Rameez Ahmad, Showkeen Ahmad Lone, Irfan Rashid, Anzar Ahmad Khuroo
Invasive alien species (IAS) are one amongst the dominant drivers of global environmental change. The reported effects of IAS on biodiversity and ecosystems are often highly variable across species, habitats, and environmental settings, which constrains our capacity to empirically generalise their overall impact. To date, meta‐analyses have investigated the ecological impacts of IAS using only mean effects, while variance effects – an equally important measure in quantifying the efficacy or generalizability of a treatment – has largely remained ignored. Using a global meta‐analysis of 586 and 522 effect sizes related to mean and variance measures respectively from 30 studies, here we provide the first quantitative synthesis of the extent to which a global plant invader Lantana camara affects the mean and variance of ecological variables relevant at species, community and ecosystem levels. Our results suggest that for individual response classes, both the mean and variance effects from the species invasion differed considerably in their magnitude and direction, with the effect on most response classes being highly heterogeneous and non‐significant. The study design had a significant effect on both the mean and variance effects from the species invasion, but the ecosystem type, continent, and latitude act as weak predictors of both mean and variance effects. By investigating both mean and variance effects, our study provides first quantitative synthesis on ecological impacts of a globally problematic invasive plant. Based on our findings, we highlight the current knowledge gaps and suggest future research directions, particularly the need to focus on causes of variance in invasion impact studies for effective management and restoration of invaded landscapes.
{"title":"Ecological impacts of a global plant invader: synthesizing mean and variance effects using meta‐analysis","authors":"Rameez Ahmad, Showkeen Ahmad Lone, Irfan Rashid, Anzar Ahmad Khuroo","doi":"10.1111/oik.10102","DOIUrl":"https://doi.org/10.1111/oik.10102","url":null,"abstract":"Invasive alien species (IAS) are one amongst the dominant drivers of global environmental change. The reported effects of IAS on biodiversity and ecosystems are often highly variable across species, habitats, and environmental settings, which constrains our capacity to empirically generalise their overall impact. To date, meta‐analyses have investigated the ecological impacts of IAS using only mean effects, while variance effects – an equally important measure in quantifying the efficacy or generalizability of a treatment – has largely remained ignored. Using a global meta‐analysis of 586 and 522 effect sizes related to mean and variance measures respectively from 30 studies, here we provide the first quantitative synthesis of the extent to which a global plant invader <jats:italic>Lantana camara</jats:italic> affects the mean and variance of ecological variables relevant at species, community and ecosystem levels. Our results suggest that for individual response classes, both the mean and variance effects from the species invasion differed considerably in their magnitude and direction, with the effect on most response classes being highly heterogeneous and non‐significant. The study design had a significant effect on both the mean and variance effects from the species invasion, but the ecosystem type, continent, and latitude act as weak predictors of both mean and variance effects. By investigating both mean and variance effects, our study provides first quantitative synthesis on ecological impacts of a globally problematic invasive plant. Based on our findings, we highlight the current knowledge gaps and suggest future research directions, particularly the need to focus on causes of variance in invasion impact studies for effective management and restoration of invaded landscapes.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"54 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141187904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Raquel Díaz‐Borrego, María Ángeles Pérez‐Navarro, Luciana Jaime, Nuria J. Elvira, Francisco Lloret
Positive plant–plant interactions (facilitation) may enhance the recruitment and establishment of species less adapted to local macroclimatic conditions. A major cause of this effect is climatic buffering, which implies an increased mismatch between the macroclimatic conditions and the climatic requirements of the existing community – climatic disequilibrium – of plants living under canopies. Here we explore the effect of drought‐induced defoliation of Mediterranean shrubland canopy on the recruitment of woody species. We analyzed the differences in the climatic disequilibrium across different categories of canopy defoliation and plant–plant interactions: facilitation, neutral and inhibition. Climatic disequilibrium was estimated as the Euclidean distance in the multivariate environmental space between observed macroclimate and community inferred climate. The inferred climate was calculated by averaging the coordinates of the species' climatic niche centroids, obtained from species distribution, weighted by the species' relative abundances in each community. We found that the recruiting community growing under canopy showed higher climatic disequilibrium than the community growing in the gaps. The facilitated recruiting community growing under dead and living canopy showed the highest disequilibrium, followed by the community growing under mid‐affected canopy. The climatic disequilibrium of the recruiting communities experiencing neutral and inhibited interaction was not affected by canopy defoliation. These findings indicate that the climatic disequilibrium of the recruiting community is determined by the facilitation–competition balance. Living canopy provides climatic buffering, but it also implies competition, while dead canopy may provide some structural climatic buffering, without implying competition for resources. These results highlight the relevance of incorporating plant–plant interactions, particularly facilitation, to better forecast plant community responses to extreme climate events and climate change.
