Theofilos Dostos, Pantelitsa D. Kapagianni, N. Monokrousos, G. Stamou, E. Papatheodorou
Abstract. Biological soil crust (BSC) is an essential part of arid and semiarid regions; however information concerning the spatial heterogeneity of the interactions between crust, plants and soil microbes is limited. Sampling was confined to an area either covered with Erica spp. shrubs interspaced by crust cover (Cladonia rangiformis) or uncovered by crust. Along a straight line of 100 cm from the base of the shrubs towards their periphery and at successive distances of 20 cm, soil samples were collected once. The biomass, the composition and the network of interactions among the members of the soil microbial communities as well as the activity of soil enzymes involved in the C, N and P cycle were estimated. Crust coverage exerted a significant allelopathic negative effect on soil microbial biomasses due to the leaching of lichen's antimicrobial substances. In contrast, the crust effect on enzyme activity was positive, probably due to the amelioration of soil abiotic conditions. The distance from the base of Erica spp. affected the total microbial and bacterial biomass, with lower values at the base of the shrubs. The composition of microbial communities between the different sampling points exhibited significant dissimilarities. Network analysis revealed that in uncrusted soils the most connected microbial network was at samples collected from a distance of >60 cm (bare soils), while in crusted soils this was at samples collected at the base of shrubs. We concluded that microbial biomass showed limited response to spatial heterogeneity, while the composition and the topology of interactions among the microbial members reflected a heterogeneous soil environment existing on a small spatial scale in Mediterranean areas. The microbial community in bare soil appeared to be the most robust against future disturbances.
{"title":"Spatial heterogeneity of <i>Cladonia rangiformis</i> and <i>Erica</i> spp. induces variable effects on soil microbial communities which are most robust in bare-soil microhabitats","authors":"Theofilos Dostos, Pantelitsa D. Kapagianni, N. Monokrousos, G. Stamou, E. Papatheodorou","doi":"10.5194/we-22-21-2022","DOIUrl":"https://doi.org/10.5194/we-22-21-2022","url":null,"abstract":"Abstract. Biological soil crust (BSC) is an essential part of arid and semiarid regions;\u0000however information concerning the spatial heterogeneity of the interactions\u0000between crust, plants and soil microbes is limited. Sampling was confined to\u0000an area either covered with Erica spp. shrubs interspaced by crust cover\u0000(Cladonia rangiformis) or uncovered by crust. Along a straight line of 100 cm from the\u0000base of the shrubs towards their periphery and at successive distances of 20 cm, soil samples were collected once. The biomass, the composition and the\u0000network of interactions among the members of the soil microbial communities\u0000as well as the activity of soil enzymes involved in the C, N and P cycle were\u0000estimated. Crust coverage exerted a significant allelopathic negative effect\u0000on soil microbial biomasses due to the leaching of lichen's antimicrobial\u0000substances. In contrast, the crust effect on enzyme activity was positive,\u0000probably due to the amelioration of soil abiotic conditions. The distance\u0000from the base of Erica spp. affected the total microbial and bacterial biomass,\u0000with lower values at the base of the shrubs. The composition of microbial\u0000communities between the different sampling points exhibited significant\u0000dissimilarities. Network analysis revealed that in uncrusted soils the most\u0000connected microbial network was at samples collected from a distance\u0000of >60 cm (bare soils), while in crusted soils this was at samples\u0000collected at the base of shrubs. We concluded that microbial biomass showed\u0000limited response to spatial heterogeneity, while the composition and the\u0000topology of interactions among the microbial members reflected a\u0000heterogeneous soil environment existing on a small spatial scale in\u0000Mediterranean areas. The microbial community in bare soil appeared to be the\u0000most robust against future disturbances.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"5 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2022-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81677032","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}
Jhoana P. Romero–Leiton, Alejandro P. Gutiérrez, I. F. Benavides, O. E. Molina, Alejandra Pulgarín
Abstract. In this work, populations of adult and immature honeybees and their honey production are studied through mathematical and statistical modeling approaches. Those models are complementary and are presented in disjunct form. They were used to show different modeling methods for honey bee population dynamics. The statistical approach consisted of a generalized linear model using data from the Department of Agriculture of the United States of America (USDA), which showed that the relationship between the number of colonies and the rate of honey production is not constant in time but decrease over the years. These models showed that when a bee population is subjected to a stress factor (i.e., habitat destruction, Varroa mite, climate variability, season, neonicotinoids, among others), the abundance of individuals decreases over time as well as the honey produced by the colonies. Finally, the mathematical approach consisted of two models: (1) a smooth model, in which conditions of existence and stability of the equilibrium solutions are determined by an ecological threshold value, and (2) a non-smooth model where the mortality rate of bees is included as a function of the number of adult bees in the population.
