PeerJ Preprints: Biosphere Interactionshttps://peerj.com/preprints/index.atom?journal=peerj&subject=1403Biosphere Interactions articles published in PeerJ PreprintsMilankovitch forcing of Early Jurassic wildfireshttps://peerj.com/preprints/279912019-09-272019-09-27Teuntje Parnassia HollaarSarah Jane BakerJean-Francois DeconinckLuke ManderMicha RuhlStephen P HesselboClaire M Belcher
The Early Jurassic was characterized by major climatic and environmental perturbations which can be seen preserved at high resolution on orbital timescales. The Early Jurassic is a period of overall global warmth, and therefore serves as a suitable modern-day analogue to understand changes in the Earth System. Presently, Earth’s climate is warming and the frequency of large wildfires appears to be increasing. Recent research has indicated that Quaternary deposits reveal that wildfires respond to orbital forcings; however, to date no study has been able to test whether wildfire activity corresponds to changes over Milankovitch timescales in the deep past.
A high-resolution astrochronology exists for the Upper Pliensbachian in the Llanbedr (Mochras Farm) borehole (NW Wales). Ruhl et al. (2016) show that elemental concentration recorded by hand-held X-ray fluorescence (XRF), changes mainly at periodicities of ~21,000 year, ~100,000 year and ~400,000 year, and which can be related to visually described sedimentary bundles. We have quantified the abundance of fossil charcoal at a high resolution (10-15 cm) to test the hypothesis that these well-preserved climatic cycles influenced fire activity throughout this globally warm period.
Preliminary results suggest that variations in charcoal abundance are coupled to Milankovitch forcings over periods of ~21,000 and ~100,000 years. We suggest that these changes in fire relate to changes in seasonality and monsoonal activity that drove changes in vegetation that are linked to variations in the orbital forcing. Supplementary to the charcoal record, a high-resolution clay mineralogy dataset has been generated to further explain the climatic cyclicity observed in the wildfire record regarding the hydrology on land.
The Early Jurassic was characterized by major climatic and environmental perturbations which can be seen preserved at high resolution on orbital timescales. The Early Jurassic is a period of overall global warmth, and therefore serves as a suitable modern-day analogue to understand changes in the Earth System. Presently, Earth’s climate is warming and the frequency of large wildfires appears to be increasing. Recent research has indicated that Quaternary deposits reveal that wildfires respond to orbital forcings; however, to date no study has been able to test whether wildfire activity corresponds to changes over Milankovitch timescales in the deep past.A high-resolution astrochronology exists for the Upper Pliensbachian in the Llanbedr (Mochras Farm) borehole (NW Wales). Ruhl et al. (2016) show that elemental concentration recorded by hand-held X-ray fluorescence (XRF), changes mainly at periodicities of ~21,000 year, ~100,000 year and ~400,000 year, and which can be related to visually described sedimentary bundles. We have quantified the abundance of fossil charcoal at a high resolution (10-15 cm) to test the hypothesis that these well-preserved climatic cycles influenced fire activity throughout this globally warm period.Preliminary results suggest that variations in charcoal abundance are coupled to Milankovitch forcings over periods of ~21,000 and ~100,000 years. We suggest that these changes in fire relate to changes in seasonality and monsoonal activity that drove changes in vegetation that are linked to variations in the orbital forcing. Supplementary to the charcoal record, a high-resolution clay mineralogy dataset has been generated to further explain the climatic cyclicity observed in the wildfire record regarding the hydrology on land.Socio-environmental extremes: rethinking extraordinary events as outcomes of interacting biophysical and social systemshttps://peerj.com/preprints/278772019-07-302019-07-30Jennifer BalchVirginia IglesiasAnna BraswellMatthew RossiMaxwell B JosephAdam L MahoodWilliam TravisTrisha ShrumCaitlin T WhiteVictoria SchollBryce McGuireClaire KarbanMollie Buckland
Extreme droughts, heat waves, fires, hurricanes, floods, and landslides cause the largest losses in the United States, and globally, from natural hazards linked to weather and climate. There is evidence that the frequency of such extremes is increasing, particularly for heat waves, large fires, and intense precipitation, making better understanding of the probability and consequences of these events imperative. Further, these events are not isolated, but rather interact with each other, and with social and ecological vulnerability, to amplify impacts. Less is known about the nature and strength of these interactions. Natural and social science subfields frame extreme events with different definitions and analytical approaches, and most analyses neglect interactions and the subsequent novel extremes that can arise. Here we propose a framework for socio-environmental extremes, defined as extraordinary events that emerge from interactions among biophysical and social phenomena and have some degree of social impact. We review how different fields approach extremes as interacting phenomena and propose a synthetic framework for conceptualizing and defining extremes from both an environmental and social perspective. This approach recognizes multiple drivers and responses that yield extreme events and extreme outcomes, and reconciles the gap between understanding extremes as biophysical processes and their social underpinnings and impacts. We conclude with a future research agenda that adds clarity and direction to understanding the extreme events that matter to society. This agenda will help to identify where, when, and why communities may have high exposure and vulnerability to socio- environmental extremes—informing future mitigation and adaptation strategies.
