Response of mature Norway spruce (Picea abies) to elevated atmospheric CO²

The aim of this thesis was to identify pathways and rates of C allocation in tall forest trees, and to identify effects of elevated CO2 on respiratory processes and root growth. Correspondingly, this thesis is divided into three separate parts: Chapter 2) Long-term 13C labeling provides evidence for temporal and spatial carbon allocation patterns in mature Picea abies (published in Oecologia) Chapter 3) Respiratory fluxes and fine root responses in mature Picea abies trees exposed to elevated atmospheric CO2 concentrations (published in Biogeochemistry) Chapter 4) Photosynthetic enhancement and diurnal stem and soil carbon fluxes in a mature Norway spruce stand under elevated CO2 (published in Environmental and Experimental Botany) The work was conducted at the Swiss canopy crane (SCC) research site in Hofstetten near Basel, Switzerland, and explored signals produced by free air CO2 enrichment (FACE) in 110-year-old, ca. 37m tall P. abies trees. Chapter 2 capitalizes on the isotopic signal carried by the CO2 gas used for CO2 enrichment, yet does not address effects of elevated CO2 as such, but rather deals with basic questions of C transfer in tall trees. Chapter 3 explores the longer-term CO2 effects on mature P. abies (i.e. 2.5 years), whereas chapter 4 reports short-term (diurnal) responses to elevated CO2. In the following, I will provide a summary of the results of the three chapters of my thesis, extended by a conclusion that links these chapters. Chapter 2) Long-term 13C labeling of Picea abies As a side effect, the FACE technique provided the unique opportunity to study C translocation within the tree body using the stable isotope 13C signal the FACE gas carries. Since control trees are not (can not) be similarly labeled with 13C the tree responses to elevated CO2 were not the subject of this chapter. Yet, FACE resembles a continuous 13C labeling of new assimilates. Tracking the fate of these assimilates over a period of 2.5 years in tall trees offers new insights in tree C relations under steady state conditions. We tracked 13C signals in mature P. abies trees at a high spatial and temporal resolution, i.e. from the canopy (needles and branchlets), down to the tree trunk (year rings and stem CO2 efflux), and into the soil compartment (fine roots, fungi, soil CO2 efflux). The following key questions were answered: 1. How long does it take for new C to arrive at a certain tissue type or respiratory flux? 2. What is the proportional contribution of newly assimilated C to concurrent tree tissue production and maintenance? 3. How long does it take until old C is replaced by new C in various tissues? Generally, we observed a reduction of new assimilate investment with distance from the canopy, which can be explained by a progressive dilution of new C into the existing C storage pools in the tree. New sunlit needles (and adjacent branchlets) exhibited a nearly 100% share of new C, whereas shaded needles also used some older C. Stem wood isotope signals evidenced a complete exchange of old C by new C within 2 years. Fine roots contained only 49-56% new C, hence are using older C pools for a longer period of time. A surprisingly low fraction of novel C (26-43%) was recovered from fungal sporocarps, presumably related to the influence of neighboring trees that were not CO2 enriched. The first appearance of new C in soil and stem CO2 release occurred after 12 days, reflecting a lag due to the long transport distances in these 37m tall trees. The CO2 released by stems was composed of 50% new C already in the first year of FACE. In contrast, only ca. 15% new C contributed to soil CO2 efflux, reflecting the use of older substrates, and the influence of older roots and litter from neighboring trees blown in by wind. These findings indicate a rapid contribution of new assimilates to tissue formation, and thus, a fast replacement of mobile C reserves with new C, and a progressive signal dilution from treetop to the bottom. The two-year replacement time in stem xylem shows that the storage pool is contributing substantially to tree ring formation. We speculate that the turnover of mobile C pools might be enhanced by elevated CO2, and the metabolic costs of this turnover might compensate for some of the extra C taken up at elevated CO2 concentrations, and thus, may explain the ‘missing C’ at the whole tree level. These metabolic costs are unlikely to produce measurable signals at tissue level, given the large heterotrophic volume of such trees. Chapter 3) Responses of Picea abies to elevated CO2 Most FACE experiments revealed strong initial growth responses to elevated CO2 that diminished over the first 3 years (Körner 2006). Since growth in natural undisturbed systems is commonly not showing a continued stimulation under altered CO2 for reasons of nutrient supply, a step increase in CO2 concentration should induce overflow responses in terms of enhanced respiration and fine root expansion, the latter in order to forage for nutrients to balance the additional C input. In this web-FACE experiment, established in a natural Central European forest, we investigated mature ca. 110-year-old P. abies trees in their steady state of growth (C cycle coupled to the nutrient cycle; Körner 2006). In this publication we were particularly interested in: 1. Seasonal shifts in assimilate allocation; 2. Locations of C-investment; 3. Residence times (turnover) of mobile C pools. We tracked the respiratory and fine root growth responses of these trees before and directly after the start of FACE, and for further 2.5 years. The CO2 concentration in the canopy (e.g. 540 ppm) was about twice the pre-industrial level. We anticipated a stimulation of CO2 release, and faster root expansion into root-free soil space (in-growth core method), but we also expected a weaker signal in these mature trees