Search

Made available in DSpace on 2022-04-28T19:52:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-18 Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale. Department of Biology University of Toronto Mississauga ON Centre for Urban Environments University of Toronto Mississauga ON Department of Biology University of North Carolina, Chapel Hill Department of Biology University of Louisiana LA Department of Biology Queen's University ON Department of Biology Concordia University QC Department of Biological Sciences DePaul University Department of Biology DePauw University IN Department of Urban Design and Planning, University of Washington, Seattle, WA, USA Colegio de Ciencias Biológicas y Ambientales Universidad San Francisco de Quito USFQ Department of Genetics University of Georgia Department of Ecology and Genetics Evolutionary Biology Centre Uppsala University Field Science Center for Northern Biosphere Hokkaido University Natural History Museum Zoology University of New England NSW Programa de Pós-Graduação em Geografia da UFMT campus de Rondonópolis Department of Botany and Biodiversity Research Centre University of British Columbia Graduate Program in Genome Sciences and Technology Genome Sciences Centre University of British Columbia Department of Microbiology and Immunology University of British Columbia Red de Biología Evolutiva Instituto de Ecología A. C. School of the Environment Yale University CT Departamento de Ciencias Ecológicas Universidad de Chile, Facultad de Ciencias Instituto de Ecología y Biodiversidad Universidad de Chile Department of Biology Mount Allison University Red de Ecoetología Instituto de Ecología A. C. Department of Biology University of Ottawa ON Department of Zoology University of Cambridge Department of Biology, Washington University in St. Louis, St. Louis, MO, USA Department of Biology University of Miami FL Centro de Investigación en Recursos Naturales y Sustentabilidad (CIRENYS) Universidad Bernardo O'Higgins Department of Biology, University of La Verne, La Verne, CA, USA Département des sciences du bois et de la forêt Université Laval QC Evolution & Ecology Research Centre School of Biological Earth and Environmental Sciences UNSW Sydney NSW Department of Biology Ghent University Department of Biology Monmouth University West Long Branch Centre for Ecology Evolution and Environmental Changes Faculdade de Ciências Universidade de Lisboa Lisboa Department of Biology KU Leuven School of Agriculture and Environment Wildlife and Ecology group Massey University, Palmerston North Department of Biological Sciences University of Cape Town Institute of Landscape Ecology University of Münster Gosnell School of Life Sciences, Rochester Institute of Technology, Rochester, NY, USA Department of Biological Sciences University of Alberta AB Louis Calder Center and Department of Biological Sciences, Fordham University, Armonk, NY, USA Departamento de Ecología Tropical, Universidad Autónoma de Yucatán, Mérida, Yucatán, México School of Life Sciences University of Sussex Department of Ecology Environment and Plant Sciences Stockholm University iBIOTROP Instituto de Biodiversidad Tropical Universidad San Francisco de Quito Department of Biology, San Francisco State University, San Francisco, CA, USA Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán AC, Mérida, Yucatán, México School of Ecological and Environmental Sciences East China Normal University Shanghai Engineering Research Center of Sustainable Plant Innovation Centre for Ecosystem Science School of Biological Earth and Environmental Sciences UNSW Sydney NSW Department of Ecology and Evolutionary Biology University of Michigan MI Department of Biosciences Rice University TX IFEVA Universidad de Buenos Aires Facultad de Agronomía, CONICET Biology Department Saint Mary's University NS Department of Biological Sciences, Universidad de los Andes Department of Biology and Biochemistry University of Houston TX Université de Rennes Department of Zoology and Biodiversity Research Centre University of British Columbia Department of Environmental Studies Dordt University Sioux Center IA Department of Biology Minneapolis Community and Technical College MN Department of Natural Sciences Ecology and Environment Research Centre Manchester Metropolitan University Instituto de Investigaciones en Ecosistemas y Sustentabilidad UNAM Department of Botany School of Biology Aristotle University of Thessaloniki Faculty of Biological and Environmental Science Organismal & Evolutionary Biology Research Programme University of Helsinki Institute of Biodiversity Animal Health and Comparative Medicine University of Glasgow Department of Biology Hendrix College Department of Ecological Science Vrije Universiteit Amsterdam Departamento de Ciencias Biológicas y Agropecuarias Universidad Técnica Particular de Loja Departamento de Biologia Universidade Federal de Santa Maria (UFSM) Department of Plant Sciences School of Biology College of Science University of Tehran NTNU University Museum Norwegian University of Science and Technology Red de Estudios Moleculares Avanzados Instituto de Ecología A. C. School of Biological Sciences, University of Reading, Whiteknights Park, Reading, Berkshire, UK Department of Biology Northern Arizona University AZ Department of Biological Sciences MacEwan University AB Max Planck Institute for Plant Breeding Research Departamento de Ecología Evolutiva Instituto de Ecología Universidad Nacional Autónoma de México Max Planck Institute of Molecular Plant Physiology Potsdam-Golm BIO5 Institute University of Arizona AZ Alaska Center for Conservation Science University of Alaska Anchorage Tropical Diversity, Royal Botanical Garden of Edinburgh Département de biologie Université de Moncton Department of Biological Sciences University of Manitoba MB Departments of Microbiology & Statistics University of Manitoba MB Department of Biology University of New Brunswick Department of Biology Kalamazoo College MI BioProtection Research Centre Lincoln University Departamento de Ciencias Facultad de Artes Liberales Universidad Adolfo Ibáñez Department