{"title":"An approach to the modeling of honey bee colonies","authors":"Jhoana P. Romero–Leiton, Alejandro P. Gutiérrez, I. F. Benavides, O. E. Molina, Alejandra Pulgarín","doi":"10.5194/we-22-7-2022","DOIUrl":"https://doi.org/10.5194/we-22-7-2022","url":null,"abstract":"Abstract. In this work, populations of adult and immature honeybees and their honey production are studied through mathematical and statistical modeling approaches. Those models are complementary and are presented in disjunct form. They were used to show different modeling methods for honey bee population dynamics. The statistical approach consisted of a generalized linear model using data from the Department of Agriculture of the United States of America (USDA), which showed that the relationship between the number of colonies and the rate of honey production is not constant in time but decrease over the years. These models showed that when a bee population is subjected to a stress factor (i.e., habitat destruction, Varroa mite, climate variability, season, neonicotinoids, among others), the abundance of individuals decreases over time as well as the honey produced by the colonies. Finally, the mathematical approach consisted of two models: (1) a smooth model, in which conditions of existence and stability of the equilibrium solutions are determined by an ecological threshold value, and (2) a non-smooth model where the mortality rate of bees is included as a function of the number of adult bees in the population.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"2013 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2022-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88069426","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. Neutral landscape models based on fractal algorithms are used widely by landscape ecologists. Perlin noise is a spectral synthesis algorithm that has not been widely adopted by landscape ecologists, even though the hierarchical properties of Perlin noise are particularly relevant to landscape ecology. To encourage the use of Perlin noise, I provide an explanation of the algorithm in the context of neutral landscape models to demonstrate that the hierarchical nature of the algorithm not only allows for a wide range of possible spatial patterns to be produced, but also usefully parallels theories about the hierarchical structure of landscapes.
{"title":"Perlin noise as a hierarchical neutral landscape model","authors":"T. Etherington","doi":"10.5194/we-22-1-2022","DOIUrl":"https://doi.org/10.5194/we-22-1-2022","url":null,"abstract":"Abstract. Neutral landscape models based on fractal algorithms are used widely by landscape ecologists. Perlin noise is a spectral synthesis algorithm that has not been widely adopted by landscape ecologists, even though the hierarchical properties of Perlin noise are particularly relevant to landscape ecology. To encourage the use of Perlin noise, I provide an explanation of the algorithm in the context of neutral landscape models to\u0000demonstrate that the hierarchical nature of the algorithm not only allows for a wide range of possible spatial patterns to be produced, but also\u0000usefully parallels theories about the hierarchical structure of landscapes.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"104 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2022-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72943322","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. Along with habitat transformation, climate change has profound impacts on biodiversity and may alter ecosystem services on which human welfare depends. Many studies of the carbon cycle have focused on lowland tropical forests; however, upland forests have been less explored despite their pivotal role in carbon sequestration. Here, I synthesized the state of knowledge on the allocation of carbon in its different stocks (aboveground, belowground, and soil) as well as in its main fluxes (plant decomposition, respiration, and litterfall) in tropical upland ecosystems of the planet. In November 2020, a systematic review was carried out to identify references published from 2000 to 2020 through a combination of key terms in Google Scholar and Scopus databases, thus analysing bibliographic, geographical, methodological, and carbon cycling information of the global upland tropics (between 23.5∘ N–23.5∘ S). After analysing a total of 1967 references according to inclusion–exclusion criteria, 135 references published in the last 20 years were selected. Most of the studies were conducted in the tropical and subtropical moist broadleaf forest of South America. The main factors studied were elevation and forest type. Forest structure and soil variables were largely associated when studying carbon cycling in these ecosystems. Estimations of carbon stocks comprised three-fourths of the total studies, while the remaining fraction focused on carbon fluxes. Aboveground biomass and carbon in soils were highly investigated, while plant decomposition