Leading trait dimensions in flood-tolerant plants

Background and AimsWhile trait-based approaches have provided critical insights in general plant functioning, we lack a comprehensive quantitative view on plant strategies in flooded conditions. Plants adapted to flooded conditions have specific traits (e.g., root porosity, low root/shoot ratio, and shoot elongation) to cope with the environmental stressors including anoxic sediments, and the subsequent presence of phytotoxic compounds. In flooded habitats, plants also respond to potential nutrient and light limitations, e.g., through the expression of leaf economics traits and size-related, respectively. However, we don’t know whether and how these trait dimensions are connected.MethodsBased on a trait dataset compiled on 131 plant species from 141 studies in flooded habitats, we quantitatively analysed how flooding-induced traits are positioned in relation to the other two dominant trait dimensions; leaf economics and size-related traits. We evaluated how these key trait components are expressed along wetness gradients, across habitat types and among plant life forms.Key ResultsWe found that flooding-induced traits constitute a trait dimension independent from leaf economics traits and size-related traits, indicating that there is no generic trade-off associated to flooding adaptations. Moreover, individual flooding-induced traits themselves are to a large extent decoupled from each other. These results suggest that adaptation to stressful environments, such as flooding, can be stressor-specific without generic adverse effects on plant functioning (e.g., causing trade-offs on leaf economics traits).ConclusionsThe trait expressions across multiple dimensions promote plant adaptations and co-existence across multi-faceted flooded environments. The decoupled trait dimensions, as related to different environmental drivers, also explain why ecosystem functioning (including e.g. methane emissions) are species- and habitat-specific. Thus, our results provide a backbone for applying trait-based approaches in wetland ecology by considering flooding-induced traits as an independent trait dimension.Environmental Biolog

A coupled channel analysis of the centrally produced K+K- and pi+pi- final states in pp interactions at 450 GeV/c

A coupled channel analysis of the centrally produced K+K- and pi+pi- final states has been performed in pp collisions at an incident beam momentum of 450 GeV/c. The pole positions and branching ratios to pipi and KK of the f0(980), f0(1370), f0(1500) and f0(1710) have been determined. A systematic study of the production properties of all the resonances observed in the pi+pi- and K+K- channels has been performed.Comment: 16 pages, Latex, 5 Figure

Global patterns of the leaf economics spectrum in wetlands

The leaf economics spectrum (LES) describes consistent correlations among a variety of leaf traits that reflect a gradient from conservative to acquisitive plant strategies. So far, whether the LES holds in wetland plants at a global scale has been unclear. Using data on 365 wetland species from 151 studies, we find that wetland plants in general show a shift within trait space along the same common slope as observed in non-wetland plants, with lower leaf mass per area, higher leaf nitrogen and phosphorus, faster photosynthetic rates, and shorter leaf life span compared to non-wetland plants. We conclude that wetland plants tend to cluster at the acquisitive end of the LES. The presented global quantifications of the LES in wetland plants enhance our understanding of wetland plant strategies in terms of resources acquisition and allocation, and provide a stepping-stone to developing trait-based approaches for wetland ecology.Environmental Biolog

Experimental evidence for a vector-like behaviour of Pomeron exchange

Evidence is presented that the Pomeron act as a non-conserved vector current. A study has been made of the azimuthal angle phi, which is defined as the angle between the pT vectors of the two outgoing protons, in the reaction pp -> pp(X0) for those resonances (X0) which are compatible with being produced by double Pomeron exchange. These distributions have been compared with a model which describes the Pomeron as a non-conserved vector current and a qualitative agreement is found. In addition, when one of the particles exchanged is known to have spin 0, namely pi-Pomeron exchange, the phi distribution is flat.Comment: 13 pages, Latex, 4 Figure

