Leaf water relations for 23 angiosperm species from steppe grasslands and associated habitats in Hungary

Pressure-volume (p-V) analysis, instantaneous transpiration rate and relevant leaf structural information were used to compare leaf water relations for 23 angiosperm species from semiarid temperate loess-, sand- and saline steppe grasslands and several associated habitats representing a water availability gradient. For the species studied, the most marked differences occurred between grasses and dicots. Grasses in our survey possessed low (highly negative) osmotic potential both at water saturation and at turgor loss, moderate transpiration rate, relatively high leaf dry matter proportion (DMP) and - except for the sclerophyllous Festuca species - high specific leaf area (SLA, area per unit dry mass). In contrast, dicots had lower bulk tissue elasticity, higher (less negative) osmotic potentials, intense transpiration, and lower SLA andDMP than grasses. Therefore, grasses mainly invest in osmotic potential to extract water from drying soil, while dicots rely on relatively inelastic tissue that decreases water potential by a rapid drop of turgor with turgor loss occurring at relatively high water content. Habitat effects were significant for osmotic parameters only. Osmotic potential at full turgor and at turgor loss decreased in the following order: loess grassland ? sand grassland ??saline grassland ? loess wall. Life form influenced leaf structure only, since annuals possessed markedly higher SLA and lower DMP than perennials. Comparison of habitat specialist species within the same genus revealed that certain congeners (Achillea and Aster spp.) do not differ significantly in leaf water relations, thus they might rely on similar water supply in the three steppes. Other congeners (Festuca, Kochia and Plantago spp.) differed considerably, thus for these plants leaf function and structure must be different to ensure survival under the contrasting water regime. For the two generalist grasses (Cynodon dactylon and Dactylis glomerata) habitat-specific populations showed a tendency of increasing capacity for water extraction from soil (more negative water potential) with increasing habitat dryness, although differences were significant only between the extremes of the water availability gradient

Fact sheet of the MÉTA database 1.2

The survey results of the MÉTA program are managed with centralised relational database management system (MS SQL 2000) developed and set up in a local area network. Besides the MÉTA database server, a publishing server, an archiving server and a GIS workstation were applied. The core information entities of the MÉTA database are: information subproject, MÉTA quadrate, MÉTA hexagon, (semi-)natural habitat, potential vegetation with numerous habitats, landscape ecology and land use attributes, and surveyor. This information is coded in the nine main tables of the normalised database. In the recent state there are almost 1,500,000 records in the main tables that are managed in 241 independent fields. The published version of the MÉTA database supports the query service, and handles this information in 7 denormalised main tables. This much more redundant version is 11 GB in size. The 20.6% (179 man-month) of the human resources in the MÉTA program were devoted to the information tasks (set up and preparation, MÉTA database and information system development, replenishment and quality assessment, MÉTA query, GIS and printing services) between 2002 and 2007. The basic structure of the MÉTA database version 1.2 is finalised and the main functions regarding data processing have been developed. The accomplishment is higher than 90%, quality assessment is under way, while scientific verification and data harmonisation are started. The area of (semi-)natural and degraded vegetation of Hungary is estimated to 1,800,000 hectares (19.4% of the country) of which the natural, semi-natural is about 1,200,000 hectares (12.9% of the country). All of these are highly fragmented and unevenly distributed over the country. It is shown by several basic figures, professional content and quality measure facts of the database. There is also a fact sheet of surveyors that shapes the important characters of their field experience profile, too

Playing with Triangulations

We analyze several perfect-information combinatorial games played on planar triangulations. We introduce three broad categories of such games: constructing, transforming, and marking triangulations. In various situations, we develop polynomial-time algorithms to determine who wins a given game under optimal play, and to find a winning strategy. Along the way, we show connections to existing combinatorial games such as Kayles