George Kazakis

Recent Plant Diversity Changes on Europe’s Mountain Summits

Climb Every Mountain Mountaintop floras across Europe appear to be responding to climatic change in terms of upslope species range shifts. Pauli et al. (p. 353) systematically analyzed data gathered from standardized permanent plots on 66 high-mountain environments across Europe. On average, mountaintop species numbers have increased significantly during the last decade. However, this increase is a net effect of gains and losses, with losses particularly affecting mountains of Mediterranean regions and their endemic species. This turnover is largely consistent with model predictions and indicates that high-altitude species, and in particular the rich endemic alpine flora of many Mediterranean mountain ranges, will come under increasing pressure in the predicted warmer and drier climates in this region. European mountaintop flower species richness is increasing on northern summits but decreasing on southern summits. In mountainous regions, climate warming is expected to shift species’ ranges to higher altitudes. Evidence for such shifts is still mostly from revisitations of historical sites. We present recent (2001 to 2008) changes in vascular plant species richness observed in a standardized monitoring network across Europe’s major mountain ranges. Species have moved upslope on average. However, these shifts had opposite effects on the summit floras’ species richness in boreal-temperate mountain regions (+3.9 species on average) and Mediterranean mountain regions (–1.4 species), probably because recent climatic trends have decreased the availability of water in the European south. Because Mediterranean mountains are particularly rich in endemic species, a continuation of these trends might shrink the European mountain flora, despite an average increase in summit species richness across the region.

Plant cover as a tool for monitoring desertification in mountain Mediterranean rangelands

Plant cover was measured for three years in the rangelands of Psilorites mountain of Crete, located at a mean altitude of 1,200m and overgrazed by sheep and goats from May to October. Rangelands consist of phryganic ecosystems dominated by dwarf shrubs, often subjected to occupational burning, and secondarily by grasslands. Herbaceous cover was significantly lower in the overgrazed than in the protected sites, but woody cover was higher unless the dwarf shrubs were palatable to animals. When overgrazing was combined with occupational burning then both plant groups were reduced with total cover reaching threshold values for potential soil erosion and desertification. On the contrary, no substantial differences were found between years indicating that overgrazing and burning were much more important than environmental changes. The results suggest that plant cover is an effective tool for monitoring the impact of pastoral activities on rangeland vegetation and therefore on desertification of mountain Mediterranean rangelands.

Macrophyte community structure and species occurrence in relation to environmental determinants in the ephemeral aquatic habitats of Gavdos, Greece

The aims of this study were to explore the environmental factors that determine the distribution of plant communities in temporary rock pools and provide a quantitative analysis of vegetation–environment relationships for five study sites on the island of Gavdos, southwest of Crete, Greece. Data from 99 rock pools were collected and analysed using Two-Way Indicator Species Analysis (TWINSPAN), Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA) to identify the principal communities and environmental gradients that are linked to community distribution. A total of 46 species belonging to 21 families were recorded within the study area. The dominant families were Labiatae, Gramineae and Compositae while therophytes and chamaephytes were the most frequent life forms. The samples were classified into six community types using TWINSPAN, which were also corroborated by CCA analysis. The principal gradients for vegetation distribution, identified by CCA, were associated with water storage and water retention ability, as expressed by pool perimeter and water depth. Generalised Additive Models (GAMs) were employed to identify responses of four dominant rock pool species to water depth. The resulting species response curves showed niche differentiation in the cases of Callitrichepulchra and Tillaeavaillantii and revealed competition between Zannichellia pedunculata and Charavulgaris. The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities. Generalised Additive Models are a powerful tool in investigating species response curves to environmental gradients. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in Mediterranean ephemeral pools.

Investigation of the wind speed threshold above which discarded cigarettes are likely to be moved by the wind

Cigarette butts thrown from passing cars often become fire ignition sources. However, this is only possible if a butt ends up on dead and dry fuels on the roadside. The current paper presents two experiments, carried out in a wind tunnel, designed to investigate the wind speed thresholds above which a butt thrown on the road is unlikely to stay on the road surface but will roll with the wind. The work was done for three road surfaces: asphalt, cement, and compacted soil. The experiments demonstrated that a lower wind speed is necessary for cigarette butts to start rolling from a still condition than the wind speed needed for whole cigarettes. Three wind speed thresholds, 0.88 m s–1 for asphalt, 1.63 m s–1 for cement, and 2.33 m s–1 for compacted soil, represent a conservative lower limit below which movement of still butts is highly unlikely. Three logistic regression equations were developed for calculating the probability that a cigarette butt thrown on the road surface under wind will continue to roll. They show that for wind speeds of less than 4.5 m s–1, a cigarette butt thrown on a dirt road is much less likely to be carried by the wind than if it was thrown on an asphalt or cement surface. The wind speed values refer to a height of 5 cm. The present paper provides a discussion of how this value relates to commonly used meteorological wind previsions. It also includes an example of how the findings can be used for fire prevention purposes.

Evaluation of forest fire retardant removal from forest fuels by rainfall

Long-term forest fire retardants for fire prevention purposes are currently used, or are under consideration, in many parts of the world. Their use requires, among other things, knowledge about weathering of retardants with time, which may lead to the need for re-application. Rainfall is a factor that can lead to retardant depletion from the fuels. In this study, the rate of depletion was evaluated experimentally using Aleppo pine (Pinus halepensis) needles. The needles were made into small bundles and immersed in retardant, which was FIRE-TROL 936 concentrate, diluted to 20% (v/v) with water. The retardant-treated needles, after drying, were exposed to natural rain in three different rainfall events, and retardant depletion was measured. A regression equation was developed with percentage retardant removal as the dependent variable. The natural logarithm of rainfall quantity, expressed in mm of rain, and the duration of rain, expressed in min, were the two independent variables. A simple equation can be used to support pre-suppression planning and to assess environmental effects.