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Gan HY, Hohberg K, Schneider C, Ebner M, Marais E, Miranda T, Lehmitz R, Maggs-Kölling G, Bocherens H. The hidden oases: unveiling trophic dynamics in Namib's fog plant ecosystem. Sci Rep 2024; 14:13334. [PMID: 38858480 PMCID: PMC11164947 DOI: 10.1038/s41598-024-61796-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 05/09/2024] [Indexed: 06/12/2024] Open
Abstract
The Namib Desert is a hyperarid coastal desert where fog is a major moisture source. We hypothesized that the fog-harvesting grass Stipagrostis sabulicola establishes an important ecological niche, termed the "Fog-Plant-Oases" (FPOs), and serves as the primary carbon source for the invertebrate community. To determine this, we measured the natural variations of the stable carbon and nitrogen isotopes (δ13C and δ15N) of invertebrates as well as that of plant biomass and belowground detritus and estimated the contributions of the fog plants in their diets. Our findings revealed a complex trophic structure and demonstrated that S. sabulicola fuels carbon flow from lower to higher trophic levels in the aboveground food web. The distinct δ13C values of bacterial- and fungal-feeding nematodes indicated however the separation of the aboveground niche, which is primarily sustained by S. sabulicola, from the belowground niche, where wind-blown sediments may serve as the main energy source for the soil biota. Our findings further accentuate the critical role of S. sabulicola FPOs in establishing complex trophic dynamics and a distinctive food web within the hyperarid Namib dunes.
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Affiliation(s)
- Huei Ying Gan
- Senckenberg Centre for Human Evolution and Palaeoenvironment, University of Tübingen, Hölderlindstr. 12, 72074, Tübingen, Germany.
| | - Karin Hohberg
- Senckenberg Museum of Natural History Görlitz, Am Museum 1, 02826, Görlitz, Germany
| | - Clément Schneider
- Senckenberg Museum of Natural History Görlitz, Am Museum 1, 02826, Görlitz, Germany
| | - Martin Ebner
- Department of Geosciences, Biogeology, University of Tübingen, Hölderlindstr. 12, 72074, Tübingen, Germany
| | - Eugene Marais
- Gobabeb-Namib Research Institute, Walvis Bay, 13013, Namibia
| | - Tatiana Miranda
- Senckenberg Centre for Human Evolution and Palaeoenvironment, University of Tübingen, Hölderlindstr. 12, 72074, Tübingen, Germany
| | - Ricarda Lehmitz
- Senckenberg Museum of Natural History Görlitz, Am Museum 1, 02826, Görlitz, Germany
| | | | - Hervé Bocherens
- Senckenberg Centre for Human Evolution and Palaeoenvironment, University of Tübingen, Hölderlindstr. 12, 72074, Tübingen, Germany
- Department of Geosciences, Biogeology, University of Tübingen, Hölderlindstr. 12, 72074, Tübingen, Germany
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2
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Liu L, Sayer EJ, Deng M, Li P, Liu W, Wang X, Yang S, Huang J, Luo J, Su Y, Grünzweig JM, Jiang L, Hu S, Piao S. The grassland carbon cycle: Mechanisms, responses to global changes, and potential contribution to carbon neutrality. FUNDAMENTAL RESEARCH 2023; 3:209-218. [PMID: 38932925 PMCID: PMC11197582 DOI: 10.1016/j.fmre.2022.09.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 09/22/2022] [Accepted: 09/28/2022] [Indexed: 11/07/2022] Open
Abstract
Grassland is one of the largest terrestrial biomes, providing critical ecosystem services such as food production, biodiversity conservation, and climate change mitigation. Global climate change and land-use intensification have been causing grassland degradation and desertification worldwide. As one of the primary medium for ecosystem energy flow and biogeochemical cycling, grassland carbon (C) cycling is the most fundamental process for maintaining ecosystem services. In this review, we first summarize recent advances in our understanding of the mechanisms underpinning spatial and temporal patterns of the grassland C cycle, discuss the importance of grasslands in regulating inter- and intra-annual variations in global C fluxes, and explore the previously unappreciated complexity in abiotic processes controlling the grassland C balance, including soil inorganic C accumulation, photochemical and thermal degradation, and wind erosion. We also discuss how climate and land-use changes could alter the grassland C balance by modifying the water budget, nutrient cycling and additional plant and soil processes. Further, we examine why and how increasing aridity and improper land use may induce significant losses in grassland C stocks. Finally, we identify several priorities for future grassland C research, including improving understanding of abiotic processes in the grassland C cycle, strengthening monitoring of grassland C dynamics by integrating ground inventory, flux monitoring, and modern remote sensing techniques, and selecting appropriate plant species combinations with suitable traits and strong resistance to climate fluctuations, which would help design sustainable grassland restoration strategies in a changing climate.
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Affiliation(s)
- Lingli Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Emma J. Sayer
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, United Kingdom
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland
| | - Meifeng Deng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Ping Li
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Weixing Liu
- National Hulunber Grassland Ecosystem Observation and Research Station, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Xin Wang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Sen Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Junsheng Huang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jie Luo
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yanjun Su
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - José M. Grünzweig
- Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Lin Jiang
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332, United States
| | - Shuijin Hu
- Department of Plant Pathology, North Carolina State University, Raleigh, NC 27607, United States
| | - Shilong Piao
- Sino-French Institute for Earth System Science, College of Urban and Environmental Science, Peking University, Beijing 100871, China
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3
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Soil fungal diversity and assembly along a xeric stress gradient in the central Namib Desert. Fungal Biol 2023; 127:997-1003. [PMID: 37024159 DOI: 10.1016/j.funbio.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 03/02/2023] [Accepted: 03/06/2023] [Indexed: 03/09/2023]
Abstract
The Namib Desert of south-western Africa is one of the oldest deserts in the world and possesses unique geographical, biological and climatic features. While research through the last decade has generated a comprehensive survey of the prokaryotic communities in Namib Desert soils, little is yet known about the diversity and function of edaphic fungal communities, and even less of their responses to aridity. In this study, we have characterized soil fungal community diversity across the longitudinal xeric gradient across the Namib desert (for convenience, divided into the western fog zone, the central low-rainfall zone and the eastern high-rainfall zone), using internal transcribed sequence (ITS) metabarcoding. Ascomycota, Basidiomycota and Chytridiomycota consistently dominated the Namib Desert edaphic fungal communities and a core mycobiome composed of only 15 taxa, dominated by members of the class Dothideomycetes (Ascomycota), was identified. However, fungal community structures were significantly different in the fog, low-rainfall and high-rainfall zones. Furthermore, Namib Desert gravel plain fungal community assembly was driven by both deterministic and stochastic processes; the latter dominating in the all three xeric zones. We also present data that suggest that the inland limit of fog penetration represents an ecological barrier to fungal dispersal across the Namib Desert.
