- Effects from climate change, adaptations and
greenhouse gas reduction at 2050

Abstract:

Progress Report of AP B3 for the FACE2FACE plenary meeting

Abstract:

A pink-pigmented, Gram-stain-negative, rod-shaped, non-spore-forming bacterial strain, PP-F2F-G21T, was isolated from the phyllosphere of Galium album. Phylogenetic analysis of the nearly full-length 16S rRNA gene sequence of strain PP-F2F-G21T showed the closest relationship to type strains of the species Mucilaginibacter lutimaris (97.7?%), Mucilaginibacter soli (97.3?%) and Mucilaginibacter rigui (97.1?%). Sequence similarities to all other type strains were below 97?%. The predominant cellular fatty acids of strain PP-F2F-G21T are C16?:?1 ?7c/iso-C15?:?0 2-OH (measured as summed feature 3 fatty acids) and iso-C15?:?0 followed by iso-C17?:?0 3-OH, C16?:?1 ?5c and C16?:?0. The major compound in the polyamine pattern was sym-homospermidine and the diamino acid of the peptidoglycan was meso-diaminopimelic acid. The quinone system was exclusively composed of menaquinone MK-7. The polar lipid profile contained the major lipid phosphatidylethanolamine and in addition 18 unidentified lipids. Based on phylogenetic, chemotaxonomic and phenotypic analyses, we propose a novel species of the genus Mucilaginibacter named Mucilaginibacter phyllosphaerae sp. nov. The type strain is PP-F2F-G21T (=CCM 8625T=CIP 110921T=LMG 29118T).

Abstract:

Four yellow-pigmented, Gram-stain-negative, rod-shaped bacteria, strains PP-WC-4G-234T, PP-CE-2G-454T, PP-WC-1G-202 and PP-CC-3G-650, were isolated from the phyllosphere of Galium album. The strains shared 99.7–100?% 16S rRNA gene sequence similarity but could be differentiated by genomic fingerprinting using rep- and random amplification of polymorphic DNA PCRs. Phylogenetic analysis based on the 16S rRNA gene placed the strains within the family Aurantimonadaceae with highest 16S rRNA gene sequence similarity of 97.2–97.3?% to the type strain of Aureimonas phyllosphaerae. Sequence similarities to all other Aurantimonadaceae were below 97?%. The main cellular fatty acids of the strains were C18?:?1 ?7c as the predominant fatty acid followed by C16?:?0 and summed feature 3 (C16?:?1 ?7c/C16?:?1 ?8c). The polyamine patterns of strains PP-WC-4G-234T and PP-CE-2G-454T contained sym-homospermidine as a major compound, and the major respiratory quinone was ubiquinone Q-10. Predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, phosphatidylcholine, sulfoquinovosyldiacylglycerol, three unidentified phospholipids and one unidentified lipid only detectable after total lipid staining. The DNA G+C content was 66.4, 68.9, 67.4 and 70.5 mol% for strains PP-WC-4G-234T, PP-CE-2G-454T, PP-WC-1G-202 and PP-CC-3G-650, respectively. Based on phylogenetic, chemotaxonomic and phenotypic analyses we propose two novel species of the genus Aureimonas, Aureimonas galii sp. nov. with PP-WC-4G-234T (=LMG 28655T=CIP 110892T) as the type strain and Aureimonas pseudogalii sp. nov. with PP-CE-2G-454T (=LMG 29411T=CCM 8665T) as the type strain and two further strains representing the same species, PP-WC-1G-202 and PP-CC-3G-650.

Abstract:

The increase in atmospheric greenhouse gas concentrations from anthropogenic activities is the major driver of recent global climate change1. The stimulation of plant photosynthesis due to rising atmospheric carbon dioxide concentrations ([CO2]) is widely assumed to increase the net primary productivity (NPP) of C3 plants—the CO2 fertilization effect (CFE). However, the magnitude and persistence of the CFE under future climates, including more frequent weather extremes, are controversial. Here we use data from 16 years of temperate grassland grown under ‘free-air carbon dioxide enrichment’ conditions to show that the CFE on above-ground biomass is strongest under local average environmental conditions. The observed CFE was reduced or disappeared under wetter, drier and/or hotter conditions when the forcing variable exceeded its intermediate regime. This is in contrast to predictions of an increased CO2 fertilization effect under drier and warmer conditions. Such extreme weather conditions are projected to occur more intensely and frequently under future climate scenarios. Consequently, current biogeochemical models might overestimate the future NPP sink capacity of temperate C3 grasslands and hence underestimate future atmospheric [CO2] increase.