of Ecology Evolution Behaviour University of Minnesota MN Department of Biological Sciences Brock University Department of Environmental Toxicology, University of California, Davis, CA, USA ICB - University of Talca School of Molecular and Life Science Curtin University College of Science Health Engineering and Education Murdoch University, Murdoch School of Life and Environmental Sciences University of Sydney NSW School of Biological Sciences, Monash University, Melbourne, VIC, Australia Department of Biological Sciences Wayne State University MI Department of Biology Western Oregon University, OR School of Natural Resources and the Environment University of Arizona AZ Departamento de Ecología Humana, Cinvestav Mérida Departamento de Ciencias Biológicas y Departamento de Ecología y Biodiversidad Facultad de Ciencias de la Vida, Universidad Andrés Bello Institute of Ecology and Biodiversity (IEB) Department of Biology Lund University Department of Biology Norwegian University of Science and Technology Escuela Superiro de Desarrollo Sustentable Universidad Autónoma de Guerrero -CONACYT Clarkson Secondary School Peel District School Board ON Homelands Sr. Public School Peel District School Board ON Department of Biological Sciences University of Illinois at Chicago Dufferin-Peel Catholic District School Board, St. James Catholic Global Learning Centre Department of Biosciences University of Calgary AB Ecological Processes Branch U.S. Army ERDC-CERL Department of Biology, Oberlin College, Oberlin, OH, USA Escuela Nacional de Estudios Superiores Unidad Morelia UNAM Institute of Evolution and Ecology University of Tübingen Tübingen Department of Evolutionary Biology and Environmental Studies University of Zurich, Winterthurerstrasse Urban Wildlife Institute Department of Conservation and Science, Lincoln Park Zoo Departamento de Ecología Universidad Católica de la Santísima Concepción Department of Biological Sciences University of Denver CO Department of Biological Sciences Mississippi State University MS Department of Biology Center for Computational & Integrative Biology Rutgers University-Camden Kunming Institute of Botany Chinese Academy of Sciences Department of Chemistry & Biochemistry Laurentian University ON Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering College of Life Sciences Beijing Normal University School of BioSciences, University of Melbourne, Melbourne, VIC, Australia Posgrado en Ciencias Biológicas Universidad Nacional Autónoma de México Department of Biological Sciences, Auburn University, Auburn, AL, USA Department of Entomology and Nematology, University of California, Davis, CA, USA Department of Biology University of New Mexico NM Department of Biology University of Wisconsin - Eau Claire Agriculture Institute Iranian Research Organization for Science and Technology (IROST) Department of Biology Colby College ME Instituto de Biología Universidad de Antioquia Department of Biology University of Massachusetts Boston MA Agricultural Biology Colorado State University CO Departamento de Biología Vegetal y Ecología Facultad de Biología Universidad de Sevilla, Av. Reina Mercedes s/n Facultad de Estudios Interdisciplinarios Centro GEMA- Genómica Universidad Mayor Evolutionary Ecology Group Naturalis Biodiversity Center Department of Biology and Chemistry Nipissing University ON, North Bay Center for Ecological Research Kyoto University Bonanza Creek Long Term Ecological Research Program University of Alaska Fairbanks Department of Botany and Molecular Evolution Senckenberg Research Institute and Natural History Museum Frankfurt Departamento de Biodiversidade Instituto de Biociências Univ Estadual Paulista - UNESP Nelson Institute for Environmental Studies University of Wisconsin-Madison WI Department of Biology, California State University, Northridge, Los Angeles, CA, USA Department of Ecology Swedish University of Agricultural Sciences Facultad de Ciencias y Biotecnologia Universidad CES Department of Biology Hofstra University Faculty of Biosciences and Aquaculture Nord University, Bodø Division of Biological Sciences, University of California San Diego, San Diego, CA, USA Department of Biology University of Richmond VA Estación de Biodiversidad Tiputini Colegio de Ciencias Biológicas y Ambientales Universidad San Francisco de Quito USFQ Department of Biological Sciences Institute of Environment Florida International University FL Agronomy Department University of Almería Department of Biological Sciences and Center for Urban Ecology and Sustainability Butler University IN Department of Biological Sciences Louisiana State University LA Faculty of Biological Sciences, Goethe University Frankfurt Institute of Biology Leiden Leiden University Department of Biological and Environmental Science University of Jyväskylä Jyväskylä Department of Biology University of Louisville KY Organization for Programs on Environmental Science University of Tokyo CNRS AgroParisTech Ecologie Systématique et Evolution, Université Paris-Saclay Department of Biology, Providence College, Providence, RI, USA General Zoology Institute for Biology Martin Luther University Halle-Wittenberg International Arctic Research Center University of Alaska Fairbanks Science, Technology and Society Department, Rochester Institute of Technology, Rochester, NY, USA SLU Swedish Species Information Centre Swedish University of Agricultural Sciences Department of Biology Westfield State University MA Centre of New Technologies University of Warsaw Department of Biology, Stanford University, Stanford, CA, USA Plant Biology Department Michigan State University MI Biology Department Davidson College College of Horticulture and Forestry Sciences/ Hubei Engineering Technology Research Center for Forestry Information Huazhong Agricultural University School of Life Sciences Technical University of Munich School of Life Sciences Lanzhou University Institute of Ecology and Evolution University of Bern Department of Evolution Ecology and Behaviour University of Liverpool Departamento de Biodiversidade Instituto de Biociências Univ Estadual Paulista - UNESP