and respiration were the components that received the least attention. Even though in the last 20 years there was a slight increase in the number of studies on carbon cycle in tropical upland forests, I found bias associated with the biomes and ecoregions studied (especially in the Andes). Elevation was the main factor examined but other essential aspects such as the successional gradient, landscape management, diversity–productivity relationship, faunal and microbial effect, trophic cascades, and Gadgil effect require more attention. The inclusion of different litter species and origins (i.e. roots and stems) and theoretical frameworks including home-field advantage, substrate–matrix interaction, and phenology–substrate match may provide explanatory mechanisms to better understand litter decomposition over these forests. Despite respiration being a paramount link that is closely tied to above- and belowground compartment, this flux constitutes one of the important gaps to fulfil in future research. For a comprehensive understanding of the carbon cycle in upland forests, it is necessary to obtain information on its main fluxes and integrate them into climate change mitigation plans.
{"title":"Carbon cycle in tropical upland ecosystems: a global review","authors":"Dennis Castillo-Figueroa","doi":"10.5194/we-21-109-2021","DOIUrl":"https://doi.org/10.5194/we-21-109-2021","url":null,"abstract":"Abstract. Along with habitat transformation, climate change has profound impacts on biodiversity and may alter ecosystem services on which human welfare depends. Many studies of the carbon cycle have focused on lowland tropical forests; however, upland forests have been less explored despite their pivotal role in carbon sequestration. Here, I synthesized the state of knowledge on the allocation of carbon in its different stocks (aboveground,\u0000belowground, and soil) as well as in its main fluxes (plant decomposition,\u0000respiration, and litterfall) in tropical upland ecosystems of the planet. In November 2020, a systematic review was carried out to identify references published from 2000 to 2020 through a combination of key terms in Google Scholar and Scopus databases, thus analysing bibliographic, geographical, methodological, and carbon cycling information of the global upland tropics (between 23.5∘ N–23.5∘ S). After analysing a total of 1967 references according to inclusion–exclusion criteria, 135 references published in the last 20 years were selected. Most of the studies were conducted in the tropical and subtropical moist broadleaf forest of South America. The main factors studied were elevation and forest type. Forest structure and soil variables were largely associated when studying carbon cycling in these ecosystems. Estimations of carbon stocks comprised three-fourths of the total studies, while the remaining fraction focused on carbon fluxes. Aboveground biomass and carbon in soils were highly investigated, while plant decomposition and respiration were the components that received the least attention. Even though in the last 20 years there was a slight increase in the number of studies on carbon cycle in tropical upland forests, I found bias associated with the biomes and ecoregions studied (especially in the Andes). Elevation was the main factor examined but other essential aspects such as the successional gradient, landscape management, diversity–productivity relationship, faunal and microbial effect, trophic cascades, and Gadgil effect require more attention. The inclusion of different litter species and origins (i.e. roots and stems) and theoretical frameworks including home-field advantage, substrate–matrix interaction, and phenology–substrate match may provide explanatory mechanisms to better understand litter decomposition over these forests. Despite respiration being a paramount link that is closely tied to above- and belowground compartment, this flux constitutes one of the important gaps to fulfil in future research. For a comprehensive understanding of the carbon cycle in upland forests, it is necessary to obtain information on its main fluxes and integrate them into climate change mitigation plans.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"41 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90630759","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}
Gabriella Süle, S. Fóti, L. Körmöczi, Dóra Petrás, L. Kardos, J. Balogh