{"title":"Climatic disequilibrium of recruit communities across a drought‐induced die‐off gradient in Mediterranean shrubland","authors":"Raquel Díaz‐Borrego, María Ángeles Pérez‐Navarro, Luciana Jaime, Nuria J. Elvira, Francisco Lloret","doi":"10.1111/oik.10465","DOIUrl":"https://doi.org/10.1111/oik.10465","url":null,"abstract":"Positive plant–plant interactions (facilitation) may enhance the recruitment and establishment of species less adapted to local macroclimatic conditions. A major cause of this effect is climatic buffering, which implies an increased mismatch between the macroclimatic conditions and the climatic requirements of the existing community – climatic disequilibrium – of plants living under canopies. Here we explore the effect of drought‐induced defoliation of Mediterranean shrubland canopy on the recruitment of woody species. We analyzed the differences in the climatic disequilibrium across different categories of canopy defoliation and plant–plant interactions: facilitation, neutral and inhibition. Climatic disequilibrium was estimated as the Euclidean distance in the multivariate environmental space between observed macroclimate and community inferred climate. The inferred climate was calculated by averaging the coordinates of the species' climatic niche centroids, obtained from species distribution, weighted by the species' relative abundances in each community. We found that the recruiting community growing under canopy showed higher climatic disequilibrium than the community growing in the gaps. The facilitated recruiting community growing under dead and living canopy showed the highest disequilibrium, followed by the community growing under mid‐affected canopy. The climatic disequilibrium of the recruiting communities experiencing neutral and inhibited interaction was not affected by canopy defoliation. These findings indicate that the climatic disequilibrium of the recruiting community is determined by the facilitation–competition balance. Living canopy provides climatic buffering, but it also implies competition, while dead canopy may provide some structural climatic buffering, without implying competition for resources. These results highlight the relevance of incorporating plant–plant interactions, particularly facilitation, to better forecast plant community responses to extreme climate events and climate change.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"44 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141187905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anthropogenic biodiversity loss can impair ecosystem functioning. Human activities are often managed with the aim of reversing biodiversity loss and its associated functional impacts. However, it is currently unknown whether biodiversity–ecosystem function (BEF) relationships observed during biodiversity recovery are the same as those observed during biodiversity loss. This will depend on how species extirpation and recolonisation sequences compare and how different species influence ecosystem functioning. Using data from a marine benthic invertebrate community, we modelled how bioturbation potential – a proxy for benthic ecosystem functioning – changes along biodiversity loss and recovery sequences governed by species' sensitivity to physical disturbance and recolonisation capability, respectively. BEF relationships for biodiversity loss and recovery were largely the same despite species extirpation and recolonisation sequences being different. This held true irrespective of whether populations were assumed to exhibit compensatory responses as species were removed or added. These findings suggest that the functional consequences of local biodiversity loss can be reversed by alleviating its drivers, as different species present at comparable levels of species richness during biodiversity loss and recovery phases have similar functional effects. Empirically verifying and determining the generality of our model‐based results are potential next steps for future research.
