Productivity Gradient Research Articles

Foraging consistency of coral reef fishes across environmental gradients in the central Pacific.

We take advantage of a natural gradient of human exploitation and oceanic primary production across five central Pacific coral reefs to examine foraging patterns in common coral reef fishes. Using stomach content and stable isotope (δ15N and δ13C) analyses, we examined consistency across islands in estimated foraging patterns. Surprisingly, species within the piscivore-invertivore group exhibited the clearest pattern of foraging consistency across all five islands despite there being a considerable difference in mean body mass (14g-1.4kg) and prey size (0.03-3.8g). In contrast, the diets and isotopic values of the grazer-detritivores varied considerably and exhibited no consistent patterns across islands. When examining foraging patterns across environmental contexts, we found that δ15N values of species of piscivore-invertivore and planktivore closely tracked gradients in oceanic primary production; again, no comparable patterns existed for the grazer-detritivores. The inter-island consistency in foraging patterns within the species of piscivore-invertivore and planktivore and the lack of consistency among species of grazer-detritivores suggests a linkage to different sources of primary production among reef fish functional groups. Our findings suggest that piscivore-invertivores and planktivores are likely linked to well-mixed and isotopically constrained allochthonous oceanic primary production, while grazer-detritivores are likely linked to sources of benthic primary production and autochthonous recycling. Further, our findings suggest that species of piscivore-invertivore, independent of body size, converge toward consuming low trophic level prey, with a hypothesized result of reducing the number of steps between trophic levels and increasing the trophic efficiency at a community level.

Zooplankton and Micronekton Active Flux Across the Tropical and Subtropical Atlantic Ocean

Quantification of the actual amount of carbon export to the mesopelagic layer by both zooplankton and micronekton is at present a gap in the knowledge of the biological pump. These organisms perform diel vertical migrations exporting carbon through respiration, excretion, mortality, and egestion during their residence at depth. The role of zooplankton in active flux is nowadays partially assessed. However, micronekton active flux is scarcely known and only a few studies addressed this downward transport. Even less is known about the capacity of both communities to export carbon in the ocean. Here, we show the results of zooplankton and micronekton active flux across a productivity gradient in the tropical and subtropical Atlantic Ocean. Biomass vertical distribution from the surface up to 800 m depth by day and night was studied during April 2015 in a transect from 9oS to 25oN, covering from the quite oligotrophic zone off Brazil to the meso- and eutrophic areas of the equator, Guinea Dome, and the oceanic upwelling off Northwest Africa. Zooplankton and micronekton migrant biomass was estimated from day and night catches at different layers of the water column using MOCNESS-1 (1 m2 mouth area) and Mesopelagos (35 m2) nets, respectively. Respiratory flux was assessed by measuring the enzymatic activity of the electron transfer system (ETS) of organisms at depth. Results showed a close relationship between migrant biomass and respiratory flux in zooplankton and micronekton as expected. Using a rather conservative 50% of efficiency for the net used to capture micronekton, respiratory flux resulted in similar values for both communities. Gravitational (passive) flux measured using sediment traps increased from the oligotrophic towards the meso- and eutrophic zones. Total active flux (including respiration and estimated mortality, excretion, and gut flux) by zooplankton and micronekton accounted for about 25% of total flux (passive plus active) in oligotrophic zones. Total active flux also increased towards meso- and eutrophic zones, reaching about 80% of total flux and being at least 2-fold higher than passive flux. These results alert about an important underestimation of the ocean biological pump using only passive flux measurements.

Niche width expansion of coral reef fishes along a primary production gradient in the remote central Pacific

Niche width expansion of coral reef fishes along a primary production gradient in the remote central Pacific

Photocatalytic Micromotors Activated by UV to Visible Light for Environmental Remediation, Micropumps, Reversible Assembly, Transportation, and Biomimicry.

Photocatalytic micromotors are light-induced, chemically powered micromachines based on photocatalytic materials, activated by light illumination, and have redox reactions with environmental solutions to produce chemical gradients and bubbles that propel the micromachines through self-diffusiophoresis, self-electrophoresis, and bubble recoil. Due to the fact that excitation light relates largely to the bandgaps of selected materials, the development of photocatalytic micromotors has experienced an evolution from ultraviolet-light-activated to visible-light-activated and potentially biocompatible systems. Furthermore, due to the strong redox capacity and physical effects caused by the products or product gradients, photocatalytic micromotors have applications in environmental remediation, micropumps, reversible assembly, transportation, and biomimicry.