Abstract. Forest–steppe habitats in central Hungary have contrasting canopy structure with strong influence on the spatiotemporal variability of ecosystem functions. Canopy differences also co-vary with terrain feature effects, hampering the detection of key drivers of carbon cycling in this threatened habitat. We carried out seasonal measurements of ecosystem functions (soil respiration and leaf area index), microclimate and soil variables as well as terrain features along transects for 3 years in poplar groves and the surrounding grasslands. We found that the terrain features and the canopy differences co-varyingly affected the abiotic and biotic factors of this habitat. Topography had an effect on the spatial distribution of soil organic carbon content. Canopy structure had a strong modifying effect through allocation patterns and microclimatic conditions, both affecting soil respiration rates. Due to the vegetation structure difference between the groves and grasslands, spatial functional diversity was observed. We found notably different conditions under the groves with high soil respiration, soil water content and leaf area index; in contrast, on the grasslands (especially in E–SE–S directions from the trees) soil temperature and vapor pressure deficit showed high values. Processes of aridification due to climate change threaten these habitats and may cause reduction in the amount and extent of forest patches and decrease in landscape diversity. Owing to habitat loss, reduction in carbon stock may occur, which in turn has a significant impact on the local and global carbon cycles.
{"title":"Co-varying effects of vegetation structure and terrain attributes are responsible for soil respiration spatial patterns in a sandy forest–steppe transition zone","authors":"Gabriella Süle, S. Fóti, L. Körmöczi, Dóra Petrás, L. Kardos, J. Balogh","doi":"10.5194/we-21-95-2021","DOIUrl":"https://doi.org/10.5194/we-21-95-2021","url":null,"abstract":"Abstract. Forest–steppe habitats in central Hungary have contrasting canopy structure\u0000with strong influence on the spatiotemporal variability of ecosystem\u0000functions. Canopy differences also co-vary with terrain feature effects,\u0000hampering the detection of key drivers of carbon cycling in this threatened\u0000habitat. We carried out seasonal measurements of ecosystem functions (soil\u0000respiration and leaf area index), microclimate and soil variables as well\u0000as terrain features along transects for 3 years in poplar groves and the\u0000surrounding grasslands. We found that the terrain features and the canopy\u0000differences co-varyingly affected the abiotic and biotic factors of this\u0000habitat. Topography had an effect on the spatial distribution of soil\u0000organic carbon content. Canopy structure had a strong modifying effect\u0000through allocation patterns and microclimatic conditions, both affecting\u0000soil respiration rates. Due to the vegetation structure difference between\u0000the groves and grasslands, spatial functional diversity was observed. We\u0000found notably different conditions under the groves with high soil\u0000respiration, soil water content and leaf area index; in contrast, on the\u0000grasslands (especially in E–SE–S directions from the trees) soil temperature\u0000and vapor pressure deficit showed high values. Processes of aridification\u0000due to climate change threaten these habitats and may cause reduction in the\u0000amount and extent of forest patches and decrease in landscape diversity.\u0000Owing to habitat loss, reduction in carbon stock may occur, which in turn\u0000has a significant impact on the local and global carbon cycles.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"42 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84230928","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}
R. Tsiakiris, J. Halley, K. Stara, N. Monokrousos, Chryso Karyou, Nicolaos Kassinis, M. Papadopoulos, S. Xirouchakis
Abstract. Vultures are among the most threatened avian taxa in the world. When vultures aggregate in large numbers to feed, poisoned carcasses can extirpate entire populations at once. In the light of shrinking numbers worldwide, restocking and reintroduction projects, where wild or captive-bred vultures are released back into nature, constitute a crucial management tool, successfully implemented in many countries. However, reestablishment of sustainable vulture populations to their historical ranges remains a serious challenge, especially if the threat of poisoning persists, which is usually the case. In this study, we model the outcome of a restocking project where an initial colony is subject to repeated poisoning events. We use as an example the isolated population of the griffon vulture (Gyps fulvus) in Cyprus. Mathematical considerations and model simulations show that the probability of colony persistence depends on the initial population size and the intensity and frequency of the poisoning incidents. This type of scenario creates an Allee effect that requires a colony to exceed a minimum size in order to survive. Also in this scenario, a sequence of small but frequent poisoning episodes is worse on average than a few large and rare ones of the same cumulative mortality. Future population reinforcement efforts for vultures should focus on the release of adult birds in adequate numbers for the successful establishment of sustainable colonies and should involve a reduction in small but persistent sources of mortality such as the poison baiting of small canids that until now has been neglected by conservation scientists.