Extreme droughts, heat waves, fires, hurricanes, floods, and landslides cause the largest losses in the United States, and globally, from natural hazards linked to weather and climate. There is evidence that the frequency of such extremes is increasing, particularly for heat waves, large fires, and intense precipitation, making better understanding of the probability and consequences of these events imperative. Further, these events are not isolated, but rather interact with each other, and with social and ecological vulnerability, to amplify impacts. Less is known about the nature and strength of these interactions. Natural and social science subfields frame extreme events with different definitions and analytical approaches, and most analyses neglect interactions and the subsequent novel extremes that can arise. Here we propose a framework for socio-environmental extremes, defined as extraordinary events that emerge from interactions among biophysical and social phenomena and have some degree of social impact. We review how different fields approach extremes as interacting phenomena and propose a synthetic framework for conceptualizing and defining extremes from both an environmental and social perspective. This approach recognizes multiple drivers and responses that yield extreme events and extreme outcomes, and reconciles the gap between understanding extremes as biophysical processes and their social underpinnings and impacts. We conclude with a future research agenda that adds clarity and direction to understanding the extreme events that matter to society. This agenda will help to identify where, when, and why communities may have high exposure and vulnerability to socio- environmental extremes—informing future mitigation and adaptation strategies.Ground data confirm warming and drying are at a critical level for forest survival in western equatorial Africahttps://peerj.com/preprints/278482019-07-102019-07-10Emma R BushKathryn JefferyNils BunnefeldCaroline TutinRuth MusgraveGhislain MoussavouVianet MihindouYadvinder MalhiDavid LehmannJosué Edzang NdongLoïc MakagaKatharine A Abernethy
Background.The humid tropical forests of Central Africa influence weather worldwide and play a major role in the global carbon cycle. However they are also an ecological anomaly, with evergreen forests dominating the western equatorial region despite less than 2000mm total annual rainfall. Meteorological data for Central Africa are notoriously sparse and incomplete and there are substantial issues with satellite-derived data because of inability to ground-truth estimates and persistent cloudiness. Long-term climate observations are urgently needed to verify regional climate and vegetation models, shed light on the mechanisms that drive climatic variability and assess the viability of evergreen forests in equatorial Africa under future climate scenarios.
Methods. We have the rare opportunity to analyse a 34-year dataset of rainfall and temperature (and shorter periods of absolute humidity, wind speed, solar radiation and aerosol optical depth) from Lopé National Park, a long-term ecological research site in western equatorial Africa. We used linear mixed models and spectral analyses to assess seasonal and inter-annual variation, long-term trends and oceanic influences on local weather patterns.
Results. Lopé’s weather is characterised by a light-deficient, cool, long dry season. Long-term climatic means have changed significantly over the last three decades, with warming occurring at a rate of 0.23°C per decade (minimum daily temperature) and drying at a rate of 50mm per decade (total annual rainfall). Inter-annual variability is highly influenced by sea surface temperatures of the major oceans. In El Niño years Lopé experiences both higher temperatures and less rainfall with increased contrast between wet and dry seasons. Lopé rainfall observations lend support for the role of the Atlantic cold tongue in “dry” models of climate change in the region.
