Climate warming promotes species diversity, but with greater taxonomic redundancy, in complex environments

Life goes on: Spatial heterogeneity promotes biodiversity in an urbanized coastal marine ecosystem

Both human populations and marine biodiversity are concentrated along coastlines, with growing conservation interest in how these ecosystems can survive intense anthropogenic impacts. Tropical urban centres provide valuable research opportunities because these megacities are often adjacent to mega-diverse coral reef systems. The Pearl River Delta is a prime exemplar, as it encompasses one of the most densely populated and impacted regions in the world and is located just northwest of the Coral Triangle. However, the spatial and taxonomic complexity of this biodiversity, most of which is small, cryptic in habitat and poorly known, make comparative analyses challenging. We deployed standardized settlement structures at seven sites differing in the intensity of human impacts and used COI metabarcoding to characterize benthic biodiversity, with a focus on metazoans. We found a total of 7184 OTUs, with an average of 665 OTUs per sampling unit; these numbers exceed those observed in many previous studies using comparable methods, despite the location of our study in an urbanized environment. Beta diversity was also high, with 52% of the OTUs found at just one site. As expected, we found that the sites close to point sources of pollution had substantially lower diversity (44% less) relative to sites bathed in less polluted oceanic waters. However, the polluted sites contributed substantially to the total animal diversity of the region, with 25% of all OTUs occurring only within polluted sites. Further analysis of Arthropoda, Annelida and Mollusca showed that phylogenetic clustering within a site was common, suggesting that environmental filtering reduced biodiversity to a subset of lineages present within the region, a pattern that was most pronounced in polluted sites and for the Arthropoda. The water quality gradients surrounding the PRD highlight the unique role of in situ studies for understanding the impacts of complex urbanization pressures on biodiversity.

Mechanisms and implications of bacterial-fungal competition for soil resources

Elucidating complex interactions between bacteria and fungi that determine microbial community structure, composition, and functions in soil, as well as regulate carbon (C) and nutrient fluxes, is crucial to understand biogeochemical cycles. Among the various interactions, competition for resources is the main factor determining the adaptation and niche differentiation between these two big microbial groups in soil. This is because C and energy limitations for microbial growth are a rule rather than an exception. Here, we review the C and energy demands of bacteria and fungi-the two major kingdoms in soil-the mechanisms of their competition for these and other resources, leading to niche differentiation, and the global change impacts on this competition. The normalized microbial utilization preference showed that bacteria are 1.4-5 times more efficient in the uptake of simple organic compounds as substrates, whereas fungi are 1.1-4.1 times more effective in utilizing complex compounds. Accordingly, bacteria strongly outcompete fungi for simple substrates, while fungi take advantage of complex compounds. Bacteria also compete with fungi for the products released during the degradation of complex substrates. Based on these specifics, we differentiated spatial, temporal, and chemical niches for these two groups in soil. The competition will increase under the main five global changes including elevated CO2, N deposition, soil acidification, global warming, and drought. Elevated CO2, N deposition, and warming increase bacterial dominance, whereas soil acidification and drought increase fungal competitiveness.

Distribution, Ecological Factors, Molecular Diversity, and Specific PCR for Major Species of Pin Nematodes (Paratylenchus spp.) in Prunus Plantations in Spain

This study aimed to evaluate the prevalence and distribution of Paratylenchus species in the main areas of Prunus spp. production in Spain, their ecological constraints, and new molecular tools for the specific identification of major species. Pin nematodes are recognized as plant-parasitic nematodes with a wide host range and global distribution. Therefore, understanding the environmental and agronomic factors involved in their distribution is critical to design environmental and sustainable management strategies to reduce plant damage. A total of 219 sampling sites were surveyed and 12 Paratylenchus species were identified based on an integrative taxonomic approach (P. baldaccii, P. enigmaticus, P. goodeyi, P. hamatus, P. holdemani, P. indalus, P. israelensis, P. pedrami, P. tateae, P. tenuicaudatus, P. veruculatus, and P. zurgenerus). The most common pin nematode was P. hamatus, followed by P. tenuicaudatus. Nematode abundance was influenced by climatic characteristics, soil chemical properties, and agronomic management practices. Nine explanatory variables were selected as the most strongly associated with Paratylenchus distribution. Specifically, P. tenuicaudatus was significantly correlated with soil chemical characteristics, such as pH and carbon, sulfur, and sodium content, whereas P. goodeyi was closely related to fields with <10 years of almond cultivation. Species-specific PCRs were developed for P. hamatus and P. tenuicaudatus and their validity was evaluated studying the molecular variability of these species and against other Paratylenchus species.

