1,933 research outputs found

    Mask R-CNN and OBIA Fusion Improves the Segmentation of Scattered Vegetation in Very High-Resolution Optical Sensors

    Get PDF
    This research was funded by the European Research Council (ERC Grant agreement 647038 [BIODESERT]), the European LIFE Project ADAPTAMED LIFE14 CCA/ES/000612, the RH2OARID (P18-RT-5130) and RESISTE (P18-RT-1927) funded by Consejeria de Economia, Conocimiento, Empresas y Universidad from the Junta de Andalucia, and by projects A-TIC-458-UGR18 and DETECTOR (A-RNM-256-UGR18), with the contribution of the European Union Funds for Regional Development. E.R-C was supported by the HIPATIA-UAL fellowship, founded by the University of Almeria. S.T. is supported by the Ramon y Cajal Program of the Spanish Government (RYC-201518136).Vegetation generally appears scattered in drylands. Its structure, composition and spatial patterns are key controls of biotic interactions, water, and nutrient cycles. Applying segmentation methods to very high-resolution images for monitoring changes in vegetation cover can provide relevant information for dryland conservation ecology. For this reason, improving segmentation methods and understanding the effect of spatial resolution on segmentation results is key to improve dryland vegetation monitoring. We explored and analyzed the accuracy of Object-Based Image Analysis (OBIA) and Mask Region-based Convolutional Neural Networks (Mask R-CNN) and the fusion of both methods in the segmentation of scattered vegetation in a dryland ecosystem. As a case study, we mapped Ziziphus lotus, the dominant shrub of a habitat of conservation priority in one of the driest areas of Europe. Our results show for the first time that the fusion of the results from OBIA and Mask R-CNN increases the accuracy of the segmentation of scattered shrubs up to 25% compared to both methods separately. Hence, by fusing OBIA and Mask R-CNNs on very high-resolution images, the improved segmentation accuracy of vegetation mapping would lead to more precise and sensitive monitoring of changes in biodiversity and ecosystem services in drylands.European Research Council (ERC) 647038European LIFE Project ADAPTAMED LIFE14 CCA/ES/000612Junta de Andalucia P18-RT-1927 P18-RT-5130DETECTOR A-RNM-256-UGR18European Union Funds for Regional DevelopmentHIPATIA-UAL fellowshipSpanish Government RYC-201518136A-TIC-458-UGR1

    Effects of climate change and land use intensification on regional biological soil crust cover and composition in southern Africa

    Get PDF
    Biological soil crusts (biocrusts) form a regular and relevant feature in drylands, as they stabilize the soil, fix nutrients, and influence water cycling. However, biocrust forming organisms have been shown to be dramatically vulnerable to climate and land use change occurring in these regions. In this study, we used Normalized Difference Vegetation Index (NDVI) data of biocrust-dominated pixels (NDVIbiocrust) obtained from hyperspectral and LANDSAT-7 data to analyse biocrust development over time and to forecast future NDVIbiocrust development under different climate change and livestock density scenarios in southern Africa. We validated these results by analysing the occurrence and composition of biocrusts along a mesoclimatic gradient within the study region. Our results show that NDVIbiocrust, which reached maximum values of 0.2 and 0.4 in drier and wetter years, respectively, mainly depended on water availability. A predicted decrease in rainfall events according to all future climate scenarios combined with increased temperatures suggested a pronounced decrease in NDVIbiocrust by the end of the 21st century caused by reduced biocrust coverage. Livestock trampling had similar effects and exacerbated the negative impacts of climate change on biocrust coverage and composition. Data assessed in the field concurred with these results, as reduced biocrust cover and a shift from well-developed to early stages of biocrust development were observed along a gradient of decreasing precipitation and increasing temperatures and livestock density. Our study demonstrates the suitability of multi-temporal series of historical satellite images combined with high-resolution mapping data and Earth system models to identify climate change patterns and their effects on biocrust and vegetation patterns at regional scales.ERC was supported by a Nobel Laureate Paul Crutzen fellowship; the REBIOARID (2018-101921-B-I00) project, funded by the FEDER/Science and Innovation Ministry-National Research Agency through the Spanish National Plan for Research and the European Union Funds for Regional Development; Consejería de Economía, Conocimiento, Empresas y Universidad from the Junta de Andalucía (GlobCRUST project EMERGIA20_0033), the Biodiversity Foundation of the Ministry for the Ecological Transition (BIOCOST project) and the RH2OARID (P18-RT-5130) funded by Consejería de Economía, Conocimiento, Empresas y Universidad from the Junta de Andalucía and the European Union Funds for Regional Development. BW was supported by the Max Planck Society (Nobel Laureate Fellowship) and the German Research Foundation (projects WE2393/2-1 and WE2393/2-2). EG is supported by the European Research Council grant agreement n° 647038 (BIODESERT). The research of US was supported by the German Federal Ministry of Education and Research (BMBF, promotion number 01LG1201N)