UNDERSTANDING THE SCALAR MESON qqˉq\bar q NONET

It is shown that one can fit the available data on the a0(980), f0(980), f0(1300) and K*0(1430) mesons as a distorted 0++ qq bar nonet using very few (5-6) parameters and an improved version of the unitarized quark model. This includes all light two-pseudoscalar thresholds, constraints from Adler zeroes, flavour symmetric couplings, unitarity and physically acceptable analyticity. The parameters include a bare uu bar or dd bar mass, an over-all coupling constant, a cutoff and a strange quark mass of 100 MeV, which is in accord with expectations from the quark model. It is found that in particular for the a0(980) and f0(980) the KK bar component in the wave function is large, i.e., for a large fraction of the time the qq bar state is transformed into a virtual KK bar pair. This KK bar component, together with a similar component of eta' pi for the a0(980) , and eta eta, eta eta' and eta' eta' components for the f0(980), causes the substantial shift to a lower mass than what is naively expected from the qq bar component alone. Mass, width and mixing parameters, including sheet and pole positions, of the four resonances are given, with a detailed pedagogical discussion of their meaning.Comment: 35 pages in plain latex (ZPC in press), 10 figures obtainable from the author ([email protected]) with regular mail or as a large PS fil

Higher moments of nucleon spin structure functions in heavy baryon chiral perturbation theory and in a resonance model

The third moment $d_2$ of the twist-3 part of the nucleon spin structure function $g_2$ is generalized to arbitrary momentum transfer $Q^2$ and is evaluated in heavy baryon chiral perturbation theory (HBChPT) up to order ${\mathcal{O}}(p^4)$ and in a unitary isobar model (MAID). We show how to link $d_2$ as well as higher moments of the nucleon spin structure functions $g_1$ and $g_2$ to nucleon spin polarizabilities. We compare our results with the most recent experimental data, and find a good description of these available data within the unitary isobar model. We proceed to extract the twist-4 matrix element $f_2$ which appears in the $1/Q^2$ suppressed term in the twist expansion of the spin structure function $g_1$ for proton and neutron.Comment: 30 pages, 7 figure

Active Amplification of the Terrestrial Albedo to Mitigate Climate Change: An Exploratory Study

This study explores the potential to enhance the reflectance of solar insolation by the human settlement and grassland components of the Earth's terrestrial surface as a climate change mitigation measure. Preliminary estimates derived using a static radiative transfer model indicate that such efforts could amplify the planetary albedo enough to offset the current global annual average level of radiative forcing caused by anthropogenic greenhouse gases by as much as 30 percent or 0.76 W/m2. Terrestrial albedo amplification may thus extend, by about 25 years, the time available to advance the development and use of low-emission energy conversion technologies which ultimately remain essential to mitigate long-term climate change. However, additional study is needed to confirm the estimates reported here and to assess the economic and environmental impacts of active land-surface albedo amplification as a climate change mitigation measure.Comment: 21 pages, 3 figures. In press with Mitigation and Adaptation Strategies for Global Change, Springer, N

A partial wave analysis of the centrally produced K+K- and K0K0 systems in pp interactions at 450 GeV/c and new information on the spin of the fJ(1710)

A partial wave analysis of the centrally produced K+K- and K0K0 channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found in each channel. The striking feature is the observation of peaks in the S-wave corresponding to the f0(1500) and fJ(1710) with J = 0. The D-wave shows evidence for the f2(1270)/a2(1320), the f2(1525) and the f2(2150) but there is no evidence for a statistically significant contribution in the D-wave in the 1.7 GeV mass region.Comment: 15 pages, Latex, 5 Figure

A partial wave analysis of the centrally produced pi+pi- system in pp interactions at 450 GeV/c

A partial wave analysis of the centrally produced pi+pi- channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f0(980), f0(1300), f0(1500) and fJ(1710) with J = 0 in the the S-wave. The rho(770) is observed dominantly in the P0-wave and the f2(1270) is observed dominantly in the D0-wave. In addition, there is evidence for a broad enhancement in the D-wave below 1 GeV.Comment: 12 pages, Latex, 4 Figure