Characteristics of aquatic biospheres on temperate planets around Sun-like stars and M dwarfs

ABSTRACT Aquatic biospheres reliant on oxygenic photosynthesis are expected to play an important role on Earth-like planets endowed with large-scale oceans insofar as carbon fixation (i.e. biosynthesis of organic compounds) is concerned. We investigate the properties of aquatic biospheres comprising Earth-like biota for habitable rocky planets orbiting Sun-like stars and late-type M dwarfs such as TRAPPIST-1. In particular, we estimate how these characteristics evolve with the available flux of photosynthetically active radiation (PAR) and the ambient ocean temperature (TW), the latter of which constitutes a key environmental variable. We show that many salient properties, such as the depth of the photosynthesis zone and the net primary productivity (i.e. the effective rate of carbon fixation), are sensitive to PAR flux and TW and decline substantially when the former is decreased or the latter is increased. We conclude by exploring the implications of our analysis for exoplanets around Sun-like stars and M dwarfs.

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Testing Seven Hypotheses to Determine What Explains the Current Planthopper (Fulgoridae) Geographical and Species Richness Patterns in China

Insects ◽

10.3390/insects11120892 ◽

2020 ◽

Vol 11 (12) ◽

pp. 892

Author(s):

Zheng-Xue Zhao ◽

Lin Yang ◽

Jian-Kun Long ◽

Zhi-Min Chang ◽

Zheng-Xiang Zhou ◽

...

Keyword(s):

Species Richness ◽

Large Scale ◽

Net Primary Productivity ◽

Model Averaging ◽

Ordinary Least Squares ◽

Environmental Variable ◽

Vital Role ◽

Mean Annual Temperature ◽

Spatial Error ◽

Richness Patterns

Although many hypotheses have been proposed to understand the mechanisms underlying large-scale richness patterns, the environmental determinants are still poorly understood, particularly in insects. Here, we tested the relative contributions of seven hypotheses previously proposed to explain planthopper richness patterns in China. The richness patterns were visualized at a 1° × 1° grid size, using 14,722 distribution records for 1335 planthoppers. We used ordinary least squares and spatial error simultaneous autoregressive models to examine the relationships between richness and single environmental variables and employed model averaging to assess the environmental variable relative roles. Species richness was unevenly distributed, with high species numbers occurring in the central and southern mountainous areas. The mean annual temperature change since the Last Glacial Maximum was the most important factor for richness patterns, followed by mean annual temperature and net primary productivity. Therefore, historical climate stability, ambient energy, and productivity hypotheses were supported strongly, but orogenic processes and geological isolation may also play a vital role.

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More individuals but fewer species: testing the ‘more individuals hypothesis’ in a diverse tropical fauna

Biology Letters ◽

10.1098/rsbl.2010.0103 ◽

2010 ◽

Vol 6 (4) ◽

pp. 490-493 ◽

Cited By ~ 28

Author(s):

Terrence P. McGlynn ◽

Michael D. Weiser ◽

Robert R. Dunn

Keyword(s):

Species Richness ◽

Primary Productivity ◽

Large Scale ◽

Positive Relationship ◽

Tropical Rainforest ◽

Net Primary Productivity ◽

Resource Abundance ◽

Monotonic Increase ◽

Ant Diversity ◽

Unimodal Relationship

A positive relationship between species richness and productivity is often observed in nature, but the causes remain contentious. One mechanism, the ‘more individuals hypothesis’ (MIH), predicts richness increases monotonically with density, as a function of resource flux. To test the MIH, we manipulated resource abundance in a community of tropical rainforest litter ants and measured richness and density responses. A unimodal relationship between richness and density most closely fitted the control and disturbance (resource removal) treatments in contrast to expectations of the MIH. Resource addition resulted in a monotonic increase in richness relative to density, a shift from the pattern in the control. In the disturbance treatment, richness was greater than in the control, opposite to expectations of the MIH. While large-scale correlations between ant diversity and net primary productivity or temperature are reconcilable with the MIH, key elements of the hypothesis are not supported.

