Phytolith-occluded carbon (PhytOC) is an important long-term stable carbon fraction in grassland ecosystems, and plays a promising role in global carbon sequestration. Determination of the PhytOC traits of different plants in major grassland types is crucial for precisely assessing their PhytOC sequestration potential. Precipitation is the predominant factor in controlling net primary productivity (NPP) and species composition of the semiarid steppe grasslands. We selected three representative steppe communities of desert steppe, dry typical steppe and wet typical steppe in Northern Grasslands of China along a precipitation gradient, to investigate their species composition, biomass production and PhytOC content for quantifying its long-term carbon sequestration potential. Our results showed that (i) the phytolith and PhytOC contents in plants differed significantly among species, with dominant grass and sedge species having relatively high contents, and the contents are significantly higher in below- than the aboveground parts. (ii) The phytolith contents of plant communities were 16.68, 17.94 and 15.85 g kg-1 in the above- and 85.44, 58.73 and 76.94 g kg-1 in the belowground biomass of desert steppe, dry typical steppe and wet typical steppe, respectively; and the PhytOC contents were 0.68, 0.48 and 0.59 g kg-1 in the above- and 1.11, 0.72 and 1.02 g kg-1 in the belowground biomass of the three steppe types. (iii) Climatic factors affected phytolith and PhytOC production of steppe communities mainly through altering plant production, whereas their effects on phytolith and PhytOC contents were relatively small. Plant aboveground biomass and PhytOC content were strongly associated with the current-year climate and soil bio-available Si content; while plant belowground biomass and PhytOC content were relatively stable, and their variation across the sites is in accordance with the spatial variation in the long-term means of climatic and soil factors, reflecting the perenniality of plant belowground part.

The desert harvester ant Veromessor pergandei displays geographic variation in colony founding with queens initiating nests singly (haplometrosis) or in groups (pleometrosis). The transition from haplo- to pleometroic founding is associated with lower rainfall. Numerous hypotheses have been proposed to explain the evolution of cooperative founding in this species, but the ultimate explanation remains unanswered. In laboratory experiments, water level was positively associated with survival, condition, and brood production by single queens. Queen survival also was positively influenced by water level and queen number in a two-factor experiment. Water level also was a significant effect for three measures of queen condition, but queen number was not significant for any measure. Foundress queens excavated after two weeks of desiccating conditions were dehydrated compared to alate queens captured from their natal colony, indicating that desiccation can be a source of queen mortality. Long-term monitoring in central Arizona, USA, documented that recruitment only occurred in 4 of 20 years. A discriminant analysis using rainfall as a predictor of recruitment correctly predicted recruitment in 17 of 20 years for total rainfall from January–June (the period for mating flights and establishment) and in 19 of 20 years for early plus late rainfall (January–March and April–June, respectively), often with a posterior probability > 0.90. Moreover, recruitment occurred only in years in which both early and late rainfall exceeded the long-term mean. This result also was supported by the discriminant analysis predicting no recruitment when long-term mean early and late rainfall were included as ungrouped periods. These data suggest that pleometrosis in V. pergandei evolved to enhance colony survival in areas with harsh abiotic (desiccating) conditions, facilitating colonization of habitats in which solitary queens could not establish even in wet years. This favorable-year hypothesis supports enhanced worker production as the primary advantage of pleometrosis.

Body mass is often viewed as a proxy of past access to resources and of future survival and reproductive success. Links between body mass and survival or reproduction are, however, likely to differ between age classes and sexes. Remarkably, this is rarely taken into account in selection analyses. Selection on body mass is likely to be the primary target accounting for juvenile survival until reproduction but may weaken after recruitment. Males and females also often differ in how they use resources for reproduction and survival. Using a long-term study on yellow-bellied marmots (Marmota flaviventer), we show that body mass was under stabilizing selection in the first years of life, before recruitment, which changed to positive directional selection as age increased and animals matured. We found no evidence that selection across age-classes on body mass differed between sexes. By investigating the link between running speed and body mass, we show that the capacity to escape predators was not consistent across age classes and followed a quadratic relationship at young ages only. Overall, our results indicate that mature age classes exhibit traditional patterns of positive selection on body mass, as expected in a hibernating mammal, but that mass in the first years of life is subject to stabilizing selection which may come from additional predation pressures that negate the benefits of the largest body masses. Our study highlights the importance to disentangle selection pressures on traits across critical age (or life) classes.

