Large Geographic Scales Research Articles

Influence of projected climate change, urban development and heat adaptation strategies on end of twenty-first century urban boundary layers across the Conterminous US

The urban environment directly influences Urban Boundary Layer (UBL) dynamics. Commonly proposed heat adaptation strategies focused on reducing the impacts of global change and urban induced warming are also expected to decrease the intensity of convective mixing thereby reducing UBL depth, with important consequences for air pollutant dilution and dispersion. We use 20-km grid spacing Regional Climate Model decadal scale simulations that account for end of twenty-first century greenhouse gas emissions, urban development and intensive and uniform implementation of a suite of heat adaptation strategies, to investigate the individual and combined impacts of such drivers on UBL dynamics over the Continental US (CONUS). Results indicate that combined impacts of climate change and urban development are expected to increase summer (JJA) daytime UBL height in the eastern CONUS. Heat adaptation strategies lead to a summer daytime UBL depth reduction of several hundred meters across CONUS regions, primarily as a consequence of reduced surface sensible heat fluxes and associated turbulence. Our results confirm that heat adaptation is expected to increase the static stability of both daytime and nighttime UBLs and decrease the magnitude of vertical winds, inducing stronger subsidence. In addition, the large geographical scale of our analysis indicates that adaptation impacts are greater inland and smaller over coastal cities. In Southern California, the adaptation induced increase in latent heat can counterbalance the projected decrease in UBL depth. Future work addressing these projected UBL impacts with convection permitting, high-resolution coupled atmosphere-chemistry simulations is needed to explicitly determine potential unintended consequences for urban air quality.

Childhood leukemia near nuclear sites in Belgium: An ecological study at small geographical level

BackgroundA previous investigation of the occurrence of childhood acute leukemia around the Belgian nuclear sites has shown positive associations around one nuclear site (Mol-Dessel). In the following years, the Belgian Cancer Registry has made data available at the smallest administrative unit for which demographic information exists in Belgium, i.e. the statistical sector. This offers the advantage to reduce the potential misclassification due to large geographical scales. MethodsThe current study performed for the period 2006–2016 uses Poisson models to investigate (i) the incidence of childhood acute leukemia within 20 km around the four Belgian nuclear sites, (ii) exposure-response relationships between cancer incidence and surrogate exposures from the nuclear sites (distance, wind direction frequency and exposure by hypothetical radioactive discharges taking into account historical meteorological conditions). All analyses are carried out at statistical sector level. ResultsHigher incidence rate ratios were found for children <15 years (7 cases, RR = 3.01, 95% CI: 1.43;6.35) and children <5 years (< 5 cases, RR = 3.62, 95% CI: 1.35;9.74) living less than 5 km from the site of Mol-Dessel. In addition, there was an indication for positive exposure-response relationships with the different types of surrogate exposures. ConclusionResults confirm an increased incidence of acute childhood leukemia around Mol-Dessel, but the number of cases remains very small. Random variation cannot be excluded and the ecological design does not allow concluding on causality. These findings emphasize the need for more in-depth research into the risk factors of childhood leukemia, for a better understanding of the etiology of this disease.

Monitoring Sustainability and Targeting Interventions: Indicators, Planetary Boundaries, Benefits and Costs