{"title":"Ecosystem functioning during biodiversity loss and recovery","authors":"David S. Clare, Clement Garcia, Stefan G. Bolam","doi":"10.1111/oik.10154","DOIUrl":"https://doi.org/10.1111/oik.10154","url":null,"abstract":"Anthropogenic biodiversity loss can impair ecosystem functioning. Human activities are often managed with the aim of reversing biodiversity loss and its associated functional impacts. However, it is currently unknown whether biodiversity–ecosystem function (BEF) relationships observed during biodiversity recovery are the same as those observed during biodiversity loss. This will depend on how species extirpation and recolonisation sequences compare and how different species influence ecosystem functioning. Using data from a marine benthic invertebrate community, we modelled how bioturbation potential – a proxy for benthic ecosystem functioning – changes along biodiversity loss and recovery sequences governed by species' sensitivity to physical disturbance and recolonisation capability, respectively. BEF relationships for biodiversity loss and recovery were largely the same despite species extirpation and recolonisation sequences being different. This held true irrespective of whether populations were assumed to exhibit compensatory responses as species were removed or added. These findings suggest that the functional consequences of local biodiversity loss can be reversed by alleviating its drivers, as different species present at comparable levels of species richness during biodiversity loss and recovery phases have similar functional effects. Empirically verifying and determining the generality of our model‐based results are potential next steps for future research.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"79 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141187880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Douglas Sponsler, Christophe Dominik, Carolin Biegerl, Hanna Honchar, Oliver Schweiger, Ingolf Steffan‐Dewenter
Competition among pollinators for floral resources is a phenomenon of both basic and applied importance. While competition is difficult to measure directly under field conditions, it can be inferred indirectly through the measurement of floral resource depletion. In this study, we conducted a pollinator exclusion experiment to calculate nectar depletion rates in summer across 16 grassland sites in the German regions of Franconia and Saxony‐Anhalt. Overall depletion rates were estimated at 95% in Franconia and 79% in Saxony‐Anhalt, indicating strong nectar limitation and likely competition among pollinators for nectar. Despite being ubiquitous in our study regions, honey bees were scarce at our sites at the time of nectar sampling. This demonstrates that wild pollinators alone are capable of massive nectar depletion, and the addition of managed honey bees to wild pollinator communities may intensify already competitive conditions. Nevertheless, the manifest diversity of the pollinator communities at our sites indicates that other factors, such as non‐trophic constraints or temporal variation in nectar limitation, can mitigate competitive exclusion despite immediate conditions of acute nectar scarcity.
{"title":"High rates of nectar depletion in summer grasslands indicate competitive conditions for pollinators","authors":"Douglas Sponsler, Christophe Dominik, Carolin Biegerl, Hanna Honchar, Oliver Schweiger, Ingolf Steffan‐Dewenter","doi":"10.1111/oik.10495","DOIUrl":"https://doi.org/10.1111/oik.10495","url":null,"abstract":"Competition among pollinators for floral resources is a phenomenon of both basic and applied importance. While competition is difficult to measure directly under field conditions, it can be inferred indirectly through the measurement of floral resource depletion. In this study, we conducted a pollinator exclusion experiment to calculate nectar depletion rates in summer across 16 grassland sites in the German regions of Franconia and Saxony‐Anhalt. Overall depletion rates were estimated at 95% in Franconia and 79% in Saxony‐Anhalt, indicating strong nectar limitation and likely competition among pollinators for nectar. Despite being ubiquitous in our study regions, honey bees were scarce at our sites at the time of nectar sampling. This demonstrates that wild pollinators alone are capable of massive nectar depletion, and the addition of managed honey bees to wild pollinator communities may intensify already competitive conditions. Nevertheless, the manifest diversity of the pollinator communities at our sites indicates that other factors, such as non‐trophic constraints or temporal variation in nectar limitation, can mitigate competitive exclusion despite immediate conditions of acute nectar scarcity.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"42 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141187906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mukhtar M. Yahaya, James G. Rodger, Pietro Landi, Cang Hui
Specialisation enhances the efficiency of plant–pollinator networks through the exchange of conspecific pollen transfer for floral resources. Floral resources form the currency of plant–pollinator interactions, but the understanding of how floral resources affect the structure of plant–pollinator networks remains modest. Previous theory predicts that optimally foraging animal species will specialise to improve resource acquisition under high resource availability. Although floral resource availability depends on both the plant production and animal consumption of the resources, previous work has assumed that production and availability are equivalent. This potentially may have led to erroneous inferences on the effect of resource availability on specialisation. We develop a mutualistic Lotka–Volterra consumer‐resource model to investigate the influence of floral resource availability on plant–pollinator network structure. The model incorporates animal adaptive foraging behaviour, floral resource dynamics, and density‐dependent dynamics. Specialisation, nestedness and modularity of simulated networks generated from the model under a wide range of parameters were explained using the generalised linear model. We found that the distinction between floral resource dynamics and plant density dynamics was necessary for partial specialisation of plant–pollinator networks. This is because floral resource dynamics constrained animal preference due to its depletion by animal species. Floral resource abundance had a positive effect on network specialisation, but animal density had a negative effect on network specialisation. Floral resource dynamics thus play key roles in the structure of plant–pollinator networks, distinctive from plant species density dynamics.