1. Ongoing intensification and fragmentation of European agricultural landscapes dramatically reduce biodiversity and associated functions. To sustain ecosystem services such as ant mediated pest control, the enhancement of perennial non-crop areas holds great potential. 2. To study the potential of newly established grasslands to enhance ant diversity and associated functions, we used hand collection data to investigate differences in ant community composition (a) between cereal crops, old grasslands, and new grassland transects of three years age; (b) depending on ant functional traits; and linked to (c) natural pest control services quantified through predation experiments. 3. Ant species richness did not significantly differ between new and old grasslands, but was significantly higher in grasslands compared to cereal crops. Contrary, ant community composition of new grasslands was more similar to cereal crops and distinct from the species-pool of old grasslands. The functional trait space covered by the ant communities overlapped between old and new grasslands but was extended in the old grasslands. Pest control did not differ significantly between habitat types, and therefore could not be linked to the prevalence of functional traits related to biocontrol services in new grasslands. 4. Our findings show trends of convergence between old and new grasslands, but also indicate that enhancing ant diversity through newly established grasslands takes longer than three years to provide comparable biodiversity and functions. 5. Synthesis and applications Newly established grasslands can increase ant species richness, abundance, and pest control in agroecosystems. However, three years after establishment, new grasslands were still dominated by common agrobiont ant species and lacked habitat specialists present in old grasslands, who require a constant supply of food resources and long colonization times. New grasslands represent a promising measure for enhancing agricultural landscapes but must be preserved in the longer term to sustain biodiversity and associated ecosystem services.

Huanglongbing (HLB) is the most devastating citrus disease worldwide. The causal organism of the disease is spread by an insect vector, Diaphorina citri, commonly known as Asian citrus psyllid (ACP). Current management of HLB relies either on physical removal of the infected plants or on chemical control of ACP. Both methods are not overly effective and costly. In addition, public concerns regarding insecticide residues in fruit have greatly increased in recent years. It has been hypothesized that plant volatiles could act as repellents to ACP, thus reduce the incidence of HLB. To test this hypothesis, the repellency of fresh tissues of 41 aromatic plant species to ACP was investigated. The repellency of individual species was determined using a Y-tube olfactometer. Our results showed that volatiles of five plant species were highly effective in repelling ACP with repellency as much as 76%. Among these, the tree species, Camptotheca acuminate, and the two shrubs, Lantana camara and Mimosa bimucronata, could potentially be planted as a landscape barrier. The two herbs, Capsicum annuum and Gynura bicolor, could potentially be used as interrow plantings in orchards. This is the first time that the repellency of fresh tissues from a diverse range of plant species to ACP has been determined. Although further field evaluation of various interplanting regimes and landscape barriers are needed to assess their effectiveness, our results showed that these aromatic species, being highly repellent to ACT, offer great potential as more cost-effective and environmentally sustainable alternatives to the current methods of managing HLB.

Interspecific hybrid frequencies can vary considerably across contact zones of a single pair of progenitor species. The reasons for this are not well understood, but could help explain processes such as species diversification or the range expansion of invasive hybrids. The widespread cattails Typha latifolia and T. angustifolia seldom hybridize in some parts of their range, but in other areas produce the dominant hybrid T. × glauca. We used a combination of field and greenhouse experiments to investigate why T. × glauca has invaded wetlands in the Laurentian Great Lakes region of southern Ontario, Canada, but is much less common in the coastal wetlands of Nova Scotia in eastern Canada. One potentially important environmental difference between these two regions is salinity. We therefore tested three hypotheses: 1) T. latifolia and T. angustifolia in Nova Scotia are genetically incompatible; 2) the germination or growth of T. × glauca is reduced by salinity; and 3) T. latifolia, a main competitor of T. × glauca, is locally adapted to saline conditions in Nova Scotia. Our experiments showed that Nova Scotia T. latifolia and T. angustifolia are genetically compatible, and that saline conditions do not impede growth of hybrid plants. However, we also found that under conditions of high salinity, germination rates of hybrid seeds were substantially lower than those of Nova Scotia T. latifolia. In addition, germination rates of Nova Scotia T. latifolia were higher than those of Ontario T. latifolia, suggesting local adaptation to salinity in coastal wetlands. This study adds to the growing body of literature which identifies the important roles that local habitat and adaptation can play in the distributions and characteristics of hybrid zones.