This article shows how sustainability indicators (SIs) which have proliferated, and downscaled planetary boundaries (DPBs) which have recently emerged, can be used to target remedial interventions. I offer an integrative analysis drawing upon the existing literature, challenging, clarifying, and amending it in some ways, and extending it with new insights. The exposition is couched in the example of pollution control, but the analysis also applies to resource management with only modest amendments. Key conclusions are summarized. (i) In a default case where damage is indifferent to location within the problem shed and transactions costs are trivial, minimizing abatement costs requires that all units face the same marginal price of emissions and can be implemented by price setting at the jurisdictional level or cap and trade in pollution reduction credits. Larger geographic scale tends to reduce the average cost of abatement, an argument for coordination at the problem-shed level. Deviations from the default policy may be appropriate for addressing large point sources and local hot spots where damage is concentrated. (ii) A framework winnowing the proliferation of SIs includes the following principles: for quantitative target setting, SIs should address sustainability in its long-term context; SIs should be measured in ratio scale, whereas ordinal-scale SIs are common; and SIs should be selected for their usefulness in mapping the relationships among emissions, ambient concentrations, and damage. (iii) Target setting requires science-based empirical relationships and social values to assess trade-offs between abatement and its opportunity costs and suggest upper limits on tolerable damage. (iv) PBs that address global public goods can usefully be downscaled to set abatement targets. The PBs are science based and, in their original form, propose replacing social values with imperatives: violating the PB will doom the planet, which is unacceptable given any plausible value system. Given that PB = ∑DPB over all jurisdictions, global trading of credits would minimize costs of honoring the PB. Trade among a willing subset of jurisdictions could minimize the costs of meeting its aggregate DPB. (v) In contrast to most SI approaches, a cost–benefit (CB) approach can deal with substitutability and complementarity among sustainability objectives and evaluate multi-component policies. Net benefits are maximized when the marginal cost of abatement equals the marginal benefit for all units in the problem shed. This can be attained by price setting at the jurisdictional level or trade in credits. (vi) A major advantage of the CB approach is its well-defined relationship to weak sustainability. However, its value measures over-weight the preferences of the well-off. Equity considerations suggest relief from strict CB criteria in the case of essentials such as human health and nutrition, and subsidization by rich countries of sustainability projects in low-income countries.

Population connectivity, dispersal, and swimming behavior in Daphnia.

The water flea Daphnia has the capacity to respond rapidly to environmental stressors, to disperse over large geographical scales, and to preserve its genetic material by forming egg banks in the sediment. Spatial and temporal distributions of D. magna have been extensively studied over the last decades using behavioral or genetic tools, although the correlation between the two has rarely been the focus. In the present study, we therefore investigated the population genetic structure and behavioral response to a lethal threat, ultraviolet radiation (UVR), among individuals from two different water bodies. Our results show two genetic populations with moderate gene flow, highly correlated with geographical location and with inheritable traits through generations. However, despite the strong genetic differences between populations, we show homogeneous refuge demand between populations when exposed to the lethal threat solar UVR.

Spatial patterns of leaf carbon, nitrogen, and phosphorus stoichiometry and nutrient resorption in Chinese fir across subtropical China

Understanding patterns and drivers of leaf carbon (C), nitrogen (N), phosphorus (P) stoichiometry and nutrient resorption at large geographical scales is important to understand the plant adaptation strategy under climate changes. However, most current knowledge was obtained from multi-species based on field investigation and literature data. Whether it is equally applicable to individual speciesneeds further exploration.Here, we determined C, N, and P concentrations of matureleaf and leaf litter, and calculated the nutrient resoprtion efficiency (NuRE)from 19 Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) plantations across subtropical China with relatively widerangesof latitudeand altitude.Results showed that leaf C concentration was high, while leaf N and P concentrations were low, leading to high C:N and C:P ratios in leaf. The CRE was relatively low, and PRE was significantly higher than NRE. Leaf C concentration and CRE increased with latitude, mainly driven by mean annual temperature(MAT). Leaf P concentration and PRE increased, and C:P and N:P ratios decreased with altitude, mainly driven by soil P concentration. In middle-aged group, stand age significantly affected the leaf N and P concentrations, and the C:N and C:P ratios. CRE and PRE were influenced by leaf C and P concentration, respectively. These results indicated that leaf C, N and P stoichiometry and nutrient resorptiondisplayed different spatial patterns in subtropical China, which were mainly induced by the variations of heatsand soil P status.Additionally, our findings suggested that forest development affected the leaf stoichiometry but not the nutrient resorption in the middle-agedgroup. Overall, this study is expected to reveal the nutrient trade-off mechanism of Chinese fir in response to future climate change, and to provide reference for basic stoichiometric parameters of individual species for the establishment schemes in the carbon and nutrient cycling model for large-scale plantation.