    Dynamics of organic carbon losses by water erosion after biocrust removal

    Get PDF
    In arid and semiarid ecosystems, plant interspaces are frequently covered by communities of cyanobacteria, algae, lichens and mosses, known as biocrusts. These crusts often act as runoff sources and are involved in soil stabilization and fertility, as they prevent erosion by water and wind, fix atmospheric C and N and contribute large amounts of C to soil. Their contribution to the C balance as photosynthetically active surfaces in arid and semiarid regions is receiving growing attention. However, very few studies have explicitly evaluated their contribution to organic carbon (OC) lost from runoff and erosion, which is necessary to ascertain the role of biocrusts in the ecosystem C balance. Furthermore, biocrusts are not resilient to physical disturbances, which generally cause the loss of the biocrust and thus, an increase in runoff and erosion, dust emissions, and sediment and nutrient losses. The aim of this study was to find out the influence of biocrusts and their removal on dissolved and sediment organic carbon losses. One-hour extreme rainfall simulations (50 mm h-1) were performed on small plots set up on physical soil crusts and three types of biocrusts, representing a development gradient, and also on plots where these crusts were removed from. Runoff and erosion rates, dissolved organic carbon (DOC) and organic carbon bonded to sediments (SdOC) were measured during the simulated rain. Our results showed different SdOC and DOC for the different biocrusts and also that the presence of biocrusts substantially decreased total organic carbon (TOC) (average 1.80±1.86 g m-2) compared to physical soil crusts (7.83±3.27 g m-2). Within biocrusts, TOC losses decreased as biocrusts developed, and erosion rates were lower. Thus, erosion drove TOC losses while no significant direct relationships were found between TOC losses and runoff. In both physical crusts and biocrusts, DOC and SdOC concentrations were higher during the first minutes after runoff began and decreased over time as nutrient-enriched fine particles were washed away by runoff water. Crust removal caused a strong increase in water erosion and TOC losses. The strongest impacts on TOC losses after crust removal occurred on the lichen plots, due to the increased erosion when they were removed. DOC concentration was higher in biocrust-removed soils than in intact biocrusts, probably because OC is more strongly retained by BSC structures, but easily blown away in soils devoid of them. However, SdOC concentration was higher in intact than removed biocrusts associated with greater OC content in the top crust than in the soil once the crust is scraped off. Consequently, the loss of biocrusts leads to OC impoverishment of nutrient-limited interplant spaces in arid and semiarid areas and the reduction of soil OC heterogeneity, essential for vegetation productivity and functioning of this type of ecosystems.This work was partially supported by several research projects: COSTRAS (RNM 3614), funded by the Consejería de Innovación, Ciencia y Empresa (Junta de Andalucía) including ERD (European Union of Regional Development) Funds, BACARCOS (CGL2011–29429) funded by Spanish national Plan for Research, Development and Innovation and including European Union of Regional Development Funds ERDF funds

    Non-Destructive Biomass Estimation in Mediterranean Alpha Steppes: Improving Traditional Methods for Measuring Dry and Green Fractions by Combining Proximal Remote Sensing Tools