{"title":"Emergence of structure in plant–pollinator networks: low floral resource constrains network specialisation","authors":"Mukhtar M. Yahaya, James G. Rodger, Pietro Landi, Cang Hui","doi":"10.1111/oik.10533","DOIUrl":"https://doi.org/10.1111/oik.10533","url":null,"abstract":"Specialisation enhances the efficiency of plant–pollinator networks through the exchange of conspecific pollen transfer for floral resources. Floral resources form the currency of plant–pollinator interactions, but the understanding of how floral resources affect the structure of plant–pollinator networks remains modest. Previous theory predicts that optimally foraging animal species will specialise to improve resource acquisition under high resource availability. Although floral resource availability depends on both the plant production and animal consumption of the resources, previous work has assumed that production and availability are equivalent. This potentially may have led to erroneous inferences on the effect of resource availability on specialisation. We develop a mutualistic Lotka–Volterra consumer‐resource model to investigate the influence of floral resource availability on plant–pollinator network structure. The model incorporates animal adaptive foraging behaviour, floral resource dynamics, and density‐dependent dynamics. Specialisation, nestedness and modularity of simulated networks generated from the model under a wide range of parameters were explained using the generalised linear model. We found that the distinction between floral resource dynamics and plant density dynamics was necessary for partial specialisation of plant–pollinator networks. This is because floral resource dynamics constrained animal preference due to its depletion by animal species. Floral resource abundance had a positive effect on network specialisation, but animal density had a negative effect on network specialisation. Floral resource dynamics thus play key roles in the structure of plant–pollinator networks, distinctive from plant species density dynamics.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"49 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140838566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Martin Godefroid, Christine N. Meynard, Anne‐Laure Clamens, Megan Popkin, Emmanuelle Jousselin
Asexual lineages often exhibit broad distributions and can thrive in extreme habitats compared to their sexual counterparts. Several hypotheses can be proposed to explain this pattern. Asexual lineages could be versatile genotypes with wide environmental tolerance, enabling their dispersal and persistence across large geographic areas. Alternatively, asexual genotypes could be ecological specialists that thrive in specific environments and outcompete relative colonizing distantly related with similar conditions in the process. Several aphid species feature widespread obligate asexual lineages, commonly known as ‘superclones'. Yet it is often unknown whether these clones are widespread ecological generalists or successful specialists. To explore these hypotheses, we examined climatic niche differentiation among six globally distributed obligate asexual lineages of the cosmopolitan aphid pest, Brachycaudus helichrysi. To ensure that we were investigating the aphid genotype niche and not a by‐product of their association with endosymbionts mediating thermal tolerance, we first verified that clones hosted similar endosymbiont communities. Subsequently, we conducted multivariate analyses on clone occurrence data on a worldwide scale. Our results revealed that, despite their global distribution, B. helichrysi superclones occupy different climatic niches. This study represents the first evidence that aphid superclone distribution can be mediated by distinctive ranges of climatic tolerance.