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The up-scaling of ecosystem functions in a heterogeneous world

Scientific Reports ◽

10.1038/srep10349 ◽

2015 ◽

Vol 5 (1) ◽

Cited By ~ 22

Author(s):

Andrew M. Lohrer ◽

Simon F. Thrush ◽

Judi E. Hewitt ◽

Casper Kraan

Keyword(s):

Primary Productivity ◽

Ecosystem Functioning ◽

Large Scale ◽

Net Primary Productivity ◽

Marine Ecosystem ◽

Ecosystem Functions ◽

Small Scale ◽

Biodiversity Crisis ◽

Positive Effects ◽

Marine Habitats

Abstract Earth is in the midst of a biodiversity crisis that is impacting the functioning of ecosystems and the delivery of valued goods and services. However, the implications of large scale species losses are often inferred from small scale ecosystem functioning experiments with little knowledge of how the dominant drivers of functioning shift across scales. Here, by integrating observational and manipulative experimental field data, we reveal scale-dependent influences on primary productivity in shallow marine habitats, thus demonstrating the scalability of complex ecological relationships contributing to coastal marine ecosystem functioning. Positive effects of key consumers (burrowing urchins, Echinocardium cordatum) on seafloor net primary productivity (NPP) elucidated by short-term, single-site experiments persisted across multiple sites and years. Additional experimentation illustrated how these effects amplified over time, resulting in greater primary producer biomass (sediment chlorophyll a content) in the longer term, depending on climatic context and habitat factors affecting the strengths of mutually reinforcing feedbacks. The remarkable coherence of results from small and large scales is evidence of real-world ecosystem function scalability and ecological self-organisation. This discovery provides greater insights into the range of responses to broad-scale anthropogenic stressors in naturally heterogeneous environmental settings.

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Super-Earths, M Dwarfs, and Photosynthetic Organisms: Habitability in the Lab

Life ◽

10.3390/life11010010 ◽

2020 ◽

Vol 11 (1) ◽

pp. 10

Author(s):

Riccardo Claudi ◽

Eleonora Alei ◽

Mariano Battistuzzi ◽

Lorenzo Cocola ◽

Marco Sergio Erculiani ◽

...

Keyword(s):

Light Condition ◽

Oxygenic Photosynthesis ◽

Space Telescopes ◽

M Dwarfs ◽

Orbital Periods ◽

Light Components ◽

Photosynthetic Performances ◽

Rocky Planets ◽

M Dwarf

In a few years, space telescopes will investigate our Galaxy to detect evidence of life, mainly by observing rocky planets. In the last decade, the observation of exoplanet atmospheres and the theoretical works on biosignature gasses have experienced a considerable acceleration. The most attractive feature of the realm of exoplanets is that 40% of M dwarfs host super-Earths with a minimum mass between 1 and 30 Earth masses, orbital periods shorter than 50 days, and radii between those of the Earth and Neptune (1–3.8 R⊕). Moreover, the recent finding of cyanobacteria able to use far-red (FR) light for oxygenic photosynthesis due to the synthesis of chlorophylls d and f, extending in vivo light absorption up to 750 nm, suggests the possibility of exotic photosynthesis in planets around M dwarfs. Using innovative laboratory instrumentation, we exposed different cyanobacteria to an M dwarf star simulated irradiation, comparing their responses to those under solar and FR simulated lights. As expected, in FR light, only the cyanobacteria able to synthesize chlorophyll d and f could grow. Surprisingly, all strains, both able or unable to use FR light, grew and photosynthesized under the M dwarf generated spectrum in a similar way to the solar light and much more efficiently than under the FR one. Our findings highlight the importance of simulating both the visible and FR light components of an M dwarf spectrum to correctly evaluate the photosynthetic performances of oxygenic organisms exposed under such an exotic light condition.

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Assessment of net primary productivity over India using Indian geostationary satellite (INSAT-3A) data

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xl-8-561-2014 ◽

2014 ◽

Vol XL-8 ◽

pp. 561-568 ◽

Cited By ~ 3

Author(s):

S. K. Goroshi ◽

R. P. Singh ◽

R. Pradhan ◽

J. S. Parihar

Keyword(s):