{"title":"Models of poisoning effects on vulture populations show that small but frequent episodes have a larger effect than large but rare ones","authors":"R. Tsiakiris, J. Halley, K. Stara, N. Monokrousos, Chryso Karyou, Nicolaos Kassinis, M. Papadopoulos, S. Xirouchakis","doi":"10.5194/we-21-79-2021","DOIUrl":"https://doi.org/10.5194/we-21-79-2021","url":null,"abstract":"Abstract. Vultures are among the most threatened avian taxa in the world. When vultures aggregate in large numbers to feed, poisoned carcasses can extirpate entire populations at once. In the light of shrinking numbers worldwide, restocking and reintroduction projects, where wild or captive-bred vultures are released back into nature, constitute a crucial management tool, successfully implemented in many countries. However, reestablishment of sustainable vulture populations to their historical ranges remains a serious challenge, especially if the threat of poisoning persists, which is usually the case. In this study, we model the outcome of a restocking project where an initial colony is subject to repeated poisoning events. We use as an example the isolated population of the griffon vulture (Gyps fulvus) in Cyprus. Mathematical considerations and model simulations show that the probability of colony persistence depends on the initial population size and the intensity and frequency of the poisoning incidents. This type of scenario creates an Allee effect that requires a colony to exceed a minimum size in order to survive. Also in this scenario, a sequence of small but frequent poisoning episodes is worse on average than a few large and rare ones of the same cumulative mortality. Future population reinforcement efforts for vultures should focus on the release of adult birds in adequate numbers for the successful establishment of sustainable colonies and should involve a reduction in small but persistent sources of mortality such as the poison baiting of small canids that until now has been neglected by conservation scientists.\u0000","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"39 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2021-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85821911","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 induction of biocrusts through inoculation-based techniques has gained increasing scientific attention in the last 2 decades due to its potential to address issues related to soil degradation and desertification. The technology has shown the most rapid advances in the use of biocrust organisms, particularly cyanobacteria and mosses, as inoculants and biocrust initiators. Cyanobacteria and mosses are poikilohydric organisms – i.e., desiccation-tolerant organisms capable of reactivating their metabolism upon rehydration – that can settle on bare soils in abiotically stressing habitats, provided that selected species are used and an appropriate and customized protocol is applied. The success of inoculation of cyanobacteria and mosses depends on the inoculant's physiology, but also on the ability of the practitioner to identify and control, with appropriate technical approaches in each case study, those environmental factors that most influence the inoculant settlement and its ability to develop biocrusts. This review illustrates the current knowledge and results of biocrust induction biotechnologies that use cyanobacteria or mosses as inoculants. At the same time, this review's purpose is to highlight the current technological gaps that hinder an efficient application of the technology in the field.