Fine‐scale interactions between boats and large albatrosses indicate variable susceptibility to bycatch risk according to species and populations

AbstractMany seabirds are attracted to fishing boats where they exploit foraging opportunities, often involving bycatch‐related mortality. Bycatch risk is generally estimated by overlapping seabirds foraging ranges with coarse‐scale monthly maps of fishing efforts, but a more direct estimation would be the time birds actually spend attending fishing boats. Here we matched data from Automatic Identification Systems from all declared boats in the Southern Ocean, with 143 simultaneous foraging trips from all populations of large albatrosses (Diomedea amsterdamensis and Diomedea exulans) breeding in the Indian Ocean (Marion, Crozet, Kerguelen, Amsterdam islands). We quantified and compared real‐time co‐occurrence between boats and albatrosses, at different scales (100, 30 and 5 km). We also examined to what extent co‐occurrence at a large‐scale (5×5° grid cell) predicted fine‐scale attendance (5 km). Albatrosses on average spent about 3 h per trip attending fishing boats (&lt;5 km) at both Amsterdam and Marion and about 30 h per trip at Kerguelen. In all populations, &gt;90% of declared fishing boat attendances occurred within Economic Exclusive Zones (EEZ) where bycatch mitigation measures are enforced. Outside EEZs, birds from all populations to a large extent also attended non‐fishing boats. Fishing boat density at a large scale (5 × 5°, 100 km) was a poor predictor of time spent attending fishing boats (&lt;5 km) across populations. Our results indicate a large variation in fishing boat densities within the foraging ranges of different populations and in the time birds spent attending boats. We discuss the pros and cons of considering bycatch risk at a large geographical scale and methods that can be implemented to improve the estimation of seabird vulnerability to fishing activities when fine‐scale data are available, particularly for the conservation of those highly threatened species.

Geographic Mosaics of Fly Pollinators With Divergent Color Preferences Drive Landscape-Scale Structuring of Flower Color in Daisy Communities.

The striking variation in flower color across and within Angiosperm species is often attributed to divergent selection resulting from geographic mosaics of pollinators with different color preferences. Despite the importance of pollinator mosaics in driving floral divergence, the distributions of pollinators and their color preferences are seldom quantified. The extensive mass-flowering displays of annual daisy species in Namaqualand, South Africa, are characterized by striking color convergence within communities, but also color turnover within species and genera across large geographic scales. We aimed to determine whether shifts between orange and white-flowered daisy communities are driven by the innate color preferences of different pollinators or by soil color, which can potentially affect the detectability of different colored flowers. Different bee-fly pollinators dominated in both community types so that largely non-overlapping pollinator distributions were strongly associated with different flower colors. Visual modeling demonstrated that orange and white-flowered species are distinguishable in fly vision, and choice experiments demonstrated strongly divergent color preferences. We found that the dominant pollinator in orange communities has a strong spontaneous preference for orange flowers, which was not altered by conditioning. Similarly, the dominant pollinator in white communities exhibited an innate preference for white flowers. Although detectability of white flowers varied across soil types, background contrast did not alter color preferences. These findings demonstrate that landscape-level flower color turnover across Namaqua daisy communities is likely shaped by a strong qualitative geographic mosaic of bee-fly pollinators with divergent color preferences. This is an unexpected result given the classically generalist pollination phenotype of daisies. However, because of the dominance of single fly pollinator species within communities, and the virtual absence of bees as pollinators, we suggest that Namaqua daisies function as pollination specialists despite their generalist phenotypes, thus facilitating differentiation of flower color by pollinator shifts across the fly pollinator mosaic.