    Get PDF
    The Mediterranean region is experiencing a stronger warming effect than other regions, which has generated a cascade of negative impacts on productivity, biodiversity, and stability of the ecosystem. To monitor ecosystem status and dynamics, aboveground biomass (AGB) is a good indicator, being a surrogate of many ecosystem functions and services and one of the main terrestrial carbon pools. Thus, accurate methodologies for AGB estimation are needed. This has been traditionally done by performing direct field measurements. However, field-based methods, such as biomass harvesting, are destructive, expensive, and time consuming and only provide punctual information, not being appropriate for large scale applications. Here, we propose a new non-destructive methodology for monitoring the spatiotemporal dynamics of AGB and green biomass (GB) of M. tenacissima L. plants by combining structural information obtained from terrestrial laser scanner (TLS) point clouds and spectral information. Our results demonstrate that the three volume measurement methods derived from the TLS point clouds tested (3D convex hull, voxel, and raster surface models) improved the results obtained by traditional field-based measurements. (Adjust-R2 = 0.86–0.84 and RMSE = 927.3–960.2 g for AGB in OLS regressions and Adjust-R2 = 0.93 and RMSE = 376.6–385.1 g for AGB in gradient boosting regression). Among the approaches, the voxel model at 5 cm of spatial resolution provided the best results; however, differences with the 3D convex hull and raster surface-based models were very small. We also found that by combining TLS AGB estimations with spectral information, green and dry biomass fraction can be accurately measured (Adjust-R2 = 0.65–0.56 and RMSE = 149.96–166.87 g in OLS regressions and Adjust-R2 = 0.96–0.97 and RMSE = 46.1–49.8 g in gradient boosting regression), which is critical in heterogeneous Mediterranean ecosystems in which AGB largely varies in response to climatic fluctuations. Thus, our results represent important progress for the measurement of M. tenacissima L. biomass and dynamics, providing a promising tool for calibration and validation of further studies aimed at developing new methodologies for AGB estimation at ecosystem regional scales

    Overview and seasonality of PM10 and PM2.5 in Guayaquil, Ecuador

    Get PDF
    The focus of this study is the assessment of total suspended particles (TSP) and particulate matter (PM) with various aerodynamic diameters in ambient air in Guayaquil, a city in Ecuador that features a tropical climate. The urban annual mean concentrations of TSP (Total Suspended Particles), and particle matter (PM) with various aerodynamic diameters such as: PM10, PM2.5 and PM1 are 31 ± 14 µg m−3, 21 ± 9 µg m−3, 7 ± 2 µg m−3 and 1 ± 1 µg m−3, respectively. Air mass studies reveal that the city receives a clean Southern Ocean breeze. Backward trajectory analysis show differences between wet and dry seasons. During the dry season, most winds come from the south and southwest, while air masses from the peri urban may contribute as pollutant sources during the wet season. Although mean values of PM10 and PM2.5 were below dangerous levels, our year-round continuous monitoring study reveals that maximum values often surpassed those permissible limits allowed by the Ecuadorian norms. A cluster analysis shows four main paths in which west and southwest clusters account for more than 93% of the pollution. Total vertical column of NO2 shows the pollution footprint is strongest during the dry season, as opposed to the wet season. A microscopic morphological characterization of ambient particles within the city during the wet and the dry season reveals coarse mode particles with irregular and rounded shapes. Particle analysis reveals that samples are composed of urban dust, anthropogenic and organic debris during the dry season while mainly urban dust during the wet season

    The role of emotions in human–nature connectedness within Mediterranean landscapes in Spain

    Full text link
    Landscapes can lead to different emotions towards nature that in turn shape people’s environmental behavior and decision processes. This study explores the role of emotions that Mediterranean landscapes foster in people and to what extent these emotions are associated with human–nature connectedness (HNC). We conducted 176 face-to-face surveys to explore HNC and the diversity of emotions associated with a suite of landscapes in Southeast Spain. Results revealed that Marine and Coastal Protected Areas received the highest number of positive emotions, whereas Greenhouses and Non-Protected Littoral were linked to negative emotions. We propose a framework for classifying emotional landscapes according to four groups: emotionally positive, negative, polarized or neutral. Results showed that emotions might play a key role in shaping HNC in Spanish Mediterranean landscapes and may be used as a common ground for understanding roots underpinning human decisions and actions that lead to sustainable management or landscape degradationHORIZON EUROPE Marie Sklodowska-Curie Actions (Grant no. 101031168

    Osteoconductive Potential of Barrier NanoSiO2 PLGA Membranes Functionalized by Plasma Enhanced Chemical Vapour Deposition