{"title":"Drought-tolerant cyanobacteria and mosses as biotechnological tools to attain land degradation neutrality","authors":"A. Adessi, R. De Philippis, F. Rossi","doi":"10.5194/WE-21-65-2021","DOIUrl":"https://doi.org/10.5194/WE-21-65-2021","url":null,"abstract":"Abstract. The induction of biocrusts through inoculation-based techniques has gained increasing scientific attention in the last 2 decades due to its potential to address issues related to soil degradation and desertification. The technology has shown the most rapid advances in the use of biocrust organisms, particularly cyanobacteria and mosses, as inoculants and biocrust initiators. Cyanobacteria and mosses are\u0000poikilohydric organisms – i.e., desiccation-tolerant organisms capable of\u0000reactivating their metabolism upon rehydration – that can settle on bare soils in abiotically stressing habitats, provided that selected species are used and an appropriate and customized protocol is applied. The success of inoculation of cyanobacteria and mosses depends on the inoculant's physiology, but also on the ability of the practitioner to\u0000identify and control, with appropriate technical approaches in each case\u0000study, those environmental factors that most influence the inoculant\u0000settlement and its ability to develop biocrusts. This review illustrates the current knowledge and results of biocrust\u0000induction biotechnologies that use cyanobacteria or mosses as inoculants. At the same time, this review's purpose is to highlight the current\u0000technological gaps that hinder an efficient application of the technology in the field.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"267 1","pages":"65-78"},"PeriodicalIF":2.2,"publicationDate":"2021-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82793743","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}
R. V. Gonçalves, J. C. Cardoso, P. Oliveira, D. Oliveira
Abstract. Changes in the vegetation of Brazilian Cerrado may occur over time. However, long-term dynamics are not fully understood yet, especially woody plant encroachment (WPE). The objective of this study was to examine changes in vegetation structure in a preserved area in Triângulo Mineiro region, within the southern Brazilian Cerrado domain, over 32 years (1987, 2005, and 2019). We based the study on field and literature surveys, as well as satellite imagery, and hypothesized that, due to the absence of periodic fires or grazing, Cerrado open formations (i.e., grassland or savanna) tend to become denser due to WPE. Shrubby grassland cover assessed in 1987 disappeared in the following periods (from 30.0 % to 0.0 % in 2019) while forest formations increased (from 7.0 % in 1987 to 11.0 % in 2019). Changes between 2005 and 2019 occurred within the stricto sensu cerrado subdivisions, with reduction of sparse cerrado (from 34.2 % to 7.7 %) and an increase in dense cerrado (from 6.9 % to 39.8 %). Normalized difference vegetation index (NDVI) applied for similar periods indicates a progressive increase of values over time (from 1986 ( 0.61±0.10 ) to 2004 ( 0.65±0.06 ) and 2018 ( 0.78±0.05 )) and corroborates the WPE process. These patterns imply the loss of biodiversity in open plant formation. Another major consequence was the reduction of wetlands and possible impact on water supply. Such patterns are important to support plant management plans for the threatened Cerrado open plant formations.