Evaluating the island effect on phenotypic evolution in the Italian wall lizard,Podarcis siculus(Reptilia: Lacertidae)

AbstractIslands are compelling natural laboratories for studying evolutionary processes. Nevertheless, the existence of general rules underlying morphological evolution on islands remains an unresolved issue. In this study, we investigated the insular phenotypic variability of the Italian wall lizard (Podarcis siculus) on a large geographical scale, in order to assess the putative existence of an island effect on three morphological head traits: shape, size and degree of sexual dimorphism. A geometric morphometric analysis was performed on 30 island and 24 mainland populations, involving a total of 992 specimens, and we analysed differences in both mean trait values and variances (disparity). We found increased shape disparity in insular lizards with respect to mainland ones. On the other hand, both size disparity and mean head dimensions of males decreased on islands, leading to a reduction in sexual dimorphism. Our results provide evidence for a multidirectional morphological diversification on islands concerning head shape of both sexes, while directional and canalizing selection likely occurred for head size, but only in males. Our findings improve our knowledge on the effect of insularity in Podarcis siculus, and highlight the need for an exstensive sampling scheme and a multi-trait methodological approach.

Temperature sensitivity of soil microbial respiration in soils with lower substrate availability is enhanced more by labile carbon input

The temperature sensitivity (Q10) of soil microbial respiration (Rs) is a critical parameter for predicting soil carbon (C) fluxes under changing climatic conditions, and labile C is continuously input into soil via root exudates or plant litter in field. However, how Q10 responds to labile C input remains uncertain, especially across large geographical regions. We collected eight soils from tropical to cold-temperate forests along a north–south transect in eastern China, and soils were added with either water as a control or glucose as an analogue for labile C input to investigate how Q10 responds to labile C input at a large geographical scale. Then, soils were incubated under varying temperature conditions from 5 to 30 °C for 2-weeks, and Rs was measured at a high frequency (each sample was measured at 20 min intervals within 12 h) after 1 d, 7 d and 14 d incubation. Rs and Q10 were then calculated for both the control and glucose addition treatments. Compared with those in the control, glucose addition significantly increased Rs and Q10 in all forest soils. The increase in Q10 (ΔQ10) between the control and glucose addition treatments differed significantly among the eight forest soils and was the highest in mid-latitude regions. Furthermore, ΔQ10 was significantly and negatively correlated with the soil C availability index (CAI), indicating that the Q10 of soils with lower basal substrate availability (e.g., soils in mid-latitudes of eastern China) are enhanced more by labile C input than those of higher basal substrate availability. A significant negative relationship between Q10 and substrate quality (SQI, measured as basal microbial respiration rate at 0 °C) without glucose addition supported the carbon quality temperature hypothesis; however, this hypothesis was not always valid after adding glucose. Our findings highlight the importance of basal substrate availability in influencing Q10 after labile C addition, suggesting that C-climate models should incorporate different scenarios of labile C input in the future.

Evidence for seasonal changes in population structure of Reed Buntings (Emberiza schoeniclus) in the Lake Neusiedl Region: a stable-isotope approach

Migrating species and populations are affected by conditions existing across large geographical scales. The degree to which populations mix at stop-over sites and wintering grounds is variable and can involve important fitness consequences. Thus, the link between breeding and wintering grounds and seasonal shifts in population structure are important to understand population demographics, local adaption and diversification patterns. This work aims to infer migration patterns and population connectivity in the Reed Bunting (Emberiza schoeniclus) community of a Ramsar-designated wetland, Lake Neusiedl, Seewinkel, Austria. Stable isotope markers (hydrogen, δ2H, carbon, δ13C) in feathers were analyzed to assign individuals to a specific breeding or natal area. Based on the geographic assignment, birds were compared with respect to their ecomorphological traits and their habitat selection (large reed bed versus more open habitat at shore of an alkaline lake) during winter to assess potential ecological differences and possibly associated morphological divergence. Stable isotope data revealed that the local Reed Bunting community undergoes seasonal changes in population structure. Three different populations that vary in their δ2H signature and to some extent in morphological characteristics as well as in δ13C values were identified. Indications for differential migration related to age and/or sex were additionally found, since males and females as well as first-year birds and adults showed remarkable differences in their traits and feather isotope values. δ2H values diverged significantly between these groups in both age and sex classes and birds with highest feather δ2H values were considered to represent the local breeding population at Lake Neusiedl and possibly also Reed Buntings from close surroundings. Moreover, this group had the highest δ13C values in first-year individuals as well as in adults. In both sex classes, the assignment of Reed Buntings to different populations was ultimately possible due to differences in bill shape with residents being characterized by more massive bills than individuals belonging to populations visiting the study area only during migration or for wintering. During winter, beak shape and feather δ2H and δ13C values differed significantly between birds caught in the reed stand of Lake Neusiedl and those captured near the salt pan, hence, indicating differential habitat selection among co-occurring populations during winter. These findings suggest that morphological attributes, such as bill shape and size as well as linked adaptations to different food sources play a decisive role for niche segregation among wintering populations. The results provide evidence that different populations mix during migration and during winter at Lake Neusiedl and the extent to which they are specialized to a specific habitat varied.

