Effects of climate extremes on the terrestrial carbon cycle : concepts, processes and potential future impacts

This article is protected by copyright. All rights reserved. Acknowledgements This work emerged from the CARBO-Extreme project, funded by the European Community’s 7th framework programme under grant agreement (FP7-ENV-2008-1-226701). We are grateful to the Reviewers and the Subject Editor for helpful guidance. We thank to Silvana Schott for graphic support. Mirco Miglivacca provided helpful comments on the manuscript. Michael Bahn acknowledges support from the Austrian Science Fund (FWF; P22214-B17). Sara Vicca is a postdoctoral research associate of the Fund for Scientific Research – Flanders. Wolfgang Cramer contributes to the Labex OT-Med (n° ANR-11- LABX-0061) funded by the French government through the A*MIDEX project (n° ANR-11-IDEX-0001-02). Flurin Babst acknowledges support from the Swiss National Science Foundation (P300P2_154543).Peer reviewedPublisher PD

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Influence of Spring and Autumn Phenological Transitions on Forest Ecosystem Productivity

We use eddy covariance measurements of net ecosystem productivity (NEP) from 21 FLUXNET sites (153 site-years of data) to investigate relationships between phenology and productivity (in terms of both NEP and gross ecosystem photosynthesis, GEP) in temperate and boreal forests. Results are used to evaluate the plausibility of four different conceptual models. Phenological indicators were derived from the eddy covariance time series, and from remote sensing and models. We examine spatial patterns (across sites) and temporal patterns (across years); an important conclusion is that it is likely that neither of these accurately represents how productivity will respond to future phenological shifts resulting from ongoing climate change. In spring and autumn, increased GEP resulting from an ¿extra¿ day tends to be offset by concurrent, but smaller, increases in ecosystem respiration, and thus the effect on NEP is still positive. Spring productivity anomalies appear to have carry-over effects that translate to productivity anomalies in the following autumn, but it is not clear that these result directly from phenological anomalies. Finally, the productivity of evergreen needleleaf forests is less sensitive to phenology than is productivity of deciduous broadleaf forests. This has implications for how climate change may drive shifts in competition within mixed-species stands.JRC.H.5-Land Resources Managemen

Synergy of extreme drought and shrub invasion reduce ecosystem functioning and resilience in water-limited climates

Extreme drought events and plant invasions are major drivers of global change that can critically affect ecosystem functioning and alter ecosystem-atmosphere exchange. Invaders are expanding worldwide and extreme drought events are projected to increase in frequency and intensity. However, very little is known on how these drivers may interact to affect the functioning and resilience of ecosystems to extreme events. Using a manipulative shrub removal experiment and the co-occurrence of an extreme drought event (2011/2012) in a Mediterranean woodland, we show that native shrub invasion and extreme drought synergistically reduced ecosystem transpiration and the resilience of key-stone oak tree species. Ecosystem transpiration was dominated by the water use of the invasive shrub Cistus ladanifer, which further increased after the extreme drought event. Meanwhile, the transpiration of key-stone tree species decreased, indicating a competitive advantage in favour of the invader. Our results suggest that in Mediterranean-type climates the invasion of water spending species and projected recurrent extreme drought events may synergistically cause critical drought tolerance thresholds of key-stone tree species to be surpassed, corroborating observed higher tree mortality in the invaded ecosystems. Ultimately, this may shift seasonally water limited ecosystems into less desirable alternative states dominated by water spending invasive shrubs

Chorioretinal Biopsy-Proven Ocular Sarcoidosis in a Patient with a History of B-Cell Lymphoma

The purpose of this report is to describe biopsy-proven ocular sarcoidosis (OS) in a 67-year-old patient with a history of sarcoidosis and diffuse large B-cell lymphoma (DLBCL). Nonspecific posterior chorioretinal lesions in a patient with prior malignancy necessitated chorioretinal biopsy to rule out metastatic lymphoma. The association between sarcoidosis and malignancy remains unclear and can complicate management of similar patients with nonspecific posterior segment findings. Chorioretinal biopsy may, therefore, be required to rule out malignancy in patients with a leading history

Heatwave breaks down the linearity between sun-induced fluorescence and gross primary production

Sun-induced fluorescence in the far-red region (SIF) is increasingly used as a remote and proximal-sensing tool capable of tracking vegetation gross primary production (GPP). However, the use of SIF to probe changes in GPP is challenged during extreme climatic events, such as heatwaves. Here, we examined how the 2018 European heatwave (HW) affected the GPP-SIF relationship in evergreen broadleaved trees with a relatively invariant canopy structure. To do so, we combined canopy-scale SIF measurements, GPP estimated from an eddy covariance tower, and active pulse amplitude modulation fluorescence. The HW caused an inversion of the photosynthesis-fluorescence relationship at both the canopy and leaf scales. The highly nonlinear relationship was strongly shaped by nonphotochemical quenching (NPQ), that is, a dissipation mechanism to protect from the adverse effects of high light intensity. During the extreme heat stress, plants experienced a saturation of NPQ, causing a change in the allocation of energy dissipation pathways towards SIF. Our results show the complex modulation of the NPQ-SIF-GPP relationship at an extreme level of heat stress, which is not completely represented in state-of-the-art coupled radiative transfer and photosynthesis models.Peer reviewe