The interannual variation (IAV) of net ecosystem carbon production (NEP) plays an important role in understanding the mechanisms of the carbon cycle in the agriculture ecosystem. NEP is usually partitioned into the diffecence between gross ecosystem productivity (GEP) and ecosystem respiration (RE), or the integration of the carbon uptake or release peak and the corresponding duration. In this study, the climatic and biotic controls of the IAV of NEP, which were expressed as annual values and anomalies, were investigated based on an eddy covariance dataset of rain-fed spring maize during 2005–2018 in the northeast of China. The annual NEP was 270±115 g C m−2yr −1. Annual values and anomalies of NEP were positively correlated with that of precipitation (PPT), GEP and daily maximum NEP (NEPmax). 78.9% of annual anomalies of NEP were explained by the interaction of climate, soil and plant variables, and the atmospheric water vapor deficit (VPD) played a dominated role. Annual anomalies of NEP were dominantly and positively controlled by the soil water content (SWC) through GEP and the soil temperature (Ts) through RE. In comparison, annual anomalies of NEP were dominantly and negatively controlled by summer VPD through the NEPmax, positively adjusted by spring precipitation and the effective accumulative temperature through the beginning date (BDOY) of the affecting carbon uptake period (CUP), and by autumn precipitation and leaf area index through the end date (EDOY) of the affecting CUP. Residues restrained the carbon release at the beginning of the year, and accelerated the carbon release at the end of the year. Our results hightlight that NEP might be more sensitive to the change of water condition (such as PPT, SWC and VPD) induced by the climate changes.

Earthworms are a major component of soil fauna communities with positive effects on soil chemical, biological and physical processes. A study was carried out at Chinhoyi University of Technology experimental farm, Zimbabwe, to investigate the medium-term effects of cultural practices on earthworm communities in a maize-based cropping system. Data were collected in the 2018/2019 cropping season from a six-year old experiment with tillage system (conventional, rip line seeding and basin planting), fertiliser application rate (zero, low: 35.2 kg ha−1 N + 12.2 kg ha−1 P2O5 + 6.6 kg ha−1K2O, medium: 41.5 kg ha−1 N + 14 kg ha−1 P2O5 + 7 kg ha−1 K2O, and high: 83 kg ha−1 N + 28 kg ha−1 P2O5: 14 kg ha−1 K2O.) and weeding intensity (twice, four times and clean weeding) as the main, sub- and sub-subplots, respectively. Lumbricus (34.4%) and Diplocardia (38.3%) were the dominant genera while endogeic earthworms (48.4%) dominated the community structure among other earthworm functional groups. Lumbricus abundance, total earthworm abundance, genus richness and Shannon diversity index were higher in clean weeded plots under the basin planting system relative to other treatments. Inorganic fertiliser application in the conventional tillage (CT) system reduced Eisenia abundance and genus richness. There was a positive correlation between total earthworm abundance (r = 0.34, P < 0.001) and negative correlation of Diplocardia abundance (r = -21, P < 0.05) with maize grain yield. These results suggest that in minimum tillage systems clean weeding has positive effects on earthworms while in CT, application of high doses of inorganic fertiliser is detrimental to earthworm communities.

The theory of ecological divergence provides a useful framework to understand the adaptation of many species to anthropogenic (‘domestic’) habitats. The mosquito Aedes aegypti, a global vector of several arboviral diseases, presents an excellent study system. Ae. aegypti originated in African forests, but the populations that invaded other continents have specialized in domestic habitats. In its African native range, the species can be found in both forest and domestic habitats like villages. A crucial behavioral change between mosquitoes living in different habitats is their oviposition choices. Forest Ae. aegypti lay eggs in natural water containers like tree holes, while their domestic counterparts heavily rely on artificial containers such as plastic buckets. These habitat-specific containers likely have different environmental conditions, which could drive the incipient divergent evolution of oviposition in African Ae. aegypti. To examine this hypothesis, we conducted field research in two African locations, La Lopé, Gabon and Rabai, Kenya, where Ae. aegypti live in both forests and nearby villages. We first characterized a series of environmental conditions of natural oviposition sites, including physical characteristics, microbial density, bacterial composition, and volatile profiles. Our data showed that in both locations, environmental conditions of oviposition sites did differ between habitats. To examine potential behavioral divergence, we then conducted field and laboratory oviposition choice experiments to compare the oviposition preference of forest and village mosquitoes. The field experiment suggested that forest mosquitoes readily accepted artificial containers. In laboratory oviposition assays, forest and village mosquito colonies did not show a differential preference towards several conditions that featured forest versus village oviposition sites. Collectively, there is little evidence from our study that environmental differences lead to strong and easily measurable divergence in oviposition behavior between Ae. aegypti that occupy nearby forest and domestic habitats within Africa, despite clear divergence between African and non-African Ae. aegypti.