Phytoplankton communities in the crater lakes of western Uganda, and their indicator species in relation to lake trophic status

Abstract The freshwater crater lakes of western Uganda represent an important natural resource for the region’s rural communities, but their capacity to provide drinking-quality water and other ecosystem services is being threatened by rapidly intensifying human activity within their catchments. This study investigated the relationship between the composition of pelagic phytoplankton communities in these lakes and their trophic status, to assess how phytoplankton surveys with recognition of indicator species can assist in the assessment of water-resource vulnerability to human impact. For this purpose we analyzed 70 phytoplankton samples with linked environmental data from 26 crater lakes spanning the entire regional gradients of primary productivity and land-use intensity, with each lake sampled two to four times and during both dry and rainy seasons. At this equatorial location, nutrient concentrations and phytoplankton biomass (measured as the concentration of chlorophyll-a) showed no consistent seasonal pattern. In total we recorded 118 phytoplankton taxa from 72 genera, and from 20 to 54 taxa per lake. The phytoplankton community of most lakes and in most seasons was dominated by cyanobacteria (on average 78% of total cell counts) followed by green algae (17%) and diatoms (4%); euglenophytes, dinoflagellates, chrysophytes and cryptophytes together contributed less than 1% on average. Many species were found to have a wide distribution along the productivity gradient, which complicated characterization of phytoplankton communities typical of different trophic states. Cluster analysis revealed four groups of samples, of which two broadly represented the least and most highly productive lakes. The two other groups comprised a mixture of lakes with intermediate productivity, suggesting that phytoplankton composition in these lakes is structured by other factors in addition to nutrient availability. In total 25 taxa displayed a significant association with one of these groups, but only 12 of them can be considered robust indicators of a particular trophic level; among these, the cyanobacteria Planktolyngbya limnetica and Microcystis aeruginosa qualify as strong indicator species for lakes with low and high productivity, respectively. Based on the distributional turnover between indicator species, we propose that the fresh Ugandan crater lakes comprise four trophic levels, of which the boundaries are situated higher up the chlorophyll-a gradient than those between the four classic trophic levels defined for temperate-region lakes. For practical use, Ugandan crater lakes with a chlorophyll-a concentration up to 6 µg/L can be defined as oligotrophic; similarly, we situate the mesotrophic/eutrophic boundary at ca 20 µg/L, and the eutrophic/hypertrophic boundary at ca 60 µg/L.

Organic matter supply and bacterial community composition predict methanogenesis rates in temperate lake sediments

AbstractThe objective of our study was to identify environmental conditions that structure lake sediment microbial communities and determine whether community composition explained inter‐lake variation in potential methanogenesis rates. We performed a comparative analysis of microbial communities and methanogenesis rates in 14 lake sediments along gradients of pH and primary productivity. Variation in methanogen community composition and non‐methanogen microbial community composition was best explained by pH and sediment organic matter content. However, these regulators of methanogen community structure were not associated with differences in methanogenesis rates. Instead, variation in lake methanogenesis rates was best explained by proxies for organic matter supplied to sediments (lake chlorophyll a concentration and sediment pore‐water total phosphorus) and the composition of the non‐methanogen microbial community. Our results suggest a role for sediment bacterial community in influencing methanogenesis via the supply of growth substrates.

Vertical size structure is associated with productivity and species diversity in a short‐stature grassland: Evidence for the importance of height variability within herbaceous communities

AbstractQuestionsLocal size structure is frequently measured in plant populations and forested systems due to its association with population‐ and community‐level processes. In contrast, size structure is rarely examined within herbaceous communities despite evidence for size‐dependent processes in these systems, suggesting an important functional vegetation property may be widely overlooked. Here, we test whether vertical size structure (a) varies within a short‐stature grassland, (b) varies along a productivity gradient, and (c) enhances the understanding of a foundational ecological pattern: the diversity–productivity relationship.LocationRough fescue grassland in Alberta, Canada.MethodsWe measured the heights of individuals within 32 plots and used average height, the Gini coefficient, and a two‐parameter Weibull distribution to estimate community‐level vertical size structure. Linear mixed models were used to test whether size structure parameters were significantly associated with productivity, species richness, and species evenness.ResultsVertical size structure varied significantly among local communities, such that some were dominated by short individuals while others were comprised of a more equal number of taller individuals. With increasing productivity, there was an increase in average plant height and a decrease in height inequality. Decreased height inequality was associated with reduced species richness with evidence that loss was not size‐dependent. The inclusion of vertical size structure parameters increased the explained variance of the diversity–productivity relationship by ~35% while also increasing its parsimony.ConclusionsEven within a short‐stature grassland, there is substantial functional variation in vertical size structure. Productivity is strongly associated with size structure patterns, and the inclusion of height inequalities greatly enhances productivity–diversity relationships, likely because they are the product of assembly mechanisms such as size‐asymmetric competition, assemblage‐level thinning, and niche complementarity. Overall, this demonstrates that vertical size structure has been a missing mechanism in most community assembly theories and models and should be included in the future.

