family richness) and a set of 16 predictor variables were analysed with three modelling approaches and two statistical techniques to build: (1) models comprising all available predictor variables, (2) models using a subset of predictor variables chosen based on model performance, and (3) models using a subset of predictor variables that reduce the difference in the environmental conditions between the two reserves. The models’ performance in the training area varied considerably, but soil variables were consistently the most important predictors of plant richness. However, the transferability of all the models was consistently poor across all modelling approaches and both techniques, possibly reflecting the degree to which each reserve contains novel environments absent from the other reserve (despite being separated by only c. 60 km and sharing vegetation types). Due to the poor performance of these richness models, they are currently not useful for predicting richness to other areas in the vicinity of the reserves or in the broader region. However, in areas, like the Waterberg region, that have high plant diversity and are poorly sampled, there may be value in continued development of richness models to address biodiversity gaps, thereby providing better data to inform conservation decisions.

Do NGOs recognise the climate-biodiversity nexus? Insights from 107 climate NGOs in Germany

Biodiversity loss and climate change are deeply intertwined and constitute a complex and interdependent crisis. These interlinked sustainability issues need to be addressed through an integrated approach. However, governments have been slow to integrate the need to protect both climate and biodiversity into environmental governance. NGOs, as non-profit organisations promoting public good, are seen as having the potential to recognise and advocate for this much-needed holistic protection of climate and biodiversity. But to what extent and in what ways do NGOs recognise this climate-biodiversity nexus? This article addresses these questions through an analysis of 107 German climate NGOs, examining their 190 annual reports from two time periods, 2016/2017 and 2021/2022. We found that, while German climate NGOs have made significant progress in recognising the climate-biodiversity nexus, they lack recognition of the role of biodiversity in stabilising the climate and the unintended negative consequences of climate policies and measures for biodiversity, highlighting that NGOs are still far from being holistic environmental stewards. Climate NGOs need to integrate the interplay between climate and biodiversity objectives into their organisational activities and align their mandates to promote synergies and minimise trade-offs between climate and biodiversity actions. We suggest that one way forward is to increase collaboration between NGOs. NGOs could then complement each other’s expertise and be better placed to jointly contribute to finding integrated solutions for climate and biodiversity protection and mainstreaming biodiversity into climate policy.

Systematic planning shows more than half of the most species-rich ocean region is needed to include all species in representative protected areas

The Convention on Biological Diversity Target 3 aims for at least 30 % of each marine habitat to be protected by 2030. How much biodiversity will be protected depends on where this 30 % is located. The West Pacific region, having the richest marine biodiversity on Earth, is especially important for nature conservation. Here, using multiple data-driven measures of the breadth biodiversity, from species to ecosystems from the sea surface to seabed, at a spatial resolution of 0.5° (∼55 km latitude), we mapped the optimal “Representative Biodiversity Areas” (RBA) for West Pacific countries using decision support software. The measures included surface and near seabed Ecosystems, which were mapped by physical, biochemical and nutrient variables relevant to ecological functioning. Species richness, seagrass, kelp, mangrove, and shallow water coral reef biomes (biological habitats at a local scale) and seabed topographic variation (as rugosity) were also included as complementary measures to maximise representivity of biodiversity overall. The 30 % RBA generally covered 30 % of the Ecosystems, over 77 % of the Biomes of seagrass, kelp, mangrove, and shallow water corals, and 60 % of physical habitat heterogeneity (topography) and the most species rich areas. Because protecting only these four biomes was not sufficient to include all species, physical habitat heterogeneity and ecosystems should be included in conservation prioritisation because they extend offshore and to all depths. To cover the distributions of 80 % species in the region, at least 53 % of the total area should be under protection. Only 25 % of the RBA were in MPAs, and < 1 % in no-take MPAs. Three countries, Indonesia, Australia and New Zealand, occupied almost half (47 %) of the RBA, and 11 countries had more than 30 % of their Exclusive Economic Zones in the RBA. Opportunities exist to expand and merge existing MPA, increase levels of protection, and having MPA in areas of disputed or shared governance, including 5 % of RBA being in the study area’s High Seas. Consideration of the geographically uneven distribution of biodiversity is thus necessary in achieving the 30 % by 2030 target. Systematic conservation planning, as shown here, can lead to at least twice as much biodiversity being protected per area. That at least half of the West Pacific Ocean in MPA may be necessary to protect all marine biodiversity, indicates how critical it is to use resources outside MPA in an ecologically sustainable way.

