Abstract. The most prolific acacias in southern Europe (Acacia dealbata, A. melanoxylon and A. longifolia) are rapidly spreading in its westernmost area: Portugal and NW Spain, where congeners with invasion potential are already established. We performed a bibliographic search of acacia invasions in southern Europe and used spatial data on acacia distribution and abiotic parameters in Iberia to check the influence of abiotic factors on acacia invasion. According to our results, in Iberia A. dealbata and A. melanoxylon seem limited by high soil pH (pH CaCl 2 > 5.5 ), frequent frosts ( >21 to 40 d yr −1 ) and low annual precipitation ( to 1000 mm); data were inconclusive for A. longifolia, while A. saligna prefers neutral soils in the driest and warmest areas. The percentage of area occupied by A. dealbata and A. melanoxylon increases significantly with the percentage of burnt surface. In the literature, acacias' invasiveness is usually attributed to their high resprouting and seeding capacity and to native exclusion through their allelopathic potential; symbiotic promiscuity with rhizobia; high environmental plasticity; and adaptation to burnt, cleared and resource-poor land. However, it is unknown how acacias became so invasive in western Iberia, where native Fabaceae shrubs with similar ecological traits (and invaders outside their natural range) are abundant. Invasive acacias can modify fire and water regimes, aboveground biodiversity, and topsoil characteristics (microbial communities, pH, organic matter and macronutrients levels); nevertheless, sound comparisons with mature stands of Iberian legumes for these and other soil properties (N fluxes, micronutrients) are lacking. As several acacias outcompete Iberian Fabaceae shrubs partly thanks to enemy release, the introduction of biocontrol agents (as for A. longifolia in Portugal) can be useful for invasion control.
摘要南欧最多产的金合欢(Acacia dealbata, A. melanoxylon和A. longfolia)正在其最西部地区迅速蔓延:葡萄牙和西班牙西北部，那里已经建立了具有入侵潜力的同属植物。我们对欧洲南部的金合欢入侵进行了书目检索，并利用伊比利亚的金合欢分布和非生物参数的空间数据来检验非生物因素对金合欢入侵的影响。根据我们的研究结果，在伊比利亚，A. dealbata和A. melanoxylon似乎受到土壤pH值高(pH cac2 > 5.5)、频繁的霜冻(>21 ~ 40 d yr - 1)和年降水量低(低于1000 mm)的限制;长叶橐吾的数据不确定，而salignapap在最干燥和最温暖地区的中性土壤中。随着烧伤面积的增加，褐刺和黑梭梭所占的面积比例显著增加。在文献中，金合花的入侵性通常归因于其较高的繁殖和播种能力，以及通过其化感作用潜力产生的本地排斥;与根瘤菌的共生乱交;highenvironmental可塑性;适应被烧毁、被砍伐和资源贫乏的土地。然而，目前尚不清楚金合欢是如何在西尼伯利亚如此具有侵略性的，那里有大量具有相似生态特征的本地豆科灌木(以及在其自然范围之外的入侵者)。入侵的金合欢可以改变水火状况、地上生物多样性和表层土壤特征(微生物群落、pH值、有机质和宏量营养素水平);然而，缺乏与成熟的伊比利亚豆科植物在这些和其他土壤特性(氮通量、微量营养素)方面的合理比较。由于一些金合欢在一定程度上由于敌人的释放而胜过伊比利亚豆科灌木，因此引入生物防治剂(如葡萄牙的长叶金合欢)可用于入侵控制。
{"title":"Invasiveness, ecological impacts and control of acacias in southwestern Europe – a review","authors":"C. Vieites-Blanco, S. González-Prieto","doi":"10.5194/we-20-33-2020","DOIUrl":"https://doi.org/10.5194/we-20-33-2020","url":null,"abstract":"Abstract. The most prolific acacias in southern Europe (Acacia dealbata, A. melanoxylon and A. longifolia) are rapidly\u0000spreading in its westernmost area: Portugal and NW Spain, where congeners\u0000with invasion potential are already established. We performed a\u0000bibliographic search of acacia invasions in southern Europe and used spatial\u0000data on acacia distribution and abiotic parameters in Iberia to check the\u0000influence of abiotic factors on acacia invasion. According to our results,\u0000in Iberia A. dealbata and A. melanoxylon seem limited by high soil pH (pH CaCl 2 > 5.5 ),\u0000frequent frosts ( >21 to 40 d yr −1 ) and low annual\u0000precipitation ( to 1000 mm); data were inconclusive for A. longifolia, while A. saligna\u0000prefers neutral soils in the driest and warmest areas. The percentage of\u0000area occupied by A. dealbata and A. melanoxylon increases significantly with the percentage of burnt\u0000surface. In the literature, acacias' invasiveness is usually attributed to\u0000their high resprouting and seeding capacity and to native exclusion through\u0000their allelopathic potential; symbiotic promiscuity with rhizobia; high\u0000environmental plasticity; and adaptation to burnt, cleared and resource-poor\u0000land. However, it is unknown how acacias became so invasive in western\u0000Iberia, where native Fabaceae shrubs with similar ecological traits (and\u0000invaders outside their natural range) are abundant. Invasive acacias can\u0000modify fire and water regimes, aboveground biodiversity, and topsoil\u0000characteristics (microbial communities, pH, organic matter and\u0000macronutrients levels); nevertheless, sound comparisons with mature stands\u0000of Iberian legumes for these and other soil properties (N fluxes,\u0000micronutrients) are lacking. As several acacias outcompete Iberian Fabaceae shrubs\u0000partly thanks to enemy release, the introduction of biocontrol agents (as\u0000for A. longifolia in Portugal) can be useful for invasion control.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2020-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85788387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
H. Fatmi, S. Maalem, Bouchra Harsa, A. Dekak, Haroun Chenchouni
Abstract. The study of the morphology of living organisms is essential to understand their evolution and diversity. This study aims to determine the importance of climatic gradients in the diversity of pollen morphotypes using Atriplex halimus L. (Amaranthaceae) as a model species. Atriplex halimus is a perennial shrubby plant, polymorphic and very resistant to severe environmental conditions. In seven bioclimatic zones, ranging from mesic conditions in the north to hot–hyperarid in the south, pollen samples were collected from 49 sites, with seven accessions per bioclimate. Under a light microscope, pollen grains were selected and analyzed from three anthers of different flowers. Besides the usual pollen grain types, some previously unknown morphotypes, such as sulcate, triangular, and ovoid, were observed and described at the different climatic zones. A total of 10 pollen grain shapes were quantified and discussed following their specific occurrences within different climatic zones. Occurrence frequencies of different pollen shapes ranged between 0 % and 85.7 %, where the pantoporate spheroidal was the most widespread in all climatic zones, especially in the desert climate (85.7 %). Five pollen types occurred exclusively once per climate zone. The pantoporate prolate spheroidal in mesomediterranean climate with a long dry season (28.6 %), sulcate in the xerothermomediterranean climate (14.3%), pantoporate subtriangular in the subdesert climate with a short dry season (14.3 %), and pantoporate subprolate and boat-shaped in a subdesert climate with a long dry season with 14.3 % for each. Our findings help to understand the evolutionary effects of climate gradients on pollen morphology and variability in arid and desert areas and point towards a high degree of specialization in order to maximize trade-offs between pollination efficiency and protection of pollen grains from dehydration.