Biotic responses to climate extremes in terrestrial ecosystems

Anthropogenic climate change is increasing the incidence of climate extremes. Consequences of climate extremes on biodiversity can be highly detrimental, yet few studies also suggest beneficial effects of climate extremes on certain organisms. To obtain a general understanding of ecological responses to climate extremes, we present a review of how 16 major taxonomic/functional groups (including microorganisms, plants, invertebrates, and vertebrates) respond during extreme drought, precipitation, and temperature. Most taxonomic/functional groups respond negatively to extreme events, whereas groups such as mosses, legumes, trees, and vertebrate predators respond most negatively to climate extremes. We further highlight that ecological recovery after climate extremes is challenging to predict purely based on ecological responses during or immediately after climate extremes. By accounting for the characteristics of the recovering species, resource availability, and species interactions with neighboring competitors or facilitators, mutualists, and enemies, we outline a conceptual framework to better predict ecological recovery in terrestrial ecosystems.

Reduction of microbial diversity in grassland soil is driven by long-term climate warming

Anthropogenic climate change threatens ecosystem functioning. Soil biodiversity is essential for maintaining the health of terrestrial systems, but how climate change affects the richness and abundance of soil microbial communities remains unresolved. We examined the effects of warming, altered precipitation and annual biomass removal on grassland soil bacterial, fungal and protistan communities over 7 years to determine how these representative climate changes impact microbial biodiversity and ecosystem functioning. We show that experimental warming and the concomitant reductions in soil moisture play a predominant role in shaping microbial biodiversity by decreasing the richness of bacteria (9.6%), fungi (14.5%) and protists (7.5%). Our results also show positive associations between microbial biodiversity and ecosystem functional processes, such as gross primary productivity and microbial biomass. We conclude that the detrimental effects of biodiversity loss might be more severe in a warmer world.

Faunal communities mediate the effects of plant richness, drought, and invasion on ecosystem multifunctional stability

Understanding the stability of ecosystem multifunctionality is imperative for maintaining ecosystem health and sustainability under augmented global change. However it remains unknown whether and how biological communities mediate multifunctional stability in response to biodiversity loss and disturbances. Here, we conducted a 3-year experiment by exposing 270 plant communities of four plant richness levels, i.e., 1, 2, 4, or 8 species, to drought and exotic plant invasion disturbances. Then, the direct effects of plant richness, drought and invasion, and their indirect effects mediated by the stability of plant, litter-faunal, and soil-faunal communities on multifunctional stability were disentangled. We found that plant richness increased, while drought and invasion decreased ecosystem multifunctional stability, which were mediated by plant or faunal community stability. By incorporating the stability of communities into the complex ecological mechanisms, the completeness and goodness of ecological models for explaining and maintaining the stability of ecosystem multifunctionality will be improved.

Elevation-related climatic factors dominate soil free-living nematode communities and their co-occurrence patterns on Mt. Halla, South Korea

Nematodes play vital roles in soil ecosystems. To understand how their communities and coexistence patterns change along the elevation as well as to determine the best explanatory factors underlying these changes, we investigated free-living soil nematodes on Mt. Halla, South Korea, using an amplicon sequencing approach targeting the 18S rRNA gene. Our results showed that there was significant variation in the community diversity and composition of soil nematodes in relation to elevation. The network interactions between soil nematodes were more intensive at the lower elevations. Climatic variables were responsible explaining the elevational variation in community composition and co-occurrence pattern of the nematode community. Our study indicated that climatic factors served as the critical environmental filter that influenced not only the community structure but also the potential associations of soil nematodes in the mountain ecosystem of Mt. Halla. These findings enhance the understanding of the community structure and co-occurrence network patterns and mechanisms of soil nematode along elevation, and the response of soil nematodes to climate change on the vertical scale of mountain ecosystems.