Spatiotemporal clustering and Random Forest models to identify risk factors of African swine fever outbreak in Romania in 2018\u20132019

African swine fever (ASF) has affected Romania since July 2017, with considerable economic and social consequences, despite the implementation of control measures mainly based on stamping out of infected pig populations. On the basis of the 2973 cumulative recorded cases up to September 2019 among wild boars and domestic pigs, analysis of the epidemiological characteristics could help to identify the factors favoring the persistence and spread of ASF. A statistical framework, based on a random forest methodology, was therefore developed to assess the spatiotemporal features of the epidemics and their relationships with environmental, human, and agricultural factors. The landscape of Romania was associated with the infection dynamics, particularly concerning forested and wetland areas. Waterways were also identified as a pivotal factor, raising questions about possible waterborne transmission since these waterways are often used as a water supply for backyard holdings. However, human activity was clearly identified as the main risk factor for the spread of ASF. Although the situation in Romania cannot be directly transposed to intensive pig farming countries, the findings of this study highlight the need for strict biosecurity measures on farms, and during transportation, to avoid ASF transmission at large geographic and temporal scales.

Birds of a feather moult together: Differences in moulting distribution of four species of storm-petrels.

The non-breeding period of pelagic seabirds, and particularly the moulting stage, is an important, but understudied part of their annual cycle as they are hardly accessible outside of the breeding period. Knowledge about the moulting ecology of seabirds is important to understand the challenges they face outside and within the breeding season. Here, we combined stable carbon (δ13C) and oxygen (δ18O) signatures of rectrices grown during the non-breeding period of two pairs of storm-petrel species breeding in the northern (European storm-petrel, Hydrobates pelagicus, ESP; Leach's storm-petrel, Hydrobates leucorhous, LSP) and southern (black-bellied storm-petrel, Fregetta tropica, BBSP; Wilson's storm-petrel, Oceanites oceanicus, WSP) hemispheres to determine differences in moulting ranges within and between species. To understand clustering patterns in δ13C and δ18O moulting signatures, we examined various variables: species, sexes, years, morphologies (feather growth rate, body mass, tarsus length, wing length) and δ15N. We found that different factors could explain the differences within and between the four species. We additionally employed a geographical distribution prediction model based on oceanic δ13C and δ18O isoscapes, combined with chlorophyll-a concentrations and observational data to predict potential moulting areas of the sampled feather type. The northern species were predicted to moult in temperate and tropical Atlantic zones. BBSP was predicted to moult on the southern hemisphere north of the Southern Ocean, while WSP was predicted to moult further North, including in the Arctic and northern Pacific. While moulting distribution can only be estimated on large geographical scales using δ13C and δ18O, validating predictive outcomes with food availability proxies and observational data may provide valuable insights into important moulting grounds. Establishing those, in turn, is important for conservation management of elusive pelagic seabirds.

