Explore the vast range of titles available.

1. National and international forest biodiversity assessments largely rely on indirect indicators, based on elements of forest structure that are used as surrogates for species diversity. These proxies are reputedly easier and cheaper to assess than biodiversity. Tree microhabitats - tree-borne singularities such as cavities, conks of fungi or bark characteristics - have gained attention as potential forest biodiversity indicators. However, as with most biodiversity indicators, there is a lack of scientific evidence documenting their quantitative link with the biodiversity they are supposed to assess. 2. We explored the link between microhabitat indices and the richness and abundance of three taxonomic groups: bats, birds, and saproxylic beetles. Using a nation-wide multi-taxon sampling design in France, we compared 213 plots located inside and outside strict forest reserves. We hypothesized that the positive effect setting aside forest reserves has on biodiversity conservation is indirectly due to an increase in the proportion of large structural elements (e.g. living trees, standing and lying deadwood). These, in turn, are likely to favour the quantity and diversity of microhabitats. We analysed the relationship between the abundance and species richness of different groups and guilds (e.g. red-listed species, forest specialists, cavity dwellers) and microhabitat density and diversity. We then used confirmatory structural equation models to assess the direct and indirect effects of management abandonment, large structural elements and microhabitats on the biodiversity of the target species. 3. For several groups of birds and bats, the indirect effect of management abandonment and large structural elements on biodiversity was mediated by microhabitats. However, the magnitude of the link between microhabitat indices and biodiversity was moderate. In particular, saproxylic beetles' biodiversity was poorly explained by microhabitats, large structural elements or management abandonment. 4. Synthesis and applications: Tree microhabitats may serve as indicators for bats and birds, but they are not a universal biodiversity indicator. Rather, compared to large structural elements, they most likely have a complementary role to biodiversity. In terms of forest management and conservation, preserving diversity of microhabitats at the local scale benefits several groups of both bats and birds.

• A host-plant and its associated microbiota depend on one another. However, the assembly process and the functioning of host-associated microbiota are poorly understood. • Herein, rice was used as model plant to investigate the assemblage of bacterial microbiota, including those in the seed, root endosphere and rhizosphere. We also assessed the degree to which endosphere and rhizosphere communities were influenced by vertical transmission through seed and identified the core microbes that potentially associated with plant phenotypic properties. • Plant microhabitat, rather than subspecies type, was the major driver shaping plant-associated bacterial microbiota. Deterministic processes were primarily responsible for community assembly in all microhabitats. The influence of vertical transmission from seed to root-associated bacterial communities appeared to be quite weak (endosphere) or even absent (rhizosphere). A core microbial community composed of 15 generalist species persisted across different microhabitats and represented key connectors in networks. Host-plant functional traits were linked to the relative abundance of these generalist core microbes and could be predicted from them using machine learning algorithms. • Overall, bacterial microbiota is assembled by host-plant interactions in a deterministic-based manner. This study enhances our understanding of the driving mechanisms and associations of microbiota in various plant microhabitats and provides new perspectives to improve plant performance.

Coral reefs provide vital fisheries and coastal defense, and they urgently need protection from the damaging effects of plastic waste. Lamb et al. surveyed 159 coral reefs in the Asia-Pacific region. Billions of plastic items were entangled in the reefs. The more spikey the coral species, the more likely they were to snag plastic. Disease likelihood increased 20-fold once a coral was draped in plastic. Plastic debris stresses coral through light deprivation, toxin release, and anoxia, giving pathogens a foothold for invasion. Science , this issue p. 460 Plastic waste entanglement exacerbates the risk of coral disease outbreaks and consequent damage to reefs, as well as the loss of fisheries and coastal protection. Plastic waste can promote microbial colonization by pathogens implicated in outbreaks of disease in the ocean. We assessed the influence of plastic waste on disease risk in 124,000 reef-building corals from 159 reefs in the Asia-Pacific region. The likelihood of disease increases from 4% to 89% when corals are in contact with plastic. Structurally complex corals are eight times more likely to be affected by plastic, suggesting that microhabitats for reef-associated organisms and valuable fisheries will be disproportionately affected. Plastic levels on coral reefs correspond to estimates of terrestrial mismanaged plastic waste entering the ocean. We estimate that 11.1 billion plastic items are entangled on coral reefs across the Asia-Pacific and project this number to increase 40% by 2025. Plastic waste management is critical for reducing diseases that threaten ecosystem health and human livelihoods.