Aims The impact of nutrient increase on nutrient resorption from senescent leaves is an important topic, which is not completely understood. Mangrove species are characterized by nutrient conservation mechanisms as a consequence of adaptation to nutrient-poor environments. The understanding of the response of the traits related to nutrient conservation strategies to nutrient availability is limited. This study aims to address whether nutrient resorption of mangrove species is responsive to long-term nutrient enrichment. Methods A field-based study was carried out in a Kandelia obovata dominated mangrove stand where a nutrient gradient was generated by the long-term discharge of aquaculture wastewater. Seasonal variations of nutrient resorption and nutrient availability were assessed. Important findings The data from summer and winter showed the same results: 1) resorption proficiency or the nutrient concentrations (N and P) in senescent leaves did not varied with nutrient increases except the plot that the N availability was extremely high; 2) the resorption efficiency of both N and P was positively correlated with nutrient availability, and N resorption efficiency was also positively correlated to leaf N: P ratio; 3) N resorption was complete while the resorption of P was incomplete. These results indicate that resorption proficiency of K. obovata is less sensitive than resorption efficiency to nutrient availability, and the positive response of N resorption efficiency is related to the imbalance of nutrient availability, while the positive response of P resorption efficiency is unrelated to plant nutrient status. We suggest that caution should be taken in using resorption efficiency of mangrove species to predict plant nutrient status.

Barriers to fieldwork exist for many reasons such as physical ability, financial cost, and time availability. Unfortunately, these barriers disproportionately affect minority communities and create a disparity in access to fieldwork experience in the natural science community. Travel restrictions and the global lockdown has extended this barrier to fieldwork across the community and led to increased anxiety about gaps in productivity, especially for graduate students and early-career researchers. In this paper, we discuss Agent-Based Modeling as an open-source, accessible, and inclusive resource to substitute for lost fieldwork during COVID-19 and future scenarios of travel restrictions such as climate change. We detail the process of model development with a plethora of examples from the literature on how Agent-Based Models can be applied broadly across life-science research. We aim to amplify awareness and adoption of this technique to broaden the diversity and size of the Agent-Based Modeling community in ecology and evolutionary research. We also describe the benefits of Agent-Based models as a teaching and training resource for students across education levels. Finally, we discuss the current challenges facing Agent-Based Modeling and discuss how the field of quantitative ecology can work in tandem with traditional field ecology to improve both methods.

Resistance (host capacity to reduce parasite burden) and tolerance (host capacity to reduce impact on its health for a given parasite burden) manifest two different lines of defence. Tolerance can be independent from resistance, traded-off against it, or the two can be positively correlated because of redundancy in underlying (immune) processes. We here tested whether this coupling between tolerance and resistance could differ upon infection with closely related parasite species. We tested this in experimental infections with two parasite species of genus Eimeria. We measured proxies for resistance (the (inverse of) number of parasite transmission stages (oocysts) per gram of feces at the day of maximal shedding) and tolerance (the slope of maximum relative weight loss compared to day of infection on number of oocysts per gram of feces at the day of maximal shedding for each host strain) in four inbred mouse strains and four groups of F1 hybrids belonging to two mouse subspecies, Mus musculus domesticus and M. m. musculus. We found a negative correlation between resistance and tolerance against E. falciformis, while the two are uncoupled against E. ferrisi. We conclude that resistance and tolerance against the first parasite species might be traded off, but evolve more independently in different mouse genotypes against the latter. We argue that evolution of the host immune defences can be studied largely irrespective of parasite isolates if resistance-tolerance coupling is absent or weak (E. ferrisi) but host-parasite coevolution is more likely observable and best studied in a system with negatively correlated tolerance and resistance (E. falciformis).