{"title":"Pollen morphological variability correlates with a large-scale gradient of aridity","authors":"H. Fatmi, S. Maalem, Bouchra Harsa, A. Dekak, Haroun Chenchouni","doi":"10.5194/we-20-19-2020","DOIUrl":"https://doi.org/10.5194/we-20-19-2020","url":null,"abstract":"Abstract. The study of the morphology of living organisms is essential to understand\u0000their evolution and diversity. This study aims to determine the importance\u0000of climatic gradients in the diversity of pollen morphotypes using Atriplex halimus L.\u0000(Amaranthaceae) as a model species. Atriplex halimus is a perennial shrubby plant,\u0000polymorphic and very resistant to severe environmental conditions. In seven\u0000bioclimatic zones, ranging from mesic conditions in the north to\u0000hot–hyperarid in the south, pollen samples were collected from 49 sites,\u0000with seven accessions per bioclimate. Under a light microscope, pollen grains\u0000were selected and analyzed from three anthers of different flowers. Besides\u0000the usual pollen grain types, some previously unknown morphotypes, such as\u0000sulcate, triangular, and ovoid, were observed and described at the different\u0000climatic zones. A total of 10 pollen grain shapes were quantified and\u0000discussed following their specific occurrences within different climatic\u0000zones. Occurrence frequencies of different pollen shapes ranged between 0 %\u0000and 85.7 %, where the pantoporate spheroidal was the most widespread in\u0000all climatic zones, especially in the desert climate (85.7 %). Five\u0000pollen types occurred exclusively once per climate zone. The pantoporate\u0000prolate spheroidal in mesomediterranean climate with a long dry season\u0000(28.6 %), sulcate in the xerothermomediterranean climate (14.3%),\u0000pantoporate subtriangular in the subdesert climate with a short dry season\u0000(14.3 %), and pantoporate subprolate and boat-shaped in a subdesert\u0000climate with a long dry season with 14.3 % for each. Our findings help to\u0000understand the evolutionary effects of climate gradients on pollen\u0000morphology and variability in arid and desert areas and point towards a\u0000high degree of specialization in order to maximize trade-offs between\u0000pollination efficiency and protection of pollen grains from dehydration.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2020-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85439592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Abstract. In an era of environmental crises, conservation and management strategies need a new generation of applied ecologists. Here, we stimulate the next-generation applied ecologists to acquire a pragmatic mentality of problems solvers in real contexts, using the wide arsenal of concepts, approaches and techniques available in the project management (PM) arena using a road map based on the main steps of conservation project cycle. The acquisition of the conceptual and operational framework of PM can allow the next-generation applied ecologists to take on a more important role in nature conservation strategies: from data samplers, analyzers and interpreters to suppliers of solutions and decisions driving changes in species' targets inhabiting real contexts. Since the high number of applied ecologists, this change in approach (from analytical to operational) could make the difference in conservation science. We also provided, as a conceptual framework, a set of suggestions and approaches useful to facilitate this change.
{"title":"Toward a new generation of effective problem solvers and project-oriented applied ecologists","authors":"C. Battisti, G. Amori, L. Luiselli","doi":"10.5194/we-20-11-2020","DOIUrl":"https://doi.org/10.5194/we-20-11-2020","url":null,"abstract":"Abstract. In an era of environmental crises, conservation and management strategies\u0000need a new generation of applied ecologists. Here, we stimulate the\u0000next-generation applied ecologists to acquire a pragmatic mentality of\u0000problems solvers in real contexts, using the wide arsenal of concepts,\u0000approaches and techniques available in the project management (PM) arena using a\u0000road map based on the main steps of conservation project cycle. The\u0000acquisition of the conceptual and operational framework of PM can allow the\u0000next-generation applied ecologists to take on a more important role in\u0000nature conservation strategies: from data samplers, analyzers and\u0000interpreters to suppliers of solutions and decisions driving changes in\u0000species' targets inhabiting real contexts. Since the high number of applied\u0000ecologists, this change in approach (from analytical to operational) could\u0000make the difference in conservation science. We also provided, as a\u0000conceptual framework, a set of suggestions and approaches useful to\u0000facilitate this change.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2020-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81726460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Abstract. All organisms are ultimately dependent on a large diversity of consumptive and non-consumptive interactions established with other organisms, forming an intricate web of interdependencies. In 1992, when 1700 concerned scientists issued the first “World Scientists' Warning to Humanity”, our understanding of such interaction networks was still in its infancy. By simultaneously considering the species (nodes) and the links that glue them together into functional communities, the study of modern food webs – or more generally ecological networks – has brought us closer to a predictive community ecology. Scientists have now observed, manipulated, and modelled the assembly and the collapse of food webs under various global change stressors and identified common patterns. Most stressors, such as increasing temperature, biological invasions, biodiversity loss, habitat fragmentation, over-exploitation, have been shown to simplify food webs by concentrating energy flow along fewer pathways, threatening long-term community persistence. More worryingly, it has been shown that communities can abruptly change from highly diverse to simplified stable states with little or no warning. Altogether, evidence shows that apart from the challenge of tackling climate change and hampering the extinction of threatened species, we need urgent action to tackle large-scale biological change and specifically to protect food webs, as we are under the risk of pushing entire ecosystems outside their safe zones. At the same time, we need to gain a better understanding of the global-scale synergies and trade-offs between climate change and biological change. Here we highlight the most pressing challenges for the conservation of natural food webs and recent advances that might help us addressing such challenges.