compared to young trees. Seasonal stem CO2 efflux did not show any sign of increase during the 2.5 years under elevated CO2. This result lines up with the lack of any stem radial growth response (ongoing work). Fine roots (<0.5-2 mm) did not accumulate more dry matter in the course of 2.5 years of CO2 fertilization. Interestingly, we observed a slight but significant reduction of CO2 release from the soil despite clear evidence by isotopic signals that novel assimilates arrived in the soil. These data suggest that such mature trees do not even show a transient stimulation of respiration to a step increase of CO2, as was observed in other FACE experiments using much younger trees (Norby et al. 2010). Other growth-limiting factors appear to prevent more vigorous tree growth and thus, metabolism at high CO2 (Norby & Zak 2011). N limitation can be excluded at our site because of high N-deposition. A part of the extra C taken up by needles at elevated CO2 might have been allocated belowground, however, not to fine roots. Conversely, slightly reduced rather than increased rates of soil CO2 efflux implies that respiration of roots and/or soil organisms declined under elevated CO2, implying an overall reduced C allocation into the rhizosphere. We assume that extra C absorbed by foliage is either retained within the tree body (stored carbohydrates), recycled by respiration rates below detection limit across all heterotrophic plant tissues, or lost through enhanced leaching of dissolved organic or inorganic carbon (DIC/DOC). In summary, we conclude that mature P. abies trees at our site are roughly C saturated at current CO2 concentrations. We find no indication of stimulated belowground metabolic activity (fine roots and soil CO2 efflux). Chapter 5) Diurnal courses in P. abies under elevated CO2 Leaf-level photosynthetic stimulation in trees following a step increase of atmospheric CO2 was commonly observed in CO2 enrichment experiments, however, mostly without corresponding growth stimulation. Hence, the fate of this additional C input in tree still is not fully resolved, but C overflow mechanisms such as respiratory C losses might account for this C surplus. Since these potential variations in C fluxes might not be detectable on a daily basis, a response may emerge on shorter timescales (i.e. on a diurnal basis). This chapter (co-authorship) explored the diurnal variations in C fluxes (i.e. net photosynthesis, and CO2 efflux from the forest floor and the from stem) in mature P. abies trees exposed to elevated CO2 in the SCC web-FACE experiment. We tracked the diurnal variations of these fluxes on a summer day shortly before the onset of FACE, and twice during the FACE periods in summer 2009 and 2010. Results from this study confirmed a CO2-induced photosynthetic stimulation shortly after the onset of FACE, and a change in magnitude throughout the day. Intriguingly, this stimulation of Anet diminished in the second year under FACE, indicating photosynthetic downregulation in these trees. The respiratory fluxes from P. abies stems, as observed on a seasonal basis (chapter 4), were not affected by high levels of CO2 whereas soil CO2 efflux decreased slightly with prolonged exposure to elevated CO2. Further, the diurnal patterns of CO2 release (stems and soil) were not altered by CO2 enrichment. In conclusion, despite larger C input into the tree system in the first year of FACE, respiratory overflow mechanisms could not be observed even on a diurnal basis, corroborating our results obtained in chapter 4. Additionally, the photosynthetic downregulation observed at high CO2 confirms the assumption that these trees are C saturated. Final conclusions Stimulatory effects of elevated CO2 on tree growth are constrained by several growth-limiting factors, mainly availability of nutrients and other resources, and the developmental stage (age) of a tree. This thesis for the first time illuminates the current (chapter 2) and future (chapters 3 and 4) C balance of mature evergreen conifers subjected to prospective CO2 levels of 540 ppm in a near-natural forest in Switzerland. Isotopic labeling of fresh assimilates successfully depicted the pathways of C in these trees, thus provided basic insights into how P. abies trees handle the distribution of assimilates. We observed remarkable tree-specific variations in all pre-treatment measurements, emphasizing the importance of recording baseline conditions prior to any experiment. At current CO2 levels, all investigated tissues (except for needles in the sun), and respiratory fluxes depended only partly on new assimilates. The further away from the upper tree canopy, the greater the role of old C stores for new tissue formation and respiration. Since no aboveground growth stimulation was observed (ongoing works) despite higher but transient rates of photosynthesis, and since stem CO2 efflux remained unaffected by elevated CO2, we assume that the extra C assimilated in the first year is dissipated via respiration associated with C turnover (phloem) at rates below detection limit. These processes seem to be too small to be detectable but their accumulated rate along the entire phloem system might account for the unresolved ‘missing C’ at elevated CO2. We found no evidence for increased C investment belowground at elevated CO2 that might also account for some of the higher leaf-level C input at elevated CO2. References Körner C (2006) Plant CO2 responses: An issue of definition, time and resource supply. New Phytologist 172:393-411 Norby RJ, Warren JM, Iversen CM, Medlyn BE, McMurtie RE (2010) CO2 enhancement of forest productivity constrained by limited nitrogen availability. Proceedings of the National Academy of Sciences of the United States of America 107:19368-19373. Norby RJ, Zak DR (2011) Ecological lessons from free-air CO2 enrichment (FACE) experiments. Annual Review of Ecology, Evolution, and Systematics 42:181-20