Conclusions. Dry season cloud in western equatorial Africa plays a key role in reducing evaporative demand during seasonal drought and maintaining evergreen tropical forests despite relatively low annual rainfall. In the context of a rapidly warming and drying climate, urgent research is needed into the sensitivity of clouds to ocean temperatures and the viability of humid forests in this dry region should the clouds disappear.
Background.The humid tropical forests of Central Africa influence weather worldwide and play a major role in the global carbon cycle. However they are also an ecological anomaly, with evergreen forests dominating the western equatorial region despite less than 2000mm total annual rainfall. Meteorological data for Central Africa are notoriously sparse and incomplete and there are substantial issues with satellite-derived data because of inability to ground-truth estimates and persistent cloudiness. Long-term climate observations are urgently needed to verify regional climate and vegetation models, shed light on the mechanisms that drive climatic variability and assess the viability of evergreen forests in equatorial Africa under future climate scenarios.Methods. We have the rare opportunity to analyse a 34-year dataset of rainfall and temperature (and shorter periods of absolute humidity, wind speed, solar radiation and aerosol optical depth) from Lopé National Park, a long-term ecological research site in western equatorial Africa. We used linear mixed models and spectral analyses to assess seasonal and inter-annual variation, long-term trends and oceanic influences on local weather patterns.Results. Lopé’s weather is characterised by a light-deficient, cool, long dry season. Long-term climatic means have changed significantly over the last three decades, with warming occurring at a rate of 0.23°C per decade (minimum daily temperature) and drying at a rate of 50mm per decade (total annual rainfall). Inter-annual variability is highly influenced by sea surface temperatures of the major oceans. In El Niño years Lopé experiences both higher temperatures and less rainfall with increased contrast between wet and dry seasons. Lopé rainfall observations lend support for the role of the Atlantic cold tongue in “dry” models of climate change in the region.Conclusions. Dry season cloud in western equatorial Africa plays a key role in reducing evaporative demand during seasonal drought and maintaining evergreen tropical forests despite relatively low annual rainfall. In the context of a rapidly warming and drying climate, urgent research is needed into the sensitivity of clouds to ocean temperatures and the viability of humid forests in this dry region should the clouds disappear.California air resources board forest carbon protocol invalidates offsetshttps://peerj.com/preprints/277982019-06-132019-06-13Bruno D V MarinoMartina MinchevaAaron Doucett
The commercial asset value of sequestered forest carbon is based on protocols employed globally, however, their scientific basis has not been validated. We review and analyze commercial forest carbon protocols and offsets, claimed to have reduced net greenhouse gas emissions, issued by the California Air Resources Board and validated by the Climate Action Reserve (CARB-CAR). CARB-CAR protocol annual offsets, resulting from forest mensuration and growth simulation models, are compared with a population of forest field sites for which annual net ecosystem exchange (NEE) of carbon was measured directly as flux by CO2 eddy covariance, a meteorologically based method integrating forest carbon pools. We characterize differences between the protocols by testing the null hypothesis that the CARB-CAR commercial annual offset data fall within the boundaries of directly measured forest carbon NEE; gC m-2yr-1 are compared for both datasets. Irrespective of geographic location and project type, the CARB-CAR population annual mean value is significantly different from the NEE population mean at the 95% confidence interval, rejecting the null hypothesis. The CARB-CAR population exhibits standard deviation ~5x that of the NEE natural ranges; the variance exceeds the 5% compliance limit for invalidation of CARB-CAR offsets. Exclusion of the soil carbon pool typical for CARB-CAR net carbon budgets pose insuperable carbon accounting uncertainty for offsets that extend to vendor platforms and policies including the United Nations Program on Reducing Emissions from Deforestation and Forest Degradation and the Paris Agreement. NEE methodology for commercial forest carbon offsets ensures in situ molecular specificity, verification of claims for net carbon balance, performance-based pricing and harmonization of carbon protocols for voluntary and compliance markets worldwide, in contrast to continuing uncertainty posed by traditional estimation-based forest carbon protocols.