{"title":"Scientists' warning on endangered food webs","authors":"R. Heleno, W. Ripple, A. Traveset","doi":"10.5194/we-20-1-2020","DOIUrl":"https://doi.org/10.5194/we-20-1-2020","url":null,"abstract":"Abstract. All organisms are ultimately dependent on a large diversity of consumptive\u0000and non-consumptive interactions established with other organisms, forming\u0000an intricate web of interdependencies. In 1992, when 1700 concerned\u0000scientists issued the first “World Scientists' Warning to Humanity”, our\u0000understanding of such interaction networks was still in its infancy. By\u0000simultaneously considering the species (nodes) and the links that glue them\u0000together into functional communities, the study of modern food webs – or\u0000more generally ecological networks – has brought us closer to a predictive\u0000community ecology. Scientists have now observed, manipulated, and modelled\u0000the assembly and the collapse of food webs under various global change\u0000stressors and identified common patterns. Most stressors, such as increasing\u0000temperature, biological invasions, biodiversity loss, habitat fragmentation,\u0000over-exploitation, have been shown to simplify food webs by\u0000concentrating energy flow along fewer pathways, threatening long-term\u0000community persistence. More worryingly, it has been shown that communities\u0000can abruptly change from highly diverse to simplified stable states with\u0000little or no warning. Altogether, evidence shows that apart from the\u0000challenge of tackling climate change and hampering the extinction of\u0000threatened species, we need urgent action to tackle large-scale biological\u0000change and specifically to protect food webs, as we are under the risk of pushing\u0000entire ecosystems outside their safe zones. At the same time, we need to\u0000gain a better understanding of the global-scale synergies and trade-offs\u0000between climate change and biological change. Here we highlight the most\u0000pressing challenges for the conservation of natural food webs and recent\u0000advances that might help us addressing such challenges.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2020-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82188272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
I. Jernej, A. Bohner, R. Walcher, R. Hussain, A. Arnberger, J. Zaller, T. Frank
Abstract. Traditionally managed mountain grasslands are biodiversity hotspots in central Europe. However, socio-economic trends in agriculture during the last decades have changed farming practices, leaving steep and remote sites abandoned. Especially the abandonment of meadows is well known to directly affect plant and insect diversity. However, not much is known about the effects on soil processes and soil biota. To assess this, we studied four extensively managed (mown once a year, no fertilization) and four abandoned (no mowing, no fertilization) semi-dry meadows in a mountain region in Austria. Plant species richness, plant cover, plant traits, plant biomass, litter decomposition (tea bag index), and earthworm species richness and density were assessed. Additionally, soil temperature, moisture and electrical conductivity were measured. Results showed that managed meadows contained more plant species than abandoned meadows (118 vs. 93 species, respectively). We also observed different plant species assemblages between the two management types. In managed meadows, hemirosette and ruderal plant species were more abundant, while more plant species without rosettes and a higher plant necromass were found in abandoned meadows. Additionally, decomposition rate was higher in abandoned meadows. There was a trend towards higher earthworm densities in managed meadows, but there was no difference in earthworm species richness. We conclude that meadow management has effects on both aboveground vegetation and belowground biota and processes. Both abandoned and extensively managed meadows were important to sustain overall biodiversity and ecosystem functioning in the study region.