Phytoplankton biodiversity is more important for ecosystem functioning in highly variable thermal environments

The 21st century has seen an acceleration of anthropogenic climate change and biodiversity loss, with both stressors deemed to affect ecosystem functioning. However, we know little about the interactive effects of both stressors and in particular about the interaction of increased climatic variability and biodiversity loss on ecosystem functioning. This should be remedied because larger climatic variability is one of the main features of climate change. Here, we demonstrated that temperature fluctuations led to changes in the importance of biodiversity for ecosystem functioning. We used microcosm communities of different phytoplankton species richness and exposed them to a constant, mild, and severe temperature-fluctuating environment. Wider temperature fluctuations led to steeper biodiversity-ecosystem functioning slopes, meaning that species loss had a stronger negative effect on ecosystem functioning in more fluctuating environments. For severe temperature fluctuations, the slope increased through time due to a decrease of the productivity of species-poor communities over time. We developed a theoretical competition model to better understand our experimental results and showed that larger differences in thermal tolerances across species led to steeper biodiversity-ecosystem functioning slopes. Species-rich communities maintained their ecosystem functioning with increased fluctuation as they contained species able to resist the thermally fluctuating environments, while this was on average not the case in species-poor communities. Our results highlight the importance of biodiversity for maintaining ecosystem functions and services in the context of increased climatic variability under climate change.

Increasing climatic sensitivity of global grassland vegetation biomass and species diversity correlates with water availability

Grasslands are key repositories of biodiversity and carbon storage and are heavily impacted by effects of global warming and changes in precipitation regimes. Patterns of grassland dynamics associated with variability in future climate conditions across spatiotemporal scales are yet to be adequately quantified. Here, we performed a global meta-analysis of year and growing season sensitivities of vegetation aboveground biomass (AGB), aboveground net primary productivity (ANPP), and species richness (SR) and diversity (Shannon index, H) to experimental climate warming and precipitation shifts. All four variables were sensitive to climate change. Their sensitivities to shifts in precipitation were correlated with local background water availability, such as mean annual precipitation (MAP) and aridity, and AGB and ANPP sensitivities were greater in dry habitats than in nonwater-limited habitats. There was no effect of duration of experiment (short vs long term) on sensitivities. Temporal trends in ANPP and SR sensitivity depended on local water availability; ANPP sensitivity to warming increased over time and SR sensitivity to irrigation decreased over time. Our results provide a global overview of the sensitivities of grassland function and diversity to climate change that will improve the understanding of ecological responses across spatiotemporal scales and inform policies for conservation in dry climates.

Nematodes as Drivers of Plant Performance in Natural Systems

Nematodes form an important part of soil biodiversity as the most abundant and functionally diverse animals affecting plant performance. Most studies on plant-nematode interactions are focused on agriculture, while plant-nematode interactions in nature are less known. Here we highlight that nematodes can contribute to vegetation dynamics through direct negative effects on plants, and indirect positive effects through top-down predation on plant-associated organisms. Global change alters these interactions, of which better understanding is rapidly needed to better predict functional consequences. By expanding the knowledge of plant-nematode interactions in natural systems, an increase in basic understanding of key ecological topics such as plant-soil interactions and plant invasion dynamics will be obtained, while also increasing the insights and potential biotic repertoire to be applicable in sustainable plant management.