Aims: A possible approach to restore drylands is to recover biocrusts by inoculating cyanobacteria. Many studies have demonstrated the ability of cyanobacteria to successfully colonize soil and improve its functions. However, most studies have focused on the abiotic factors influencing the inoculation success, overlooking biotic factors. We examined the influence of the soil indigenous community on the inoculated cyanobacteria by sterilizing soils and analyzing its effects on several key soil properties. Methodology: Nostoc commune was inoculated under laboratory conditions on two soil types with different levels of degradation and under two watering frequencies. All treatments were carried out in natural and sterilized soils. Results: The analysis of the cyanobacterial coverage (30–50% in all inoculated soils), chlorophyll a, visible albedo, roughness, water repellency, organic carbon (OC) and exopolysaccharides (EPS) content showed that cyanobacterial inoculation succeeded, improving soil properties that varied depending on the soil type. The sterilization of soils had little effect: in less degraded soils, the results suggest a faster growth of the indigenous community reaching coverage values of 10% and an interaction with the inoculum that led to a decrease in 2 and 0.3 g Kg of OC and TB-EPS, respectively; in more degraded soils, the community reduced the cyanobacterial coverage around 11%, suggesting competitive interactions. Conclusions: N. commune can be employed to restore lifeless soils. Also, the analysis of native soil community should be considered before field inoculation to plan appropriate methodologies.

Dryland soil degradation is increasing due to global change and traditional restoration methods are not successful due to water scarcity. Thus, an alternative technology based on inoculating biocrust-forming cyanobacteria on degraded soils has emerged. Biocrusts are communities of mosses, lichens, cyanobacteria or fungi that colonize soil surface forming a stable and fertile layer. Previous studies have shown the benefits of inoculating cyanobacteria to restore soils at a small scale. However, to face field restoration projects, it is necessary to produce high quantities of biomass at an affordable cost. In this work, we analyze if the previously tested cyanobacteria Scytonema hyalinum, Tolypothrix distorta (heterocystous strains) and Trichocoleus desertorum (a bundle-forming one) can be produced with agricultural fertilizers. Different culture media were used: two containing pure chemicals (BG11 and BG11