Primary Productivity ◽

Vegetation Index ◽

Carbon Fixation ◽

Net Primary Productivity ◽

Meteorological Data ◽

Mixed Forest ◽

Terrestrial Ecosystems ◽

Spatial And Temporal Variability ◽

Vegetation Types ◽

Wide Range

Polar orbiting satellites (MODIS and SPOT) have been commonly used to measure terrestrial Net Primary Productivity (NPP) at regional/global scale. Charge Coupled Device (CCD) instrument on geostationary INSAT-3A platform provides a unique opportunity for continuous monitoring of ecosystem pattern and process study. An improved Carnegie-Ames-Stanford Approach (iCASA) model is one of the most expedient and precise ecosystem models to estimate terrestrial NPP. In this paper, an assessment of terrestrial NPP over India was carried out using the iCASA ecosystem model based on the INSAT CCD derived Normalized Difference Vegetation Index (NDVI) with multisource meteorological data for the year 2009. NPP estimated from the INSAT CCD followed the characteristic growth profile of most of the vegetation types in the country. NPP attained maximum during August and September, while minimum in April. Annual NPP for different vegetation types varied from 1104.55 gC m−2 year−1 (evergreen broadleaf forest) to 231.9 gC m−2 year−1 (grassland) with an average NPP of 590 gC m−2 year−1. We estimated 1.9 PgC of net carbon fixation over Indian landmass in 2009. Biome level comparison between INSAT derived NPP and MODIS NPP indicated a good agreement with the Willmott’s index of agreement (d) ranging from 0.61 (Mixed forest) to 0.99 (Open Shrubland). Our findings are consistent with the earlier NPP studies in India and indicate that INSAT derived NPP has the capability to detect spatial and temporal variability of terrestrial NPP over a wide range of terrestrial ecosystems in India. Thus INSAT-3A data can be used as one of the potential satellite data source for accurate biome level carbon estimation in India.

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Description and Validation of the Simple, Efficient, Dynamic, Global, Ecological Simulator (SEDGES v.1.0)

10.5194/gmd-2017-75 ◽

2017 ◽

Author(s):

Pablo Paiewonsky ◽

Oliver Elison Timm

Keyword(s):

Primary Productivity ◽

Land Surface ◽

Large Scale ◽

Net Primary Productivity ◽

Climate Model ◽

Hydrological Cycle ◽

Bare Soil ◽

Relative Advantage ◽

Coupling Scheme ◽

Area Index

Abstract. In this paper, we present a simple vegetation model whose primary intended use is auxiliary to the land-atmosphere coupling scheme of a climate model, particularly one of intermediate complexity. The model formulations and their derivations are presented here, in detail. The model includes some realistic and useful features for its level of complexity, including a photosynthetic dependency on light, full coupling of photosynthesis and transpiration through an interactive canopy resistance, and a soil organic carbon dependence for bare soil albedo. We evaluate the model's performance by running it using a simple land surface scheme that is driven by reanalysis data. The evaluation against observational data includes net primary productivity, leaf area index, surface albedo, and diagnosed variables relevant for the closure of the hydrological cycle. In this set up, we find that the model gives an adequate to good simulation of basic large-scale ecological and hydrological variables. Of the variables analyzed in this paper, gross primary productivity is particularly well simulated. The results also reveal the current limitations of the model. The most significant deficiency is the excessive simulation of evapotranspiration in mid- to high northern latitudes during their winter to spring transition. The model has relative advantage in situations that require some combination of computational efficiency, model transparency and tractability, and the simulation of the large scale vegetation and land surface characteristics under non-present day conditions.

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Photosynthesis on exoplanets and exomoons from reflected light

International Journal of Astrobiology ◽

10.1017/s1473550419000247 ◽

2019 ◽

Vol 19 (3) ◽

pp. 210-219 ◽

Cited By ~ 3

Author(s):

Manasvi Lingam ◽

Abraham Loeb

Keyword(s):

Carbon Fixation ◽

Giant Planets ◽

Oxygenic Photosynthesis ◽

Late Type ◽

M Dwarfs ◽

Convenient Means ◽

Reflected Light ◽

Orbital Instability ◽

Long Timescales ◽

Physiological And Biochemical

AbstractPhotosynthesis offers a convenient means of sustaining biospheres. We quantify the constraints for photosynthesis to be functional on the permanent nightside of tidally locked rocky exoplanets via reflected light from their exomoons. We show that the exomoons must be at least half the size of Earth's moon in order for conventional oxygenic photosynthesis to operate. This scenario of photosynthesis is unlikely for exoplanets around late-type M-dwarfs due to the low likelihood of large exomoons and their orbital instability over long timescales. Subsequently, we investigate the prospects for photosynthesis on habitable exomoons via reflected light from the giant planets that they orbit. Our analysis indicates that such photosynthetic biospheres are potentially sustainable on these moons except those around late-type M-dwarfs. We conclude our analysis by delineating certain physiological and biochemical features of photosynthesis and other carbon fixation pathways, and the likelihood of their evolution on habitable planets and moons.

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Ecological performance differs between range centre and trailing edge populations of a cold-water kelp: implications for estimating net primary productivity

Marine Biology ◽

10.1007/s00227-020-03743-5 ◽

2020 ◽

Vol 167 (9) ◽

Author(s):

Nathan G. King ◽

Pippa J. Moore ◽

Albert Pessarrodona ◽

Michael T. Burrows ◽

Joanne Porter ◽

...