{"title":"On the role of niche specialization in the geographic distribution of aphid asexual lineages: a case study using the leaf‐curl plum aphid superclones","authors":"Martin Godefroid, Christine N. Meynard, Anne‐Laure Clamens, Megan Popkin, Emmanuelle Jousselin","doi":"10.1111/oik.10481","DOIUrl":"https://doi.org/10.1111/oik.10481","url":null,"abstract":"Asexual lineages often exhibit broad distributions and can thrive in extreme habitats compared to their sexual counterparts. Several hypotheses can be proposed to explain this pattern. Asexual lineages could be versatile genotypes with wide environmental tolerance, enabling their dispersal and persistence across large geographic areas. Alternatively, asexual genotypes could be ecological specialists that thrive in specific environments and outcompete relative colonizing distantly related with similar conditions in the process. Several aphid species feature widespread obligate asexual lineages, commonly known as ‘superclones'. Yet it is often unknown whether these clones are widespread ecological generalists or successful specialists. To explore these hypotheses, we examined climatic niche differentiation among six globally distributed obligate asexual lineages of the cosmopolitan aphid pest, <jats:italic>Brachycaudus helichrysi</jats:italic>. To ensure that we were investigating the aphid genotype niche and not a by‐product of their association with endosymbionts mediating thermal tolerance, we first verified that clones hosted similar endosymbiont communities. Subsequently, we conducted multivariate analyses on clone occurrence data on a worldwide scale. Our results revealed that, despite their global distribution, <jats:italic>B. helichrysi</jats:italic> superclones occupy different climatic niches. This study represents the first evidence that aphid superclone distribution can be mediated by distinctive ranges of climatic tolerance.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"17 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140838503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Polyploid organisms are common and can be found across the tree of life. A key question is to understand how and why these polyploid lineages become established and persist in populations, particularly since they are predicted to have a low probability of success. While the collection of papers in this special issue addresses broad questions on the evolutionary ecology of polyploids, ultimately, these studies also highlight the myriad ways that we are examining what drives the success of polyploid lineages. In this paper we consider where we've been and the challenges that we face, and then propose several directions that will allow us to continue to propel the field towards our ultimate goal of understanding the rules that govern the establishment and persistence of polyploid populations. We conclude that developing this rule set will require a combination of model systems for which we have detailed knowledge of the phylogenetic and population genetic history, expanding our perspective beyond plants to include greater taxonomic breadth, and conducting studies in ecologically relevant settings. Additionally, we argue that future research on the evolutionary ecology of polyploidy should focus on integrating theory and empirical research, providing mechanistic linkages between the effects of whole genome duplication and population demography, and build a predictive framework to understand how anthropogenic change will impact polyploid organisms.
{"title":"Special issue.: The role of whole genome duplication in evolutionary ecology","authors":"Kari A. Segraves, Thomas J. Anneberg","doi":"10.1111/oik.10804","DOIUrl":"https://doi.org/10.1111/oik.10804","url":null,"abstract":"Polyploid organisms are common and can be found across the tree of life. A key question is to understand how and why these polyploid lineages become established and persist in populations, particularly since they are predicted to have a low probability of success. While the collection of papers in this special issue addresses broad questions on the evolutionary ecology of polyploids, ultimately, these studies also highlight the myriad ways that we are examining what drives the success of polyploid lineages. In this paper we consider where we've been and the challenges that we face, and then propose several directions that will allow us to continue to propel the field towards our ultimate goal of understanding the rules that govern the establishment and persistence of polyploid populations. We conclude that developing this rule set will require a combination of model systems for which we have detailed knowledge of the phylogenetic and population genetic history, expanding our perspective beyond plants to include greater taxonomic breadth, and conducting studies in ecologically relevant settings. Additionally, we argue that future research on the evolutionary ecology of polyploidy should focus on integrating theory and empirical research, providing mechanistic linkages between the effects of whole genome duplication and population demography, and build a predictive framework to understand how anthropogenic change will impact polyploid organisms.