The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

Co-ordination in morphological leaf traits of early diverging angiosperms is maintained following exposure to experimental palaeo-atmospheric conditions of sub-ambient O2 and elevated CO2

In order to be successful in a given environment a plant should invest in a vein network and stomatal distribution that ensures balance between both water supply and demand. Vein density (Dv) and stomatal density (SD) have been shown to be strongly positively correlated in response to a range of environmental variables in more recently evolved plant species, but the extent of this relationship has not been confirmed in earlier diverging plant lineages. In order to examine the effect of a changing atmosphere on the relationship between Dv and SD, five early-diverging plant species representing two different reproductive plant grades were grown for seven months in a palaeo-treatment comprising an O2:CO2 ratio that has occurred multiple times throughout plant evolutionary history. Results show a range of species-specific Dv and SD responses to the palaeo-treatment, however we show that the strong relationship between Dv and SD under modern ambient atmospheric composition is maintained following exposure to the palaeo-treatment. This suggests strong inter-specific co-ordination between vein and stomatal traits for our study species even under relatively extreme environmental change. This co-ordination supports existing plant function proxies that use the distance between vein endings and stomata (Dm) to infer plant palaeo-physiology

Increased atmospheric SO₂ detected from changes in leaf physiognomy across the Triassic-Jurassic boundary interval of East Greenland.

The Triassic-Jurassic boundary (Tr-J; ∼201 Ma) is marked by a doubling in the concentration of atmospheric CO2, rising temperatures, and ecosystem instability. This appears to have been driven by a major perturbation in the global carbon cycle due to massive volcanism in the Central Atlantic Magmatic Province. It is hypothesized that this volcanism also likely delivered sulphur dioxide (SO2) to the atmosphere. The role that SO2 may have played in leading to ecosystem instability at the time has not received much attention. To date, little direct evidence has been presented from the fossil record capable of implicating SO2 as a cause of plant extinctions at this time. In order to address this, we performed a physiognomic leaf analysis on well-preserved fossil leaves, including Ginkgoales, bennettites, and conifers from nine plant beds that span the Tr-J boundary at Astartekløft, East Greenland. The physiognomic responses of fossil taxa were compared to the leaf size and shape variations observed in nearest living equivalent taxa exposed to simulated palaeoatmospheric treatments in controlled environment chambers. The modern taxa showed a statistically significant increase in leaf roundness when fumigated with SO2. A similar increase in leaf roundness was also observed in the Tr-J fossil taxa immediately prior to a sudden decrease in their relative abundances at Astartekløft. This research reveals that increases in atmospheric SO2 can likely be traced in the fossil record by analyzing physiognomic changes in fossil leaves. A pattern of relative abundance decline following increased leaf roundness for all six fossil taxa investigated supports the hypothesis that SO2 had a significant role in Tr-J plant extinctions. This finding highlights that the role of SO2 in plant biodiversity declines across other major geological boundaries coinciding with global scale volcanism should be further explored using leaf physiognomy

Box plots showing the range of values for area and shape factor for each nearest living equivalent species.

<p>The box represents the lower 25 percentile, the median value and the upper 25% percentile and the whiskers represent the range of the data. Stars represent outliers (values over twice the value of the median). <i>Lepidozamia hopei</i> (A area and B shape factor); L. <i>peroffskyana</i> (C area and D shape factor); <i>Agathis australis</i> (E area and F shape factor); <i>Nageia nagi</i> (G area and H shape factor); <i>Ginkgo biloba</i> (I area and J shape factor).</p

Astartekløft stratigraphic log (A) (after [5]; [25]) compared to area changes showed as box plots in the measured fossil taxa: <i>Elatocladus</i> (B); <i>Podozamites</i> (C); <i>Baiera</i> (D); <i>Ginkgoites</i> (E); <i>Anomozamites</i> (F); <i>Pterophyllum</i> (G).

<p>Astartekløft stratigraphic log (A) (after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060614#pone.0060614-Hesselbo1" target="_blank">[5]</a>; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060614#pone.0060614-McElwain2" target="_blank">[25]</a>) compared to area changes showed as box plots in the measured fossil taxa: <i>Elatocladus</i> (B); <i>Podozamites</i> (C); <i>Baiera</i> (D); <i>Ginkgoites</i> (E); <i>Anomozamites</i> (F); <i>Pterophyllum</i> (G).</p

Examples of leaf physiognomy for each nearest living equivalent species in the study.

<p><i>Lepidozamia peroffskyana</i> (A); <i>Lepidozamia hopei</i> (B); <i>Nageia nagi</i> (C); <i>Agathis australis</i> (D); <i>Ginkgo biloba</i> (E). Lower case Roman numerals indicate the simulated palaeoatmospheric treatment that the leaf grew in: (i) control; (ii) elevated SO₂ and (iii) Tr–J type atmosphere. The scale bar in each image is 10 mm.</p

Summary of atmospheric changes compared to standing fossil richness recorded at Astartekløft and SO₂ responsiveness of both fossil and NLE taxa.

<p>Astartekløft stratigraphic log (A) (after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060614#pone.0060614-Hesselbo1" target="_blank">[5]</a>; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060614#pone.0060614-McElwain2" target="_blank">[25]</a>) compared to atmospheric CO₂ changes (B) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060614#pone.0060614-Steinthorsdottir1" target="_blank">[4]</a> with timing of likely high SO₂<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060614#pone.0060614-Schaller1" target="_blank">[3]</a>; <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060614#pone.0060614-Mander1" target="_blank">[34]</a> superimposed in grey, standing species richness (C) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0060614#pone.0060614-McElwain2" target="_blank">[25]</a> and summarized responsiveness of both fossil and NLE taxa (D).</p

Kruskal Wallis and Mann-Whitney pair-wise comparisons for each physiognomic trait in <i>Lepidozamia peroffskyana</i> in the different simulated palaeoatmospheric treatments.

<p>Kruskal Wallis and Mann-Whitney pair-wise comparisons for each physiognomic trait in <i>Lepidozamia peroffskyana</i> in the different simulated palaeoatmospheric treatments.</p

Kruskal Wallis and Mann-Whitney pair-wise comparisons for each physiognomic trait in <i>Lepidozamia hopei</i> in the different simulated palaeoatmospheric treatments.

<p>Kruskal Wallis and Mann-Whitney pair-wise comparisons for each physiognomic trait in <i>Lepidozamia hopei</i> in the different simulated palaeoatmospheric treatments.</p

Kruskal Wallis and Mann-Whitney pair-wise comparisons for each physiognomic trait in <i>Ginkgo biloba</i> in the different simulated palaeoatmospheric treatments.

<p>Kruskal Wallis and Mann-Whitney pair-wise comparisons for each physiognomic trait in <i>Ginkgo biloba</i> in the different simulated palaeoatmospheric treatments.</p