Keyword(s):

Carbon Cycling ◽

Primary Productivity ◽

Large Scale ◽

Net Primary Productivity ◽

Cold Water ◽

Standing Stock ◽

Kelp Forests ◽

Growth Season ◽

Trailing Edge ◽

Carbon Cycles

Abstract Kelp forests are extensive, widely distributed and highly productive. However, despite their importance, reliable estimates of net primary productivity (NPP) are currently unknown for most species and regions. In particular, how performance and subsequent NPP change throughout a species range is lacking. Here, we attempted to resolve this by examining growth and performance of the boreal kelp, Laminaria digitata, from range centre and trailing edge regions in the United Kingdom. During the peak growth season (March/April), range-centre individuals were up to three times heavier and accumulated biomass twice as fast as their trailing-edge counterparts. This was not apparent during the reduced growth season (August/September), when populations within both regions had similar biomass profiles. In total, annual NPP estimates were considerably lower for trailing-edge (181 ± 34 g C m−2 year−1) compared to range-centre (344 ± 33 g C m−2 year−1) populations. Our first-order UK estimates of total standing stock and NPP for L. digitata suggest this species makes a significant contribution to coastal carbon cycling. Further work determining the ultimate fate of this organic matter is needed to understand the overall contribution of kelp populations to regional and global carbon cycles. Nevertheless, we highlight the need for large-scale sampling across multiple populations and latitudes to accurately evaluate kelp species’ contributions to coastal carbon cycling.

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A CLASSIFICATION INDICES-BASED MODEL FOR NET PRIMARY PRODUCTIVITY (NPP) AND POTENTIAL PRODUCTIVITY OF VEGETATION IN CHINA

International Journal of Biomathematics ◽

10.1142/s1793524512600091 ◽

2012 ◽

Vol 05 (03) ◽

pp. 1260009 ◽

Cited By ~ 8

Author(s):

HUILONG LIN ◽

JUN ZHAO ◽

TIANGANG LIANG ◽

JAN BOGAERT ◽

ZHENQING LI

Keyword(s):

Primary Productivity ◽

Large Scale ◽

Net Primary Productivity ◽

Global Climate ◽

Terrestrial Ecosystem ◽

Terrestrial Vegetation ◽

Moisture Index ◽

Potential Productivity ◽

Climate Conditions ◽

Factors Affecting

Net Primary Productivity (NPP) is an important parameter, which is closely connected with global climate change, the global carbon balance and cycle. The study of climate-vegetation interaction is the basis for research on the responses of terrestrial ecosystem to global change and mainly comprises two important components: climate vegetation classification and the NPP of the natural vegetation. Comparing NPP estimated from the classification indices-based model with NPP derived from measurements at 3767 sites in China indicated that the classification indices-based model was capable of estimating large scale NPP. Annual cumulative temperature above 0°C and a moisture index, two main factors affecting NPP, were spatially plotted with the ArcGIS grid tool based on measured data in 2348 meteorological stations from 1961 to 2006. The distribution of NPP for potential vegetation classes under present climate conditions was simulated by the classification indices-based model. The model estimated the total NPP of potential terrestrial vegetation of China to fluctuate between 1.93 and 4.54 Pg C year-1. It provides a reliable means for scaling-up from site to regional scales, and the findings could potentially favor China's position in reducing global warming gases as outlined in the Kyoto Protocol in order to fulfill China's commitment of reducing greenhouse gases.

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Global patterns and climatic controls of belowground net carbon fixation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2006715117 ◽

2020 ◽

Vol 117 (33) ◽

pp. 20038-20043 ◽

Cited By ~ 1

Author(s):

Laureano A. Gherardi ◽

Osvaldo E. Sala

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Primary Production ◽

Primary Productivity ◽

Carbon Fixation ◽

Net Primary Productivity ◽

Net Primary Production ◽

Belowground Carbon ◽

Belowground Productivity ◽

Carbon Productivity

Carbon allocated underground through belowground net primary production represents the main input to soil organic carbon. This is of significant importance, because soil organic carbon is the third-largest carbon stock after oceanic and geological pools. However, drivers and controls of belowground productivity and the fraction of total carbon fixation allocated belowground remain uncertain. Here we estimate global belowground net primary productivity as the difference between satellite-based total net primary productivity and field observations of aboveground net primary production and assess climatic controls among biomes. On average, belowground carbon productivity is estimated as 24.7 Pg y−1, accounting for 46% of total terrestrial carbon fixation. Across biomes, belowground productivity increases with mean annual precipitation, although the rate of increase diminishes with increasing precipitation. The fraction of total net productivity allocated belowground exceeds 50% in a large fraction of terrestrial ecosystems and decreases from arid to humid ecosystems. This work adds to our understanding of the belowground carbon productivity response to climate change and provides a comprehensive global quantification of root/belowground productivity that will aid the budgeting and modeling of the global carbon cycle.

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