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"17 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140838570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Species interactions are influenced by changes to the environment, such as seasonal variations in temperature, and human‐driven warming including marine heatwaves (MHWs). Alteration of species interactions, particularly those involving foundation species, can shape ecosystem structure, stability and dynamics. Marine habitats, notably seagrass meadows, are threatened by human‐driven environmental changes including MHWs which have the potential to alter trophic interactions through effects on various community members including seagrasses, epiphytic algae, and epiphytic algae grazers. Here we examined the effects of a simulated marine heatwave (control versus + 4°C) in different seasons and grazer occurrence on seagrass traits, epiphytic algae growth, grazer biomass and grazing rate. We found the season in which the MHW occurred affected the seagrass response and grazer influence. In winter, the MHW had positive effects on seagrass growth and nitrogen content and caused significant decreases in epiphytic algae growth. However, in summer, grazer presence increased seagrass growth and biomass, but growth was reduced by the interaction with the MHW. The season in which the MHW occurred affected the magnitude of change in leaf tissue isotopic values and C:N ratio, with greater changes occurring in summer. Epiphytic algal growth was markedly reduced by the interaction between all three factors, leading to the near lack of epiphyte growth in summer with grazers present under the MHW. Summer was also associated with a greater increase in snail biomass (most notably under MHW conditions), and increased snail grazing rate. From these results, we show that winter MHWs can drive increased growth of seagrasses but minimal impacts on grazers, while in summer increased grazer activity can interact with elevated temperatures from a MHW to increase their algal consumption. By examining responses across multiple trophic levels and distinct seasons, we achieve a more representative and realistic depiction of human‐induced environmental impacts on ecosystems.
{"title":"Seasonal effects and trophic pressure shape the responses of species interactions in a tropical seagrass meadow to marine heatwaves","authors":"Alissa V. Bass, Laura J. Falkenberg","doi":"10.1111/oik.10382","DOIUrl":"https://doi.org/10.1111/oik.10382","url":null,"abstract":"Species interactions are influenced by changes to the environment, such as seasonal variations in temperature, and human‐driven warming including marine heatwaves (MHWs). Alteration of species interactions, particularly those involving foundation species, can shape ecosystem structure, stability and dynamics. Marine habitats, notably seagrass meadows, are threatened by human‐driven environmental changes including MHWs which have the potential to alter trophic interactions through effects on various community members including seagrasses, epiphytic algae, and epiphytic algae grazers. Here we examined the effects of a simulated marine heatwave (control versus + 4°C) in different seasons and grazer occurrence on seagrass traits, epiphytic algae growth, grazer biomass and grazing rate. We found the season in which the MHW occurred affected the seagrass response and grazer influence. In winter, the MHW had positive effects on seagrass growth and nitrogen content and caused significant decreases in epiphytic algae growth. However, in summer, grazer presence increased seagrass growth and biomass, but growth was reduced by the interaction with the MHW. The season in which the MHW occurred affected the magnitude of change in leaf tissue isotopic values and C:N ratio, with greater changes occurring in summer. Epiphytic algal growth was markedly reduced by the interaction between all three factors, leading to the near lack of epiphyte growth in summer with grazers present under the MHW. Summer was also associated with a greater increase in snail biomass (most notably under MHW conditions), and increased snail grazing rate. From these results, we show that winter MHWs can drive increased growth of seagrasses but minimal impacts on grazers, while in summer increased grazer activity can interact with elevated temperatures from a MHW to increase their algal consumption. By examining responses across multiple trophic levels and distinct seasons, we achieve a more representative and realistic depiction of human‐induced environmental impacts on ecosystems.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"20 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140838669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Clea N. van de Ven, Tjisse van der Heide, Tjeerd J. Bouma, Lennart van Ijzerloo, Djeli D. Lindhout, Valérie C. Reijers
Coastal vegetated ecosystems including mangroves, seagrasses, and salt marshes are often shaped by positive plant–environment feedbacks. Plants improve their own living conditions with increasing patch size and density by attenuating hydrodynamics and stabilizing sediments. As these habitat modifications are critical for survival and growth, the positive density‐dependent nature of these feedbacks can lead to establishment thresholds for young plants in absence of mature conspecifics. Although feedback strength is known to depend on hydrodynamic exposure and plant traits (e.g. stiff versus flexible stems), it remains unclear how 1) opposing morphological plant traits affect establishment in contrasting environments, and 2) whether trait plasticity influences establishment success. Here, we investigate this by transplanting two tidal species with opposing growing strategies – Spartina anglica forms tussocks of stiff stems while Zostera noltii forms patches of stress‐avoiding flexible shoots – from two different donor sites in eight experimental locations. Results show that the survival and growth of both species was most successful at field locations with diverging environmental characteristics, while overall survival was highest for Z. noltii. Mainly, S. anglica survival was highest at locations with high organic matter and silt content and higher elevation relative to the tidal amplitude. In contrast, Z. noltii survival was highest at locations with larger grainsize and lower relative elevations. Furthermore, despite initial differences in plant traits between the two donor sites of Z. noltii, we found no effects of donor origin. Contrastingly, we found a significant effect of donor origin on S. anglica growth, even though transplants from the two donor sites showed no initial trait differences. Collectively, these results suggest that the stress‐tolerance strategy of S. anglica hampers establishment in exposed conditions, whereas the stress‐avoiding Z. noltii appears to be more susceptible to stress from desiccation and silty sediments.