In tropical forests, vascular epiphyte diversity increases with tree size, which could result from an increase in area, time for colonization or an increase in microhabitat heterogeneity within‐tree crowns if vascular epiphyte species are specialized to particular microhabitats within the crown. The importance of microhabitats in structuring epiphyte communities has been hypothesized for more than 120 years but not yet confirmed. We tested the importance of microhabitats in structuring epiphyte communities by examining microhabitat heterogeneity and epiphyte communities within the crowns of different‐sized Virola koschnyi (Myristicaceae) emergent trees in a Costa Rican tropical wet forest. We tested the degree to which epiphyte species composition was associated with environmental conditions and resources (i.e. microhabitats) using multivariate analyses and a null model that compared the observed epiphyte assemblages amongst different‐sized trees and crown zones with assemblages generated randomly. This study is the first to rigorously examine the degree of microhabitat specialization in epiphyte communities. Microhabitat heterogeneity, epiphyte species richness and abundance increased with tree size. The largest trees had the highest microhabitat and epiphyte diversity and a unique inner crown microhabitat with canopy humus. The few epiphytes found on small trees were mostly bark ferns. Large trees had different epiphyte communities in different parts of the crown; the inner crown contained species not abundant in any other microhabitat (i.e. aroids, cyclanths and humus ferns), and the outer crown contained bark ferns and atmospheric bromeliads. Variation in species composition amongst tree size classes was significantly related to the mean daily maximum vapour pressure deficit and tree diameter, while variation within large tree crowns was significantly related to canopy humus cover. Microhabitat specialization of epiphyte species increased with tree size with 6% of species significantly associated with small trees and 57% significantly associated with large trees. Of the species present in large tree crowns, 23% were specialized to the unique inner crown microhabitat. Synthesis. The increase in microhabitat heterogeneity within tree crowns as trees grow contributes to changes in epiphyte community structure, which supports decades‐old hypotheses of the importance of microhabitat diversity and specialization in structuring tropical epiphyte communities.

Aim The goal of this study was to investigate the effect of habitat heterogeneity on diversity on a local and regional scale. We tested two hypotheses: (i) the habitat diversity, given by quantity of microhabitat by macrophytes richness, increases the alpha diversity of organisms that live in those environments; (ii) the habitat heterogeneity, given by compositional difference of microhabitat, increases the beta diversity of organisms that live in those environments. Methods Samples contained cladocerans and macrophytes were collected in six wetlands from the Brazil Central during dry and rainy seasons, in Brazilian National Park (BNP) and Formosa Instruction Field (FIF). Results In local scale (wetlands) the number of macrophyte morphospecies shows the positive effect on alpha diversity of cladoceran; the compositional difference of the microhabitat positively affected the beta diversity in three wetlands studied. In regional scale, the number of macrophyte morphospecies showed the positive effect on alpha diversity; the beta diversity was higher in the BNP than in the FIF. Conclusions Our findings suggest that the species richness and dissimilarity of aquatic macrophytes increased to alpha and beta diversity of cladocerans on the local and regional scales. Thus, cladocerans richness was correlated with the number of microhabitats and the variability between microhabitats in wetlands. Resumo: Objetivo O objetivo deste estudo foi investigar o efeito da heterogeneidade do habitat na diversidade de cladóceros em escala local e regional. Nós testamos duas hipóteses: (i) a diversidade de habitat, dada pela quantidade de microhabitat, amenta a diversidade alfa de organismos que vivem nesses ambientes; (ii) a heterogeneidade de microhabitat, dada pela diferença de composição do microhabitat, aumenta a diversidade beta dos organismos que vivem nesses ambientes. Métodos Amostras de cladóceros e de macrófitas foram coletadas em seis áreas úmidas do Brasil Central, durante as estações seca e chuvosa, no Parque Nacional de Brasília (BNP) e no Campos de Instrução de Formosa (FIF). Resultados Em escala local (áreas úmidas), o número de morfoespécies de macrófitas mostrou um efeito positivo na diversidade alfa de cladóceros; a diferença de composição do microhabitat afetou positivamente a diversidade beta em três áreas úmidas estudadas. Em escala regional, o número de morfoespécies de macrófitas mostrou efeito positivo na diversidade alfa; a diversidade beta foi maior em BNP do que em FIF. Conclusões Nossos resultados indicam que a riqueza e dissimilaridade de espécies de macrófitas aquáticas aumentaram a diversidade alfa e beta de cladóceros em escala local e regional. Assim, a riqueza de cladóceros foi correlacionada ao número e a variabilidade de microhabitats em áreas úmidas.

Structural complexity provided by the living coral reef framework is the basis of the rich and dynamic biodiversity in coral reefs. In many cases today, the reduction in habitat complexity, from live coral to dead coral and rubble, has altered the abundance and diversity of many reef species with impacts on community structure, food webs and ecosystem functioning. Yet, the complex microhabitat provided by rubble can too support a great density and diversity of reef organisms, often with explicit roles in ecosystem functioning. This literature review synthesises available knowledge on the biology and ecology of coral rubble. We highlight key methodologies used to sample rubble communities, and the biological and ecological consequences of ongoing habitat degradation from coral to rubble reefs under future scenarios. We conclude with a number of key research themes that may enhance our capacity to understand the current contribution of rubble communities to reef functioning and predict their ability to modulate future impacts as net framework erosion amplifies.

