Abstract. There is a rising interest around the world for a better understanding of the economic and social value added of weather services. National hydro-meteorological services and international cooperative bodies in meteorology have ever more to justify their use of public budgets. Furthermore, the development of hydrological and meteorological services is to a large extent steered by expectations regarding the eventual benefits of the envisaged new developments. This article provides a compact overview of the impediments for uptake of socio-economic benefit (SEB) studies, methods and results of SEB studies to date. It also discusses some pitfalls and crucial steps to enhance a broader uptake of SEB studies.

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Abstract:The main objective of the study was to evaluate inter-annual ring-width variation and cumulative growth of aspen (Populus tremula L.) trees growing on the spots of different soil CO 2 concentration at natural mofette site. We hypothesized that growth rate of trees is affected by CO 2 concentration within their rooting zone. The study site was situated in the flood plain of Plesná stream near Hartoušov (Western Bohemia). Trees growing in a pure aspen stand were selected according to the CO 2 -gas regime within their rooting zone. Five high [CO 2 ] trees (10-25% CO 2 in the soil) and five low [CO 2 ] trees (up to 3% CO 2 in the soil) were sampled. Stem growth analysis of each trunk was carried out to study growth pattern in detail. High and low [CO 2 ] trees significantly differed in a growth rate. At the age of 25 years, the basal area of high [CO 2 ] trees exceeded low [CO 2 ] trees by 39 %. The positive effect of CO 2 on annual increment was pronounced particularly in the years with optimal growing conditions. Results suggest that trees can be fertilized not only by elevated atmospheric CO 2 but also when fed with CO 2 via the roots.

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A geogenic CO2 emitting site (mofette U1) at the banks of the Laacher See, Eifel Mountains, was chosen to study the relationship between heavy postvolcanic soil degassing and vegetation during spring season. To test any interrelation between soil CO2 degassing and vegetation, soil chemism (pH, water content, conductivity, and humus content) and vegetation studies (number of species, plant-soil coverage) were performed. Geogenic soil degassing patterns of carbon dioxide and oxygen were clearly inhomogeneous, resembling soil porosity and distinct permeation channels within the soil. CO2 concentrations ranged from zero to 100%. Soil CO2 increased, while soil oxygen decreased with increasing soil depth. There was a reasonable correlation between CO2 degassing and soil pH as well as soil conductivity. Soil organic matter (SOM) resembled soil water distribution. The number of plant species (from a total of 69 species) as well as plant coverage strongly followed geogenic CO2 degassing. The total number of growing species was highest in low CO2 soils (max. 17 species per m2) and lowest at high CO2-emitting sites (one species per m2). Plant coverage followed the same pattern. Total plant coverage reached values of up to 84% in slightly degassing soils and only 5-6% on heavy CO2-venting sites. One plant species proved to be highly mofettophilic (marsh sedge, Carex acutiformis) and strictly grew on CO2 degassing sites. Most other species like grove windflower, spring fumewort, fig buttercup, wood bluegrass, addersmeat, and common snowberry showed a mofettophobic behavior and strictly avoided degassing areas. Specific plant species can thus be used to detect and monitor pre- or postvolcanic CO2 degassing.