{"title":"Impact of land-use change in mountain semi-dry meadows on plants, litter decomposition and earthworms","authors":"I. Jernej, A. Bohner, R. Walcher, R. Hussain, A. Arnberger, J. Zaller, T. Frank","doi":"10.5194/we-19-53-2019","DOIUrl":"https://doi.org/10.5194/we-19-53-2019","url":null,"abstract":"Abstract. Traditionally managed mountain grasslands are biodiversity hotspots in central Europe. However, socio-economic trends in agriculture during the last decades have changed farming practices, leaving steep and remote sites abandoned. Especially the abandonment of meadows is well known to directly affect plant and insect diversity. However, not much is known about the effects on soil processes and soil biota. To assess this, we studied four extensively managed (mown once a year, no fertilization) and four abandoned (no mowing, no fertilization) semi-dry meadows in a mountain region in Austria. Plant species richness, plant cover, plant traits, plant biomass, litter decomposition (tea bag index), and earthworm species richness and density were assessed. Additionally, soil temperature, moisture and electrical conductivity were measured. Results showed that managed meadows contained more plant species than abandoned meadows (118 vs. 93 species, respectively). We also observed different plant species assemblages between the two management types. In managed meadows, hemirosette and ruderal plant species were more abundant, while more plant species without rosettes and a higher plant necromass were found in abandoned meadows. Additionally, decomposition rate was higher in abandoned meadows. There was a trend towards higher earthworm densities in managed meadows, but there was no difference in earthworm species richness. We conclude that meadow management has effects on both aboveground vegetation and belowground biota and processes. Both abandoned and extensively managed meadows were important to sustain overall biodiversity and ecosystem functioning in the study region.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2019-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79309793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
L. Concostrina‐Zubiri, J. M. Arenas, I. Martínez, A. Escudero
Abstract. Understanding patterns of habitat natural recovery after human-made disturbances is critical for the conservation of ecosystems under high environmental stress, such as drylands. In particular, the unassisted establishment of nonvascular plants such as biological soil crusts or biocrust communities (e.g., soil lichens, mosses and cyanobacteria) in newly formed habitats is not yet fully understood. However, the potential of biocrusts to improve soil structure and function at the early stages of succession and promote ecosystem recovery is enormous. In this study, we evaluated the capacity of lichen biocrusts to spontaneously establish and develop on road slopes in a Mediterranean shrubland. We also compared taxonomic and functional diversity of biocrusts between road slopes and natural habitats in the surroundings. Biocrust richness and cover, species composition, and functional structure were measured in 17 road slopes (nine roadcuts and eight embankments) along a 13 km highway stretch. Topography, soil properties and vascular plant communities of road slopes were also characterized. We used Kruskal–Wallis tests and applied redundancy analysis (RDA) to test the effect of environmental scenario (road slopes vs. natural habitat) and other local factors on biocrust features. We found that biocrusts were common in road slopes after ∼20 years of construction with no human assistance needed. However, species richness and cover were still lower than in natural remnants. Also, functional structure was quite similar between roadcuts (i.e., after soil excavation) and natural remnants, and topography and soil properties influenced species composition while environmental scenario type and vascular plant cover did not. These findings further support the idea of biocrusts as promising restoration tools in drylands and confirm the critical role of edaphic factors in biocrust establishment and development in land-use change scenarios.
{"title":"Unassisted establishment of biological soil crusts on dryland road slopes","authors":"L. Concostrina‐Zubiri, J. M. Arenas, I. Martínez, A. Escudero","doi":"10.5194/WE-19-39-2019","DOIUrl":"https://doi.org/10.5194/WE-19-39-2019","url":null,"abstract":"Abstract. Understanding patterns of habitat natural recovery after\u0000human-made disturbances is critical for the conservation of ecosystems under\u0000high environmental stress, such as drylands. In particular, the unassisted\u0000establishment of nonvascular plants such as biological soil crusts or\u0000biocrust communities (e.g., soil lichens, mosses and cyanobacteria) in newly\u0000formed habitats is not yet fully understood. However, the potential of\u0000biocrusts to improve soil structure and function at the early stages of\u0000succession and promote ecosystem recovery is enormous. In this study, we\u0000evaluated the capacity of lichen biocrusts to spontaneously establish and\u0000develop on road slopes in a Mediterranean shrubland. We also compared\u0000taxonomic and functional diversity of biocrusts between road slopes and\u0000natural habitats in the surroundings. Biocrust richness and cover, species\u0000composition, and functional structure were measured in 17 road slopes (nine\u0000roadcuts and eight embankments) along a 13 km highway stretch. Topography, soil\u0000properties and vascular plant communities of road slopes were also\u0000characterized. We used Kruskal–Wallis tests and applied redundancy analysis\u0000(RDA) to test the effect of environmental scenario (road slopes vs. natural\u0000habitat) and other local factors on biocrust features. We found that\u0000biocrusts were common in road slopes after ∼20 years of\u0000construction with no human assistance needed. However, species richness and\u0000cover were still lower than in natural remnants. Also, functional structure\u0000was quite similar between roadcuts (i.e., after soil excavation) and natural\u0000remnants, and topography and soil properties influenced species composition\u0000while environmental scenario type and vascular plant cover did not. These\u0000findings further support the idea of biocrusts as promising restoration\u0000tools in drylands and confirm the critical role of edaphic factors in\u0000biocrust establishment and development in land-use change scenarios.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2019-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89659078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Clara Pissolito, Irene A. Garibotti, S. Varela, Verónica Arana, M. González-Polo, P. Marchelli, O. Bruzzone