Integrating nature conservation effectively in forests managed for timber production implies reconciling a trade-off between ecological and economic objectives. In continuous cover forest management, this culminates in decisions about tree harvesting (or retention) determining both the prevalence of tree-related microhabitats in the forest and the economic viability of timber management. Applying an innovative mixed methods approach, we compare conservationists and foresters performing a tree selection exercise. We assess the outcomes of their forest management decisions quantitatively and explore their strategies and the underlying reasoning based on qualitative data. Our findings show that particularly the habitat trees differ greatly between the two groups: while conservationists retained almost exclusively large oaks at often high opportunity costs, foresters retained a notable number of smaller-diameter hornbeams. These differences are related to a different perception of opportunity costs of retention by both groups, as well as because they do not agree about how to value current tree-related microhabitats and their projection into the future. Such diverging patterns of reasoning imply incompatible interpretations of what constitutes a habitat tree. Our results indicate that it is important to apply benchmarks for evaluating ecological goals as well as to increase foresters’ and conservationists’ understanding about the motivations and restrictions of the respective counterpart. Our study points out a significant potential for (mutual) learning, and illustrates the complementarity of quantitative and qualitative research methods to examine tree selection behaviour.

Species-specific spatial distribution in relation to environmental characteristics underpins the species diversity of coral reef fishes. This study aimed to elucidate (1) the broad-scale spatial distribution (spatial variation of fish density at intervals of several-kilometers), influenced by topographic features (exposed reef vs. inner reef), substrate characteristics and depth, and (2) the microhabitat associations (habitat association within several centimeter scale) concerning substrate availability for seven angelfish species (family Pomacanthidae) in an Okinawan coral reef. Broad-scale analysis revealed (1) Chaetodontoplus mesoleucus was primarily found in deep inner reefs with greater coverage of branching Acropora and dead coral; (2) Centropyge bicolor and C. tibicen were primarily found at shallow inner reefs with greater coverage of branching Acropora, dead coral, and sand; (3) C. ferrugata and C. vrolikii were primarily found at shallow exposed reefs with greater coverage of rock, and (4) C. heraldi and Pygoplites diacanthus were primarily found at deep exposed reefs with greater coverage of rock. Microhabitat-scale analysis revealed that three species (C. mesoleucus, C. bicolor, and C. heraldi) showed significant positive association with acroporid corals. Centropyge tibicen showed a significant positive association with living corals. The remaining three species (C. ferrugata, C. vrolikii, and P. diacanthus) did not show a positive association with living corals. This suggests that coral loss impacts angelfish population in a species-specific manner. These two spatial scale viewpoints offer valuable insight for comprehensive understandings of angelfish spatial distribution in relation to substrate characteristics.

Considerable research is aimed at developing predictions of ecosystem responses to climate change, focusing on the spatial scale, such as range shifts and contractions, as well as activity restrictions to shaded microhabitats. On the other hand, the ability of species to shift their activity times during the diel cycle, and consequently to alter the environment in which activity occurs, has been largely neglected. Daily activity patterns are perceived as fairly fixed; however, natural changes in activity patterns have been reported in increasing numbers of species. Here, we present a framework that explores how shifts in activity patterns may buffer impacts of climate change. To demonstrate our framework, we simulated costs of activity of diurnal and nocturnal rodents and showed that future summers may decrease the energetic demands of nocturnal mammals while increasing water demands of diurnal mammals. Climate projections suggest that vegetation cover and water availability will decrease under future climate scenarios, especially in areas where water demands are expected to increase the most. These changes are expected to limit the ability of diurnal animals to restrict activity to shaded microhabitats and to keep a positive water balance. Our analysis shows that by shifting to nocturnality, diurnal mammals may mitigate the high water costs of future summers. We suggest that future research should explore the role of the diel time axis as an ecological resource when predicting the impacts of climate change.

Springs ecosystems are globally abundant, geomorphologically diverse, and bioculturally productive, but are highly imperiled by anthropogenic activities. More than a century of scientific discussion about the wide array of ecohydrological factors influencing springs has been informative, but has yielded little agreement on their classification. This lack of agreement has contributed to the global neglect and degradation of springs ecosystems by the public, scientific, and management communities. Here we review the historical literature on springs classification variables, concluding that site-specific source geomorphology remains the most diagnostic approach. We present a conceptual springs ecosystem model that clarifies the central role of geomorphology in springs ecosystem development, function, and typology. We present an illustrated dichotomous key to terrestrial (non-marine) springs ecosystem types and subtypes, and describe those types. We identify representative reference sites, although data limitations presently preclude selection of continentally or globally representative reference springs of each type. We tested the classification key using data from 244 randomly selected springs of 13 types that were inventoried in western North America. The dichotomous key correctly identified springs type in 87.5% of the cases, with discrepancies primarily due to differentiation of primary vs. secondary typology, and insufficient inventory team training. Using that information, we identified sources of confusion and clarified the key. Among the types that required more detailed explanation were hypocrenes, springs in which groundwater is expressed through phreatophytic vegetation. Overall, springs biodiversity and ecosystem complexity are due, in part, to the co-occurrence of multiple intra-springs microhabitats. We describe microhabitats that are commonly associated with different springs types, reporting at least 13 microhabitats, each of which can support discrete biotic assemblages. Interdisciplinary agreement on basic classification is needed to enhance scientific understanding and stewardship of springs ecosystems, the loss and degradation of which constitute a global conservation crisis.