TRY plant trait database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Rare and common vertebrates span a wide spectrum of population trends

Conservation biologists often assume that rare (or less abundant) species are more likely to be declining under anthropogenic change. Here, the authors synthesise population trend data for ~2000 animal species to show that population trends cover a wide spectrum of change from losses to gains, which are not related to species rarity

TRY plant trait database - enhanced coverage and open access

Plant traits—the morphological, anatomical, physiological, biochemical and phenological characteristics of plants—determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits—almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

Cinétiques rapides dans les liquides sous rayonnement : aspects théoriques

Cet article considère l’applicabilité des méthodes classiques de cinétique de réactions à des systèmes très nonhomogènes, comme les trajectoires de rayonnement. Deux modifications de la théorie sont nécessaires à cause de la proximité des particules dans la trajectoire. Premièrement, la formulation doit être stochastique, afin de prendre en considération le nombre entier de particules dans une grappe. Deuxièmement, la constante de vitesse doit dépendre du temps et décrire correctement la relaxation spatiale de la distribution nonhomogène. Trois façons d’aborder les cinétiques rapides sont décrites. Il est particulièrement important d’essayer les modèles pour s’assurer que les cinétiques théoriques représentent fidèlement la solution exacte à l’équation de diffusion

On the approximation of independent pairs in diffusion kinetics: correlation of distances in a three-body system

This study investigates the problem of diffusion kinetics in a three-body system, motivated by the theory of radiation chemical kinetics. The backward diffusion equation for the joint density of the distances is formulated, and an explicit formula for the infinitesimal covariance of two diffusing distances is derived. The Clifford-Green theorem is used to show how the infinitesimal covariance of two distances is linked to the covariance of the corresponding two squared distances as time evolves. In addition, computer simulations for the problem are presented, which indicate that hitting probabilities are also correlated. While the results indicate that more work is needed before a usable correction to the independence approximation is possible, clear progress has been made

Scavenging and recombination kinetics in a radiation spur: The successive ordered scavenging events

This study describes stochastic models to investigate the successive ordered scavenging events in a spur of four radicals, a model system based on a radiation spur. Three simulation models have been developed to obtain the probabilities of the ordered scavenging events: (i) a Monte Carlo random flight (RF) model, (ii) hybrid simulations in which the reaction rate coefficient is used to generate scavenging times for the radicals and (iii) the independent reaction times (IRT) method. The results of these simulations are found to be in agreement with one another. In addition, a detailed master equation treatment is also presented, and used to extract simulated rate coefficients of the ordered scavenging reactions from the RF simulations. These rate coefficients are transient, the rate coefficients obtained for subsequent reactions are effectively equal, and in reasonable agreement with the simple correction for competition effects that has recently been proposed

Modélisation de la chimie dans des traces de rayonnement. Problèmes inattendus et solutions possibles

(i) Nous décrivons une méthode pour simuler la recombinaison dans une grappe tout en suivant simultanément l’évolution temporelle de la fonction d’onde du spin en utilisant des paramétrisations réalistes de l’interaction d’échange. Nous utilisons cette méthode pour résoudre une controverse concernant le rôle de l’échange de spin durant l’évolution de la grappe. (ii) Les structures de trace Monte Carlo sont générées dans un milieu supposé continu, sans considération pour la configuration sous-jacente des molécules. Des événements peuvent être modélisés pour être plus proches l’un de l’autre que la plus petite distance entre deux molécules d’eau. Nous avons vérifié que ce problème pourrait avoir un effet significatif sur la chimie modélisée en superposant des traces Monte Carlo sur des configurations simulées par dynamique moléculaire