Seasonal Stabilities of Soil Nematode Communities and Their Relationships with Environmental Factors in Different Temperate Forest Types on the Chinese Loess Plateau

The bottom-up effects of vegetation have been documented to be strong drivers of the soil food web structure and functioning in temperate forests. However, how the forest type affects the stability of the soil food web is not well known. In the Ziwuling forest region of the Loess Plateau, we selected three typical forests, Pinus tabuliformis Carrière (PT), Betula platyphylla Sukaczev (BP), and Quercus liaotungensis Koidz. (QL), to investigate the soil nematode community characteristics in the dry (April) and rainy (August) season, and analyzed their relationships with the soil properties. The results showed that the characteristics of the soil nematode communities and their seasonal variations differed markedly among the forest types. Compared to P. tabuliformis (PT), the B. platyphylla (BP) and Q. liaotungensis (QL) forests had higher plant diversity and more easily decomposed litters, which were more effective for improving the soil resource availability, thus, leading to more beneficial effects on the soil nematode community. In both the dry and rainy season, the soil nematode abundance was the highest in the BP forest. The Shannon–Wiener diversity index (H’), Pielou’s evenness index (J’), and nematode channel ratio index (NCR) were higher, while the Simpson dominance index (λ) and plant parasite index (PPI) were lower, in the BP and QL forests compared with in the PT forest. From the dry to rainy season, the total nematode abundance and the abundance of fungivores, bacterivores, and omnivore-predators, significantly increased in the QL and PT forests, and the values of the Wasilewska index (WI), maturity index (MI), H’, J’, λ, and NCR showed the most significant seasonal variability in the PT forest, which were mainly driven by changes in the soil labile C and N and the moisture content between the two seasons. Generally, the seasonal stability of the soil nematode communities was the highest in the BP forest and the poorest in the PT forest, probably due to variations in the plant diversity. Our results suggest the importance of tree species and diversity as bottom-up regulating factors of the soil food web structure, function, and seasonal stability, which has important implications for sustainable forest management in the Loess Plateau and other temperate regions.

Global Distribution of the Reniform Nematode Genus Rotylenchulus with the Synonymy of Rotylenchulus macrosoma with Rotylenchulus borealis

Reniform nematodes of the genus Rotylenchulus are semi-endoparasites of numerous herbaceous and woody plant roots that occur largely in regions with temperate, subtropical, and tropical climates. In this study, we compared 12 populations of Rotylenchulusborealis and 16 populations of Rotylenchulusmacrosoma, including paratypes deposited in nematode collections, confirming that morphological characters between both nematode species do not support their separation. In addition, analysis of molecular markers using nuclear ribosomal DNA (28S, ITS1) and mitochondrial DNA (coxI) genes, as well as phylogenetic approaches, confirmed the synonymy of R. macrosoma with R. borealis. This study also demonstrated that R. borealis (= macrosoma) from Israel has two distinct rRNA gene types in the genome, specifically the two types of D2-D3 (A and B). We provide a global geographical distribution of the genus Rotylenchulus. The two major pathogenic species (Rotylenchulusreniformis and Rotylenchulusparvus) showed their close relationship with warmer areas with high annual mean temperature, maximum temperature of the warmest month, and minimum temperature of the coldest month. The present study confirms the extraordinary morphological and molecular diversity of R. borealis in Europe, Africa, and the Middle East and comprises a paradigmatic example of remarkable flexibility of ecological requirements within reniform nematodes.

Disturbance regulates the density-body-mass relationship of soil fauna

Theory on the density-body-mass (DBM) relationship predicts that the density of animal species decreases by the power of -0.75 per unit increase in their body mass, or by the power of -1 when taxa across trophic levels are studied. This relationship is, however, largely debated, as the slope often deviates from the theoretical predictions. Here, we tested the ability of the DBM relationship to reflect changes in the structure of communities subjected to an anthropogenic disturbance. The slope would become less steep if smaller animals were more impacted by the disturbance than the larger ones, whereas the slope would become steeper if larger animals were more affected than the smaller ones. We tested the changes in the DBM relationship by sampling soil fauna, i.e., nematodes, Collembola, and larger arthropods, from a semiarid grassland before and after spraying diesel fuel as disturbance. We applied three different treatments: a control, a light disturbance, and an intense disturbance. We found that the slopes of the DBM relationships before the disturbance were around -1 as predicted by theory. The slope became more positive (i.e., less steep) just after the disturbance, especially after the intense disturbance as smaller fauna suffered the most and early colonizers had larger body mass. Interestingly, we observed that the slopes converged back to -1 by 2 months post-disturbance. Our findings show that the response of soil fauna communities to anthropogenic disturbances could explain the large variation in observed slopes of the DBM relationships. We experimentally demonstrate that an animal community, when disturbed, shows a temporal pattern of DBM relationships ranging from deviations from the predicted slope to convergence to the predicted slope with time. We recommend that deviations in the DBM relationships after disturbances can provide insights in the trajectory of community recovery, and hence could be used for biomonitoring.