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4
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Grünzweig JM, De Boeck HJ, Rey A, Santos MJ, Adam O, Bahn M, Belnap J, Deckmyn G, Dekker SC, Flores O, Gliksman D, Helman D, Hultine KR, Liu L, Meron E, Michael Y, Sheffer E, Throop HL, Tzuk O, Yakir D. Dryland mechanisms could widely control ecosystem functioning in a drier and warmer world. Nat Ecol Evol 2022; 6:1064-1076. [PMID: 35879539 DOI: 10.1038/s41559-022-01779-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/28/2022] [Indexed: 11/09/2022]
Abstract
Responses of terrestrial ecosystems to climate change have been explored in many regions worldwide. While continued drying and warming may alter process rates and deteriorate the state and performance of ecosystems, it could also lead to more fundamental changes in the mechanisms governing ecosystem functioning. Here we argue that climate change will induce unprecedented shifts in these mechanisms in historically wetter climatic zones, towards mechanisms currently prevalent in dry regions, which we refer to as 'dryland mechanisms'. We discuss 12 dryland mechanisms affecting multiple processes of ecosystem functioning, including vegetation development, water flow, energy budget, carbon and nutrient cycling, plant production and organic matter decomposition. We then examine mostly rare examples of the operation of these mechanisms in non-dryland regions where they have been considered irrelevant at present. Current and future climate trends could force microclimatic conditions across thresholds and lead to the emergence of dryland mechanisms and their increasing control over ecosystem functioning in many biomes on Earth.
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Affiliation(s)
- José M Grünzweig
- Institute of Plant Sciences and Genetics in Agriculture, the Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel.
| | - Hans J De Boeck
- Plants and Ecosystems, Department of Biology, Universiteit Antwerpen, Wilrijk, Belgium
| | - Ana Rey
- Department of Biogeography and Global Change, National Museum of Natural History, Spanish National Research Council (CSIC), Madrid, Spain
| | - Maria J Santos
- Department of Geography, University of Zurich, Zurich, Switzerland
| | - Ori Adam
- The Fredy and Nadine Herrmann Institute of Earth Sciences, the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Michael Bahn
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Jayne Belnap
- US Geological Survey, Southwest Biological Science Center, Moab, UT, USA
| | - Gaby Deckmyn
- Plants and Ecosystems, Department of Biology, Universiteit Antwerpen, Wilrijk, Belgium
| | - Stefan C Dekker
- Copernicus Institute of Sustainable Development, Utrecht University, Utrecht, the Netherlands
| | - Omar Flores
- Plants and Ecosystems, Department of Biology, Universiteit Antwerpen, Wilrijk, Belgium.,Department of Biogeography and Global Change, National Museum of Natural History, Spanish National Research Council (CSIC), Madrid, Spain
| | - Daniel Gliksman
- Institute for Hydrology and Meteorology, Faculty of Environmental Sciences, Technische Universität Dresden, Tharandt, Germany.,Institute of Geography, Technische Universität Dresden, Dresden, Germany
| | - David Helman
- Institute of Environmental Sciences, the Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel.,Advanced School for Environmental Studies, the Hebrew University of Jerusalem, Jerusalem, Israel
| | - Kevin R Hultine
- Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, AZ, USA
| | - Lingli Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Xiangshan, Beijing, China
| | - Ehud Meron
- Department of Physics, Ben-Gurion University of the Negev, Beer Sheva, Israel.,Department of Solar Energy and Environmental Physics, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Israel
| | - Yaron Michael
- Institute of Environmental Sciences, the Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
| | - Efrat Sheffer
- Institute of Plant Sciences and Genetics in Agriculture, the Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
| | - Heather L Throop
- School of Earth and Space Exploration, and School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Omer Tzuk
- Department of Physics, Ben-Gurion University of the Negev, Beer Sheva, Israel.,Department of Industrial Engineering, Faculty of Engineering, Tel-Aviv University, Tel Aviv-Yafo, Israel
| | - Dan Yakir
- Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
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5
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Treonis AM, Marais E, Maggs‐Kölling G. Nematode communities indicate diverse soil functioning across a fog gradient in the Namib Desert gravel plains. Ecol Evol 2022; 12:e9013. [PMID: 35784044 PMCID: PMC9205675 DOI: 10.1002/ece3.9013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 05/09/2022] [Accepted: 05/23/2022] [Indexed: 11/27/2022] Open
Abstract
Soil nematodes are fundamentally aquatic animals, requiring water to move, feed, and reproduce. Nonetheless, they are ubiquitous in desert soils because they can enter an anhydrobiotic state that allows them to persist when water is biologically unavailable. In the hyper-arid Namib Desert of Namibia, rain is rare, but fog routinely moves inland from the coast and supports plant and animal life. Very little is understood about how this fog may affect soil organisms. We investigated the role of fog moisture in the ecology of free-living, soil nematodes across an 87-km fog gradient in the gravel plains of the Namib Desert. We found that nematodes emerged from anhydrobiosis and became active during a fog event, suggesting that they can utilize fog moisture to survive. Nematode abundance did not differ significantly across the fog gradient and was similar under shrubs and in interplant spaces. Interplant soils harbor biological soil crusts that may sustain nematode communities. As fog declined along the gradient, nematode diversity increased in interplant soils. In areas where fog is rare, sporadic rainfall events can stimulate the germination and growth of desert ephemerals that may have a lasting effect on nematode diversity. In a 30-day incubation experiment, nematode abundance increased when soils were amended with water and organic matter. However, these responses were not evident in field samples, which show no correlations among nematode abundance, location in the fog gradient, and soil organic matter content. Soil nematodes are found throughout the Namib Desert gravel plains under a variety of conditions. Although shown to be moisture- and organic matter-limited and able to use moisture from the fog for activity, variation in fog frequency and soil organic matter across this unique ecosystem may be biologically irrelevant to soil nematodes in situ.