Abstract. In the quest to understand how biotic interactions respond to climate change, one area that remains poorly explored is how interactions involving organisms other than vascular plants will respond. However the interactions between plants and biological soil crusts (BSCs) are relevant in many ecosystems and they will likely respond uniquely to climate change. Simultaneous considerations of both plant–plant and plant–BSC interactions may substantially improve our understanding of this topic. The aim of this study is to assess whether water availability differentially affects the biotic effects of BSCs and pioneer shrubs on the early life-history stage of tree seedling growth. We conducted a greenhouse factorial experiment with soil surface cover (bare soil, soil covered by a creeping shrub and BSC covered soil) and water regime (control and drought) as factors. We monitored Nothofagus pumilio (a native tree species of ecological and economic relevance) seedling water status and growth as well as changes in soil water content and soil properties. The shrub cover had a positive effect on soil water conservation and on the water balance of seedlings under water stress. However, its effect was negative for seedling growth under both water conditions. The BSC also contributed to soil water conservation and apparently added nutrients to the soil. The net effect of the BSC on seedling growth was negative under full-watering conditions but positive under water stress conditions. This result highlights how the studied biotic interactions, and especially interactions involving BSCs, depend on changes in water availability.
{"title":"Water-mediated changes in plant–plant and biological soil crust–plant interactions in a temperate forest ecosystem","authors":"Clara Pissolito, Irene A. Garibotti, S. Varela, Verónica Arana, M. González-Polo, P. Marchelli, O. Bruzzone","doi":"10.5194/WE-19-27-2019","DOIUrl":"https://doi.org/10.5194/WE-19-27-2019","url":null,"abstract":"Abstract. In the quest to understand how biotic interactions respond to climate change, one area that remains poorly explored is how interactions involving organisms other than vascular plants will respond. However the interactions between plants and biological soil crusts (BSCs) are relevant in many ecosystems and they will likely respond uniquely to climate change. Simultaneous considerations of both plant–plant and plant–BSC interactions may substantially improve our understanding of this topic. The aim of this study is to assess whether water availability differentially affects the biotic effects of BSCs and pioneer shrubs on the early life-history stage of tree seedling growth. We conducted a greenhouse factorial experiment with soil surface cover (bare soil, soil covered by a creeping shrub and BSC covered soil) and water regime (control and drought) as factors. We monitored Nothofagus pumilio (a native tree species of ecological and economic relevance) seedling water status and growth as well as changes in soil water content and soil properties. The shrub cover had a positive effect on soil water conservation and on the water balance of seedlings under water stress. However, its effect was negative for seedling growth under both water conditions. The BSC also contributed to soil water conservation and apparently added nutrients to the soil. The net effect of the BSC on seedling growth was negative under full-watering conditions but positive under water stress conditions. This result highlights how the studied biotic interactions, and especially interactions involving BSCs, depend on changes in water availability.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2019-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84994323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Abstract. Biological control of pests aims at lowering population levels of pest species by favouring natural enemies, in order to reduce the use of pesticides. The movement behaviour of natural enemies is decisive in the success of biological control: when low habitat quality hinders the diffusion of natural enemies from the border, the density of natural enemies may frequently be heterogeneous inside agricultural plots. We hypothesise that the specific relationship between habitat quality and movement behaviour may allow the improvement of biological control by means of a careful allocation of habitat qualities inside and around the plot. We used three tested individual-based movement models, with different levels of complexity ranging from simple cell-to-cell movements to complex strategies including the sinuosity of the path, boundary crossings, perceptual range, and directional persistence. We used the models to explore how the manipulation of habitat quality may allow significant improvements to the residence time of natural enemies inside the field. We suggest that existing field designs are generally inadequate to retain natural enemies. Mechanistic explanations leading to the highest and lowest residence times are used to draw specific management recommendations.