Linking Remote Sensing and Geodiversity and Their Traits Relevant to Biodiversity—Part I: Soil Characteristics

In the face of rapid global change it is imperative to preserve geodiversity for the overall conservation of biodiversity. Geodiversity is important for understanding complex biogeochemical and physical processes and is directly and indirectly linked to biodiversity on all scales of ecosystem organization. Despite the great importance of geodiversity, there is a lack of suitable monitoring methods. Compared to conventional in-situ techniques, remote sensing (RS) techniques provide a pathway towards cost-effective, increasingly more available, comprehensive, and repeatable, as well as standardized monitoring of continuous geodiversity on the local to global scale. This paper gives an overview of the state-of-the-art approaches for monitoring soil characteristics and soil moisture with unmanned aerial vehicles (UAV) and air- and spaceborne remote sensing techniques. Initially, the definitions for geodiversity along with its five essential characteristics are provided, with an explanation for the latter. Then, the approaches of spectral traits (ST) and spectral trait variations (STV) to record geodiversity using RS are defined. LiDAR (light detection and ranging), thermal and microwave sensors, multispectral, and hyperspectral RS technologies to monitor soil characteristics and soil moisture are also presented. Furthermore, the paper discusses current and future satellite-borne sensors and missions as well as existing data products. Due to the prospects and limitations of the characteristics of different RS sensors, only specific geotraits and geodiversity characteristics can be recorded. The paper provides an overview of those geotraits.

The effects of global change on soil faunal communities: a meta-analytic approach

Human impacts are causing an unprecedented change of biodiversity across scales. To quantify the nature and degree of the biodiversity change, there have been a number of meta-analysis studies investigating the effects of global change drivers (land use, climate, etc.). However, these studies include few primary literature studies of soil biodiversity. Soil biodiversity is important for a variety of ecosystem services that are critical for human wellbeing. Yet, we know little about how soil organisms may respond to changing environmental conditions. Although studies have investigated the impact of global change drivers on soil biodiversity, they lack sufficient depth in the number of drivers and/or taxa included. Additionally, the previous focus on aboveground organisms has also resulted in a bias towards certain global change drivers in the primary literature. For example, climate change and land use change are more often studied, whilst pollution is typically understudied as a global change driver. Building on previous studies, we will conduct a meta-analysis to compare the effects of global change drivers (land use, habitat fragmentation/loss, fire, climate change, invasive species, pollution, and nutrient enrichment) on soil fauna (micro- to macro-invertebrates). This project aims to fill the current gaps in the literature, and actively participate in incorporating soil biodiversity into future global biodiversity assessments, by creating the first global open-acess dataset on the impacts of multiple global change drivers on soil fauna.