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Affiliation(s)
- Amy M. Treonis
- Department of BiologyUniversity of RichmondRichmondVirginiaUSA
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6
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Lakra K, Avishek K. A review on factors influencing fog formation, classification, forecasting, detection and impacts. RENDICONTI LINCEI. SCIENZE FISICHE E NATURALI 2022; 33:319-353. [PMID: 35309246 PMCID: PMC8918085 DOI: 10.1007/s12210-022-01060-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 02/05/2022] [Indexed: 11/17/2022]
Abstract
With the changing climate and environment, the nature of fog has also changed and because of its impact on humans and other systems, study of fog becomes essential. Hence, the study of its controlling factors such as the characteristics of condensation nuclei, microphysics, air–surface interaction, moisture, heat fluxes and synoptic conditions also become crucial, along with research in the field of prediction and detection. The current review expands for the period between 1976 to 2021, however, especially focused on the research articles published in the last two decades. It considers 250 research papers/research letters, 24 review papers, four book chapters/manuals, five news articles, 15 reports, six conference papers and five other online readings. This review is a compilation of the pros and cons of the techniques used to determine the factors influencing fog formation, its classification, tools and techniques available for its detection and forecast. Some recent advanced are also discussed in this review: role of soil properties on fogs, application of microwave communication links in the detection of fog, new class of smog, and how the cognitive abilities of humans are affected by fog. Recently India and China are facing an emergence and repetitions of fog haze/smog and thus their policies initiatives are also briefly discussed. It is concluded that the complexity in fog forecasting is high due to multiple factors playing a role at multiple levels. Most of the researchers have worked upon the role of humidity, temperature, wind, and boundary layer to predict fogs. However, the role of global wind circulations, soil properties, and anthropogenic heat requires further investigations. Literature shows that fog is being harnessed to address water insecurity in various countries, however, coastal areas of Angola, Namibia and South Africa, Kenya, Eastern Yemen, Oman, China, India, Sri Lanka, Mexico, along with the mountainous regions of Peru, Chile, and Ecuador, are some of the potential sites that can benefit from the installation of fog water harvesting systems.
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7
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Logan JR, Barnes P, Evans SE. Photodegradation of plant litter cuticles enhances microbial decomposition by increasing uptake of non‐rainfall moisture. Funct Ecol 2022. [DOI: 10.1111/1365-2435.14053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- J. Robert Logan
- W.K. Kellogg Biological Station Hickory Corners 3700 East Gull Lake Drive MI 49060 USA
- Department of Integrative Biology Michigan State University 288 Farm Lane East Lansing MI 7 48824 USA
- Ecology, Evolution, and Behavior Program Michigan State University 293 Farm Lane East, Lansing MI 48824 USA
| | - Paul Barnes
- Department of Biological Sciences and Environment Program Loyola University New Orleans 6363 St. Charles Avenue New Orleans LA 70118 USA
| | - Sarah E. Evans
- W.K. Kellogg Biological Station Hickory Corners 3700 East Gull Lake Drive MI 49060 USA
- Department of Integrative Biology Michigan State University 288 Farm Lane East Lansing MI 7 48824 USA
- Ecology, Evolution, and Behavior Program Michigan State University 293 Farm Lane East, Lansing MI 48824 USA
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8
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Abstract
Arid ecosystems cover ∼40% of the Earth's terrestrial surface and store a high proportion of the global nitrogen (N) pool. They are low-productivity, low-biomass, and polyextreme ecosystems, i.e., with (hyper)arid and (hyper)oligotrophic conditions and high surface UV irradiation and evapotranspiration. These polyextreme conditions severely limit the presence of macrofauna and -flora and, particularly, the growth and productivity of plant species. Therefore, it is generally recognized that much of the primary production (including N-input processes) and nutrient biogeochemical cycling (particularly N cycling) in these ecosystems are microbially mediated. Consequently, we present a comprehensive survey of the current state of knowledge of biotic and abiotic N-cycling processes of edaphic (i.e., open soil, biological soil crust, or plant-associated rhizosphere and rhizosheath) and hypo/endolithic refuge niches from drylands in general, including hot, cold, and polar desert ecosystems. We particularly focused on the microbially mediated biological nitrogen fixation, N mineralization, assimilatory and dissimilatory nitrate reduction, and nitrification N-input processes and the denitrification and anaerobic ammonium oxidation (anammox) N-loss processes. We note that the application of modern meta-omics and related methods has generated comprehensive data sets on the abundance, diversity, and ecology of the different N-cycling microbial guilds. However, it is worth mentioning that microbial N-cycling data from important deserts (e.g., Sahara) and quantitative rate data on N transformation processes from various desert niches are lacking or sparse. Filling this knowledge gap is particularly important, as climate change models often lack data on microbial activity and environmental microbial N-cycling communities can be key actors of climate change by producing or consuming nitrous oxide (N2O), a potent greenhouse gas.
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Chamizo S, Rodríguez-Caballero E, Moro MJ, Cantón Y. Non-rainfall water inputs: A key water source for biocrust carbon fixation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 792:148299. [PMID: 34146814 DOI: 10.1016/j.scitotenv.2021.148299] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/01/2021] [Accepted: 06/01/2021] [Indexed: 06/12/2023]
Abstract
Links between water and carbon (C) cycles in drylands are strongly regulated by biocrusts. These widespread communities in the intershrub spaces of drylands are able to use non-rainfall water inputs (NRWI) (fog, dewfall and water vapour) to become active and fix carbon dioxide (CO2), converting biocrusts into the main soil C contributors during periods in which vegetation remains inactive. In this study, we first evaluated the influence of biocrust type on NRWI uptake using automated microlysimeters, and second, we performed an outdoor experiment to examine how NRWI affected C exchange (photosynthesis and respiration) in biocrusts. NRWI uptake increased from incipient cyanobacteria to well-developed cyanobacteria and lichen biocrusts. NRWI triggered biocrust activity but with contrasting effects on CO2 fluxes depending on the main NRWI source. Fog mainly stimulated respiration of biocrust-covered soils, reaching net CO2 emissions of 0.68 μmol m-2 s-1, while dew had a greater effect stimulating biocrust photosynthesis and resulted in net CO2 uptake of 0.66 μmol m-2 s-1. These findings demonstrate the key role that NRWI play in biocrust activity and the soil C balance in drylands.
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Affiliation(s)
- Sonia Chamizo
- Department of Agronomy, University of Almeria, 04120 Almeria, Spain; Research Centre for Scientific Collections from the University of Almeria (CECOUAL), 04120 Almeria, Spain.