Prototype Biodiversity Digital Twin: Phylogenetic Diversity

Phylogenetic diversity (PD) represents a fundamental measure of biodiversity, encapsulating the extent of evolutionary history within species groups. This measure, pivotal for understanding biodiversity's full dimension, has gained recognition by major environmental and scientific organisations, including the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services. Unlike traditional taxonomic richness, PD offers a comprehensive, evolutionary perspective on biodiversity, essential for conservation planning and biodiversity management. This manuscript describes the development of a BioDT (Biodiversity Digital Twin) prototype, aimed at facilitating the calculation and visualisation of biodiversity metrics from global, dynamic data sources. By utilising the PhyloNext pipeline and integrating with global phylogenetic and species occurrence databases like the Open Tree of Life (OToL) and the Global Biodiversity Information Facility (GBIF), the prototype aims to significantly reduce computation time and enhance user interaction. This enables dynamic visualisation and potentially hypothesis testing, making it a valuable tool for researchers, monitoring initiatives, policy-makers and the public. The prototype's development focuses on improving the PhyloNext pipeline's scalability and creating a more intuitive user interface, expanding its utility for conservation efforts and biodiversity exploration. Our work illustrates the potential impact of the BioDT prototype in supporting diverse user groups in visualising and exploring PD, thus contributing to more informed decision-making in conservation and biodiversity management.

Understanding marine biodiversity patterns and drivers: The fall of Icarus

AbstractBiodiversity patterns are fundamental in our understanding of the distribution of life, ecosystem function, and conservation. In this concept analysis, A survey of the existing knowledge on marine biodiversity patterns and drivers across latitudes, longitudes, and depths indicates that none of the postulated patterns represent a rule. The paradigm of latitudinal gradients or bathymetric patterns of diversity vary across biogeographic regions or biodiversity components, kingdoms, or body sizes. The same holds true for the hypothesized longitudinal and cost‐offshore patterns. Food availability and temperature influence all life forms and appear to be the most relevant factors shaping marine biodiversity. However, these drivers interact with many other variables such as spatial heterogeneity, ecological and physical processes creating a complex mosaic of shaping factors that limits any prediction. Climate change, with its implications for global primary productivity and temperature rise, can represent one of the major influences on future marine biodiversity. Understanding biodiversity emphasizes the need to complete the census of marine life in the next decade. The effort must use the most advanced technologies, develop holistic approaches and promote the integration of morphological‐ and genetic‐based taxonomy to explore the biodiversity of organisms of all size classes, at large spatial scales and across habitat types, particularly open ocean and deep‐sea ecosystems. Without this basic knowledge, coupled with identification of the drivers shaping the observed patterns, we will be unable to fill these knowledge gaps that are crucial for developing adequate conservation measures of marine biodiversity at global scale.

Monitoring insect numbers and biodiversity with a vertical-beam entomological radar.

Concerns about perceived widespread declines in insect numbers have led to recognition of a requirement for long-term monitoring of insect biodiversity. Here we examine whether an existing, radar-based, insect monitoring system developed for research on insect migration could be adapted to this role. The radar detects individual larger (greater than 10 mg) insects flying at heights of 150-2550 m and estimates their size and mass. It operates automatically and almost continuously through both day and night. Accumulation of data over a 'half-month' (approx. 15 days) averages out weather effects and broadens the source area of the wind-borne observation sample. Insect counts are scaled or interpolated to compensate for missed observations; adjustment for variation of detectability with range and insect size is also possible. Size distributions for individual days and nights exhibit distinct peaks, representing different insect types, and Simpson and Shannon-Wiener indices of biodiversity are calculated from these. Half-month count, biomass and index statistics exhibit variations associated with the annual cycle and year to year changes that can be attributed to drought and periods of high rainfall. While species-based biodiversity measures cannot be provided, the radar's capacity to estimate insect biomass over a wide area indicates utility for tracking insect population sizes. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Identifying anomalous patterns in ecological communities’ diversity: leveraging functional boxplots and clustering of normalized Hill’s numbers and their integral functions