The commercial asset value of sequestered forest carbon is based on protocols employed globally, however, their scientific basis has not been validated. We review and analyze commercial forest carbon protocols and offsets, claimed to have reduced net greenhouse gas emissions, issued by the California Air Resources Board and validated by the Climate Action Reserve (CARB-CAR). CARB-CAR protocol annual offsets, resulting from forest mensuration and growth simulation models, are compared with a population of forest field sites for which annual net ecosystem exchange (NEE) of carbon was measured directly as flux by CO2 eddy covariance, a meteorologically based method integrating forest carbon pools. We characterize differences between the protocols by testing the null hypothesis that the CARB-CAR commercial annual offset data fall within the boundaries of directly measured forest carbon NEE; gC m-2yr-1 are compared for both datasets. Irrespective of geographic location and project type, the CARB-CAR population annual mean value is significantly different from the NEE population mean at the 95% confidence interval, rejecting the null hypothesis. The CARB-CAR population exhibits standard deviation ~5x that of the NEE natural ranges; the variance exceeds the 5% compliance limit for invalidation of CARB-CAR offsets. Exclusion of the soil carbon pool typical for CARB-CAR net carbon budgets pose insuperable carbon accounting uncertainty for offsets that extend to vendor platforms and policies including the United Nations Program on Reducing Emissions from Deforestation and Forest Degradation and the Paris Agreement. NEE methodology for commercial forest carbon offsets ensures in situ molecular specificity, verification of claims for net carbon balance, performance-based pricing and harmonization of carbon protocols for voluntary and compliance markets worldwide, in contrast to continuing uncertainty posed by traditional estimation-based forest carbon protocols.Why mountains matter for biodiversityhttps://peerj.com/preprints/277682019-05-302019-05-30Allison PerrigoCarina HoornAlexandre Antonelli
Mountains are arguably Earth’s most striking features. They play a major role in determining global and regional climates, are the source of most rivers, act as cradles, barriers and bridges for species, and are crucial for the survival and sustainability of many human societies. The complexity of mountains is tightly associated with high biodiversity, but the processes underlying this association are poorly known. Solving this puzzle requires researchers to generate more primary data, and better integrate available geological and climatic data into biological models of diversity and evolution. We coordinated the efforts of many researchers to jointly produce an edited book, Mountains, Climate and Biodiversity, where this integration of disciplines is presented and discussed in detail. In this perspective, we highlight some of the emerging insights, which stress the importance of mountain building through time as a generator and reservoir of biodiversity. We also discuss recently proposed parallels between surface uplift, habitat formation, and species diversification. We exemplify these links and discuss other factors, such as Quaternary climatic variations, which may have obscured some mountain-building evidence due to erosion and other processes. Biological evolution is complex and the build-up of mountains is certainly not the only explanation, but biological and geophysical processes are probably more intertwined than many of us realise. The overall conclusion is that geology sets the stage for speciation, where ecological interactions, adaptive and non-adaptive radiations, and stochastic processes co-act to increase biodiversity. Further integration of these fields may yield novel and robust insights.