{"title":"Changes in the Cerrado vegetation structure: insights from more than three decades of ecological succession","authors":"R. V. Gonçalves, J. C. Cardoso, P. Oliveira, D. Oliveira","doi":"10.5194/WE-21-55-2021","DOIUrl":"https://doi.org/10.5194/WE-21-55-2021","url":null,"abstract":"Abstract. Changes in the vegetation of Brazilian Cerrado may occur over time. However, long-term dynamics are not fully understood yet, especially woody plant encroachment (WPE). The objective of this study was to examine changes in vegetation structure in a preserved area in Triângulo Mineiro region, within the southern Brazilian Cerrado domain, over 32 years (1987, 2005, and 2019). We based the study on field and literature surveys, as well as satellite imagery, and hypothesized that, due to the absence of periodic fires or grazing, Cerrado open formations (i.e., grassland or savanna) tend to become denser due to WPE. Shrubby grassland cover assessed in 1987 disappeared in the following periods (from 30.0 % to 0.0 % in 2019) while forest formations increased (from 7.0 % in 1987 to 11.0 % in 2019). Changes between 2005 and 2019 occurred within the stricto sensu cerrado subdivisions, with reduction of sparse cerrado (from 34.2 % to 7.7 %) and an increase in dense cerrado (from 6.9 % to 39.8 %). Normalized difference vegetation index (NDVI) applied for similar periods indicates a progressive increase of values over time (from 1986 ( 0.61±0.10 ) to 2004 ( 0.65±0.06 ) and 2018 ( 0.78±0.05 )) and corroborates the WPE process. These patterns imply the loss of biodiversity in open plant formation. Another major consequence was the reduction of wetlands and possible impact on water supply. Such patterns are important to support plant management plans for the threatened Cerrado open plant formations.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"91 1","pages":"55-64"},"PeriodicalIF":2.2,"publicationDate":"2021-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89009591","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. Close-to-nature management (CTNM) has been proposed as a promising forestry management approach to improve the structure and quality of forests, which integrates wood production and ecological service functions. Research on the effect of CTNM on the univariate and bivariate distribution of the spatial structure of forest stands provides a scientific basis for the evaluation of CTNM implemented in forestry. Here, we analyzed and compared the spatial-structure characteristics of Masson pine (Pinus massoniana) plantations (young, middle-age, and near-mature stages) under CTNM 8 years after selective cutting and unmanaged control. We used univariate and bivariate distribution of three spatial-structure parameters: mingling ( M ), dominance ( U ), and uniform-angle index ( W ). Results showed that the effect of CTNM on spatial structure was more remarkable in middle-aged and near-mature Masson pine forests compared with the young forest. CTNM significantly improved mingling degree and promoted the horizontal distribution, thereby changing from a cluster to a random distribution. Moreover, CTNM improved the proportion of trees with a high mixing degree and random distribution and the proportion of trees having a micro-structure of random distribution with a high degree of mixture and dominance with a high degree of mixture in middle-aged and near-mature Masson pine forest. Overall, the implementation of CTNM 8 years ago showed a positive effect on the improvement of the spatial structure of Masson pine forest, but the present spatial structure is suboptimal. Further implementation of CTNM to adjust the mingling and uniform-angle index is necessary, and CTNM according to this method of frequency distribution of stand structure parameters can improve the success of forest management.
{"title":"Close-to-nature management positively improves the spatial structure of Masson pine forest stands","authors":"Xianfeng Fang, W. Tan, Xiaoye Gao, Zongzheng Chai","doi":"10.5194/WE-21-45-2021","DOIUrl":"https://doi.org/10.5194/WE-21-45-2021","url":null,"abstract":"Abstract. Close-to-nature management (CTNM) has been proposed as a promising\u0000forestry management approach to improve the structure and quality of\u0000forests, which integrates wood production and ecological service functions.\u0000Research on the effect of CTNM on the univariate and\u0000bivariate distribution of the spatial structure of forest stands provides a\u0000scientific basis for the evaluation of CTNM implemented in forestry. Here,\u0000we analyzed and compared the spatial-structure characteristics of Masson\u0000pine (Pinus massoniana) plantations (young, middle-age, and near-mature stages) under CTNM\u00008 years after selective cutting and unmanaged control. We used\u0000univariate and bivariate distribution of three spatial-structure parameters:\u0000mingling ( M ), dominance ( U ), and uniform-angle index ( W ). Results showed that\u0000the effect of CTNM on spatial structure was more remarkable in middle-aged\u0000and near-mature Masson pine forests compared with the young forest. CTNM\u0000significantly improved mingling degree and promoted the horizontal\u0000distribution, thereby changing from a cluster to a random distribution.