A multitrophic perspective on biodiversity-ecosystem functioning research

Concern about the functional consequences of unprecedented loss in biodiversity has prompted biodiversity-ecosystem functioning (BEF) research to become one of the most active fields of ecological research in the past 25 years. Hundreds of experiments have manipulated biodiversity as an independent variable and found compelling support that the functioning of ecosystems increases with the diversity of their ecological communities. This research has also identified some of the mechanisms underlying BEF relationships, some context-dependencies of the strength of relationships, as well as implications for various ecosystem services that mankind depends upon. In this paper, we argue that a multitrophic perspective of biotic interactions in random and non-random biodiversity change scenarios is key to advance future BEF research and to address some of its most important remaining challenges. We discuss that the study and the quantification of multitrophic interactions in space and time facilitates scaling up from small-scale biodiversity manipulations and ecosystem function assessments to management-relevant spatial scales across ecosystem boundaries. We specifically consider multitrophic conceptual frameworks to understand and predict the context-dependency of BEF relationships. Moreover, we highlight the importance of the eco-evolutionary underpinnings of multitrophic BEF relationships. We outline that FAIR data (meeting the standards of findability, accessibility, interoperability, and reusability) and reproducible processing will be key to advance this field of research by making it more integrative. Finally, we show how these BEF insights may be implemented for ecosystem management, society, and policy. Given that human well-being critically depends on the multiple services provided by diverse, multitrophic communities, integrating the approaches of evolutionary ecology, community ecology, and ecosystem ecology in future BEF research will be key to refine conservation targets and develop sustainable management strategies.

Biodiversity and thermal ecological function: The influence of freshwater algal diversity on local thermal environments

The influence of temperature on diversity and ecosystem functioning is well studied; the converse however, that is, how biodiversity influences temperature, much less so. We manipulated freshwater algal species diversity in microbial microcosms to uncover how diversity influenced primary production, which is well documented in biodiversity research. We then also explored how visible-spectrum absorbance and the local thermal environment responded to biodiversity change. Variations in the local thermal environment, that is, in the temperature of the immediate surroundings of a community, are known to matter not only for the rate of ecosystem processes, but also for persistence of species assemblages and the very relationship between biodiversity and ecosystem functioning. In our microcosm experiment, we found a significant positive association between algal species richness and primary production, a negative association between primary production and visible-spectrum absorbance, and a positive association between visible-spectrum absorbance and the response of the local thermal environment (i.e., change in thermal infrared emittance over a unit time). These findings support an indirect effect of algal diversity on the local thermal environment pointing to a hitherto unrecognized biodiversity effect in which diversity has a predictable influence on local thermal environments.

Why and How to Create Nighttime Warming Treatments for Ecological Field Experiments

While average global temperatures are increasing, a disproportionate amount of warming can be attributed to increasing nighttime temperatures rather than increasing daytime temperatures. Theory predicts that the timing of warming can generate different effects on organisms and their interactions within ecosystems. This occurs because an organism's response to warming depends on the current temperature. For example, warming when temperatures are low may have positive effects on an organism, while warming when temperatures are already high may have negative effects on an organism. Most field experiments that examine the ecological effects of climate warming employ warming methodologies that disproportionately elevate daytime warming treatments. The bias towards daytime warming treatments may arise because daytime temperatures can be manipulated with relatively simple and inexpensive technology that capitalizes on solar energy, such as open-top chambers that create a "greenhouse effect" or shade structures that reduce temperatures. However, these popular methods are ineffective when solar radiation is absent, and thus do not create warming treatments that accurately mimic the temporal patterns of climate warming. To encourage the investigation of nighttime warming's effect on ecosystems, we discuss why daytime and nighttime warming may have different effects on organisms, then present a review of methods that can be employed to elevate nighttime temperature in terrestrial field experiments. For each method, we offer a brief explanation, an evaluation of its pros and cons, and citations for further reference, as well as empirical data when possible. While some are impractical, we attempt to provide a comprehensive list of potential nighttime warming methods in hopes of stimulating ideas and discussions.

Temperature effects on prey and basal resources exceed that of predators in an experimental community

Climate warming alters the structure of ecological communities by modifying species interactions at different trophic levels. Yet, the consequences of warming-led modifications in biotic interactions at higher trophic levels on lower trophic groups are lesser known. Here, we test the effects of multiple predator species on prey population size and traits and subsequent effects on basal resources along an experimental temperature gradient (12-15°C, 17-20°C, and 22-25°C). We experimentally assembled food web modules with two congeneric predatory mites (Hypoaspis miles and Hypoaspis aculeifer) and two Collembola prey species (Folsomia candida and Proisotoma minuta) on a litter and yeast mixture as the basal resources. We hypothesized that warming would modify interactions within and between predator species, and that these alterations would cascade to basal resources via changes in the density and traits (body size and lipid: protein ratio) of the prey species. The presence of congeners constrained the growth of the predatory species independent of warming despite warming increased predator density in their respective monocultures. We found that warming effects on both prey and basal resources were greater than the effects of predator communities. Our results further showed opposite effects of warming on predator (increase) and prey densities (decrease), indicating a warming-induced trophic mismatch, which are likely to alter food web structures. We highlight that warmer environments can restructure food webs by its direct effects on lower trophic groups even without modifying top-down effects.