| | - Emilio Rodríguez-Caballero
- Department of Agronomy, University of Almeria, 04120 Almeria, Spain; Research Centre for Scientific Collections from the University of Almeria (CECOUAL), 04120 Almeria, Spain
| | - María José Moro
- Department of Ecology, University of Alicante, 03690 Alicante, Spain
| | - Yolanda Cantón
- Department of Agronomy, University of Almeria, 04120 Almeria, Spain; Research Centre for Scientific Collections from the University of Almeria (CECOUAL), 04120 Almeria, Spain
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10
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Wenndt AJ, Evans SE, van Diepeningen AD, Logan JR, Jacobson PJ, Seely MK, Jacobson KM. Why Plants Harbor Complex Endophytic Fungal Communities: Insights From Perennial Bunchgrass Stipagrostis sabulicola in the Namib Sand Sea. Front Microbiol 2021; 12:691584. [PMID: 34168636 PMCID: PMC8217645 DOI: 10.3389/fmicb.2021.691584] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 05/10/2021] [Indexed: 01/16/2023] Open
Abstract
All perennial plants harbor diverse endophytic fungal communities, but why they tolerate these complex asymptomatic symbioses is unknown. Using a multi-pronged approach, we conclusively found that a dryland grass supports endophyte communities comprised predominantly of latent saprophytes that can enhance localized nutrient recycling after senescence. A perennial bunchgrass, Stipagrostis sabulicola, which persists along a gradient of extreme abiotic stress in the hyper-arid Namib Sand Sea, was the focal point of our study. Living tillers yielded 20 fungal endophyte taxa, 80% of which decomposed host litter during a 28-day laboratory decomposition assay. During a 6-month field experiment, tillers with endophytes decomposed twice as fast as sterilized tillers, consistent with the laboratory assay. Furthermore, profiling the community active during decomposition using next-generation sequencing revealed that 59-70% of the S. sabulicola endophyte community is comprised of latent saprophytes, and these dual-niche fungi still constitute a large proportion (58-62%) of the litter community more than a year after senescence. This study provides multiple lines of evidence that the fungal communities that initiate decomposition of standing litter develop in living plants, thus providing a plausible explanation for why plants harbor complex endophyte communities. Using frequent overnight non-rainfall moisture events (fog, dew, high humidity), these latent saprophytes can initiate decomposition of standing litter immediately after tiller senescence, thus maximizing the likelihood that plant-bound nutrients are recycled in situ and contribute to the nutrient island effect that is prevalent in drylands.
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Affiliation(s)
- Anthony J Wenndt
- Plant Pathology and Plant-Microbe Biology, School of Integrative Plant Sciences, Cornell University, Ithaca, NY, United States
| | - Sarah E Evans
- Department of Integrative Biology, Michigan State University, East Lansing, MI, United States.,W.K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, United States
| | - Anne D van Diepeningen
- B.U. Biointeractions and Plant Health, Wageningen Plant Research, Wageningen University and Research, Wageningen, Netherlands
| | - J Robert Logan
- Department of Integrative Biology, Michigan State University, East Lansing, MI, United States.,W.K. Kellogg Biological Station, Michigan State University, Hickory Corners, MI, United States
| | - Peter J Jacobson
- Department of Biology, Grinnell College, Grinnell, IA, United States
| | - Mary K Seely
- Desert Research Foundation of Namibia, Windhoek, Namibia
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11
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Moreira EA, Persinoti GF, Menezes LR, Paixão DAA, Alvarez TM, Cairo JPLF, Squina FM, Costa-Leonardo AM, Rodrigues A, Sillam-Dussès D, Arab A. Complementary Contribution of Fungi and Bacteria to Lignocellulose Digestion in the Food Stored by a Neotropical Higher Termite. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.632590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Lignocellulose digestion in termites is achieved through the functional synergy between gut symbionts and host enzymes. However, some species have evolved additional associations with nest microorganisms that collaborate in the decomposition of plant biomass. In a previous study, we determined that plant material packed with feces inside the nests of Cornitermes cumulans (Syntermitinae) harbors a distinct microbial assemblage. These food nodules also showed a high hemicellulolytic activity, possibly acting as an external place for complementary lignocellulose digestion. In this study, we used a combination of ITS sequence analysis, metagenomics, and metatranscriptomics to investigate the presence and differential expression of genes coding for carbohydrate-active enzymes (CAZy) in the food nodules and the gut of workers and soldiers. Our results confirm that food nodules express a distinct set of CAZy genes suggesting that stored plant material is initially decomposed by enzymes that target the lignin and complex polysaccharides from fungi and bacteria before the passage through the gut, where it is further targeted by a complementary set of cellulases, xylanases, and esterases produced by the gut microbiota and the termite host. We also showed that the expression of CAZy transcripts associated to endoglucanases and xylanases was higher in the gut of termites than in the food nodules. An additional finding in this study was the presence of fungi in the termite gut that expressed CAZy genes. This study highlights the importance of externalization of digestion by nest microbes and provides new evidence of complementary digestion in the context of higher termite evolution.
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12
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Logan JR, Jacobson KM, Jacobson PJ, Evans SE. Fungal Communities on Standing Litter Are Structured by Moisture Type and Constrain Decomposition in a Hyper-Arid Grassland. Front Microbiol 2021; 12:596517. [PMID: 33716999 PMCID: PMC7943874 DOI: 10.3389/fmicb.2021.596517] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 02/03/2021] [Indexed: 12/26/2022] Open
Abstract
Non-rainfall moisture (fog, dew, and water vapor; NRM) is an important driver of plant litter decomposition in grasslands, where it can contribute significantly to terrestrial carbon cycling. However, we still do not know whether microbial decomposers respond differently to NRM and rain, nor whether this response affects litter decomposition rates. To determine how local moisture regimes influence decomposer communities and their function, we examined fungal communities on standing grass litter at an NRM-dominated site and a rain-dominated site 75 km apart in the hyper-arid Namib Desert using a reciprocal transplant design. Dominant taxa at both sites consisted of both extremophilic and cosmopolitan species. Fungal communities differed between the two moisture regimes with environment having a considerably stronger effect on community composition than did stage of decomposition. Community composition was influenced by the availability of air-derived spores at each site and by specialization of fungi to their home environment; specifically, fungi from the cooler, moister NRM Site performed worse (measured as fungal biomass and litter mass loss) when moved to the warmer, drier rain-dominated site while Rain Site fungi performed equally well in both environments. Our results contribute to growing literature demonstrating that as climate change alters the frequency, magnitude and type of moisture events in arid ecosystems, litter decomposition rates may be altered and constrained by the composition of existing decomposer communities.