\u0000Moreover, CTNM improved the proportion of trees with a high mixing degree\u0000and random distribution and the proportion of trees having a micro-structure\u0000of random distribution with a high degree of mixture and dominance with a\u0000high degree of mixture in middle-aged and near-mature Masson pine forest.\u0000Overall, the implementation of CTNM 8 years ago showed a positive effect\u0000on the improvement of the spatial structure of Masson pine forest, but the\u0000present spatial structure is suboptimal. Further implementation of CTNM to\u0000adjust the mingling and uniform-angle index is necessary, and CTNM according\u0000to this method of frequency distribution of stand structure parameters can\u0000improve the success of forest management.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"40 1","pages":"45-54"},"PeriodicalIF":2.2,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74950332","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}
G. Gleiser, Nicolay Leme da Cunha, A. Sáez, M. Aizen
Abstract. Artificial selection and genetic engineering plus an expanding repertoire and use of agrochemical inputs have allowed a rapid and continuous increase in crop yield (i.e., volume production per unit area) over the last century, which is needed to fulfill food demands from a growing human population. However, the first signs of yield deceleration and stagnation have already been reported for some globally important crops. Therefore, the study of the drivers of yield growth and its variation is essential for directing research and policies aiming at ensuring food security in the forthcoming years. We used data on mean and variability in annual yield growth for 107 globally important crops to assess the role of environmental (i.e., climatic region) and plant intrinsic traits (i.e., type of harvested organ, pollinator dependence, and life form) as drivers of change in yield growth and its stability. We applied a comparative approach to control for biases associated with phylogenetic non-independence among crops, an approach rarely used in agronomic studies. Average yield growth and its variation were not phylogenetically structured. Yield growth decreased with increasing pollinator dependence in tree crops but not in herbaceous and shrubby crops. Interannual yield variation tended to increase with increasing pollinator dependence, and it was higher in crops from temperate regions, in those cultivated for their reproductive organs, and in tree and shrubby crops as compared with herbaceous ones. Information on ecological correlates of crop yield growth and interannual yield variation can be used in the design of more sustainable and diversified agriculture schemes.
{"title":"Ecological correlates of crop yield growth and interannual yield variation at a global scale","authors":"G. Gleiser, Nicolay Leme da Cunha, A. Sáez, M. Aizen","doi":"10.5194/WE-21-15-2021","DOIUrl":"https://doi.org/10.5194/WE-21-15-2021","url":null,"abstract":"Abstract. Artificial selection and genetic engineering plus an expanding repertoire\u0000and use of agrochemical inputs have allowed a rapid and continuous increase\u0000in crop yield (i.e., volume production per unit area) over the last century,\u0000which is needed to fulfill food demands from a growing human population. However, the\u0000first signs of yield deceleration and stagnation have already been reported\u0000for some globally important crops. Therefore, the study of the drivers of\u0000yield growth and its variation is essential for directing research and\u0000policies aiming at ensuring food security in the forthcoming years. We used\u0000data on mean and variability in annual yield growth for 107 globally\u0000important crops to assess the role of environmental (i.e., climatic region)\u0000and plant intrinsic traits (i.e., type of harvested organ, pollinator\u0000dependence, and life form) as drivers of change in yield growth and its\u0000stability. We applied a comparative approach to control for biases\u0000associated with phylogenetic non-independence among crops, an approach\u0000rarely used in agronomic studies. Average yield growth and its variation\u0000were not phylogenetically structured. Yield growth decreased with increasing\u0000pollinator dependence in tree crops but not in herbaceous and shrubby crops.\u0000Interannual yield variation tended to increase with increasing pollinator\u0000dependence, and it was higher in crops from temperate regions, in those\u0000cultivated for their reproductive organs, and in tree and shrubby crops as\u0000compared with herbaceous ones. Information on ecological correlates of crop\u0000yield growth and interannual yield variation can be used in the design of\u0000more sustainable and diversified agriculture schemes.","PeriodicalId":54320,"journal":{"name":"Web Ecology","volume":"56 1","pages":"15-43"},"PeriodicalIF":2.2,"publicationDate":"2021-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86417088","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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