Hyplant-Derived Sun-Induced Fluorescence—A New Opportunity to Disentangle Complex Vegetation Signals from Diverse Vegetation Types

Hyperspectral remote sensing (RS) provides unique possibilities to monitor peatland vegetation traits and their temporal dynamics at a fine spatial scale. Peatlands provide a vital contribution to ecosystem services by their massive carbon storage and wide heterogeneity. However, monitoring, understanding, and disentangling the diverse vegetation traits from a heterogeneous landscape using complex RS signal is challenging, due to its wide biodiversity and distinctive plant species composition. In this work, we aim to demonstrate, for the first time, the large heterogeneity of peatland vegetation traits using well-established vegetation indices (VIs) and Sun-Induced Fluorescence (SIF) for describing the spatial heterogeneity of the signals which may correspond to spatial diversity of biochemical and structural traits. SIF originates from the initial reactions in photosystems and is emitted at wavelengths between 650–780 nm, with the first peak at around 687 nm and the second peak around 760 nm. We used the first HyPlant airborne data set recorded over a heterogeneous peatland area and its surrounding ecosystems (i.e., forest, grassland) in Poland. We deployed a comparative analysis of SIF and VIs obtained from differently managed and natural vegetation ecosystems, as well as from diverse small-scale peatland plant communities. Furthermore, spatial relationships between SIF and VIs from large-scale vegetation ecosystems to small-scale peatland plant communities were examined. Apart from signal variations, we observed a positive correlation between SIF and greenness-sensitive VIs, whereas a negative correlation between SIF and a VI sensitive to photosynthesis was observed for large-scale vegetation ecosystems. In general, higher values of SIF were associated with higher biomass of vascular plants (associated with higher Leaf Area Index (LAI)). SIF signals, especially SIF760, were strongly associated with the functional diversity of the peatland vegetation. At the peatland area, higher values of SIF760 were associated with plant communities of high perennials, whereas, lower values of SIF760 indicated peatland patches dominated by Sphagnum. In general, SIF760 reflected the productivity gradient on the fen peatland, from Sphagnum-dominated patches with the lowest SIF and fAPAR values indicating lowest productivity to the Carex-dominated patches with the highest SIF and fAPAR values indicating highest productivity.

Two Decades of Experimental Manipulation Reveal Potential for Enhanced Biomass Accumulation and Water Use Efficiency in Ponderosa Pine Plantations Across Climate Gradients

AbstractIn this study, we report 20 years of data from three ponderosa pine plantations in northern California. Our sites span a natural gradient of forest productivity where climate variability and edaphic conditions delineate marked differences in baseline productivity (approximately threefold). Experimental herbicide application and fertilization significantly reduced competition and improved tree growth by 1.4‐ to 2.2‐fold across sites. At the site of lowest productivity, where soils are poorly developed and water limiting, tree growth increased strongly in response to understory suppression. Small but significant improvements in tree growth were observed in response to understory suppression at the moderate‐productivity site. At the site of highest productivity, where climate is favorable and soils well developed, fertilization increased productivity to a greater extent than did understory suppression. In most cases, the effect of understory suppression and fertilization caused an unexpected growth release, exceeding the anticipated maximum productivity by >5 m of additional height and 60–100% more basal area. At the site of highest productivity, however, understory suppression caused a weak increase on late‐season growth compared to fertilization alone, suggesting a beneficial effect of understory vegetation on long‐term growth at that site. Tree ring cellulose carbon isotopes indicate a negative relationship between intrinsic water use efficiency (iWUE) and tree growth in control stands, which shifted to a positive relationship as both iWUE and tree growth increased in response to management. Cellulose oxygen isotope ratios (δ18O) were positively correlated with iWUE and negatively correlated with vapor pressure deficit across sites, but δ18O was not a strong predictor of tree growth.