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Affiliation(s)
- J Robert Logan
- W.K. Kellogg Biological Station, Hickory Corners, MI, United States.,Department of Integrative Biology, Michigan State University, East Lansing, MI, United States.,Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, United States
| | | | - Peter J Jacobson
- Department of Biology, Grinnell College, Grinnell, IA, United States
| | - Sarah E Evans
- W.K. Kellogg Biological Station, Hickory Corners, MI, United States.,Department of Integrative Biology, Michigan State University, East Lansing, MI, United States.,Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, United States
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13
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Functional importance and diversity of fungi during standing grass litter decomposition. Oecologia 2021; 195:499-512. [PMID: 33423104 DOI: 10.1007/s00442-020-04838-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/17/2020] [Indexed: 01/16/2023]
Abstract
Although microbial participation in litter decomposition is widely known within terrestrial soils, the role and significance of microorganisms during the aerial standing litter phase of decomposition remains poorly investigated. We examined the fungi inhabiting standing leaf litter of Schizachyrium scoparium and Schizachyrium tenerum in a Longleaf Pine savanna ecosystem and estimated their contribution to litter decomposition. We identified fungal phylotypes associated with leaf litter and quantified leaf C mass loss, fungal biomass production, and microbial respiration during decomposition. These data were used to construct budgets estimating C flow into and through fungi. Significant losses in S. scoparium (55%) and S. tenerum (67%) leaf C mass were observed during standing decomposition along with concomitant increases in fungal biomass, which reached a maximum of 36 and 33 mgC/g detrital C, respectively. Cumulative fungal production during decomposition totaled 99 ± 6 mgC/g initial detrital C in S. scoparium and 73 ± 5 mgC/g initial detrital C in S. tenerum, indicating that 18 and 11% of the litter C was converted into fungal biomass, respectively. Corresponding estimates of cumulative fungal respiration totaled 106 ± 7 and 174 ± 11 mgC/g initial detrital C in S. scoparium and S. tenerum, respectively. Next generation sequencing identified several fungal phylotypes, with the majority of sequences belonging to the Ascomycota (Dothideomycetes) and Basidiomycota (Agaricomycetes). Fungal phylotypes were similar between litter species and changed over time, showing a successional pattern. These findings extend our understanding of fungal processes to standing litter in terrestrial ecosystems, and highlight the quantitative importance of fungi in C cycling processes.
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Impact of Field and Laboratory Environmental Conditions on the Diversity of Wood-Decay Fungi in the Forests of Northwest Arkansas. JOURNAL OF PURE AND APPLIED MICROBIOLOGY 2020. [DOI: 10.22207/jpam.14.3.18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Environmental factors such as temperature and humidity directly affect the growth and fruit bodies of fungi. We studied the diversity of wood decaying fungal species, which have grown on same substrate in forest as well as laboratory environment. Ten specimens of fruit body of wood-decaying fungi and 24 random pieces of coarse wooden debris were collected from the forest of northwest Arkansas. The samples of coarse woody debris were incubated in laboratory-growth chambers for two months to promote the fungal growth. Fourty-two different species of wood-decay fungal isolates were recovered and identified by internal transcribed spacer (ITS) region sequencing. The isolates from the forest belonged to twenty-two different taxa whereas twenty taxonomic groups were reported from the growth compartments. Remarkably, data observed from two sets did not shared any taxon. These results indicated that environmental growth conditions play crucial role on fungal diversity even if grown on same substrates.
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Macro-detritivores Assist Resolving the Dryland Decomposition Conundrum by Engineering an Underworld Heaven for Decomposers. Ecosystems 2020. [DOI: 10.1007/s10021-020-00504-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Wang J, Liu W, Li P, Jia Z, Deng M, Yang S, Liu L. Long‐term deepened snow cover alters litter layer turnover rate in temperate steppes. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13531] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jing Wang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China
- College of Life Sciences Hebei University Baoding China
| | - Weixing Liu
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China
| | - Ping Li
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Zhou Jia
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Meifeng Deng
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China
| | - Sen Yang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Lingli Liu
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
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Non-rainfall Moisture: A Key Driver of Microbial Respiration from Standing Litter in Arid, Semiarid, and Mesic Grasslands. Ecosystems 2019. [DOI: 10.1007/s10021-019-00461-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Abstract
Models assume that rainfall is the major moisture source driving decomposition. Non-rainfall moisture (NRM: high humidity, dew, and fog) can also induce standing litter decomposition, but there have been few measurements of NRM-mediated decomposition across sites and no efforts to extrapolate the contribution of NRM to larger scales to assess whether this mechanism can improve model predictions. Here, we show that NRM is an important, year-round source of moisture in grassland sites with contrasting moisture regimes using field measurements and modeling. We first characterized NRM frequency and measured NRM-mediated decomposition at two sites in the Namib Desert, Namibia (hyper-arid desert), and at one site in Iowa, USA (tallgrass prairie). NRM was frequent at all sites (85–99% of hours that litter was likely to be wet were attributed to NRM) and tended to occur in cool, high-humidity periods for several hours or more at a time. NRM also resulted in CO2 release from microbes in standing litter at all sites when litter became sufficiently wet (> 5% gravimetric moisture for fine litter and > 13% for coarse), and significantly contributed to mass loss, particularly in the western Namib site that received almost no rain. When we modeled annual mass loss induced by NRM and rain and extrapolated our characterization of NRM decomposition to a final semiarid site (Sevilleta, New Mexico), we found that models driven by rainfall alone underestimated mass loss, while including NRM resulted in estimates within the range of observed mass loss. Together these findings suggest that NRM is an important missing component in quantitative and conceptual models of litter decomposition, but there is nuance involved in modeling NRM at larger scales.
Specifically, temperature and physical features of the substrate emerge as factors that affect the microbial response to litter wetting under NRM in our sites, and require further study. Hourly humidity can provide an adequate proxy of NRM frequency, but site-specific calibration with litter wetness is needed to accurately attribute decomposition to periods when NRM wets litter. Greater recognition of NRM-driven decomposition and its interaction with other processes like photodegradation is needed, especially since fog, dew, and humidity are likely to shift under future climates.
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Sagi N, Grünzweig JM, Hawlena D. Burrowing detritivores regulate nutrient cycling in a desert ecosystem. Proc Biol Sci 2019; 286:20191647. [PMID: 31662076 PMCID: PMC6842856 DOI: 10.1098/rspb.2019.1647] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Nutrient cycling in most terrestrial ecosystems is controlled by moisture-dependent decomposer activity. In arid ecosystems, plant litter cycling exceeds rates predicted based on precipitation amounts, suggesting that additional factors are involved. Attempts to reveal these factors have focused on abiotic degradation, soil-litter mixing and alternative moisture sources. Our aim was to explore an additional hypothesis that macro-detritivores control litter cycling in deserts. We quantified the role different organisms play in clearing plant detritus from the desert surface, using litter baskets with different mesh sizes that allow selective entry of micro-, meso- or macrofauna. We also measured soil nutrient concentrations in increasing distances from the burrows of a highly abundant macro-detritivore, the desert isopod Hemilepistus reaumuri. Macro-detritivores controlled the clearing of plant litter in our field site. The highest rates of litter removal were measured during the hot and dry summer when isopod activity peaks and microbial activity is minimal. We also found substantial enrichment of inorganic nitrogen and phosphorous near isopod burrows. We conclude that burrowing macro-detritivores are important regulators of litter cycling in this arid ecosystem, providing a plausible general mechanism that explains the unexpectedly high rates of plant litter cycling in deserts.