Nowadays, land use change and the impacts of climate change are accelerating land degradation processes in drylands. These regions occupy around 40% of the Earth land’s surface and their extension is likely to represent around 45% by 2050. Biocrusts (complex communities formed by bacteria, cyanobacteria, microalgae, fungi, lichens and mosses which live in the uppermost layer of soil and can cover up to 70% of the interplant areas) play a decisive role in soil stabilization and fertility in these regions, so that they have been proposed as restoration agents in degraded dryland sites, where water scarcity and the harsh environmental conditions can hinder traditional restoration based on the use of vegetation establishment. Within the different biocrust-forming organisms, the use of cyanobacteria as a biotechnological tool to combat soil degradation, is gaining increasing importance. Cyanobacteria are the pioneer colonizers of terrestrial ecosystems, they are able to resist extreme environmental conditions, i.e. high temperatures, prolonged UV radiation and nutrients scarcity. At the same time, they improve physical-chemical properties of the soil by fixing carbon and many species also the atmospheric nitrogen and by producing exopolysaccharides that strongly increase soil stability and eventually creating a more favorable environment for colonization by other organisms. Despite several laboratory studies demonstrate the effectiveness of inoculating soil with cyanobacteria and their effect in increasing soil carbon and nutrient content, few field studies are available and many of them show a limited success probably because of the harsh environmental conditions that hamper an optimal growth. In the present work, soils collected from different ecosystems in SE Spain were inoculated with a consortium of four native cyanobacteria species: Nostoc comune, Trichocoleus desertorum, Tolypothrix distorta and Leptolyngbia sp., and different techniques to reduce abiotic stresses were tested in outdoors conditions: 1) cyanobacteria + soil covered with a mesh made of Stipa tenacissima, 2) cyanobacteria+ Plantago-based stabilizer amendment, and 3) cyanobacteria + sewage sludge (incorporated as an organic amendment) . The application of plant-based ameliorating strategies resulted in a higher chlorophyll a content, which reflects an improvement of cyanobacterial growth compared to the inoculation lacking the application of ameliorating techniques. The soil albedo also decreased due to surface darkening, thus also indicating a higher cyanobacterial growth in these treatments. Wind tunnel experiments also demonstrated a lower susceptibility to wind erosion in the cyanobacteria-inoculated soils combined with application of the plant mesh or the Plantago amendment. These results highlight the importance of using plant-based amelioration techniques to reduce abiotic stresses, especially in the early stages of soil colonization after cyanobacteria inoculation. Regarding the use of sewage sludge, it was demonstrated that their application at low doses improved cyanobacteria growth, which was reflected in an increase in chlorophyll a content as well as in a significant increase of aggregate stability and reduced soil susceptibility to wind erosion. This study shows promising results to enhance cyanobacterial growth and prevent cyanobacteria inoculum loss under natural conditions. Ongoing experiments will evaluate the effectiveness of these strategies under field conditions.

In recent years, soil inoculation with cyanobacteria has become one of the most promising biotechnological strategies for restoring soil functionality in degraded drylands because of their critical role in increasing soil fertility and preventing erosion. Nevertheless, in order to fully exploit this biotechnology on a large scale, it must still be shown whether inoculated cyanobacteria are capable of developing in soils with different physicochemical properties, and new candidates adapted to desert conditions must be explored. To evaluate the potential of cyanobacteria for restoring soil functions of degraded dryland soils, in this laboratory study, we analyzed the effect of inoculating three native N‐fixing species (Nostoc commune, Scytonema hyalinum, and Tolypothrix distorta), individually and as a consortium, on soil properties from three different semiarid ecosystems in southeast Spain. The biocrust colonization was monitored by determining chlorophyll a content (the typical surrogate used for biocrust biomass). Other methodologies, such as the analysis of soil spectral response and image classification were also applied for cover estimation of the biocrust. After 3 months, all inoculated soils showed cyanobacteria cover of up to 50%, lower albedo and higher chlorophyll a content. Cyanobacterial inoculation also improved soil functions, as they promoted a significant gain in total organic carbon and total nitrogen in all soils. Among inoculation treatments, Nostoc commune and the mixture of all three species promoted the most cyanobacteria coverage, chlorophyll content, and surface darkening, as well as organic carbon and total nitrogen gains in the soil, highlighting their excellent performance in biocrust development.