Rapid growth and defence evolution following multiple introductions.

Rapid adaptation can aid invasive populations in their competitive success. Resource allocation trade‐off hypotheses predict higher resource availability or the lack of natural enemies in introduced ranges allow for increased growth and reproduction, thus contributing to invasive success. Evidence for such hypotheses is however equivocal and tests among multiple ranges over productivity gradients are required to provide a better understanding of the general applicability of these theories.Using common gardens, we investigated the adaptive divergence of various constitutive and inducible defence‐related traits between the native North American and introduced European and Australian ranges, while controlling for divergence due to latitudinal trait clines, individual resource budgets, and population differentiation, using >11,000 SNPs.Rapid, repeated clinal adaptation in defence‐related traits was apparent despite distinct demographic histories. We also identified divergence among ranges in some defence‐related traits, although differences in energy budgets among ranges may explain some, but not all, defence‐related trait divergence. We do not identify a general reduction in defence in concert with an increase in growth among the multiple introduced ranges as predicted trade‐off hypotheses. Synthesis: The rapid spread of invasive species is affected by a multitude of factors, likely including adaptation to climate and escape from natural enemies. Unravelling the mechanisms underlying invasives' success enhances understanding of eco‐evolutionary theory and is essential to inform management strategies in the face of ongoing climate change. OPEN RESEARCH BADGES This article has been awarded Open Materials, Open Data, Preregistered Research Designs Badges. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.6084/m9.figshare.8028875.v1, https://github.com/lotteanna/defence_adaptation,https://doi.org/10.1101/435271.

Spatial patterns of rainbow smelt energetic condition in Lakes Huron and Erie in 2017: Evidence for Lake Huron resource limitation

Rainbow smelt (Osmerus mordax) is a key planktivore and prey fish in Lake Huron. Given the declining offshore productivity in the lake since the early 2000s, we described the energy content of rainbow smelt in 2017 across five different regions (North Channel, Georgian Bay, Saginaw Bay, northern main basin, southern main basin) where phytoplankton and zooplankton productivity likely varied. To increase contrast across the productivity gradient, rainbow smelt energy content was also estimated from western Lake Erie. Within the North Channel where large fish (≥90 mm, total length) were sampled most frequently, mean energy density (kJ/g wet weight) varied seasonally: 4.29 in April (month of spawning), 3.86 in June, 3.99 in July, and up to 4.35 in September. Energy density of rainbow smelt from higher productivity western Lake Erie was 37% (large fish ≥90 mm) to 60% higher (small fish <90 mm) than that of fish from Lake Huron. Within Lake Huron, energy density of rainbow smelt from North Channel was slightly higher than those from other regions; rainbow smelt from Georgian Bay generally had the lowest energy density. Across regions, including western Lake Erie, energy density increased with chlorophyll a concentration. Compared with Lake Huron studies prior to 2004, when oligotrophication had not yet accelerated, energy density of rainbow smelt in 2017 was up to 31% lower. The decline in rainbow smelt energy density is likely the result of declining primary and secondary pelagic production and increased resource limitation for planktivorous fish.

The global geography of fish diadromy modes

AbstractAimGeographical gradients in resource production are likely to translate into macroecological patterns in the biodiversity of migratory organisms, but few studies have addressed this question at a global scale. Here, we tested a hypothesis based on uncoupled latitudinal gradients in marine and freshwater primary productivities aimed at explaining where (e.g., at which latitude) and at which stage of the life cycle (larvae, amphidromy; juvenile, catadromy; or adult, anadromy) migration from ocean to freshwater occurs (diadromy).LocationGlobal.Time periodCurrent.Major taxa studiedFishes.MethodsWe modelled, using multinomial regressions, the proportion of catadromous, anadromous and amphidromous species in 994 river basins as a function of freshwater and marine net primary productivities (NPP; in milligrams of carbon per square metre per day) and additional biotic and abiotic variables. Using data extracted from the Global Biodiversity Information Facility (GBIF) database, we tested whether diadromous, catadromous and amphidromous species differed with respect to the NPP of their marine and freshwater occurrences.ResultsAmong diadromous species, anadromous species are present in higher proportions when conditions for growth are more favourable in the sea (higher productivity, higher temperature and lower number of competitors) than in freshwaters. The model reconstructs the latitudinal pattern observed in the proportion of anadromous species, including an asymmetry between the Northern and Southern Hemispheres. According to GBIF occurrences, the ratio of marine over freshwater productivity is higher for anadromous species compared with catadromous and amphidromous species.Main conclusionsOur results support the hypothesis stating that migration between ocean and freshwater occurs by choosing the biome that optimizes pre‐reproductive growth and is one more example of the importance of primary productivity in shaping large‐scale community patterns. This result suggests that some diadromous fish populations and species may suffer from anticipated climate change if interbiome productivity gradients are affected.