包括红树林、海草和盐沼在内的沿海植被生态系统通常是由植物-环境正反馈形成的。随着斑块面积和密度的增加，植物通过减弱水动力和稳定沉积物来改善自身的生存条件。由于这些生境的改变对植物的生存和生长至关重要，因此这些正反馈的密度依赖性会导致幼苗在没有成熟同种植物的情况下达到建群阈值。尽管已知反馈强度取决于水动力暴露和植物性状（如硬茎与柔茎），但目前仍不清楚：1）植物的相反形态性状如何影响对比环境中的建群；2）性状可塑性是否影响建群成功率。在此，我们通过将两种生长策略截然相反的潮汐物种--Spartina anglica（形成硬茎草丛）和 Zostera noltii（形成可规避压力的柔性芽块）--从两个不同的供体地点移植到八个实验地点，对此进行了研究。结果表明，在环境特征不同的野外地点，这两个物种的存活和生长都最为成功，而 noltii 的总体存活率最高。主要是在有机物和淤泥含量高、海拔高度相对于潮汐涨落幅度较高的地点，S. anglica 的存活率最高。与此相反，在粒径较大、相对海拔较低的地点，糯稻的存活率最高。此外，尽管诺尔特藻类在两个供体地点的植物性状存在初步差异，但我们没有发现供体来源的影响。与此形成鲜明对比的是，我们发现供体来源对 S. anglica 的生长有显著影响，尽管来自两个供体地点的移栽植物没有表现出初始性状差异。总之，这些结果表明，S. anglica的耐压策略会阻碍其在暴露条件下的生长，而避免应激的Z. noltii似乎更容易受到干燥和淤泥的应激。
{"title":"Co‐occurring intertidal ecosystem engineers with opposing growth strategies show opposite responses to environmental gradients during establishment","authors":"Clea N. van de Ven, Tjisse van der Heide, Tjeerd J. Bouma, Lennart van Ijzerloo, Djeli D. Lindhout, Valérie C. Reijers","doi":"10.1111/oik.10546","DOIUrl":"https://doi.org/10.1111/oik.10546","url":null,"abstract":"Coastal vegetated ecosystems including mangroves, seagrasses, and salt marshes are often shaped by positive plant–environment feedbacks. Plants improve their own living conditions with increasing patch size and density by attenuating hydrodynamics and stabilizing sediments. As these habitat modifications are critical for survival and growth, the positive density‐dependent nature of these feedbacks can lead to establishment thresholds for young plants in absence of mature conspecifics. Although feedback strength is known to depend on hydrodynamic exposure and plant traits (e.g. stiff versus flexible stems), it remains unclear how 1) opposing morphological plant traits affect establishment in contrasting environments, and 2) whether trait plasticity influences establishment success. Here, we investigate this by transplanting two tidal species with opposing growing strategies – <jats:italic>Spartina anglica</jats:italic> forms tussocks of stiff stems while <jats:italic>Zostera noltii</jats:italic> forms patches of stress‐avoiding flexible shoots – from two different donor sites in eight experimental locations. Results show that the survival and growth of both species was most successful at field locations with diverging environmental characteristics, while overall survival was highest for <jats:italic>Z. noltii</jats:italic>. Mainly, <jats:italic>S. anglica</jats:italic> survival was highest at locations with high organic matter and silt content and higher elevation relative to the tidal amplitude. In contrast, <jats:italic>Z. noltii</jats:italic> survival was highest at locations with larger grainsize and lower relative elevations. Furthermore, despite initial differences in plant traits between the two donor sites of <jats:italic>Z. noltii</jats:italic>, we found no effects of donor origin. Contrastingly, we found a significant effect of donor origin on <jats:italic>S. anglica</jats:italic> growth, even though transplants from the two donor sites showed no initial trait differences. Collectively, these results suggest that the stress‐tolerance strategy of <jats:italic>S. anglica</jats:italic> hampers establishment in exposed conditions, whereas the stress‐avoiding <jats:italic>Z. noltii</jats:italic> appears to be more susceptible to stress from desiccation and silty sediments.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"36 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140625218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Miguel Verdú, Esther Bochet, Tíscar Espigares, Jordi Margalef‐Marrasé, José Manuel Nicolau, Yu Yue, César Azorin‐Molina, Patricio Garcia‐Fayos