Regional, seasonal, biennial and landscape-associated distribution of Anaplasma phagocytophilum and Rickettsia spp. infections in Ixodes ticks in northern Germany and implications for risk assessment at larger spatial scales

Tick-associated Rickettsiales are important pathogens with relevance for public and animal health; therefore, knowledge regarding their distribution is essential for risk assessment and disease prevention. To investigate the prevalence of Anaplasma phagocytophilum and Rickettsia spp. in northern Germany, Ixodes ticks were flagged monthly from April to October in 2018 and 2019 at three collection sites each in the regions of Bremen, Emsland, Hanover, Kassel and Uelzen. A total of 3150 ticks (1052 females, 1048 males and 1050 nymphs) were individually examined for rickettsial infections using probe-based quantitative real-time PCR. Overall prevalence of A. phagocytophilum was 6.4 % (202/3150; 6.7 % [71/1052] in females, 7.5 % [79/1048] in males and 5.0 % [52/1050] in nymphs). For Rickettsia spp., the overall prevalence was 29.6 % (931/3150; 33.4 % [351/1052] in females, 28.3 % [297/1048] in males and 27.0 % [283/1050] in nymphs). Rickettsia species identification by real-time pyrosequencing on a subset of 409 positive samples was successful in 407 cases (99.5 %). Rickettsia helvetica was the predominant species with a detection rate of 99.8 % (406/407). Additionally, Rickettsia monacensis was detected in one tick (0.2 %). Generalized linear mixed models showed significant regional as well as monthly differences regarding the prevalence of both pathogens. In addition, the prevalence of both pathogens was significantly higher in 2018 (A. phagocytophilum: 8.0 % [126/1575], Rickettsia spp.: 35.4 % [558/1575]) than in 2019 (A. phagocytophilum: 4.8 % [76/1575], Rickettsia spp.: 23.9 % [373/1575]). In contrast, no effect of landscape type on pathogen prevalence was found. As Rickettsia spp.-detection was based on the single-copy gene gltA, it was possible to calculate the individual pathogen load per tick, which was significantly higher in female ticks than in nymphs (mean values: 8.19 × 104 vs. 9.58 × 103). Regional, seasonal and biennial prevalence differences of tick-transmitted Rickettsiales show the necessity to investigate ticks from multiple locations, over several months and in more than one year to reliably assess the infection risk on a larger geographical scale.

Consistent choice of landscape urbanization level across the annual cycle in a migratory waterbird species

Rapid urbanization has a great impact on avian distribution, ecology, habitat selection, and behavior. Recent avian studies indicated that individuals remain consistent in their behavioral responses to human disturbance across short periods of time. However, there is still little information about keeping consistent behaviors in distinct locations across different stages of the annual cycle. In this study, we aimed to test for long-term consistency in habitat selection with respect to urbanization in a migratory waterbird species, the Eurasian coot Fulica atra. For this purpose, we individually marked ca. 300 coots from four populations that varied in urbanization level and tracked their habitat preferences during the non-breeding season. We found that individuals from urban breeding populations selected habitats with a higher share of artificial areas during the non-breeding season, when compared to non-urban individuals. Also, a comparison of non-breeding sites selected by birds from our study populations with random sites showed that urban birds selected sites with higher urbanization level than resulting from random availability. Finally, we found a seasonal variation in habitat preferences in coots—individuals from all study populations selected more urbanized areas as the non-breeding season progressed. The results indicate that birds are able to remain consistent in habitat preferences not only at a large geographical scale, but also across different seasons. Marked between-population variation in habitat selection across the annual cycle may reflect personality differences of coots from urban and non-urban populations, and it stays in line with the personality-matching habitat choice hypothesis.

The geographical scale dependence of diazotroph assembly and activity: Effect of a decade fertilization