{"title":"Keep your enemies closer: enhancing biological control through individual movement rules to retain natural enemies inside the field","authors":"T. Delattre, B. Collard, C. Lavigne","doi":"10.5194/WE-19-15-2019","DOIUrl":"https://doi.org/10.5194/WE-19-15-2019","url":null,"abstract":"Abstract. Biological control of pests aims at lowering population levels of pest\u0000species by favouring natural enemies, in order to reduce the use of\u0000pesticides. The movement behaviour of natural enemies is decisive in the\u0000success of biological control: when low habitat quality hinders the diffusion\u0000of natural enemies from the border, the density of natural enemies may\u0000frequently be heterogeneous inside agricultural plots. We hypothesise that the specific relationship between habitat quality and\u0000movement behaviour may allow the improvement of biological control by means\u0000of a careful allocation of habitat qualities inside and around the plot. We used three tested individual-based movement models, with different levels\u0000of complexity ranging from simple cell-to-cell movements to complex\u0000strategies including the sinuosity of the path, boundary crossings,\u0000perceptual range, and directional persistence. We used the models to explore\u0000how the manipulation of habitat quality may allow significant improvements\u0000to the residence time of natural enemies inside the field. We suggest that\u0000existing field designs are generally inadequate to retain natural enemies.\u0000Mechanistic explanations leading to the highest and lowest residence times\u0000are used to draw specific management recommendations.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2019-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88144271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Milad Shokri, Mario Ciotti, F. Vignes, V. Gjoni, A. Basset
Abstract. Standard metabolic rate is a major functional trait with large inter-individual variability in many groups of aquatic species. Here we present results of an experimental study to address variation in standard metabolic rates, over different scales of organisation and environments, within a specific group of aquatic macro-invertebrates (i.e. gammarid amphipods) that represent the primary consumers in detritus food webs. The study was carried out using flow-through microrespirometric techniques on male specimens of three gammarid species from freshwater, transitional water and marine ecosystems. We examined individual metabolic rate variations at three scales: (1) at the individual level, during an 8 h period of daylight; (2) at the within-population level, along body-size and body-condition gradients; (3) at the interspecific level, across species occurring in the field in the three different categories of aquatic ecosystems, from freshwater to marine. We show that standard metabolic rates vary significantly at all three scales examined, with the highest variation observed at the within-population level. Variation in individual standard metabolic rates during the daylight hours was generally low (coefficient of variation, CV<10 %) and unrelated to time. The average within-population CV ranged between 30.0 % and 35.0 %, with body size representing a significant source of overall inter-individual variation in the three species and individual body condition exerting only a marginal influence. In all species, the allometric equations were not as steep as would be expected from the 3∕4 power law, with significant variation in mass-specific metabolic rates among populations. The population from the transitional water ecosystem had the highest mass-specific metabolic rates and the lowest within-population variation. In the gammarid species studied here, body-size-independent variations in standard individual metabolic rates were higher than those explained by allometric body size scaling, and the costs of adaptation to short-term periodic variations in water salinity in the studied ecosystems also seemed to represent a major source of variation.
{"title":"Components of standard metabolic rate variability in three species of gammarids","authors":"Milad Shokri, Mario Ciotti, F. Vignes, V. Gjoni, A. Basset","doi":"10.5194/WE-19-1-2019","DOIUrl":"https://doi.org/10.5194/WE-19-1-2019","url":null,"abstract":"Abstract. Standard metabolic rate is\u0000a major functional trait with large inter-individual variability in many\u0000groups of aquatic species. Here we present results of an experimental study\u0000to address variation in standard metabolic rates, over different scales of\u0000organisation and environments, within a specific group of aquatic\u0000macro-invertebrates (i.e. gammarid amphipods) that represent the primary\u0000consumers in detritus food webs. The study was carried out using flow-through\u0000microrespirometric techniques on male specimens of three gammarid species\u0000from freshwater, transitional water and marine ecosystems. We examined\u0000individual metabolic rate variations at three scales: (1) at the individual\u0000level, during an 8 h period of daylight; (2) at the within-population level,\u0000along body-size and body-condition gradients; (3) at the interspecific level,\u0000across species occurring in the field in the three different categories of\u0000aquatic ecosystems, from freshwater to marine. We show that standard metabolic rates vary significantly at all three scales\u0000examined, with the highest variation observed at the within-population level.