Mountains are arguably Earth’s most striking features. They play a major role in determining global and regional climates, are the source of most rivers, act as cradles, barriers and bridges for species, and are crucial for the survival and sustainability of many human societies. The complexity of mountains is tightly associated with high biodiversity, but the processes underlying this association are poorly known. Solving this puzzle requires researchers to generate more primary data, and better integrate available geological and climatic data into biological models of diversity and evolution. We coordinated the efforts of many researchers to jointly produce an edited book, Mountains, Climate and Biodiversity, where this integration of disciplines is presented and discussed in detail. In this perspective, we highlight some of the emerging insights, which stress the importance of mountain building through time as a generator and reservoir of biodiversity. We also discuss recently proposed parallels between surface uplift, habitat formation, and species diversification. We exemplify these links and discuss other factors, such as Quaternary climatic variations, which may have obscured some mountain-building evidence due to erosion and other processes. Biological evolution is complex and the build-up of mountains is certainly not the only explanation, but biological and geophysical processes are probably more intertwined than many of us realise. The overall conclusion is that geology sets the stage for speciation, where ecological interactions, adaptive and non-adaptive radiations, and stochastic processes co-act to increase biodiversity. Further integration of these fields may yield novel and robust insights.The Global Museum: natural history collections and the future of evolutionary biology and public educationhttps://peerj.com/preprints/276662019-04-192019-04-19Freek T. BakkerAlexandre AntonelliJulia ClarkeJoseph A CookScott V EdwardsPer GP EricsonSøren FaurbyNuno FerrandMagnus GelangRosemary G GillespieMartin IrestedtKennet LundinEllen LarssonPável Matos-MaravíJohannes MüllerTed von ProschwitzGeorge K RoderickAlexander SchliepNiklas WahlbergJohn WiedenhoeftMari Källersjö
Natural history museums are unique spaces for interdisciplinary research and for educational innovation. Through extensive exhibits and public programming and by hosting rich communities of amateurs, students, and researchers at all stages of their careers, they provide a place-based window to focus on integration of science and discovery, as well as a locus for community engagement. At the same time, like a synthesis radio telescope, when joined together through emerging digital resources, the global community of museums (the ‘Global Museum’) is more than the sum of its parts, allowing insights and answers to diverse biological, environmental, and societal questions at the global scale, across eons of time, and spanning vast diversity across the Tree of Life. We argue that, whereas natural history collections and museums began with a focus on describing the diversity and peculiarities of species on Earth, they are now increasingly leveraged in new ways that significantly expand their impact and relevance. These new directions include the possibility to ask new, often interdisciplinary questions in basic and applied science; inform biomimetic design; and even provide solutions to climate change, global health and food security challenges. As institutions, they are incubators for cutting-edge research in biology and simultaneously protect core infrastructure for present and future societal needs. In this perspective, we discuss challenges to the realization of the full potential of natural history collections and museums to serve society. After reviewing collections and types of museums, including local and global efforts, we discuss the value of specimens and the importance of observations. We then focus on mapping and modelling of museum data (including place-based approaches and discovery), and explore the main projects, platforms and databases enabling this. We also explore ways in which improved infrastructure will allow higher quality science and increased opportunities for interdisciplinary research and communication, as well as new uses of collections. Finally, we aim to improve relevant protocols for the long-term storage of specimens and tissues, ensuring proper connection with tomorrow’s technologies and hence further increasing the relevance of natural history museums.
Natural history museums are unique spaces for interdisciplinary research and for educational innovation. Through extensive exhibits and public programming and by hosting rich communities of amateurs, students, and researchers at all stages of their careers, they provide a place-based window to focus on integration of science and discovery, as well as a locus for community engagement. At the same time, like a synthesis radio telescope, when joined together through emerging digital resources, the global community of museums (the ‘Global Museum’) is more than the sum of its parts, allowing insights and answers to diverse biological, environmental, and societal questions at the global scale, across eons of time, and spanning vast diversity across the Tree of Life. We argue that, whereas natural history collections and museums began with a focus on describing the diversity and peculiarities of species on Earth, they are now increasingly leveraged in new ways that significantly expand their impact and relevance. These new directions include the possibility to ask new, often interdisciplinary questions in basic and applied science; inform biomimetic design; and even provide solutions to climate change, global health and food security challenges. As institutions, they are incubators for cutting-edge research in biology and simultaneously protect core infrastructure for present and