    Get PDF
    The possibility of tailoring membrane surfaces with osteoconductive potential, in particular in biodegradable devices, to create modified biomaterials that stimulate osteoblast response should make them more suitable for clinical use, hopefully enhancing bone regeneration. Bioactive inorganic materials, such as silica, have been suggested to improve the bioactivity of synthetic biopolymers. An in vitro study on HOB human osteoblasts was performed to assess biocompatibility and bioactivity of SiO2 functionalized poly(lactide-co-glycolide) (PLGA) membranes, prior to clinical use. A 15 nm SiO2 layer was deposited by plasma enhanced chemical vapour deposition (PECVD), onto a resorbable PLGA membrane. Samples were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and infrared spectroscopy (FT-IR). HOB cells were seeded on sterilized test surfaces where cell morphology, spreading, actin cytoskeletal organization, and focal adhesion expression were assessed. As proved by the FT-IR analysis of samples, the deposition by PECVD of the SiO2 onto the PLGA membrane did not alter the composition and other characteristics of the organic membrane. A temporal and spatial reorganization of cytoskeleton and focal adhesions and morphological changes in response to SiO2 nanolayer were identified in our model. The novedous SiO2 deposition method is compatible with the standard sterilization protocols and reveals as a valuable tool to increase bioactivity of resorbable PLGA membranes.Junta de Andalucía P09-CTS-5189Junta de Andalucía TEP5283Junta de Andalucía FQM-6900Ministerio de Economía y Competitividad CONSOLIDER CSD 2008-00023Ministerio de Economía y Competitividad MAT2010-21228Ministerio de Economía y Competitividad MAT2010-18447Instituto de Salud Carlos III FIS PI 09/0050

    Population genomics of parallel evolution in gene expression and gene sequence during ecological adaptation

    Get PDF
    Natural selection often produces parallel phenotypic changes in response to a similar adaptive challenge. However, the extent to which parallel gene expression differences and genomic divergence underlie parallel phenotypic traits and whether they are decoupled or not remains largely unexplored. We performed a population genomic study of parallel ecological adaptation among replicate ecotype pairs of the rough periwinkle (Littorina saxatilis) at a regional geographical scale (NW Spain). We show that genomic changes underlying parallel phenotypic divergence followed a complex pattern of both repeatable differences and of differences unique to specific ecotype pairs, in which parallel changes in expression or sequence are restricted to a limited set of genes. Yet, the majority of divergent genes were divergent either for gene expression or coding sequence, but not for both simultaneously. Overall, our findings suggest that divergent selection significantly contributed to the process of parallel molecular differentiation among ecotype pairs, and that changes in expression and gene sequence underlying phenotypic divergence could, at least to a certain extent, be considered decoupled processesMinisterio de Economía y Competitividad | Ref. BFU2013- 44635-PMinisterio de Economía y Competitividad | Ref. CGL2016-75482-PMinisterio de Economía y Competitividad | Ref. CGL2016-75904-C2-1Xunta de Galicia | Ref. ED431C 2016-037Xunta de Galicia | Ref. INCITE09 310 006 PRSwedish Research Councils VR | Ref. Linnaeus grant Formas 217-2008-171

    Osteoblasts Interaction with PLGA Membranes Functionalized with Titanium Film Nanolayer by PECVD. In vitro Assessment of Surface Influence on Cell Adhesion during Initial Cell to Material Interaction

    Get PDF
    New biomaterials for Guided Bone Regeneration (GBR), both resorbable and non-resorbable, are being developed to stimulate bone tissue formation. Thus, the in vitro study of cell behavior towards material surface properties turns a prerequisite to assess both biocompatibility and bioactivity of any material intended to be used for clinical purposes. For this purpose, we have developed in vitro studies on normal human osteoblasts (HOB®) HOB® osteoblasts grown on a resorbable Poly (lactide-co-glycolide) (PLGA) membrane foil functionalized by a very thin film (around 15 nm) of TiO2 (i.e., TiO2/PLGA membranes), designed to be used as barrier membrane. To avoid any alteration of the membranes, the titanium films were deposited at room temperature in one step by plasma enhanced chemical vapour deposition. Characterization of the functionalized membranes proved that the thin titanium layer completely covers the PLGA foils that remains practically unmodified in their interior after the deposition process and stands the standard sterilization protocols. Both morphological changes and cytoskeletal reorganization, together with the focal adhesion development observed in HOB osteoblasts, significantly related to TiO2 treated PLGA in which the Ti deposition method described has revealed to be a valuable tool to increase bioactivity of PLGA membranes, by combining cell nanotopography cues with the incorporation of bioactive factors.Junta de Andalucía P09CTS5189Ministerio de Ciencia e Innovación FIS PI 0900508Ministerio de Ciencia e Innovación CONSOLIDER CSD2008-00023Ministerio de Ciencia e Innovación MAT2010-2122
    corecore