\u0000Variation in individual standard metabolic rates during the daylight hours\u0000was generally low (coefficient of variation, CV<10 %) and\u0000unrelated to time. The average within-population CV ranged between 30.0 %\u0000and 35.0 %, with body size representing a significant source of overall\u0000inter-individual variation in the three species and individual body condition\u0000exerting only a marginal influence. In all species, the allometric equations\u0000were not as steep as would be expected from the 3∕4 power law, with\u0000significant variation in mass-specific metabolic rates among populations. The\u0000population from the transitional water ecosystem had the highest\u0000mass-specific metabolic rates and the lowest within-population variation. In the gammarid species studied here, body-size-independent variations in\u0000standard individual metabolic rates were higher than those explained by\u0000allometric body size scaling, and the costs of adaptation to short-term\u0000periodic variations in water salinity in the studied ecosystems also seemed\u0000to represent a major source of variation.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2019-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79117341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Abstract. The detection of community or population structure through analysis of explicit cause–effect modeling of given observations has received considerable attention. The complexity of the task is mirrored by the large number of existing approaches and methods, the applicability of which heavily depends on the design of efficient algorithms of data analysis. It is occasionally even difficult to disentangle concepts and algorithms. To add more clarity to this situation, the present paper focuses on elaborating the system analytic framework that probably encompasses most of the common concepts and approaches by classifying them as model-based analyses of latent factors. Problems concerning the efficiency of algorithms are not of primary concern here. In essence, the framework suggests an input–output model system in which the inputs are provided as latent model parameters and the output is specified by the observations. There are two types of model involved, one of which organizes the inputs by assigning combinations of potentially interacting factor levels to each observed object, while the other specifies the mechanisms by which these combinations are processed to yield the observations. It is demonstrated briefly how some of the most popular methods (Structure, BAPS, Geneland) fit into the framework and how they differ conceptually from each other. Attention is drawn to the need to formulate and assess qualification criteria by which the validity of the model can be judged. One probably indispensable criterion concerns the cause–effect character of the model-based approach and suggests that measures of association between assignments of factor levels and observations be considered together with maximization of their likelihoods (or posterior probabilities). In particular the likelihood criterion is difficult to realize with commonly used estimates based on Markov chain Monte Carlo (MCMC) algorithms. Generally applicable MCMC-based alternatives that allow for approximate employment of the primary qualification criterion and the implied model validation including further descriptors of model characteristics are suggested.
{"title":"Model-based analysis of latent factors","authors":"H. Gregorius","doi":"10.5194/WE-18-153-2018","DOIUrl":"https://doi.org/10.5194/WE-18-153-2018","url":null,"abstract":"Abstract. The detection of community or population structure\u0000through analysis of explicit cause–effect modeling of given observations has\u0000received considerable attention. The complexity of the task is mirrored by the\u0000large number of existing approaches and methods, the applicability of which\u0000heavily depends on the design of efficient algorithms of data analysis. It is\u0000occasionally even difficult to disentangle concepts and algorithms. To add\u0000more clarity to this situation, the present paper focuses on elaborating the\u0000system analytic framework that probably encompasses most of the common\u0000concepts and approaches by classifying them as model-based analyses of latent\u0000factors. Problems concerning the efficiency of algorithms are not of primary\u0000concern here. In essence, the framework suggests an input–output model system\u0000in which the inputs are provided as latent model parameters and the output is\u0000specified by the observations. There are two types of model involved, one of\u0000which organizes the inputs by assigning combinations of potentially\u0000interacting factor levels to each observed object, while the other specifies\u0000the mechanisms by which these combinations are processed to yield the\u0000observations. It is demonstrated briefly how some of the most popular methods\u0000(Structure, BAPS, Geneland) fit into the framework and how they differ\u0000conceptually from each other. Attention is drawn to the need to formulate and\u0000assess qualification criteria by which the validity of the model can be\u0000judged. One probably indispensable criterion concerns the cause–effect\u0000character of the model-based approach and suggests that measures of\u0000association between assignments of factor levels and observations be\u0000considered together with maximization of their likelihoods (or posterior\u0000probabilities). In particular the likelihood criterion is difficult to realize\u0000with commonly used estimates based on Markov chain Monte Carlo (MCMC)\u0000algorithms. Generally applicable MCMC-based alternatives that\u0000allow for approximate employment of the primary qualification criterion and\u0000the implied model validation including further descriptors of model\u0000characteristics are suggested.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2018-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76448035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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