future societal needs. In this perspective, we discuss challenges to the realization of the full potential of natural history collections and museums to serve society. After reviewing collections and types of museums, including local and global efforts, we discuss the value of specimens and the importance of observations. We then focus on mapping and modelling of museum data (including place-based approaches and discovery), and explore the main projects, platforms and databases enabling this. We also explore ways in which improved infrastructure will allow higher quality science and increased opportunities for interdisciplinary research and communication, as well as new uses of collections. Finally, we aim to improve relevant protocols for the long-term storage of specimens and tissues, ensuring proper connection with tomorrow’s technologies and hence further increasing the relevance of natural history museums.Evolution of cellular metabolism and the rise of a globally productive biospherehttps://peerj.com/preprints/272692019-04-182019-04-18Rogier Braakman
The metabolic processes of cells and chemical processes in the environment are fundamentally intertwined and have evolved in concert over billions of years. Here I argue that intrinsic properties of cellular metabolism imposed central constraints on the historical trajectories of biopsheric productivity and atmospheric oxygenation. Photosynthesis depends on iron, but iron is highly insoluble under the aerobic conditions produced by oxygenic photosynthesis. These counteracting constraints led to two major stages of Earth oxygenation. Cyanobacterial photosynthesis drove a major biospheric expansion near the Archean-Proterozoic boundary but subsequently remained largely restricted to continental boundaries and shallow aquatic environments, where weathering inputs made iron more accessible. The anoxic deep open ocean was rich in free iron during the Proterozoic, but this iron remained effectively inaccessible since a photosynthetic expansion would have quenched its own supply. Near the Proterozoic-Phanerozoic boundary, bioenergetic innovations allowed eukaryotic photosynthesis to expand into the deep open oceans and onto the continents, where nutrients are inherently harder to come by. Key insights into the ecological rise of eukaryotic photosynthesis emerge from analyses of marine Synechococcus and Prochlorococcus, abundant marine picocyanobacteria whose ancestors colonized the oceans in the Neoproterozoic. The reconstructed evolution of Prochlorococcus reveals a sequence of innovations that ultimately produced a form of photosynthesis more like that of green plant cells than other cyanobacteria. Innovations increased the energy flux of cells, thereby enhancing their ability to acquire sparse nutrients, and as by-product also increased the production of organic carbon waste. Some of these organic waste products in turn had the ability to chelate iron and make it bioavailable, thereby indirectly pushing the oceans through a transition from an anoxic state rich in free iron to an oxygenated state with organic carbon-bound iron. The periods of Earth history around cyanobacteria- and eukaryote-driven biospheric expansions share several other parallels. Both epochs have also been linked to major carbon cycle perturbations and global glaciations, as well as changes in the nature of mantle convection and plate tectonics. This suggests the dynamics of life and Earth are intimately intertwined across many levels and that general principles governed Neoarchean and Neoproterozoic transitions in these coupled dynamics.
The metabolic processes of cells and chemical processes in the environment are fundamentally intertwined and have evolved in concert over billions of years. Here I argue that intrinsic properties of cellular metabolism imposed central constraints on the historical trajectories of biopsheric productivity and atmospheric oxygenation. Photosynthesis depends on iron, but iron is highly insoluble under the aerobic conditions produced by oxygenic photosynthesis. These counteracting constraints led to two major stages of Earth oxygenation. Cyanobacterial photosynthesis drove a major biospheric expansion near the Archean-Proterozoic boundary but subsequently remained largely restricted to continental boundaries and shallow aquatic environments, where weathering inputs made iron more accessible. The anoxic deep open ocean was rich in free iron during the Proterozoic, but this iron remained effectively inaccessible since a photosynthetic expansion would have quenched its own supply. Near the Proterozoic-Phanerozoic boundary, bioenergetic innovations allowed eukaryotic photosynthesis to expand into the deep open oceans and onto the continents, where nutrients are inherently harder to come by. Key insights into the ecological rise of eukaryotic photosynthesis emerge from analyses of marine Synechococcus and Prochlorococcus, abundant marine picocyanobacteria whose ancestors colonized the oceans in the Neoproterozoic. The reconstructed evolution of Prochlorococcus reveals a sequence of innovations that ultimately produced a form of photosynthesis more like that of green plant cells than other cyanobacteria. Innovations increased the energy flux of cells, thereby enhancing their ability to acquire sparse nutrients, and as by-product also increased the production of organic carbon waste. Some of these organic waste products in turn had the ability to chelate iron and make it bioavailable, thereby indirectly pushing the oceans through a transition from an anoxic state rich in free iron to an oxygenated state with organic carbon-bound iron. The periods of Earth history around cyanobacteria- and eukaryote-driven biospheric expansions share several other parallels. Both epochs have also been linked to major carbon cycle perturbations and global glaciations, as well as changes in the nature of mantle convection and plate tectonics. This suggests the dynamics of life and Earth are intimately intertwined across many levels and that general principles governed Neoarchean and Neoproterozoic transitions in these coupled dynamics.Differences in the use of surface water resources by desert birds are revealed using isotopic tracershttps://peerj.com/preprints/31672018-11-212018-11-21Ben SmitStephan WoodborneBlair O WolfAndrew E McKechnie