AbstractDiversity is fundamental in many disciplines, such as ecology, business, biology, and medicine. From a statistical perspective, calculating a measure of diversity, whatever the context of reference, always poses the same methodological challenges. For example, in the ecological field, although biodiversity is widely recognised as a positive element of an ecosystem, and there are decades of studies in this regard, there is no consensus measure to evaluate it. The problem is that diversity is a complex, multidimensional, and multivariate concept. Limiting to the idea of diversity as variety, recent studies have presented functional data analysis to deal with diversity profiles and their inherently high-dimensional nature. A limitation of this recent research is that the identification of anomalies currently still focuses on univariate measures of biodiversity. This study proposes an original approach to identifying anomalous patterns in environmental communities’ biodiversity by leveraging functional boxplots and functional clustering. The latter approaches are implemented to standardised and normalised Hill’s numbers treating them as functional data and Hill’s numbers integral functions. Each of these functional transformations offers a peculiar and exciting point of view and interpretation. This research is valuable for identifying warning signs that precede pathological situations of biodiversity loss and the presence of possible pollutants.

A Cross-Decadal Change in the Fish and Crustacean Community of Lower Yaquina Bay, Oregon, USA

Natural environmental change, anthropogenic development, and inter-annual variability can affect the ecology of estuarine fish and invertebrates. Yaquina Bay, Oregon, a well-studied estuary, has undergone intense development, as well as deep-draft dredging during the latter half of the 20th century, resulting in the alteration of ~45% of the lower estuary’s natural shoreline. In 1967, the United States Environmental Protection Agency (USEPA) conducted a 21-month survey of Yaquina Bay to characterize the demersal fishes and epibenthic crustaceans that occupy the bay. From 2003 to 2005, we conducted a 25-month survey to replicate that work and provide a comparative snapshot of the demersal fish and epibenthic crustacean community in the bay. A comparison of the trawl survey datasets reveals a 91% decline in total catch per unit effort (CPUE) between surveys, as well as a decline in multiple measures of biodiversity. Furthermore, the fishes and crustaceans of Yaquina Bay have experienced a shift in species dominance from demersal fishes in the late 1960s to epibenthic crustaceans in the 2000s, marked most notably by a nine-fold increase in the Dungeness crab CPUE. While this work does not establish a causal relationship between changes in the demersal communities of this West Coast estuary and human or natural events, it does document substantial changes in both the diversity and total abundance of animals in that community over a three-plus decade period of development and environmental variability. Hence, this forms a second baseline for continued long-term monitoring.

Monitoring spatial tree diversity indices using relascope sampling: Estimators, interactions and limitations

With ongoing climate change the monitoring of tree diversity has become very important for avoiding or at least decelerating the loss of biodiversity and for maintaining forest ecosystem resilience. As part of such monitoring, spatial indices of tree diversity which are calculated for individual trees often serve as surrogates for more direct measures of biodiversity. Mainly for its efficiency and ease of application, relascope sampling is a widespread method applied in forest inventory of many countries and thus has often been suggested as a data source for the monitoring of tree diversity. Since the interaction between sampling design and spatial diversity indices is not always clear to data analysts, we reviewed existing estimators and experimentally examined a new one, conducted extensive sampling simulations using different indices and estimators and additionally analysed the data from a large-scale forest inventory in Austria. We found that both forest structure and index algorithm greatly influence the sampling error. The largest source of sampling error was the index variance and contrary to our expectation not so much the bias due to spatial effects. For diversity indices related to distances, it has turned out to be best to apply estimators that include spatial edge correction methods. For all other indices an estimator performed better that included information on both the sample trees and their nearest neighbours, as it much reduced overall index variance. However, if possible the plus-sampling edge correction method should be applied.