Restoring vegetation can effectively reduce soil erosion and significantly improve soil properties and quality. To analyze the response of soil organic carbon components and related enzymes to different vegetation types in the northern Loess Plateau, we collected soil samples of four vegetation types: Xanthoceras sorbifolia (XS), Hippophae rhamnoides (HR), Caragana korshinskii (CK), and Grassland (GL). We used these samples to analyze the organic carbon components (i.e., soil organic carbon (SOC), microbial biomass carbon (MBC), easily oxidized carbon (EOC), particulate organic carbon (POC) )and enzyme activities (i.e., amylase, catalase, urease and sucrase). We found that the content of the soil organic carbon fractions and the enzyme activities was greater in the upper layer than in the lower layer for each vegetation type except for MBC and catalase activity, where we observed no significant difference between soil layers. The EOC and amylase of GL vegetation were significantly higher than in other vegetation types. POC, SOC, urease and sucrase were considerably higher in SX vegetation than in other vegetation types. The maximum soil MBC content was found in HR vegetation, and among the four vegetation types, MBC content varied significantly differences in the lower layer, but no significant difference was observed in the surface soil. Correlation analysis demonstrated that the MBC content significantly influenced urease and sucrase activities, and that SOC significantly influenced urease and sucrase activities. These results emphasize the importance of the organic components of soil and the activities of soil enzymes in different kinds of vegetation in the Loess Plateau, providing a basis for improving the sustainable restoration of vegetative ecosystems.

Nutritional geometry has advanced our understanding of how macronutrients (e.g., proteins and carbohydrates) influence the expression of life history traits and their corresponding trade-offs. For example, recent work has revealed that reproduction and immune function in male decorated crickets are optimized at very different protein:carbohydrate (P:C) dietary ratios. However, it is unclear how an individual’s macronutrient intake interacts with its perceived infection status to determine investment in reproduction or other key life history traits. Here, we employed a fully factorial design in which calling effort and immune function were quantified for male crickets fed either diets previously demonstrated to maximize calling effort (P:C = 1:8) or immune function (P:C = 5:1), and then administered a treatment from a spectrum of increasing infection cue intensity using heat-killed bacteria. Both diet and a simulated infection threat independently influenced the survival, immunity, and reproductive effort of males. If they called, males increased calling effort at the low infection cue dose, consistent with the terminal investment hypothesis, but interpretation of responses at the higher threat levels was hampered by the differential mortality of males across infection cue and diet treatments. A high protein, low carbohydrate diet severely reduced the health, survival, and overall fitness of male crickets. There was, however, no evidence of an interaction between diet and infection cue dose on calling effort, suggesting that the threshold for terminal investment was not contingent on diet as investigated here.

Phenotypic variation among individuals and species is a fundamental principle of natural selection. In this review, we focus on numerous experiments involving the model species Daphnia (Crustacea) and categorize the factors, especially secondary ones, affecting intraspecific variations in inducible defense. Primary factors, such as predator type and density, determine the degree to which inducible defense expresses and increases or decreases. Secondary factors, on the other hand, act together with primary factors to inducible defense, or without primary factors on inducible defense. The secondary factors increase intra-species variation in inducible defense, and thus the level of adaptation of organisms varies within species. Future research will explore the potential for new secondary factors, as well as the relative importance between factors needs to be clarified.