The scarcity of free-standing water sources is a key determinant of animal and plant community structure in arid environments, and an understanding of the extent to which particular species use surface water is vital for modelling the effects of climate change on desert avifauna. We investigated interspecific variation in the use of artificial water sources among birds in the Kalahari Desert, South Africa, by 1) observations at waterholes and 2) tracing spatial water-use patterns during summer by isotopically-labelled water sources and blood sampling. More than 50% of the avian community (primarily insectivores and omnivores) were not observed to drink. The majority (53%) of species drinking at waterholes were granivorous, and their use of surface water was best predicted by their relative abundance in the community. Species representing the remaining dietary guilds drank significantly more on hot days. Blood samples revealed that only 11 of 42 species (mostly granivores and a few omnivores) showed evidence of drinking at a waterhole with enriched deuterium values; on average, in the latter birds, water from the enriched waterhole accounted for ~38% of their body water pool. These findings illustrate that two methods employed in this study provide different, but complementary data on the relative importance of a water source for an avian community. Although our results suggest that most avian species are independent of surface water, drinking patterns on the hottest days during our study period suggest that free-standing water might become more important for some of the non-drinking species under hotter climatic conditions.
The scarcity of free-standing water sources is a key determinant of animal and plant community structure in arid environments, and an understanding of the extent to which particular species use surface water is vital for modelling the effects of climate change on desert avifauna. We investigated interspecific variation in the use of artificial water sources among birds in the Kalahari Desert, South Africa, by 1) observations at waterholes and 2) tracing spatial water-use patterns during summer by isotopically-labelled water sources and blood sampling. More than 50% of the avian community (primarily insectivores and omnivores) were not observed to drink. The majority (53%) of species drinking at waterholes were granivorous, and their use of surface water was best predicted by their relative abundance in the community. Species representing the remaining dietary guilds drank significantly more on hot days. Blood samples revealed that only 11 of 42 species (mostly granivores and a few omnivores) showed evidence of drinking at a waterhole with enriched deuterium values; on average, in the latter birds, water from the enriched waterhole accounted for ~38% of their body water pool. These findings illustrate that two methods employed in this study provide different, but complementary data on the relative importance of a water source for an avian community. Although our results suggest that most avian species are independent of surface water, drinking patterns on the hottest days during our study period suggest that free-standing water might become more important for some of the non-drinking species under hotter climatic conditions.Reef growth and limestone erosionhttps://peerj.com/preprints/9632018-07-032018-07-03David Blakeway
Because the shapes and forms of many coral reefs resemble karst (erosion landforms created by dissolution of limestone), it is widely believed that those reefs have grown on karst foundations, and that Holocene growth perpetuates the underlying topography. However, this concept has become difficult to reconcile with the increasing amount of seismic and coring evidence demonstrating that several karst-like reef features are entirely constructional. Here I use cellular automata simulations to show that coral reefs resemble karst limestones not because they are built on karst foundations, but because reef growth and limestone erosion are fundamentally the same process, running in opposite directions. Coral reef landscapes resemble karst because they are in fact inverse karst—the basic spectrum of reef growth forms mirrors the basic spectrum of limestone erosion forms. In both growth and erosion, the development of form is a self-organized process emerging from local-scale interactions. The essential morphological control in both cases is slope stability, which depends on the composition of each system: coral type in reefs and lithology (rock type) in limestones. Solid, well-cemented reefs and limestones, which can maintain steep slopes without collapsing, produce nodular reefs and tower karst respectively, whereas unconsolidated, friable reefs and limestones, which frequently collapse, produce cellular reefs and cone karst. The growth forms produced in the model should theoretically apply to all modular skeleton-building organisms growing in a fluid medium, and may therefore provide useful templates in the search for extraterrestrial life. While none of the model forms can be considered unequivocally diagnostic of life, because all could conceivably arise through inanimate crystallization, the model’s seemingly accurate rendition of biogenic carbonate morphology on earth suggests that it may provide a useful foundation for evaluating and exploring the range of macroscale self-organized biogenic structures that could arise on other planets.