Carbon and Nitrogen Concentrations, Stocks, and Isotopic Compositions in Red Sea Seagrass and Mangrove Sediments

Coastal vegetated ecosystems are intense global carbon (C) sinks; however, seagrasses and mangroves in the Central Red Sea are depleted in organic C (Corg). Here, we tested whether Corg depletion prevails across the whole Red Sea, or if sediment Corg and nitrogen (N) stocks reflect the latitudinal productivity gradient of the Red Sea. We assessed Corg and N concentrations, stocks, isotopic compositions (δ13C and δ15N), and the potential contribution of primary producers to the organic matter accumulation in seagrass and mangrove sediments along the Eastern coast of the Red Sea. Sediment Corg concentration was higher in mangroves than seagrasses, while N concentrations were similar, resulting in higher C/N ratios in mangrove than seagrass sediments. Mangrove Corg stocks (integrated over the top 10 cm) were two-fold higher than those of seagrasses, respectively. N concentrations and stocks decreased from south to north in seagrass sediments matching the productivity gradient while Corg concentrations and stocks were uniform. The δ15N decreased from south to north in seagrass and mangrove sediments, reflecting a shift from nitrate and nitrite as N sources in the south, to N2 fixation towards the north. Stable isotope mixing models showed that seagrass leaves and macroalgae blades were the major contributors to the organic matter accumulation in seagrass sediments; while mangrove leaves were the major contributors in mangrove sediments. Overall, vegetated sediments in the Red Sea tend to be carbonate-rich and depleted in Corg and N, compared to coastal habitats elsewhere. Specifically, mean Corg stocks in Red Sea seagrass and mangrove sediments (7.2 ± 0.4 and 14.5 ± 1.4 Mg C ha-1, respectively) are lower than previously reported mean global values. This new information of Blue Carbon resources in the Red Sea provides a background for Blue Carbon programs in the region while also helping to balance global estimates.

Winning and losing with microbes: how microbially mediated fitness differences influence plant diversity.

Interactions between plants and soil microbes can strongly influence plant diversity and community dynamics. Soil microbes may promote plant diversity by driving negative frequency-dependent plant population dynamics, or may favor species exclusion by providing one species an average fitness advantage over others. However, past empirical research has focused overwhelmingly on the consequences of frequency-dependent feedbacks for plant species coexistence and has generally neglected the consequences of microbially mediated average fitness differences. Here we use theory to develop metrics that quantify microbially mediated plant fitness differences, and show that accounting for these effects can profoundly change our understanding of how microbes influence plant diversity. We show that soil microbes can generate fitness differences that favour plant species exclusion when they disproportionately harm (or favour) one plant species over another, but these fitness differences may also favor coexistence if they trade off with competition for other resources or generate intransitive dominance hierarchies among plants. We also show how the metrics we present can quantify microbially mediated fitness differences in empirical studies, and explore how microbial control over coexistence varies along productivity gradients. In all, our analysis provides a more complete theoretical foundation for understanding how plant-microbe interactions influence plant diversity.

Carbon control on terrestrial ecosystem function across contrasting site productivities: the carbon connection revisited.