Systems for testing the efficacy of biofungicides and resistance inducers against grapevine downy mildew (REPCO project)

Abstract –At present grapevine downy mildew is controlled by fungicides mostly not suitable for or-ganic viticulture. The aim of REPCO (Replacement of Copper Fungicides in Organic Production if Grapevine and Apple in Europe) is to find new copper replacing products. Also the activation of the innate defence response by resistance inducers is a potential ap-proach for the biological control of grapevine downy mildew in organic viticulture. The efficacy of potential biofungicides and resistance inducers against grape-vine downy mildew was tested on leaf discs and on cell suspension culture, respectively. In a first step the direct effect on the pathogen is assessed in a leaf disc test. The activation of defence response is de-termined in a cell suspension culture. Molecules from microbes, products from the secondary plant metabo-lism and oligosaccharides from animals and plants showed an efficacy against the pathogen and induced resistance response

Long-term 13C labeling provides evidence for temporal and spatial carbon allocation patterns in mature Picea abies

There is evidence of continued stimulation of foliage photosynthesis in trees exposed to elevated atmospheric CO2 concentrations; however, this is mostly without a proportional growth response. Consequently, we lack information on the fate of this extra carbon (C) acquired. By a steady application of a 13CO2 label in a free air CO2 enrichment (FACE) experiment, we traced the fate of C in 37-m-tall, ca. 110-year-old Picea abies trees in a natural forest in Switzerland. Hence, we are not reporting tree responses to elevated CO2 (which would require equally 13C labeled controls), but are providing insights into assimilate processing in such trees. Sunlit needles and branchlets grow almost exclusively from current assimilates, whereas shaded parts of the crowns also rely on stored C. Only 2.5years after FACE initiation, tree rings contained 100% new C. Stem-respiratory CO2 averaged 50% of new C over the entire FACE period. Fine roots and mycorrhizal fungi contained 49-56 and 26-43% new C, respectively, after 2.5years. The isotopic signals in soil CO2 arrived 12days after the onset of FACE, yet it contained only ca. 15% new C thereafter. We conclude that new C first feeds into fast turnover C pools in the canopy and becomes increasingly mixed with older C sources as one moves away (downward) from the crown. We speculate that enhanced C turnover (its metabolic cost) along the phloem path, as evidenced by basipetal isotope signal depletion, explains part of the ‘missing carbon' in trees that assimilated more C under elevated CO2