Land degradation, as a result of increased soil erosion and loss of fertility among other factors, is currently one of the most serious environmental problems. In recent years, the role of cyanobacteria from soil biocrusts in re-establishing soil function of degraded areas is gaining interest due to the potential of these organisms for soil stabilization and increase of soil fertility. In order to fully exploit the use of cyanobacteria in large-scale restoration of degraded lands, new approaches that facilitate their application must be explored in order to face with the harsh abiotic conditions of these environments. In this presentation, we showcase two different methods for the inoculation of cyanobacteria from soil biocrust in degraded soils of Australian dryland ecosystems: i) direct inoculation of cyanobacteria cultures and ii) incorporation of cyanobacteria within extruded pellets. Three soil native cyanobacterial strains from two representative N-fixing genera (Nostoc and Scytonema) and a non-heterocystous filamentous genus (Leptolyngbya) previously collected from the Pilbara region (north-west Western Australia), were used as inoculum. Then, in a multifactorial microcosm experiment under laboratory conditions, we evaluated the survival and establishment of the cyanobacteria for both methods. For the direct inoculation, cultures of isolated cyanobacteria and a mixture of them were applied as a liquid inoculum directly into a degraded soil from the Pilbara. In the case of application using extruded pellets, fresh cultures of each strain alone and an equal mixed of them were added into a substrate composed of commercial bentonite powder and sand (1:10 weight ratio). The composed solution was extruded through a jerky gun with an extruder nozzle into pellets (1 cm diameter x 2 cm length) and dried at 30oC for 24h. Pellets were then placed on the surface of three different degraded soils representative of Australian drylands: a mine waste from an active mine site in the Pilbara, a degraded soil from the Cobar Peneplain (New South Wales), and a soil from the Simpson Strzelecki Dunefields (South Australia). In both experiments, cyanobacteria growth and establishment were monitored. Our results showed that in both treatments cyanobacteria colonize almost the entire Petri dish surface in all treatments. Furthermore, the levels of chlorophyll a (a proxy for cyanobacterial biomass) remained constant on inoculated samples during the study period, suggesting that cyanobacteria survived the pelleting process. In the case of direct inoculation, a decrease of chlorophyll a was observed in the beginning but then it stabilized and started to increase at the final stage of the experiment. This process may be due to the adaptation period of the cyanobacteria in the new environment, which is most progressive in the case of pellets application. Overall, our results showed that cyanobacteria can be successfully applied as a liquid inoculum and incorporated into extruded pellets, quickly colonizing degraded soi substrates. These technologies are ready for further testing and refining through field trials, opening a wide range of opportunities to face with large scale restoration programs.

The role of cyanobacteria from soil biocrusts in restoring degraded land is gaining interest in recent years because of their critical role in enhancing soil fertility and preventing erosion. However, soil restoration through cyanobacterial inoculation remains a challenge for large-scale restoration efforts and new methodologies for effective cyanobacterial application need to be developed. Here, we propose a bioenvironmental approach to inoculate soils with pelletized cyanobacteria from soil biocrusts. Fresh cultures of three soil native cyanobacteria strains from two representative N-fixing genera (Nostoc and Scytonema) and a non-heterocystous filamentous genus (Leptolyngbya) were added into a substrate composed of commercial bentonite powder and sand (1:10 wt ratio) and extruded into pellets. Then, in two multifactorial microcosm experiments under glasshouse conditions, we evaluated (i) the survival and establishment over time of the cyanobacteria encapsulated in pellets, and ii) the viability of pelletized cyanobacteria after drying and storing for 30 d, on soils from three arid regions in Australia. Our results showed that pellets can dissolve completely and spread out in all treatments. Scytonema and the consortium of the three cyanobacteria species showed significant (P 0.001) deeper CR

© 2020 by the authors., Arid and semi-arid ecosystems are characterized by patchy vegetation and variable resource availability. The interplant spaces of these ecosystems are very often covered by cyanobacteria-dominated biocrusts, which are the primary colonizers of terrestrial ecosystems and key in facilitating the succession of other biocrust organisms and plants. Cyanobacterial biocrusts regulate the horizontal and vertical fluxes of water, carbon and nutrients into and from the soil and play crucial hydrological, geomorphological and ecological roles in these ecosystems. In this paper, we analyze the influence of cyanobacterial biocrusts on water balance components (infiltration-runoff, evaporation, soil moisture and non-rainfall water inputs (NRWIs)) in representative semiarid ecosystems in southeastern Spain. The influence of cyanobacterial biocrusts, in two stages of their development, on runoff-infiltration was studied by rainfall simulation and in field plots under natural rainfall at different spatial scales. Results showed that cover, exopolysaccharide content, roughness, organic carbon, total nitrogen, available water holding capacity, aggregate stability, and other properties increased with the development of the cyanobacterial biocrust. Due to the effects on these soil properties, runoff generation was lower in well-developed than in incipient-cyanobacterial biocrusts under both simulated and natural rainfall and on different spatial scales. Runoff yield decreased at coarser spatial scales due to re-infiltration along the hillslope, thus decreasing hydrological connectivity. Soil moisture monitoring at 0.03 m depth revealed higher moisture content and slower soil water loss in plots covered by cyanobacterial biocrusts compared to bare soils. Non-rainfall water inputs were also higher under well-developed cyanobacterial biocrusts than in bare soils. Disturbance of cyanobacterial biocrusts seriously affected the water balance by increasing runoff, decreasing soil moisture and accelerating soil water loss, at the same time that led to a very significant increase in sediment yield. The recovery of biocrust cover after disturbance can be relatively fast, but its growth rate is strongly conditioned by microclimate. The results of this paper show the important influence of cyanobacterial biocrust in modulating the different processes supporting the capacity of these ecosystems to provide key services such as water regulation or erosion control, and also the important impacts of their anthropic disturbance., This work has been supported by several research projects: REBIOARID (RTI2018-101921-B-I00), DINCOS (CGL2016-78075-P) projects, founded by the Spanish National Plan for Research and the European Union ERDF and the BIOCOST project Supported by Biodiversity Foundation of the Ministry for the Ecological Transition., Publisher’s version