The use of biota to analyze the spatial range and distribution of biogeographic regions is essential to gain a better understanding of the ecological processes that cause biotic differentiation and biodiversity at multiple spatiotemporal scales. Recently, the collection of high-resolution biological distribution data (e.g., specimens) and advances in analytical theory have led to their quantitative analysis and more refined spatial delineation. This study was conducted to redefine floristic zones in the southern part of the Korean Peninsula and to better understand the eco-evolutionary significance of the spatial distribution patterns. Based on the distribution data of 309,333 vascular plant species in the Korean Peninsula, we derived floristic zones using self-organizing maps. We compared the characteristics of the derived regions with those of historical floristic zones and ecologically important environmental factors (climate, geology, and geography). In a clustering analysis of the floristic assemblages, four distinct regions were identified, namely, the cold floristic zone (Zone I) in high-altitude regions at the center of the Korean Peninsula, cool floristic zone (Zone II) in high-altitude regions in the south of the Korean Peninsula, warm floristic zone (Zone III) in low-altitude regions in the central and southern parts of the Korean Peninsula, and maritime warm floristic zone (Zone IV) including the volcanic islands of Jejudo and Ulleungdo. A total of 1,099 taxa were common to the four floristic zones. Zone IV had the highest abundance of specific plants (those found in only one zone), with 404 taxa. This study improves floristic zone definitions using high-resolution regional biological distribution data. It will help better understand and re-establish regional species diversity. In addition, our study provides key data for hotspot analysis techniques required for the conservation of plant diversity.

Abstract: The continuously increasing trend of large-tree growth challenges the assertion of the unimodal pattern in classical growth theories. Here, we considered the effect of changes in functional traits on growth and extended classical growth equations (i.e., Gompertz and logistic curves) to reconcile this contradiction. We speculated that under the combined effect of allometric scaling and growth plasticity, tree growth trajectories likely follow different unimodal curves before and after different stages, showing a cascade characteristic. The increasing growth trend may be related to the appearance of a larger-scale unimodal curve in the late stage of growth, which depends on some changes in functional traits relative to tree size. To test this hypothesis, we measured tree growth in four plots across the subalpine Abies fabri forest belt on Gongga Mountain in the eastern Tibetan Plateau of China, and then analyzed the relationship of tree growth with important functional traits (i.e., leaf and stem economics and morphological traits). Our results indicate that the ideal and average growth dynamics of Abies fabri follow a unimodal curve with a cascade characteristic. On the individual-scale, cascading growth is more obvious, where the length and height of unimodal curves both increase with tree size, but may be still constrained by hydraulic constraints and tree longevity. This makes sense, because as trees grow, there is an increase in the relative volume of the crown and a decrease in the relative amount of sapwood, resulting in greater carbon accumulation. The results of this study imply the potential for significant improved carbon sequestration capacity of large trees in the later growth period. This model also offers a practical way to link traits and growth performance.

Drought has become one of the major constraints on agricultural development, particularly in areas lacking water. Studying the effects of different water stresses on photosynthesis, growth, yield, water use efficiency (WUE) and water productivity (IWP) of winter wheat will provide scientific irrigation strategies for developing water-saving agriculture. According to the water field capacity, four different water stress levels were set, i.e., 30–40% of water field capacity (severe stress), 40–50% (moderate stress), 50–60% (mild stress) and 60–80% (well-watered), through an automatic irrigation system by controlling the irrigation amount. The results showed that the diurnal and seasonal changes in photosynthetic parameters such as net photosynthetic rate (Pn), intercellular carbon concentration (Ci), stomatal conductance (Gs), and transpiration (E) significantly decreased under moderate and severe stress. The Pn of mild stress only slightly decreased compared to that of well-watered and was even higher after May 16th. As a result, the dry biomass and 1000-grain weight under mild stress increased 2.07% and 1.95% compared with well-watered. Under all water stresses, the heights and straw weights of the winter wheat significantly decreased. It was also found that mild water stress increased the WUE and IWP, which further resulted in the negligible decrease of the fresh weight of the aboveground biomass, dry biomass weight, spike weight, grain weight. Conversely, WUE and IWP significantly decreased under moderate and severe stress, which can affect the growth of winter wheat. So the fresh weight of the aboveground biomass, dry biomass weight, spike weight, grain weight also significantly decreased under moderate and severe stress. Thus, mild stress results in the optimal use of water resources without a significant reduction in yield in the North China Plain. Therefore, mild stress can be considered as a suitable environment for winter wheat growth in arid areas.