Understanding how altered soil organic carbon (SOC) availability affects microbial communities and their function is imperative in predicting impacts of global change on soil carbon (C) storage and ecosystem function. However, the response of soil microbial communities and their function to depleted C availability insitu is unclear. We evaluated the role of soil C inputs in controlling microbial biomass, community composition, physiology, and function by (1) experimentally excluding plant C inputs insitu for 9 yr in four temperate forest ecosystems along a productivity gradient in Oregon, USA; and (2) integrating these findings with published data from similar C-exclusion studies into a global meta-analysis. Excluding plant C inputs for 9 yr resulted in a 13% decrease in SOC across the four Oregon sites and an overall shift in the microbial community composition, with a 45% decrease in the fungal:bacterial ratio and a 13% increase in Gram-positive:Gram-negative bacterial ratio. Although gross N mineralization decreased under C exclusion, decreases in gross N immobilization were greater, resulting in increased net N mineralization rates in all but the lowest-productivity site. Microbial biomass showed a variable response to C exclusion that was method dependent; however, we detected a 29% decrease in C-use efficiency across the sites, with greater declines occurring in less-productive sites. Although extracellular enzyme activity increased with C exclusion, C exclusion resulted in a 31% decrease in microbial respiration across all sites. Our meta-analyses of published data with similar C-exclusion treatments were largely consistent with our experimental results, showing decreased SOC, fungal:bacterial ratios, and microbial respiration, and increased Gram-positive:Gram-negative bacterial ratio following exclusion of C inputs to soil. Effect sizes of SOC and respiration correlated negatively with the duration of C exclusion; however, there were immediate effects of C exclusion on microbial community composition and biomass that were unaltered by duration of treatment. Our field-based experimental results and analyses demonstrate unequivocally the dominant control of C availability on soil microbial biomass, community composition, and function, and provide additional insight into the mechanisms for these effects in forest ecosystems.

Unimodal productivity-diversity relationships among bacterial communities in a simple polar soil ecosystem.

Unlike other macroecological principles, relationships between productivity and diversity have not been effectively tested for microbial communities. Here we describe an experiment in which the availability of resources to soil bacterial communities was manipulated in a model system, the McMurdo Dry Valleys of Antarctica. Mannitol additions were used to simulate a productivity gradient such that a response in bacterial biomass production, taxonomic diversity and functioning (e.g., enzyme activity) were induced. Resource amendment induced a positive linear response in microbial productivity (P < 0.001) but a unimodal (hump-shaped) response in microbial diversity at multiple taxonomic scales (P = 0.035). Putative oligotrophic (e.g., phyla Nitrospirae and Cyanobacteria) and copiotrophic (e.g., phylum Proteobacteria) taxa were apparent through substantial community turnover along the resource gradient. Soil enzyme activity was inversely related to bacterial biomass but positively related to diversity, suggesting the latter may be a stronger control over enzyme-mediated decomposition. The mechanisms behind this pattern are consistent with macroecological theory of a shift from environmental (e.g., stress tolerance) to biotic (e.g., competition) drivers with increasing resource availability. This evidence is among the first of its kind to document a significant unimodal productivity-diversity relationship for soil bacteria.

Biofilm systems as tools in biotechnological production.

The literature provides more and more examples of research projects that develop novel production processes based on microorganisms organized in the form of biofilms. Biofilms are aggregates of microorganisms that are attached to interfaces. These viscoelastic aggregates of cells are held together and are embedded in a matrix consisting of multiple carbohydrate polymers as well as proteins. Biofilms are characterized by a very high cell density and by a natural retentostat behavior. Both factors can contribute to high productivities and a facilitated separation of the desired end-product from the catalytic biomass. Within the biofilm matrix, stable gradients of substrates and products form, which can lead to a differentiation and adaptation of the microorganisms' physiology to the specific process conditions. Moreover, growth in a biofilm state is often accompanied by a higher resistance and resilience towards toxic or growth inhibiting substances and factors. In this short review, we summarize how biofilms can be studied and what most promising niches for their application can be. Moreover, we highlight future research directions that will accelerate the advent of productive biofilms in biology-based production processes.

Atlantic forest and leaf traits: an overview

Leaf traits in Atlantic forest are modulated by environmental filters and biotic interactions. More information about leaf traits and nutrient are needed. Categorizing tree species according to their relationships with ecosystem processes in the Atlantic forest (AF) biome is fundamental to better understand their functionality in this high biodiversity hotspot. For categorizing vegetation, leaf traits are extremely useful and this is the first compilation of leaf traits focusing on photosynthesis, water relations, nutrients, and functional diversity across major AF vegetation types: (1) rainforest (ombrophilous dense and mixed ombrophilous Araucaria forest), (2) seasonal semi-deciduous forest, (3) deciduous forests, and (4) coastal plain forests (restingas). Species showed high plasticity of photosynthetic traits from early developmental stages, including adjustments in Rubisco carboxylation capacity, maximum photosynthetic capacity, photochemical and non-photochemical quenching, specific leaf area (SLA), and chlorophyll and spongy parenchyma thickness. Montane rainforest tree species showed lower SLA and longer leaf lifespan in comparison to lowland rainforest species. Tree communities are structured by environmental filtering leading to trait convergence in early successional stages or in stressful ecosystems such as restingas, and by biotic interactions leading to trait divergence in later stages. Altitudinal gradients in litter production and below/aboveground biomass stocks in AF show contrasting patterns in comparison to other tropical forests, with important consequences for responding to climate change. However, the identity of limiting elements to growth still represents a critical gap in leaf trait data for AF species. Other gaps in knowledge of AF leaf traits are highlighted for consideration in future studies.