Chlorophyll a concentration (Chla) is a well-proven proxy of biocrust development, photosynthetic organisms’ status, and recovery monitoring after environmental disturbances. However, laboratory methods for the analysis of chlorophyll require destructive sampling and are expensive and time consuming. Indirect estimation of chlorophyll a by means of soil surface reflectance analysis has been demonstrated to be an accurate, cheap, and quick alternative for chlorophyll retrieval information, especially in plants. However, its application to biocrusts has yet to be harnessed. In this study we evaluated the potential of soil surface reflectance measurements for non-destructive Chla quantification over a range of biocrust types and soils. Our results revealed that from the different spectral transformation methods and techniques, the first derivative of the reflectance and the continuum removal were the most accurate for Chla retrieval. Normalized difference values in the red-edge region and common broadband indexes (e.g., normalized difference vegetation index (NDVI)) were also sensitive to changes in Chla. However, such approaches should be carefully adapted to each specific biocrust type. On the other hand, the combination of spectral measurements with non-linear random forest (RF) models provided very good fits (R2 > 0.94) with a mean root mean square error (RMSE) of about 6.5 µg/g soil, and alleviated the need for a specific calibration for each crust type, opening a wide range of opportunities to advance our knowledge of biocrust responses to ongoing global change and degradation processes from anthropogenic disturbance

Land degradation by erosion is especially important in drylands, which are among the most vulnerable to disturbance by human activity or climate change. Biocrusts are an essential surface component of these ecosystems and one of the most important contributors to surface resistance and stability, and therefore, keeping soil fertile in these nutrient-limited-environments. Loss of biocrusts can result in increased sediment losses and subsequent loss of soil organic carbon (SOC) and other soil resources, which are vital for vegetation and general ecosystem functioning. Despite their importance, the consequences of biocrust loss on sediment and SOC losses in drylands have been poorly analysed. In this study, we examined the influence of two biocrust types (cyanobacteria and lichen-dominated biocrusts) and biocrust removal on runoff and sediment yield, from natural rainfall during one hydrological year in a semiarid badlands catchment (Tabernas, SE Spain). The influence of biocrust type and biocrust removal on SOC losses from water erosion (dissolved and sediment organic carbon losses, DOC and SdOC, respectively) was also analysed. Our results show that sediment yield significantly increased after biocrust removal, especially during the first rain after biocrust removal, when particles were left directly exposed to raindrop impact and easily washed away by runoff. Annual sediment yield was 465, 75 and 24 g m− 2 in biocrust-removed, cyanobacteria-covered and lichen-covered soil, respectively, and the first event represented 87% of annual sediment losses on biocrust-removed plots. Biocrust removal was accompanied by a significant increase in both DOC and SdOC mobilisation. Total organic carbon (TOC) mobilisation was the highest in soils where the biocrust had been removed and decreased as the biocrust was more developed. Annual TOC mobilisation was 10.2, 3.0 and 1.4 g m− 2 in biocrust-removed, cyanobacteria-covered and lichen-covered soil, respectively. TOC mobilisation was mainly driven by sediments and thus, 89% of annual TOC mobilisation occurred during the first rain after biocrust removal. The high sediment and SOC losses recorded after biocrust removal emphasize the importance of biocrust conservation for avoiding the loss of soil resources and maintaining fertility in interplant soils in drylands.