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Affiliation(s)
- Nevo Sagi
- Risk-Management Ecology Lab, Department of Ecology, Evolution and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91905, Israel
| | - José M Grünzweig
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Dror Hawlena
- Risk-Management Ecology Lab, Department of Ecology, Evolution and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91905, Israel
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20
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Habitability of Mars: How Welcoming Are the Surface and Subsurface to Life on the Red Planet? GEOSCIENCES 2019. [DOI: 10.3390/geosciences9090361] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mars is a planet of great interest in the search for signatures of past or present life beyond Earth. The years of research, and more advanced instrumentation, have yielded a lot of evidence which may be considered by the scientific community as proof of past or present habitability of Mars. Recent discoveries including seasonal methane releases and a subglacial lake are exciting, yet challenging findings. Concurrently, laboratory and environmental studies on the limits of microbial life in extreme environments on Earth broaden our knowledge of the possibility of Mars habitability. In this review, we aim to: (1) Discuss the characteristics of the Martian surface and subsurface that may be conducive to habitability either in the past or at present; (2) discuss laboratory-based studies on Earth that provide us with discoveries on the limits of life; and (3) summarize the current state of knowledge in terms of direction for future research.
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Abstract
The Namib Desert is one of the world's only truly coastal desert ecosystem. Until the end of the 1st decade of the twenty-first century, very little was known of the microbiology of this southwestern African desert, with the few reported studies being based solely on culture-dependent approaches. However, from 2010, an intense research program was undertaken by researchers from the University of the Western Cape Institute for Microbial Biotechnology and Metagenomics, and subsequently the University of Pretoria Centre for Microbial Ecology and Genomics, and their collaborators, led to a more detailed understanding of the ecology of the indigenous microbial communities in many Namib Desert biotopes. Namib Desert soils and the associated specialized niche communities are inhabited by a wide array of prokaryotic, lower eukaryotic and virus/phage taxa. These communities are highly heterogeneous on both small and large spatial scales, with community composition impacted by a range of macro- and micro-environmental factors, from water regime to soil particle size. Community functionality is also surprisingly non-homogeneous, with some taxa retaining functionality even under hyper-arid soil conditions, and with subtle changes in gene expression and phylotype abundances even on diel timescales. Despite the growing understanding of the structure and function of Namib Desert microbiomes, there remain enormous gaps in our knowledge. We have yet to quantify many of the processes in these soil communities, from regional nutrient cycling to community growth rates. Despite the progress that has been made, we still have little knowledge of either the role of phages in microbial community dynamics or inter-species interactions. Furthermore, the intense research efforts of the past decade have highlighted the immense scope for future microbiological research in this dynamic, enigmatic and charismatic region of Africa.
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León-Sobrino C, Ramond JB, Maggs-Kölling G, Cowan DA. Nutrient Acquisition, Rather Than Stress Response Over Diel Cycles, Drives Microbial Transcription in a Hyper-Arid Namib Desert Soil. Front Microbiol 2019; 10:1054. [PMID: 31139170 PMCID: PMC6527771 DOI: 10.3389/fmicb.2019.01054] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 04/26/2019] [Indexed: 11/13/2022] Open
Abstract
Hot desert surface soils are characterized by extremely low water activities for large parts of any annual cycle. It is widely assumed that microbial processes in such soils are very limited. Here we present the first metatranscriptomic survey of microbial community function in a low water activity hyperarid desert soil. Sequencing of total mRNA revealed a diverse and active community, dominated by Actinobacteria. Metatranscriptomic analysis of samples taken at different times over 3 days indicated that functional diel variations were limited at the whole community level, and mostly affected the eukaryotic subpopulation which was induced during the cooler night hours. High levels of transcription of chemoautotrophic carbon fixation genes contrasted with limited expression of photosynthetic genes, indicating that chemoautotrophy is an important alternative to photosynthesis for carbon cycling in desiccated desert soils. Analysis of the transcriptional levels of key N-cycling genes provided strong evidence that soil nitrate was the dominant nitrogen input source. Transcriptional network analyses and taxon-resolved functional profiling suggested that nutrient acquisition processes, and not diurnal environmental variation, were the main drivers of community activity in hyperarid Namib Desert soil. While we also observed significant levels of expression of common stress response genes, these genes were not dominant hubs in the co-occurrence network.
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Affiliation(s)
- Carlos León-Sobrino
- Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
| | - Jean-Baptiste Ramond
- Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
| | | | - Don A. Cowan
- Centre for Microbial Ecology and Genomics, University of Pretoria, Pretoria, South Africa
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24
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Evans SE, Dueker ME, Logan JR, Weathers KC. The biology of fog: results from coastal Maine and Namib Desert reveal common drivers of fog microbial composition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 647:1547-1556. [PMID: 30180359 DOI: 10.1016/j.scitotenv.2018.08.045] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/28/2018] [Accepted: 08/03/2018] [Indexed: 06/08/2023]
Abstract
Fog supplies water and nutrients to systems ranging from coastal forests to inland deserts. Fog droplets can also contain bacterial and fungal aerosols, but our understanding of fog biology is limited. Using metagenomic tools and culturing, we provide a unique look at fungal and bacterial communities in fog at two fog-dominated sites: coastal Maine (USA) and the Namib Desert (Namibia). Microbial communities in the fog at both sites were diverse, distinct from clear aerosols, and influenced by both soil and marine sources. Fog from both sites contained Actinobacteria and Firmicutes, commonly soil- and air-associated phyla, but also contained bacterial taxa associated with marine environments including Cyanobacteria, Oceanospirillales, Novosphingobium, Pseudoalteromonas, and Bradyrhizobiaceae. Marine influence on fog communities was greatest near the coast, but still evident in Namib fogs 50 km inland. In both systems, differences between pre- and post-fog aerosol communities suggest that fog events can significantly alter microbial aerosol diversity and composition. Fog is likely to enhance viability of transported microbes and facilitate their deposition, making fog biology ecologically important in fog-dominated environments. Fog may introduce novel species to terrestrial ecosystems, including human and plant pathogens, warranting further work on the drivers of this important and underrecognized aerobiological transfer between marine and terrestrial systems.