Because the shapes and forms of many coral reefs resemble karst (erosion landforms created by dissolution of limestone), it is widely believed that those reefs have grown on karst foundations, and that Holocene growth perpetuates the underlying topography. However, this concept has become difficult to reconcile with the increasing amount of seismic and coring evidence demonstrating that several karst-like reef features are entirely constructional. Here I use cellular automata simulations to show that coral reefs resemble karst limestones not because they are built on karst foundations, but because reef growth and limestone erosion are fundamentally the same process, running in opposite directions. Coral reef landscapes resemble karst because they are in fact inverse karst—the basic spectrum of reef growth forms mirrors the basic spectrum of limestone erosion forms. In both growth and erosion, the development of form is a self-organized process emerging from local-scale interactions. The essential morphological control in both cases is slope stability, which depends on the composition of each system: coral type in reefs and lithology (rock type) in limestones. Solid, well-cemented reefs and limestones, which can maintain steep slopes without collapsing, produce nodular reefs and tower karst respectively, whereas unconsolidated, friable reefs and limestones, which frequently collapse, produce cellular reefs and cone karst. The growth forms produced in the model should theoretically apply to all modular skeleton-building organisms growing in a fluid medium, and may therefore provide useful templates in the search for extraterrestrial life. While none of the model forms can be considered unequivocally diagnostic of life, because all could conceivably arise through inanimate crystallization, the model’s seemingly accurate rendition of biogenic carbonate morphology on earth suggests that it may provide a useful foundation for evaluating and exploring the range of macroscale self-organized biogenic structures that could arise on other planets.Visitors’ emotional expression in urban forest parks: What can we know about on-line facial images from the Social Networking Services?https://peerj.com/preprints/34242017-11-222017-11-22Haoming GuanHonxu WeiXingyuan HeZhibin RenXin ChenPeng Guo
Urban forests can attract visitors by the function of well-being improvement, which can be evaluated by analyzing the big-data from the social networking services (SNS). In this study, 935 facial images of visitors to nine urban forest parks were screened and downloaded from check-in records in the SNS platform of Sina Micro-Blog at cities of Changchun, Harbin, and Shenyang in Northeast China. Images were recognized for facial expressions by FaceReaderTM to read out eight emotional expressions: neutral, happy, sad, angry, surprised, scared, disgusted, and contempt. The number of images by women was larger than that by men. Compared to images from Changchun, those from Shenyang harbored higher neutral degree, which showed a positive relationship with the distance of forest park from downtown. In Changchun, the angry, surprised, and disgusted degrees decreased with the increase of distance of forest park from downtown, while the happy and disgusted degrees showed the same trend in Shenyang. In forest parks at city center and remote-rural areas, the neutral degree was positively correlated with the angry, surprised and contempt degrees but negatively correlated with the happy and disgusted degrees. In the sub-urban area the correlation of neutral with both surprised and disgusted degrees disappeared. Our study can be referred to by urban planning to evaluate the perceived well-being in urban forests through analyzing facial expressions of images from SNS.
Urban forests can attract visitors by the function of well-being improvement, which can be evaluated by analyzing the big-data from the social networking services (SNS). In this study, 935 facial images of visitors to nine urban forest parks were screened and downloaded from check-in records in the SNS platform of Sina Micro-Blog at cities of Changchun, Harbin, and Shenyang in Northeast China. Images were recognized for facial expressions by FaceReaderTM to read out eight emotional expressions: neutral, happy, sad, angry, surprised, scared, disgusted, and contempt. The number of images by women was larger than that by men. Compared to images from Changchun, those from Shenyang harbored higher neutral degree, which showed a positive relationship with the distance of forest park from downtown. In Changchun, the angry, surprised, and disgusted degrees decreased with the increase of distance of forest park from downtown, while the happy and disgusted degrees showed the same trend in Shenyang. In forest parks at city center and remote-rural areas, the neutral degree was positively correlated with the angry, surprised and contempt degrees but negatively correlated with the happy and disgusted degrees. In the sub-urban area the correlation of neutral with both surprised and disgusted degrees disappeared. Our study can be referred to by urban planning to evaluate the perceived well-being in urban forests through analyzing facial expressions of images from SNS.