A dynamic leaf gas-exchange strategy is conserved in woody plants under changing ambient CO2: evidence from carbon isotope discrimination in paleo and CO2 enrichment studies

Rising atmospheric [CO2 ], ca , is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2 ], ci , a constant drawdown in CO2 (ca - ci ), and a constant ci /ca . These strategies can result in drastically different consequences for leaf gas-exchange. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf gas-exchange responses to varying ca . The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf gas-exchange responses to ca . To assess leaf gas-exchange regulation strategies, we analyzed patterns in ci inferred from studies reporting C stable isotope ratios (δ(13) C) or photosynthetic discrimination (∆) in woody angiosperms and gymnosperms that grew across a range of ca spanning at least 100 ppm. Our results suggest that much of the ca -induced changes in ci /ca occurred across ca spanning 200 to 400 ppm. These patterns imply that ca - ci will eventually approach a constant level at high ca because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization towards any single strategy, particularly maintaining a constant ci . Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low ca , when additional water loss is small for each unit of C gain, and increasingly water-conservative at high ca , when photosystems are saturated and water loss is large for each unit C gain. This article is protected by copyright. All rights reserved.Rising atmospheric [CO2], c(a), is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water, and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2], c(i), a constant drawdown in CO2 (c(a)-c(i)), and a constant c(i)/c(a). These strategies can result in drastically different consequences for leaf gas-exchange. The accuracy of Earth systems models depends in part on assumptions about generalizable patterns in leaf gas-exchange responses to varying c(a). The concept of optimal stomatal behavior, exemplified by woody plants shifting along a continuum of these strategies, provides a unifying framework for understanding leaf gas-exchange responses to c(a). To assess leaf gas-exchange regulation strategies, we analyzed patterns in c(i) inferred from studies reporting C stable isotope ratios (C-13) or photosynthetic discrimination () in woody angiosperms and gymnosperms that grew across a range of c(a) spanning at least 100ppm. Our results suggest that much of the c(a)-induced changes in c(i)/c(a) occurred across c(a) spanning 200 to 400ppm. These patterns imply that c(a)-c(i) will eventually approach a constant level at high c(a) because assimilation rates will reach a maximum and stomatal conductance of each species should be constrained to some minimum level. These analyses are not consistent with canalization toward any single strategy, particularly maintaining a constant c(i). Rather, the results are consistent with the existence of a broadly conserved pattern of stomatal optimization in woody angiosperms and gymnosperms. This results in trees being profligate water users at low c(a), when additional water loss is small for each unit of C gain, and increasingly water-conservative at high c(a), when photosystems are saturated and water loss is large for each unit C gain

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The cross sections for ϒ(1S), ϒ(2S), and ϒ(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at √sNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(ϒ(1S)) > RAA(ϒ(2S)) > RAA(ϒ(3S)). The suppression of ϒ(1S) is larger than that seen at √sNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of ϒ(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe

Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

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Electroweak production of two jets in association with a Z boson in proton-proton collisions root s =13 TeV

A measurement of the electroweak (EW) production of two jets in association with a Z boson in proton-proton collisions at root s = 13 TeV is presented, based on data recorded in 2016 by the CMS experiment at the LHC corresponding to an integrated luminosity of 35.9 fb(-1). The measurement is performed in the lljj final state with l including electrons and muons, and the jets j corresponding to the quarks produced in the hard interaction. The measured cross section in a kinematic region defined by invariant masses m(ll) > 50 GeV, m(jj) > 120 GeV, and transverse momenta P-Tj > 25 GeV is sigma(EW) (lljj) = 534 +/- 20 (stat) fb (syst) fb, in agreement with leading-order standard model predictions. The final state is also used to perform a search for anomalous trilinear gauge couplings. No evidence is found and limits on anomalous trilinear gauge couplings associated with dimension-six operators are given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -2.6 <cwww/Lambda(2) <2.6 TeV-2 and -8.4 <cw/Lambda(2) <10.1 TeV-2. The additional jet activity of events in a signal-enriched region is also studied, and the measurements are in agreement with predictions.Peer reviewe

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

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