Modeling and mapping the current and future distribution of Pseudomonas syringae pv. actinidiae under climate change in China

OBJECTIVE

Bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae (Psa) is a major threat to the kiwifruit industry throughout the world and accounts for substantial economic losses in China. The aim of the present study was to test and explore the possibility of using MaxEnt (maximum entropy models) to predict and analyze the future large-scale distribution of Psa in China.

METHOD

Based on the current environmental factors, three future climate scenarios, which were suggested by the fifth IPCC report, and the current distribution sites of Psa, MaxEnt combined with ArcGIS was applied to predict the potential suitable areas and the changing trend of Psa in China. The jackknife test and correlation analysis were used to choose dominant climatic factors. The receiver operating characteristic curve (ROC) drawn by MaxEnt was used to evaluate the accuracy of the simulation.

RESULT

The results showed that under current climatic conditions, the area from latitude 25° to 36°N and from longitude 101° to 122°E is the primary potential suitable area of Psa in China. The highly suitable area (with suitability between 66 and 100) was mainly concentrated in Northeast Sichuan, South Shaanxi, most of Chongqing, West Hubei and Southwest Gansu and occupied 4.94% of land in China. Under different future emission scenarios, both the areas and the centers of the suitable areas all showed differences compared with the current situation. Four climatic variables, i.e., maximum April temperature (19%), mean temperature of the coldest quarter (14%), precipitation in May (11.5%) and minimum temperature in October (10.8%), had the largest impact on the distribution of Psa.

CONCLUSION

The MaxEnt model is potentially useful for forecasting the future adaptive distribution of Psa under climate change, and it provides important guidance for comprehensive management.

Soil nematode abundance and diversity from four vegetation types in Central Mexico

Soil nematode abundance and MOTU diversity were estimated from a geographically broad area of Mexico that included four out of seven recognised vegetation types. Vegetation types were assessed for abundance and diversity of nematode communities and inferred ecological relationships between them. Soils were sampled from tropical rainforest, tropical dry deciduous forest, temperate coniferous forest and xerophytic shrub during 2013, 2014 and 2015. Fourteen sampling sites withca10-20 samples per site from 11 localities spread across Central Mexico were assessed. Altitudes sampled ranged from 113 m a.s.l. (tropical coastal plain) to 2400 m a.s.l. (Trans-Mexican Volcanic Belt). Samples were drawn from conserved and cultivated plots from each sampling site covering an area of ⩾100 m2. A total of 13 263 individuals from 25 identified families of nematodes were collected. Family abundance and complementarity indices between sites revealed to some extent the affinities between vegetation types. Nevertheless, statistical analyses revealed no differences between nematode family abundances between sites, only between families across all sites. Molecular operational taxonomic units (MOTU) methods were employed as a framework to assess biodiversity. From these, 77 high-quality sequences for taxonomic barcoding were recovered and later identified with morphological traits. Only six sequences matched at a 98-99% level with those reported in GenBank. Sequences amounted to a total of 41 MOTU, where 100% of the MOTU from both conserved and disturbed tropical rainforest, tropical dry deciduous forest and xerophytic shrub exhibited a ⩾3% cut-off genetic identity, whilst temperate coniferous forest and disturbed temperate coniferous forest showed 73% and 70% respectively. In addition, 12.2% MOTU were shared among localities and 87.8% exhibited an apparently locality-limited distribution. The potential for a considerable diversity of nematodes, as revealed from a small sample of MOTU diversity, is discussed.