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Affiliation(s)
- Sarah E Evans
- Kellogg Biological Station, Department of Integrative Biology, Department of Microbiology and Molecular Genetics, Michigan State University, Hickory Corners, MI, USA.
| | - M Elias Dueker
- Biology Program & Environmental and Urban Studies Program, Bard College, Campus Road, PO Box 5000, Annandale-on-Hudson, NY 12504, USA; Cary Institute of Ecosystem Studies, Box AB, Millbrook, NY 12545-0129, USA; Bard Center for the Study of Land, Air, and Water, Bard College, Campus Road, PO Box 5000, Annandale-on-Hudson, NY 12504, USA.
| | - J Robert Logan
- Kellogg Biological Station, Department of Integrative Biology, Department of Microbiology and Molecular Genetics, Michigan State University, Hickory Corners, MI, USA
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25
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Gliksman D, Haenel S, Grünzweig JM. Biotic and abiotic modifications of leaf litter during dry periods affect litter mass loss and nitrogen loss during wet periods. Funct Ecol 2017. [DOI: 10.1111/1365-2435.13018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel Gliksman
- Robert H. Smith Institute of Plant Sciences and Genetics in AgricultureRobert H. Smith Faculty of Agriculture, Food and Environmentthe Hebrew University of Jerusalem Rehovot Israel
| | - Sabine Haenel
- Faculty of Agriculture/Environment/ChemistryUniversity of Applied Sciences HTW‐Dresden Dresden Germany
| | - José M. Grünzweig
- Robert H. Smith Institute of Plant Sciences and Genetics in AgricultureRobert H. Smith Faculty of Agriculture, Food and Environmentthe Hebrew University of Jerusalem Rehovot Israel
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26
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Gliksman D, Rey A, Seligmann R, Dumbur R, Sperling O, Navon Y, Haenel S, De Angelis P, Arnone JA, Grünzweig JM. Biotic degradation at night, abiotic degradation at day: positive feedbacks on litter decomposition in drylands. GLOBAL CHANGE BIOLOGY 2017; 23:1564-1574. [PMID: 27520482 DOI: 10.1111/gcb.13465] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 06/02/2016] [Accepted: 07/25/2016] [Indexed: 06/06/2023]
Abstract
The arid and semi-arid drylands of the world are increasingly recognized for their role in the terrestrial net carbon dioxide (CO2 ) uptake, which depends largely on plant litter decomposition and the subsequent release of CO2 back to the atmosphere. Observed decomposition rates in drylands are higher than predictions by biogeochemical models, which are traditionally based on microbial (biotic) degradation enabled by precipitation as the main mechanism of litter decomposition. Consequently, recent research in drylands has focused on abiotic mechanisms, mainly photochemical and thermal degradation, but they only partly explain litter decomposition under dry conditions, suggesting the operation of an additional mechanism. Here we show that in the absence of precipitation, absorption of dew and water vapor by litter in the field enables microbial degradation at night. By experimentally manipulating solar irradiance and nighttime air humidity, we estimated that most of the litter CO2 efflux and decay occurring in the dry season was due to nighttime microbial degradation, with considerable additional contributions from photochemical and thermal degradation during the daytime. In a complementary study, at three sites across the Mediterranean Basin, litter CO2 efflux was largely explained by litter moisture driving microbial degradation and ultraviolet radiation driving photodegradation. We further observed mutual enhancement of microbial activity and photodegradation at a daily scale. Identifying the interplay of decay mechanisms enhances our understanding of carbon turnover in drylands, which should improve the predictions of the long-term trend of global carbon sequestration.
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Affiliation(s)
- Daniel Gliksman
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 7610001, Israel
| | - Ana Rey
- Department of Biogeography and Global Change, National Museum of Natural History, Spanish Scientific Council (CSIC), C/Serrano 115bis, 28006, Madrid, Spain
| | - Ron Seligmann
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 7610001, Israel
| | - Rita Dumbur
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 7610001, Israel
| | - Or Sperling
- Department of Plant Sciences, University of California, Davis, CA, USA
| | - Yael Navon
- Ramat Hanadiv Nature Park, Zichron Yakov, Israel
| | - Sabine Haenel
- Faculty of Agriculture/Landscape Management, University of Applied Sciences HTW-Dresden, Pillnitzer Platz 2, 01326, Dresden, Germany
| | - Paolo De Angelis
- DIBAF (Department for Innovation in Biological, Agro-Food and Forest Systems), University of Tuscia, Via San Camillo de Lellis, 01100, Viterbo, Italy
| | - John A Arnone
- Desert Research Institute, 2215 Raggio Pkwy, Reno, NV, 89512, USA
| | - José M Grünzweig
- Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 7610001, Israel
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27
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Wang J, Liu L, Wang X, Yang S, Zhang B, Li P, Qiao C, Deng M, Liu W. High night‐time humidity and dissolved organic carbon content support rapid decomposition of standing litter in a semi‐arid landscape. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12854] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Jing Wang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China
| | - Lingli Liu
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China
| | - Xin Wang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
| | - Sen Yang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China
| | - Beibei Zhang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China
| | - Ping Li
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China
| | - Chunlian Qiao
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China
| | - Meifeng Deng
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- College of Resources and Environment University of Chinese Academy of Sciences Beijing100049 China
| | - Weixing Liu
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
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28
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Eriksson BG. Organic textile waste as a resource for sustainable agriculture in arid and semi-arid areas. AMBIO 2017; 46:155-161. [PMID: 27665583 PMCID: PMC5274623 DOI: 10.1007/s13280-016-0822-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 08/02/2016] [Accepted: 09/13/2016] [Indexed: 05/16/2023]
Abstract
New vegetation in barren areas offers possibilities for sequestering carbon in the soil. Arid and semi-arid areas (ASAs) are candidates for new vegetation. The possibility of agriculture in ASAs is reviewed, revealing the potential for cultivation by covering the surface with a layer of organic fibres. This layer collects more water from humidity in the air than does the uncovered mineral surface, and creates a humid environment that promotes microbial life. One possibility is to use large amounts of organic fibres for soil enhancement in ASAs. In the context of the European Commission Waste Framework Directive, the possibility of using textile waste from Sweden is explored. The costs for using Swedish textile waste are high, but possible gains are the sale of agricultural products and increased land prices as well as environmental mitigation. The findings suggest that field research on such agriculture in ASAs should start as soon as possible.
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Affiliation(s)
- Bo G Eriksson
- Department of Sociology and Work Science, Retired from University of Gothenburg, Sveagatan 29, 413 14, Gothenburg, Sweden.
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29
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The Impact of Rainfall on Soil Moisture Dynamics in a Foggy Desert. PLoS One 2016; 11:e0164982. [PMID: 27764203 PMCID: PMC5072646 DOI: 10.1371/journal.pone.0164982] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 10/04/2016] [Indexed: 11/20/2022] Open
Abstract
Soil moisture is a key variable in dryland ecosystems since it determines the occurrence and duration of vegetation water stress and affects the development of weather patterns including rainfall. However, the lack of ground observations of soil moisture and rainfall dynamics in many drylands has long been a major obstacle in understanding ecohydrological processes in these ecosystems. It is also uncertain to what extent rainfall controls soil moisture dynamics in fog dominated dryland systems. To this end, in this study, twelve to nineteen months' continuous daily records of rainfall and soil moisture (from January 2014 to August 2015) obtained from three sites (one sand dune site and two gravel plain sites) in the Namib Desert are reported. A process-based model simulating the stochastic soil moisture dynamics in water-limited systems was used to study the relationships between soil moisture and rainfall dynamics. Model sensitivity in response to different soil and vegetation parameters under diverse soil textures was also investigated. Our field observations showed that surface soil moisture dynamics generally follow rainfall patterns at the two gravel plain sites, whereas soil moisture dynamics in the sand dune site did not show a significant relationship with rainfall pattern. The modeling results suggested that most of the soil moisture dynamics can be simulated except the daily fluctuations, which may require a modification of the model structure to include non-rainfall components. Sensitivity analyses suggested that soil hygroscopic point (sh) and field capacity (sfc) were two main parameters controlling soil moisture output, though permanent wilting point (sw) was also very sensitive under the parameter setting of sand dune (Gobabeb) and gravel plain (Kleinberg). Overall, the modeling results were not sensitive to the parameters in non-bounded group (e.g., soil hydraulic conductivity (Ks) and soil porosity (n)). Field observations, stochastic modeling results as well as sensitivity analyses provide soil moisture baseline information for future monitoring and the prediction of soil moisture patterns in the Namib Desert.