Facilitation is an ecological interaction that has allowed plant lineages to survive past climate aridification. This same interaction can be expected to buffer the effects of current climate change, which is tending to become more arid in the Mediterranean basin. However, facilitation may wane when stress conditions are extreme. Here we argue that the erosion of the facilitation signal between Quercus ilex and its nurses detected by García‐Fayos et al. (2020) along 50 years in the eastern Iberian Peninsula may have been due to the reversion of facilitation to competition imposed by an increasingly arid climate. To support this speculation, we reconstructed the climatic niche of Q. ilex and its nurses as well as the local climate change occurring in the populations studied. We found that the decreasing trend in precipitation is pushing Q. ilex out of its climatic optimum in the stressful (semi‐arid) but not in the mild (sub‐humid) habitats. These results suggest that facilitation will be unable to mitigate the effects of climate change, especially those related to aridification. However, other scenarios linking climatic change with herbivory and rural abandonment should be considered to fully understand the past, present and future of facilitation interactions. Reconstructing past interactions can serve as an early warning signal about the future of populations in the face of climate change.
{"title":"Climate change may alter the signal of plant facilitation in Mediterranean drylands","authors":"Miguel Verdú, Esther Bochet, Tíscar Espigares, Jordi Margalef‐Marrasé, José Manuel Nicolau, Yu Yue, César Azorin‐Molina, Patricio Garcia‐Fayos","doi":"10.1111/oik.10217","DOIUrl":"https://doi.org/10.1111/oik.10217","url":null,"abstract":"Facilitation is an ecological interaction that has allowed plant lineages to survive past climate aridification. This same interaction can be expected to buffer the effects of current climate change, which is tending to become more arid in the Mediterranean basin. However, facilitation may wane when stress conditions are extreme. Here we argue that the erosion of the facilitation signal between <jats:italic>Quercus ilex</jats:italic> and its nurses detected by García‐Fayos et al. (2020) along 50 years in the eastern Iberian Peninsula may have been due to the reversion of facilitation to competition imposed by an increasingly arid climate. To support this speculation, we reconstructed the climatic niche of <jats:italic>Q. ilex</jats:italic> and its nurses as well as the local climate change occurring in the populations studied. We found that the decreasing trend in precipitation is pushing <jats:italic>Q. ilex</jats:italic> out of its climatic optimum in the stressful (semi‐arid) but not in the mild (sub‐humid) habitats. These results suggest that facilitation will be unable to mitigate the effects of climate change, especially those related to aridification. However, other scenarios linking climatic change with herbivory and rural abandonment should be considered to fully understand the past, present and future of facilitation interactions. Reconstructing past interactions can serve as an early warning signal about the future of populations in the face of climate change.","PeriodicalId":19496,"journal":{"name":"Oikos","volume":"52 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140625495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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