Aflibercept Biosimilar MYL-1701P vs Reference Aflibercept in Diabetic Macular Edema : The INSIGHT Randomized Clinical Trial

Biosimilars may be lower-cost alternatives to originator biologic products, potentially offering expanded access or reduced economic burden, but have not been evaluated with aflibercept in diabetic macular edema (DME).To compare efficacy and safety of MYL-1701P, an aflibercept biosimilar, with reference aflibercept (Eylea [Regeneron]) in DME.This was a double-masked, randomized clinical trial that included participants at 77 centers across the US, Europe, Japan, and India. Included in the analysis were individuals 18 years and older with type 1 or type 2 diabetes with central DME and best-corrected visual acuity (BCVA) letter score of 73 to 38 in the study eye using an Early Treatment Diabetic Retinopathy Study (ETDRS) chart. Study data were analyzed from October to December 2021.Formulations of MYL-1701P (0.5-mg vial) or reference aflibercept every 4 weeks for 5 consecutive intravitreal injections, followed by every 8 weeks through week 52.The primary outcome was the adjusted difference in least squares mean (SE) change from baseline BCVA letter score at week 8 with an equivalence margin of -3 to +3 letters. Secondary outcomes included change in central subfield thickness (CST), BCVA, number of injections over 52 weeks, incidence of adverse events (AEs), and antidrug antibodies (ADAs).A total of 355 participants (mean [SD] age, 62.2 [9.2] years; 216 male [60.8%]) were randomized to MYL-1701P (179 participants [50.4%]) and aflibercept (176 participants [49.6%]). At week 8, mean (SE) change in BCVA was 6.60 (0.55) letters vs 6.56 (0.55) letters in the MYL-1701P vs aflibercept groups. The adjusted mean difference of 0.04 letters (90% CI, -1.16 to 1.24 letters) met the primary outcome. At week 8, mean (SE) change in CST was -112 (7) μm vs -124 (7) μm in the MYL-1701P vs aflibercept groups (adjusted mean difference, 12 μm; 90% CI, -3 to 26 μm). The incidence of treatment-emergent AEs in the MYL-1701P and aflibercept arms were ocular (30.9% [55 of 178] vs 29.5% [52 of 176]), serious ocular (0.6% [1 of 178] vs 1.1% [2 of 176]), nonocular (65.2% [116 of 178] vs 65.3% [115 of 176]), and serious nonocular (16.9% [30 of 178] vs 11.9% [21 of 176]). The mean (SD) total number of injections was 8.4 (2.1) vs 8.7 (1.8) in the MYL-1701P vs aflibercept groups. The incidence of treatment-induced or treatment-boosted ADAs was 2.8% (5 of 177) vs 5.7% (10 of 176) in the MYL-1701P vs aflibercept arms.MYL-1701P demonstrated clinical equivalence in regard to efficacy, with comparable safety and immunogenicity, to reference aflibercept. These findings support use of MLY-1701P as an alternative to reference aflibercept.ClinicalTrials.gov Identifier: NCT03610646

Nutrient induced changes in Sun-Induced Fluorescence emission in a Mediterranean grassland

Sun induced fluorescence (SIF), the radiation flux emitted by plant chlorophylls molecules in the 650-800 nm spectral window, is considered an indicator of photosynthetic performance. Recently it has been shown that SIF can track changes in light use efficiency (LUE), and therefore it is a good predictor of gross primary production (GPP) at various scales, from leaves and ecosystem to regional and global scale. Although SIF has been successfully used to predict GPP in various ecosystems, the mechanistic link between GPP and SIF remains not fully understood, and especially the effect of function and structure on SIF at the canopy scale remains an active area of research. SIF is emitted by the whole canopy, but only a fraction of the total emission is observed with remote sensing techniques. The escape probability of SIF (Fesc) controls the amount of SIF scattered by the canopy and is integral to separate the effect of canopy structure and function on the fluorescence signal. In this contribution we make use of data collected at the research site Majadas del Tietar, a Mediterranean grassland manipulated with Nitrogen and Phosphorus. Using the SCOPE model (Soil Canopy Observation Photochemistry and Energy fluxes) we obtain Fesc and we analyse how Top of canopy SIF and emitted SIF vary in response to the fertilization. With a combination of processes-based modelling and data driven analysis, such as relative importance analysis and structural equation modelling, we unravel the processes and causal relationship that are at the base of the GPP - SIF relationship. We show that the nutrient fertilization had an effect on plant composition, and therefore canopy structure, but also plant functioning. Nitrogen induced changes in biodiversity mainly affect leaf angle distribution of the canopy and therefore scattering properties such as Fesc. The nitrogen fertilization is also responsible for a change in plant functioning, with altered SIF emission. The simultaneous change of both canopy and structure causes the fertilization effect to be visible mainly at the emission level, but not at top of canopy, as the variation in canopy structure masks the change observed at leaf level. This contribution advances the knowledge of the highly complex dynamics involved in the GPP-SIF relationship. In depth understanding of the mechanistic processes is required to fully take advantage of the increasingly prevalent SIF data streams