Cyanobacteria inoculation to promote biocrust formation and improve soil properties has shown positive results in indoor studies, but limited success when applied under field conditions. Successful results of application of this technology in the field have been only found in desert sand dunes in China. Therefore, further development of this technique is necessary to extend its applicability to other soil types and regions. In this study, we inoculated a consortium of three N-fixing native cyanobacteria (Nostoc commune, Scytonema hyalinum and Tolypothrix distorta) on degraded soils from three semiarid study sites in south-eastern Spain with differing soil properties and soil development. After two years, chlorophyll a spectral absorption and albedo in inoculated and control plots were similar. Consequently, a second experiment was conducted to test the effectiveness of progressive cyanobacterial preacclimation before inoculation as well as the use of habitat amelioration techniques, consisting of covering the inoculated soils with a vegetal fiber mesh or a plastic grid, to improve cyanobacteria performance. Our results showed that: 1) hardening these cyanobacterial strains did not enhance their colonization capability, and 2) covering inoculated soils with a vegetal mesh did promote soil colonization by cyanobacteria, as shown by higher chlorophyll a soil content and Chla spectral absorption and lower albedo than in the uncovered plots. Moreover, it promoted the presence of more condensed, tightly-bound exopolysaccharides (EPS) and higher molecular weight molecules in the more soluble loosely-bound EPS fraction, both of which could be involved in the improvement of soil aggregation. Finally, higher abundance of xylose and galactose was also found in this treatment, likely indicating a greater development of the induced biocrusts. The results of this study show that direct soil inoculation with cyanobacteria, whether subjected to desiccation hardening or not, did not promote the artificial formation of biocrusts in the field. However, more positive results were found when the inoculated soils were covered with a vegetal mesh to help cyanobacteria cope with abiotic stress and soil erosion. Therefore, developing diversified efficient habitat amelioration strategies might be key in the successful application of this restoration technique in the field.

Cyanobacteria inoculation has recently become an innovative biotechnological tool for restoring degraded arid soils. A major challenge for researchers, however, is the search for suitable species able to cope with water stress under field conditions. The aim of this study was to test the effect of water availability on induced biocrust growth in three different degraded soils from semiarid areas of Almeria (Spain). Three native N-fixing cyanobacterial strains, Nostoc commune, Scytonema hyalinum and Tolypothrix distorta, were inoculated on soil samples from the study areas, individually and as a consortium. Two different irrigation treatments simulating the water availability in the selected areas, in a dry year (180 mm/year) and a wet year (380 mm/year), were applied for three months under laboratory conditions. Cyanobacteria cover, chlorophyll a spectral absorption (Chla spectral absorption), soil organic carbon (SOC) and total exopolysaccharide (EPS) gains were measured as indicators of biocrust development. Cyanobacteria crust cover, SOC and EPS gains were higher in inoculated soils than in uninoculated soils. Even though the hydration regime had a generally significant effect on cyanobacteria cover, Chla spectral absorption and EPS, similar biocrust development and improvement in edaphic conditions were observed under both hydration regimes for all treatments. Of the candidate inoculants, N. commune showed remarkably higher performance under dry conditions than the rest, providing evidence of high potential for growing under water-limited conditions and being a good candidate inoculant for restoration of arid degraded areas.

Cyanobacteria colonize the soil surface in deserts where they coexist with other organisms such as mosses, lichens, bacteria, fungi, archaea, and microalgae, in communities known as biocrusts. Cyanobacteria are of interest for dryland restoration due to their capacity for survival under water stress, facilitating succession and influencing soil function recovery. In addition, their large-scale culturing in bioreactors is possible. The aims of this study were to optimize the biomass production of a soil cyanobacterium (Nostoc commune) and determine the feasibility of employing fertilizers instead of chemicals for their production. The suitability of the biomass produced in different culture media for inducing biocrusts was tested by inoculation on sterilized mine substrate and then measuring several soil properties. Results showed that the growth rate of biomass cultured in the fertilizer media (0.43 day−1) was close to the chemical media. After 3 months of incubation in soil the cyanobacteria surface coverage increased up to 36% and there was no difference between soils inoculated with biomass produced in chemical or fertilizer media. As the Mann and Myers medium made with fertilizers promoted the best soil improvements, such as increased soil organic carbon and exopolysaccharide content of 8.9 g kg−1 and 2.2 mg g−1, respectively, a growth model was calculated to optimize its production in this medium for future large-scale restoration. Our results demonstrate that Nostoc commune can be economically produced for improving degraded soils, reducing the cost of the medium by 295 € ha−1.