Abstract:

The sampling design in the all six Gi-FACE rings is standardised. Subplots 1-3 are used for weekly measurements of greenhouse gas fluxes and biannual biomass harvest. Subplots 4-25 are used for biannual biomass harvests and cover more or less the two species inventory subplots for biannual vegetations surveys. Subplots 24 and 25 have been used in 2013 for a 15N-13C Tracing study and in Subplot 25 the topsoil (7.5 cm) was used in 2014 for an incubation study and the soil was replaced by soil from outside the rings. Small circles within the ring area indicate Licor soil colomne for soil respiration measurements. The yellow rectangles mark the area where soil profiles have been opened in 2015 to install new soil moisture and temperature sensors. "Needles" and asterix mark positions where soil samples have been taken.

Abstract:

The continuous increase in atmospheric carbon dioxide (CO2) contributes to changes in plant evapotranspiration and terrestrial water Budgets in two ways. Firstly, elevated CO2 can result in a water saving effect, since increasing CO2 reduces stomatal opening and therefore decreases transpiration. Secondly, CO2 fertilization increases biomass accumulation and leaf area at plant canopy Level, likely increasing plant transpiration. Vegetation and hydrological models can be used to investigate the CO2 Response and the bidirectional effects outlined above, including their relative contribution to the changes in the water cycle. However, the intrinsic plant-soil interaction and the uncertainty related to model parameterization have rarely been considered. Hence, we coupled a detailed plant growth and soil hydrological model by using the generic model frameworks Plant growth Modelling Framework (PMF) and Catchment Modelling Framework (CMF). Up to date response mechanisms have been implemented in PMF to simulate the various ways of how plant physiology is influenced by elevated CO2. Both models interact by using the Python computer language. Applying the coupled PMF-CMF model we investigate the effects of elevated CO2 in a number of plant physiological and environmental variables such as biomass, leaf area index and soil moisture using field data of a long-term Free Air Carbon dioxide Enrichment (FACE) Experiment in Giessen, Germany. In this Experiment, various grassland varieties (herbs, legumes, grasses) grow under elevated (+20%) and ambient CO2 since 1997. A Monte Carlo based uncertainty analysis (GLUE) is conducted to investigate the coupled PMF-CMF parameter space. The focus will be on the identification of parameters for plant and soil, which are the drivers for the CO2 Response of the terrestrial water balance. We will present first results of the simulation of biomass accumulation and transpiration under ambient and elevated CO2 concentrations.

Abstract:

An increase in mean soil surface temperature has been observed over the last century and it is predicted to further increase in the future. The effect of increased temperature on ecosystem carbon fluxes in a permanent temperate grassland, was studied in a long term (6 years) field experiment, using multiple temperature increments induced by IR-lamps. Ecosystem respiration (R-eco) and net ecosystem exchange (NEE) were measured, and modelled by a modified Lloyd and Taylor model including a soil moisture component for R-eco (average R2 of 0.78) and inclusion of a photosynthetic component based on temperature and radiation for NEE (R2=0.65). Modelled NEE values ranged between 2.3 and 5.3 kg CO2 m-2 year-1, depending on treatment. An increase of 2 or 3°C led to increased carbon losses, lowering the carbon storage potential by around 4 tonnes of C ha-1 year-1. The majority of significant NEE differences were found during night-time compared to daytime. This suggests that during daytime the increased respiration could be offset by an increase in photosynthetic uptake. This was also supported by differences in ?13C and ?18O, indicating prolonged increased photosynthetic activity associated with the higher temperature treatments. However, this increase in photosynthesis was insufficient to counteract the 24hr increase in respiration, explaining the higher CO2 emissions due to elevated temperature.

Abstract:

Soil respiration of terrestrial ecosystems, a major component in the global carbon cycle is affected by elevated atmospheric CO2 concentrations. However, seasonal differences of feedback effects of elevated CO2 have rarely been studied. At the Gießen Free-Air CO2 Enrichment (GiFACE) site, the effects of +20% above ambient CO2 concentration have been investigated since 1998 in a temperate grassland ecosystem. We defined five distinct annual seasons, with respect to management practices and phenological cycles. For a period of 3 years (2008–2010), weekly measurements of soil respiration were carried out with a survey chamber on vegetation-free subplots. The results revealed a pronounced and repeated increase of soil respiration under elevated CO2 during late autumn and winter dormancy. Increased CO2 losses during the autumn season (September–October) were 15.7% higher and during the winter season (November–March) were 17.4% higher compared to respiration from ambient CO2 plots. However, during spring time and summer, which are characterized by strong above- and below-ground plant growth, no significant change in soil respiration was observed at the GiFACE site under elevated CO2. This suggests (1) that soil respiration measurements, carried out only during the growing season under elevated CO2 may underestimate the true soil-respiratory CO2 loss (i.e. overestimate the C sequestered), and (2) that additional C assimilated by plants during the growing season and transferred below-ground will quickly be lost via enhanced heterotrophic respiration outside the main growing season.