1. Livestock grazing and non-native plant species affect rangeland habitats globally. These factors may have important effects on ecosystem services including pollination, yet, interactions between pollinators, grazing, and invasive plants are poorly understood. To address this, we tested the hypothesis that cattle grazing and site colonization by cheatgrass (Bromus tectorum) impact bee foraging and nesting habitats and the biodiversity of wild bee communities in a shortgrass prairie system. 2. Bee nesting habitats (litter and wood cover) were marginally improved in non-grazed sites, though foraging habitat (floral cover and richness) did not differ among grazed, non-grazed, or cheatgrass colonized sites. However, floral cover was a good predictor of bee abundance and functional dispersion. 3. Mean bee abundance, richness, α-diversity and functional diversity were significantly lower in cattle-grazed habitats than in cheatgrass-colonized or non-grazed habitats. Differences in bee diversity among habitats were pronounced early in the growing season (May) but by late-season (August) these differences eroded. Fourth-corner analysis revealed that sites with high floral cover tended to support large, social, polylectic bees; sites with high grass cover tended to support oligolectic solitary bees. Both cattle-grazed and cheatgrass-colonized sites were associated with lower abundances of above-ground nesting bees but higher abundance of below-ground nesters. 4. Synthesis and applications. Cheatgrass-invaded sites do not appear to be associated with reduced bee biodiversity or abundance, but cattle grazing was negatively associated with bee abundances and altered species composition. Although floral cover is an important predictor of bee assemblages, this was not impacted by grazing and our suggests that cattle likely impact bee communities through effects other than those mediated by forbs, including soil disturbance or nest destruction. Efforts aimed at pollinator conservation in prairie habitats should focus on managing cattle impacts early in the growing season to benefit sensitive bee species.

1. Detritivores need to up-cycle their food to increase its nutritional value. One method is to fragment detritus promoting the colonisation of nutrient-rich microbes, which consumers then ingest. This is known as microbial gardening. Observations and numerical models of the detritus-dominated ocean mesopelagic zone have suggested microbial gardening by zooplankton is fundamental process in the ocean organic carbon cycle, as it leads to increased respiration of carbon-rich detritus. However, no experimental evidence exists to prove microbial respiration is higher on smaller, fragmented detrital particles. 2. Using aquaria-reared Antarctic krill faecal pellets we showed fragmentation increased microbial particulate organic carbon (POC) turnover by 70 %, but only on brown faecal pellets of low nutritional value. Microbial POC turnover on un-and fragmented green faecal pellets of higher nutritional value was equal. Thus we find particle size alone is not enough to determine microbial activity, and the nutritional value and age of the particle are important. 3. We estimate mesopelagic zooplankton can potentially increase the proportion of essential nutrients (e.g. unsaturated fatty acids) in their food by at least 11 %. In addition we propose ‘communal gardening’ may occur whereby other mesopelagic organisms consume the particle and microbes gardened by a neighbouring detritivore. 4. Increases in microbial turnover of detrital POC reduces the sink of organic carbon in the ocean. Thus microbial gardening should be represented in models forecasting the future carbon cycle. Model parameterisations will require further understanding of the energetic gains to zooplankton communities, how microbial gardening influences other sinking particles such as detrital aggregates, and the relative importance of biological (i.e. particle lability, size and age) vs. physical (i.e. temperature and oxygen) constraints on gardening.

1. Organisms may internally or behaviourally regulate their body temperatures or conform to the ambient air temperatures. Previous studies are inconclusive on whether pigmentation influences thermoregulation in various odonates. 2. We investigated the thermal response of sympatric North American Calopteryx aequabilis and Calopteryx maculata with a thermal imaging study across a 25 °C ambient temperature range. 3. We found that regressions of thorax temperature on ambient temperature had similar slopes for male and female C. maculata, but females were consistently 1.5 °C warmer than males. 4. In contrast, the sexes of C. aequabilis differed in slope, with C. aequabilis females having a slope less than 1.0 and males having a slope greater than 1.0. 5. Given that C. aequabilis is strongly sexually dimorphic in pigment, but C. maculata is not, our findings suggest that pigmentation does influence thermal response rate in sympatric populations of both species.