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Almagro M, Martínez-López J, Maestre FT, Rey A. The Contribution of Photodegradation to Litter Decomposition in Semiarid Mediterranean Grasslands Depends on its Interaction with Local Humidity Conditions, Litter Quality and Position. Ecosystems 2016. [DOI: 10.1007/s10021-016-0036-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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van der Walt AJ, Johnson RM, Cowan DA, Seely M, Ramond JB. Unique Microbial Phylotypes in Namib Desert Dune and Gravel Plain Fairy Circle Soils. Appl Environ Microbiol 2016; 82:4592-4601. [PMID: 27208111 PMCID: PMC4984285 DOI: 10.1128/aem.00844-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/16/2016] [Indexed: 01/05/2023] Open
Abstract
UNLABELLED Fairy circles (FCs) are barren circular patches of soil surrounded by grass species. Their origin is poorly understood. FCs feature in both the gravel plains and the dune fields of the Namib Desert. While a substantial number of hypotheses to explain the origin and/or maintenance of fairy circles have been presented, none are completely consistent with either their properties or their distribution. In this study, we investigated the hypothesis that FC formation in dunes and gravel plains is due to microbial phytopathogenesis. Surface soils from five gravel plain and five dune FCs, together with control soil samples, were analyzed using high-throughput sequencing of bacterial/archaeal (16S rRNA gene) and fungal (internal transcribed spacer [ITS] region) phylogenetic markers. Our analyses showed that gravel plain and dune FC microbial communities are phylogenetically distinct and that FC communities differ from those of adjacent vegetated soils. Furthermore, various soil physicochemical properties, particularly the pH, the Ca, P, Na, and SO4 contents, the soil particle size, and the percentage of carbon, significantly influenced the compositions of dune and gravel plain FC microbial communities, but none were found to segregate FC and vegetated soil communities. Nevertheless, 9 bacterial, 1 archaeal, and 57 fungal phylotypes were identified as FC specific, since they were present within the gravel plain and dune FC soils only, not in the vegetated soils. Some of these FC-specific phylotypes were assigned to taxa known to harbor phytopathogenic microorganisms. This suggests that these FC-specific microbial taxa may be involved in the formation and/or maintenance of Namib Desert FCs. IMPORTANCE Fairy circles (FCs) are mysterious barren circular patches of soil found within a grass matrix in the dune fields and gravel plains of the Namib Desert. Various hypotheses attempting to explain this phenomenon have been proposed. To date, however, none have been successful in fully explaining the etiology of FCs, particularly since gravel plain FCs have been largely ignored. In this study, we investigated the hypothesis that microorganisms could be involved in the FC phenomenon through phytopathogenesis. We show that the microbial communities in FC and control vegetated soil samples were significantly different. Furthermore, we detected 67 FC-specific microbial phylotypes, i.e., phylotypes present solely in both gravel plain and dune FC soils, some of which were closely related to known phytopathogens. Our results, therefore, demonstrate that microorganisms may play a role in the formation and/or maintenance of Namib Desert FCs, possibly via phytopathogenic activities.
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Affiliation(s)
- Andries J van der Walt
- Centre for Microbial Ecology and Genomics (CMEG), Genomics Research Institute, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Riegardt M Johnson
- Centre for Microbial Ecology and Genomics (CMEG), Genomics Research Institute, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Don A Cowan
- Centre for Microbial Ecology and Genomics (CMEG), Genomics Research Institute, Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Mary Seely
- Gobabeb Research and Training Centre, Walvis Bay, Namibia
- School of Animal, Plant and Environmental Sciences (AP&ES), University of the Witwatersrand, Johannesburg, South Africa
| | - Jean-Baptiste Ramond
- Centre for Microbial Ecology and Genomics (CMEG), Genomics Research Institute, Department of Genetics, University of Pretoria, Pretoria, South Africa
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Ronca S, Ramond JB, Jones BE, Seely M, Cowan DA. Namib Desert dune/interdune transects exhibit habitat-specific edaphic bacterial communities. Front Microbiol 2015; 6:845. [PMID: 26388839 PMCID: PMC4560024 DOI: 10.3389/fmicb.2015.00845] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/03/2015] [Indexed: 01/20/2023] Open
Abstract
The sand dunes and inter-dune zones of the hyper-arid central Namib Desert represent heterogeneous soil habitats. As little is known about their indigenous edaphic bacterial communities, we aimed to evaluate their diversity and factors of assembly and hypothesized that soil physicochemistry gradients would strongly shape dune/interdune communities. We sampled a total of 125 samples from 5 parallel dune/interdune transects and characterized 21 physico-chemical edaphic parameters coupled with 16S rRNA gene bacterial community fingerprinting using T-RFLP and 454 pyrosequencing. Multivariate analyses of T-RFLP data showed significantly different bacterial communities, related to physico-chemical gradients, in four distinct dune habitats: the dune top, slope, base and interdune zones. Pyrosequencing of 16S rRNA gene amplicon sets showed that each dune zone presented a unique phylogenetic profile, suggesting a high degree of environmental selection. The combined results strongly infer that habitat filtering is an important factor shaping Namib Desert dune bacterial communities, with habitat stability, soil texture and mineral and nutrient contents being the main environmental drivers of bacterial community structures.
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Affiliation(s)
- Sandra Ronca
- Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria Pretoria, South Africa
| | - Jean-Baptiste Ramond
- Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria Pretoria, South Africa
| | - Brian E Jones
- Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria Pretoria, South Africa ; DuPont Industrial Biosciences Leiden, Netherlands
| | - Mary Seely
- Gobabeb Research and Training Centre Walvis Bay, Namibia ; School of Animal, Plant and Environmental Sciences, University of the Witwatersrand Johannesburg, South Africa
| | - Don A Cowan
- Department of Genetics, Centre for Microbial Ecology and Genomics, University of Pretoria Pretoria, South Africa
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