Biological nitrogen (N) fixation is one of the most significant parts of the N cycle in terrestrial ecosystems, and this process is carried out by soil diazotrophs. However, knowledge of diazotroph assembly processes and activity in response to diverse fertilization strategies in agroecosystems across a large geographical scale is still lacking. Here, we selected nine agro-ecological experimental sites that covered a wide geographical distance (~3500 km) at a continental scale, and investigated the diazotrophic communities, assembly processes, distance-decay patterns and N2 fixation activity in response to geographical factors and long-term fertilization strategies. The results showed that the dominant genera were Bradyrhizobium (~30.5%) and Azospirillum (~26.8%) in all samples, and RDA analysis showed that the relative abundance of Bradyrhizobium was positive correlated with MAP while specific negatively correlated with soil pH and the relative abundance of Azospirillum. Geographical factors (location and climate) and fertilization collectively drive diazotroph assembly processes and determine diazotroph activity. Diazotroph assembly processes were influenced by both stochastic (~36.2%) and deterministic (~63.8%) processes simultaneously at large geographical scales and under various fertilization strategies. Moreover, fertilization increased the proportion of deterministic processes under various fertilization strategies. The N fixation rate was determined by local soil properties. Fertilization changes but does not always suppress nitrogen fixation activity. Both geographical factors and fertilization through the shift of diazotroph community composition and the changes in soil properties, indirectly affected the assembly process and N fixation rate. Among soil properties, pH was the dominant factor and linearly related to diazotrophs assembly process, while N fixation rate reached peak at near-neutral pH. These results elucidate the mechanism of soil diazotroph assembly process and activity shaped by both geographical factors and fertilization; thus, expand the current understanding of the diazotroph community affected by fertilization strategies across a large geographical scale.

A classification of woody communities based on biological dissimilarity

AbstractAimsTraditional quantitative approaches to forest classification are based on differences in species abundance or incidence among communities. In these approaches, all species are regarded as biologically equidistant regardless of the biological heterogeneity. The objective of the study is to evaluate the potential of the “Discriminating Avalanche” approach, which integrates species abundance and biological heterogeneity, as a new basis for forest classification.LocationChina, India, Iran, Ukraine, Germany, Italy, Mexico, Peru, and South Africa.MethodWe illustrate our approach using a set of 35 large tree‐mapped forest plots from various regions of the world. Our dissimilarity matrices, which integrate species abundance with biological heterogeneity, are compared with the standard Bray–Curtis and Whittaker dissimilarity indices, and provide the quantitative basis for a hierarchical cluster analysis.ResultsFour distinct groups of forests were identified using the proposed forest dissimilarity matrix. Afro‐montane forests from South Africa constitute a first group. A second group includes temperate deciduous broad‐leaved forests dominated by oak (Quercus) and beech (Fagus) from Europe and China. Conifer‐dominated forests constitute a third group. The remaining forests constitute the fourth group.ConclusionBiological heterogeneity provides a practical basis for vegetation classification. The results of this study, based on a variety of temperate and tropical forests, suggest that a measure of biological dissimilarity based on evolutionary and morphological differences among species is more effective than the traditional species abundance‐based approaches to classify an arbitrary set of plant communities. This approach promises greater refinement and consistency in ecological classification. In particular, it has advantage in classifying forests along large geographic scales in situations of high beta diversity and species turnover.

Assessing bank erosion hazards along large rivers in the Anthropocene: a geospatial framework from the St. Lawrence fluvial system

Over the past decades, riparian land-use changes coupled to the multiplication of river infrastructures have enhanced vulnerability issues for societies and ecosystems located along large rivers. Exposure to geohazards is also changing due to the ongoing climate change, underlining the need for flexible management strategies for riparian environments. In this perspective, GIS-based mapping allows integrating a wide range of environmental data. However, such datasets are often incomplete and not homogeneous over large geographical scales, which can be problematic for the implementation of regional land-use planning strategies. Using the St. Lawrence fluvial system (SLFS) (Québec, Canada) as a case study, this article reports and describes a high-resolution approach to map position, characteristics and erosion susceptibility of natural and artificial riverbanks from a combination of field-based, remote sensing and local knowledge-derived data. This approach allowed identifying erosion-prone sites and highlighting dominant erosion processes and spatially constrain them along the SLFS. The proposed geospatial framework constitutes (1) an initial portrait of the riverscape that will allow an effective implementation of future monitoring and process-based studies; and (2) a first step in supporting land-use planning stakeholders in the selection of appropriate measures to ensure a greater resilience of riparian communities and ecosystems.