Herbivores can exert major controls over biogeochemical cycling. As invertebrates are highly sensitive to their environment (ectothermal), the abundances of insects in high-latitude systems, where climate warming is rapid, is expected to increase. In subarctic mountain birch forests research has focussed on geometrid moth outbreaks, while the contribution of background insect herbivory (BIH) to elemental cycling is poorly constrained. In northern Sweden, we estimated BIH along 9 elevational gradients distributed across a gradient in regional elevation, temperature and precipitation to allow evaluation of consistency in local vs. regional variation. We converted foliar loss via BIH to fluxes of C, nitrogen (N), and phosphorus (P) from the birch canopy to the soil to compare with other relevant soil inputs of the same elements, and assessed different abiotic and biotic drivers of the observed variability. We found that leaf area loss due to BIH was ~1.6% on average. This is comparable to estimates from tundra, but considerably lower than ecosystems at lower latitudes. The C, N and P fluxes from canopy to soil associated with BIH were 1-2 orders of magnitude lower than the soil input from senesced litter and external nutrient sources such as biological N fixation, atmospheric deposition of N and P weathering estimated from the literature. Hence, despite the minor contribution to overall elemental cycling in subarctic birch forests, the higher quality and earlier timing of the input of herbivore deposits to soils compared to senesced litter may make this contribution disproportionally important for various ecosystem functions. BIH increased significantly with leaf N-content as well as local elevation along each transect, yet showed no significant relationship with temperature or humidity, nor the commonly used temperature proxy, absolute elevation. The lacking consistency between the local and regional elevational trends calls for caution when using elevation gradients as climate proxies.

1. Many policies and studies globally have highlighted the pivotal role of wetland ecosystems regarding wetland biota and their ecological status. With the strengthening of wetland ecosystem management legislation and policy, wetland restoration should also consider increasing habitat diversity to improve biota. We explore whether the construction of artificial ecological islands can increase the diversity of wetland birds and macroinvertebrates before assessing the effects of actively constructing islands via human intervention on wetland protection. 2. We discuss changes in waterfowl and macroinvertebrate diversity (i) with and without islands, (ii) at different water level gradients surrounding the islands, (ⅲ) on different island substrates, and (ⅳ) at different time scales. We used ANOVA, ANOSIM and cluster analysis to test the differences. 3. The waterfowl and macroinvertebrate communities had spatially heterogeneous distributions and vary over time due to both natural and anthropogenic stresses. The establishment of islands significantly changed the community composition and biodiversity of the macroinvertebrate and the waterfowl. The waterfowl and macroinvertebrate communities had different compositions at different water levels. Macroinvertebrates are the main food components of waterfowl and are closely related to them, and overall, abundance and diversity of macroinvertebrates directly and/or indirectly affect the biodiversity of waterfowl. Potentially, the construction of islands could provide some co-benefits for the conservation of wetland birds and macroinvertebrates. Synthesis and applications. Establishing artificial ecological islands in broad open water areas and increasing the water level gradient and substrate diversity. It can increase the micro-habitat diversity by artificially increasing the heterogeneity of the water depth conditions of a habitat. These changes can accommodate aquatic organisms with different ecological niches to increase the biodiversity, affecting the ecological restoration of inland freshwater marshes and wetlands. As such, wetland parks can play a positive role in protecting important bird migration pathways in northeast Asia.

1. Fire and frost represent two major hurdles for the persistence of trees in open grassy biomes and have both been proposed as drivers of grassland-forest boundaries in Africa. 2. We assess the response of young tree seedlings, which represent a vulnerable stage in tree recruitment, to traumatic fire and frost disturbances. 3. In a greenhouse experiment, we investigated how seedling traits predicted survival and resprouting ability in response to fire vs frost; we characterised survival strategies of seedlings in response to the two disturbances, and we documented how the architecture of surviving seedlings is affected by fire vs frost injury. 4. Survival rates were similar under both treatments. However, different species displayed different levels of sensitivity to fire and frost. Seedling survival was higher for older seedlings and seedlings with more basal leaves. Survivors of a fire event lost more biomass than the survivors of a frost event. However, the architecture of recovered fire and frost treated seedlings were mostly similar. Seedlings that recovered from fire and frost treatments were often shorter than those that had not been exposed to any disturbance, with multiple thin branches, which may increase vulnerability to the next frost or fire event. 5. Synthesis. Fire caused more severe aboveground damage compared to frost, suggesting that trees in these open grassland systems may be subjected to a seedling release bottleneck maintained by fire. However, the woody species composition will almost certainly be influenced by phenomena that affect the timing and frequency of seedling exposure to damage, as mortality was found to be dependent on seedling age. Therefore, changes in fire regime and climate (esp. changes that bring about less frost and reduced fire intensity and frequency) are likely to result in changes in the composition and the structure of the woody components of these systems.