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The size and dynamics of seed banks were studied in grazed and ungrazed Mediterranean pastures at different altitudes and topography positions. The soil samples were collected in autumn and spring and the seed banks composition was determined by greenhouse germination over a 9‐month period. The percentage of bare ground and the presence of new seedlings were recorded monthly from October to July in the field. A fall in seed density and species richness in the banks and a tendency for seeds to remain in the banks were linked to a rise in altitude. Germination in lower pastures mainly occurred in October in the numerous gaps left by the summer drought. At higher altitudes, the scarcity of gaps and the harsh climate led to an autumn–spring segregation of germination. On a local scale, the low slope positions and the ungrazed plots had a larger number of persistent seed bank species and a lower percentage of bare ground where seeds could germinate than their respective plots in the upper positions and grazed plots. A higher seed density in ungrazed than grazed plots was only detected in the three highest plots. No seed bank species richness trend was detected. In populations of the same species in different types of environments, the seasonal variation of seed numbers was environment‐dependent for the majority of the species. In general, perennial grassland and its related low gaps availability appear to favour persistent seed banks.

Abstract. The similarity in species composition between seed bank and vegetation was analysed in Mediterranean grasslands in relation to altitude, topography and grazing. Soil samples were collected in permanent plots in autumn at the end of the summer drought period and in spring, before the new seed fall and after the natural winter seed stratification. The seed bank composition was determined by greenhouse germination over a nine‐month period. Presence/absence of species in the standing vegetation throughout the complete annual cycle, and the percentage area of bare ground in October, were recorded in the same plots. The species composition of the standing vegetation is clearly determined by altitude, topography and grazing, while the floristic composition of the seed banks is only related to altitude and topography in the case of autumn seed bank and with any of the three factors in the spring seed bank. Relative abundances of grasses, legumes and forbs also show different patterns in vegetation and seed bank data. Sørensen similarity between the autumn seed bank and the vegetation declines as altitude rises, but there are no significant differences for topography and grazing. This similarity decreases in the case of the spring seed bank and does not show any significant relationship with any of the factors. The perennial/ annual ratio and the proportion of bare soil in October are proposed as explanatory variables in a predictive model of similarity between the seed composition of the seed bank and vegetation.

Vegetation and buried germinable seeds were examined in Mediterranean pastures differing both in time elapsed since last ploughing and in intensity of disturbance. Densities of buried germinable seeds in the greenhouse were determined from 10 × 10 × 3 cm soil cores taken during the autumn prior to the time of germination. Abundance of pasture species was recorded on the same sites during the following spring.The species composition of t33he seed bank was very similar to that of the vegetation: 80.9 % similarity (Sørensen's index). The number of species and density of buried seeds ready to germinate increased with successional age from 0 to 4 yr and decreased later to a constant level after 9 yr. Regarding disturbance intensity, the highest species numbers are found at intermediate intensities while there is a drastic decrease at high disturbance intensity. The floristic composition of the seed bank was analyzed through Correspondence Analysis (CA) and Binary Discriminant Analysis (BDA). Seed bank composition reflected both successional stage and intensity of disturbance. Characteristic species of both gradients were identified.

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Large-scale socioeconomic changes in recent decades have driven shifts in the structure of Spanish rural landscapes, particularly in those located at the forest-agriculture interface (FAI), as well as in their wildfire regime. Using data from more than 200 16 km 2 landscape plots in Spain surveyed between 1956 and 2008 through the SISPARES monitoring framework, we assessed the FAI vulnerability to wildfires and identified the main landscape structural factors related to an increased number of wildfire events. We found that the most vulnerable landscapes were those with high road density, high diversity of land uses and, most importantly, with fine-grained forest-agriculture mixtures. Ignition frequency was lower in those landscapes where crops and woodlands coexisted but distributed in large and well-separated patches, and much lower where both land uses were combined within an integrated production and management system (''dehesas''). We discuss the geographical distribution patterns and temporal trends of the different FAI types during recent decades. We conclude that such approach is useful to forecast the mutual interactions between land use pattern changes and wildfire regime in the Mediterranean agroforestry mosaics. This would also provide an ecological base for developing a complementary, cost-effective and durable passive strategy of wildfire management targeted to modify the inherent FAI susceptibility to ignition events.

SUMMARY Harmonic current emission of photovoltaic (PV) systems is a well‐known problem. However, its quantitative characterisation, which requires the compilation and use of abundant statistical data, had never been satisfactorily dealt with. This paper discusses the multifaceted statistical characterisation of these emissions in a large PV plant. The topics addressed are harmonic current magnitude and its phase angle in relation to PV power output level and background harmonic voltages. Harmonic current emission in PV systems should be recorded during any single 1‐week period throughout a full year. Because power quality metres are expensive, it is more economical to measure this type of emission with simple, cost‐effective equipment. This paper thus presents a new assessment method for harmonic emission based on PV power output level, which is the main parameter affecting the emission, and which is easily monitored by most PV inverters. This new method uses statistical data to define a dependence model for the PV power output of PV harmonic current emissions. Such a model is rarely provided by PV inverter manufacturers. However, the simpler dependence model required for this method can be obtained by inexpensive power quality metres. This new method also produces accurate results at low process costs. Copyright © 2013 John Wiley & Sons, Ltd.

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