Spatiotemporal variation in climatic conditions across ecosystems

Environmental variation in time and space affects biological processes such as extinction risk and speed of adaptation to environmental change. The spatial structure of environmental variation may vary among ecosystems, for instance due to differences in the flow of nutrients, genes and individuals. However, inferences about ecosystem spatial scale should also include spatial autocorrelation in environmental stochasticity, such as fluctuations in weather or climate. We used spatially structured time series (19-36 yr) on temperature from 4 different ecosystems (terrestrial, limnic, coastal sea and open ocean) to assess the spatiotemporal patterns of environmental variation over large geographical scales (up to 1900 km) during summer and winter. The distance of positive spatial autocorrelation in mean temperature was greatest for the terrestrial system (range: 592-622 km), and shorter for the open ocean (range: 472-414 km), coastal sea (range: 155-814 km) and the limnic systems (range: 51-324 km), suggesting a stronger spatial structure in environmental variation in the terrestrial system. The terrestrial system had high spatial synchrony in temperature (mean correlation: winter = 0.82, summer = 0.66) with a great spatial scaling (&gt;650 km). Consequently, populations of terrestrial species experience similar environmental fluctuations even at distances up to 1000 km, compared to species in the aquatic systems (&lt;500 km). There were clear seasonal differences in environmental synchrony in the terrestrial and limnic systems, but less so in the other systems. Our results suggest that biological processes affected by environmental stochasticity occur at the largest spatial scale in terrestrial systems, but their magnitude depends on whether the process is affected by winter or summer conditions.

Climate change and primary production: Forty years in a bunchgrass prairie.

Over the past 109 years, a Montana intermountain bunchgrass prairie annually became warmer (0.7°C) and drier (27%). The temperature and precipitation trends continued since 1978, as we studied nitrogen availability, annual aboveground primary production (ANPP), plant phenology and species composition. Given the annual increase in temperature and decrease in precipitation, ANPP might be expected to decline; however, it increased by 110%, as the period of greatest production (late-May–June) became wetter and cooler, counter to the annual pattern, and this was strongest at lower elevations. Grass production increased by 251%, while dicot production declined by 65%, which increased grass relative abundance by 54%. Summer temperatures increased 12.5% which increased plant senescence by 119% and decreased fall plant regrowth by 68%. More intense summer senescence changed plant species composition in favor of more drought tolerant species. The greater ANPP and summer senescence may increase susceptibility for fire, but fire tolerance of the plant species composition did not change. Invasive plant species increased 108% over the study with annual grasses accounting for >50% of this increase, which further increased summer plant senescence. Therefore, seasonal climate changes at a smaller geographical scale (local), rather than average annual climate changes over a larger geographical scale (regional), may better reflect plant community responses, and this makes ecological forecasting of climate change more difficult.

Intercontinental genomic parallelism in multiple three-spined stickleback adaptive radiations.

Parallelism, the evolution of similar traits in populations diversifying in similar conditions, provides strong evidence of adaptation by natural selection. Many studies of parallelism focus on comparisons of different ecotypes or contrasting environments, defined a priori, which could upwardly bias the apparent prevalence of parallelism. Here, we estimated genomic parallelism associated with components of environmental and phenotypic variation at an intercontinental scale across four freshwater adaptive radiations (Alaska, British Columbia, Iceland, Scotland) of the three-spined stickleback (Gasterosteus aculeatus). We combined large-scale biological sampling and phenotyping with RAD-sequencing data from 73 freshwater lake populations and four marine ones (1,380 fish) to associate genome-wide allele frequencies with continuous distributions of environmental and phenotypic variation. Our three main findings demonstrate: 1) quantitative variation in phenotypes and environments can predict genomic parallelism; 2) genomic parallelism at the early stages of adaptive radiations, even at large geographic scales, is founded on standing variation; and 3) similar environments are a better predictor of genome-wide parallelism than similar phenotypes. Overall, this study validates the importance and predictive power of major phenotypic and environmental factors likely to influence the emergence of common patterns of genomic divergence, providing a clearer picture than analyses of dichotomous phenotypes and environments.