When Landscape Ecology Meets Physiology: Effects of Habitat Fragmentation on Resource Allocation Trade-Offs

Landscape heterogeneity is a general feature of natural environments, strongly affected by habitat fragmentation. It can affect a population’s dynamics and probability of extinction. Fragmentation increases among-patch isolation and decreases patch size, resulting in a reduction in available resources in smaller patches. To persist, animals must be able to translate the variation imposed by fragmentation into adaptive energy allocation strategies that enable populations to avoid extinction. This means that physiological adaptations are expected to reflect changes in landscape configuration, especially in the size of the natural habitat patches and degree of isolation among them. We propose a novel, integrative conceptual framework in which spatial characteristics of the environment, imposed by fragmentation, lead to specific life-history traits that increase survival (at the individual level) and decrease the likelihood of extinction (as an emergent property at the population level). We predict that a resource allocation trade-off between the life-history traits of reproduction and dispersal along a fragmentation gradient will emerge. Populations occurring in patches of different sizes and isolations along gradients of fragmentation and productivity will exhibit differences in the strength of the dispersal-reproduction trade-off. Emerging from this framework are several explicit and testable hypotheses that predict that the dispersal-reproduction trade-off will be shaped by landscape heterogeneity imposed by fragmentation. Hence, this trade-off serves as the mechanistic link that translates environmental variation created by fragmentation into variation in species abundances and population dynamics by lowering local extinction probability and increasing overall population persistence.

Optimization of operating conditions of CO2-enhanced gas recovery and carbon sequestration

Currently, the climate changes are the big issue due to increasing in amount of CO2 foot print over the time. One of the most effective solutions to reduce CO2 emissions is to inject CO2 into the earth as known as carbon sequestration. CO2 injection has two advantages for CO2 gas storage and increases gas production in depleted reservoir or known as enhanced gas recovery (EGR). Although many studies of EGR model and characterization have been done and the results show that the application of EGR has potentially increased gas production and CO2 storage; however, EGR has not been applied in the field. The obstacle remaining in application of EGR is the significant cost related to EGR technology starting from CO2 procurement cost, transportation and operational cost. The operational costs of CO2 injection depend on the operating conditions of CO2 injection which is mass flow rate, pressure and temperature of CO2 injection. In this research, CO2 EGR and carbon sequestration processes were modeled by dividing into three parts, i.e., injection well, reservoir and production well. Pressure gradient in injection and production well was modeled using Beggs–Brill, while in reservoir by using Darcy equation. Temperature gradient for each part was modeled using mass and energy balances equations. The fluid properties were predicted using Peng–Robinson vapor–liquid equilibrium under commercial software HYSYS. Validation of injection and production well models was compared with PIPESIM, and the average mean deviations are 1.919% and 1.578%, respectively. Meanwhile, the validation of pressure and temperature gradient model compared to COMSOL Multiphysics software simulation in reservoir shows the average mean deviation of 0.2003% and 0.0002%, respectively. Based on the sensitivity analysis of the model, the profit will increase proportionally if mass flow rate and temperature increase; otherwise, it will decrease if CO2 injection pressure increases. Before optimization, the presence of CO2 injection in depleted gas reservoir with normal operating conditions can produce gas recovery of about 90.09% in which the profit generated is 6175.6 USD/day. EGR optimization has been performed using several recent stochastic algorithms, and the best optimization result was obtained by using Killer Whale Algorithm, duelist algorithm and Rain Water Algorithm. The optimization results show an increase in profit from 4453.8 USD/day to 12,331.9 USD/day or about 276.9% higher than the initial condition of the injection or without optimization. By using injection parameters that have been optimized, the CO2 that can be stored is 1486.01 tons.