Biological soil crust, or biocrust communities, are the dominating life form in many extreme habitats, such as arid and semiarid badlands, where water scarcity and highly erodible substrates limit vegetation cover. While climate, soil and biotic factors have been described as environmental filters influencing biocrust distribution in such biomes, little is known about the effect of terrain attributes on creating specific microhabitats that promote or restrict biocrust colonization. This study aimed to identify the main terrain attributes controlling biocrust distribution in the driest badland system in Europe, the Tabernas Badlands (SE Spain). To do this, we analysed the influence of different terrain attributes related to landscape stability and microclimate formation on the spatial distribution of lichen and cyanobacteria, using field measurements and topographical information from a LiDAR survey. Our results showed that the spatial distribution of cyanobacteria-dominated biocrusts, which are physiologically and morphologically adapted to extreme drought and high UVA radiation, was mostly associated with areas of high potential incoming solar radiation. The exception was bare south-aspect hillslopes with very high sediment transport potential, where bare physically crusted soils were the dominant ground cover. Lichen-dominated biocrusts, in contrast, colonized near the top of north-aspect hillslopes, characterized by low potential incoming solar radiation and potential evapotranspiration, and their cover decreased downstream, as conditions became good enough for vascular plants. © 2019 John Wiley & Sons, Ltd.

Chlorophyll a concentration (Chla) is a well-proven proxy of biocrust development, photosynthetic organisms' status, and recovery monitoring after environmental disturbances. However, laboratory methods for the analysis of chlorophyll require destructive sampling and are expensive and time consuming. Indirect estimation of chlorophyll a by means of soil surface reflectance analysis has been demonstrated to be an accurate, cheap, and quick alternative for chlorophyll retrieval information, especially in plants. However, its application to biocrusts has yet to be harnessed. In this study we evaluated the potential of soil surface reflectance measurements for non-destructive Chla quantification over a range of biocrust types and soils. Our results revealed that fromthe different spectral transformation methods and techniques, the first derivative of the reflectance and the continuum removal were the most accurate for Chla retrieval. Normalized difference values in the red-edge region and common broadband indexes (e.g., normalized difference vegetation index (NDVI)) were also sensitive to changes in Chla. However, such approaches should be carefully adapted to each specific biocrust type. On the other hand, the combination of spectral measurements with non-linear random forest (RF) models provided very good fits (R > 0.94) with a mean root mean square error (RMSE) of about 6.5 μg/g soil, and alleviated the need for a specific calibration for each crust type, opening a wide range of opportunities to advance our knowledge of biocrust responses to ongoing global change and degradation processes from anthropogenic disturbance., This research was funded by the RESUCI (CGL2014-59946-R), DINCOS (CGL2016-78075-P), and REBIOARID (RTI2018-101921-B-I00) projects funded by the Spanish National Plan for Research and the European Union ERDF funds, and the project H2020-MSCA-RISE-GYPWORLD (funded by the European Union’s Horizon 2020 research and innovation program under the Marie Slodowska-Curie Grant Agreement No. 777803). Field sampling was conducted within the framework of the project “Cuantificación de flujos de carbono y agua en zonas áridas a partir de información spectral” founded by Aerial Platforms for Research-ICTS (INTA) throughout the campaign “Investigaciones de Altura.” J.R.R. was funded by the FPU predoctoral fellowship from the Educational, Culture and Sports Ministry of Spain (FPU14/05806). E.R.-C. was supported by the Juan de la Cierva incorporación fellowship (IJCI-2016-29274) and by the Hipatia postdoctoral fellowship funded by the University of Almería. B.R.-R. was supported by the foundation Tatiana Pérez de Guzmán el Bueno under its predoctoral fellowship program and S.C. was supported by the Hipatia postdoctoral fellowship funded by the University of Almería.

Despite significant efforts to restore dryland ecosystems worldwide, the rate of success of restoration is extremely low in these areas. The role of cyanobacteria from soil biocrusts in reestablishing soil functions of degraded land has been highlighted in recent years. These organisms are capable of improving soil structure and promoting soil N and C fixation. Nevertheless, their application to restore functions of reconstructed soils in dryland restoration programs is yet to be harnessed. In this study, we used microcosms under laboratory conditions to analyse the effects of inoculating soil substrates used in post-mine restoration with a mixture of N-fixing cyanobacteria isolated from soil biocrust (Nostoc commune, Tolypothrix distorta and Scytonema hyalinum) on i) the recovery of the biocrust, and ii) the carbon sequestration and mineralisation rates of these substrates. Soils were collected from an active mine site in the mining-intensive biodiverse Pilbara region (north-west Western Australia) and consisted of previously stockpiled topsoil, overburden waste material, a mixture of both substrates, and a natural soil from an undisturbed area. Our results showed that cyanobacteria rapidly colonised the mine substrates, with biocrust coverage ranging from 23.8 to 52.2% and chlorophyll a concentrations of up to 12.2 μg g−1 three months after inoculation. Notably, soil organic C contents increased 3-fold (P

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.