Aims Understanding fine‐grain diversity patterns across large spatial extents is fundamental for macroecological research and biodiversity conservation. Using the GrassPlot database, we provide benchmarks of fine‐grain richness values of Palaearctic open habitats for vascular plants, bryophytes, lichens and complete vegetation (i.e., the sum of the former three groups). Location Palaearctic biogeographic realm. Methods We used 126,524 plots of eight standard grain sizes from the GrassPlot database: 0.0001, 0.001, 0.01, 0.1, 1, 10, 100 and 1,000 m2 and calculated the mean richness and standard deviations, as well as maximum, minimum, median, and first and third quartiles for each combination of grain size, taxonomic group, biome, region, vegetation type and phytosociological class. Results Patterns of plant diversity in vegetation types and biomes differ across grain sizes and taxonomic groups. Overall, secondary (mostly semi‐natural) grasslands and natural grasslands are the richest vegetation type. The open‐access file ”GrassPlot Diversity Benchmarks” and the web tool “GrassPlot Diversity Explorer” are now available online (https://edgg.org/databases/GrasslandDiversityExplorer) and provide more insights into species richness patterns in the Palaearctic open habitats. Conclusions The GrassPlot Diversity Benchmarks provide high‐quality data on species richness in open habitat types across the Palaearctic. These benchmark data can be used in vegetation ecology, macroecology, biodiversity conservation and data quality checking. While the amount of data in the underlying GrassPlot database and their spatial coverage are smaller than in other extensive vegetation‐plot databases, species recordings in GrassPlot are on average more complete, making it a valuable complementary data source in macroecology.

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a b s t r a c tIn the last few years an increasing attention has been paid to efficient energy construction systems in the building sector. Although in this contest extensive green roofs are reported to be very effective and sustainable systems, the fact that the main agents of this systems are living organisms have generated doubts, especially in locations where the development of plants and vegetation can be greatly affected by climate. This study aims to investigate the thermal performances of a 2000 m 2 particular proprietary extensive green roof system, located on the city of Lleida (Spain), classified as Dry Mediterranean Continental climate. First, plant cover and floristic composition analysis were carried out to evaluate the dynamic of the plant layer over the surface. Then, according to the result of the botanic analysis, summer and winter study in terms of spatial and temporal factors were conducted focussing on the substrate layer, evapotranspiration effect and comparing the different behaviour of the system in low (10%) and high (80%) plant cover conditions. In this extensive green roof, the results showed temporal and spatial changes in floristic composition, with a stable cover of Sedum sp between 20 and 40 %, and a peak of colonizing species in spring and early summer. The increase in vegetation cover appears to have few effects on the above nearby roof environment because of the low moisture level in the substrate layer so that the cooling effect provided by the evapotranspiration does not take place. In addition, the increased presence of vegetation canopy may induce a limitation in substrate night cooling whereas serves as good shield for solar radiation during the day. Finally, the study also reveals the importance of the spatial factor in extensive green roofs, which can lead to not negligible variations on the thermal performance, as well as the floristic composition.

Potassium fertilization recommendations for alfalfa (Medicago sativa L.) vary depending on the area of production, soil levels, and crop management. Th e objectives of this study were to determine the impact of K fertilization on irrigated alfalfa yield, yield components, and soil exchangeable K (K e ) values in a Mediterranean climate. A fi eld experiment was conducted during a period of 4 yr (2002)(2003)(2004)(2005)(2006) in Spain, on a soil with moderate levels of K e (161 mg K kg -1 ). Th e treatments applied were fi ve annual rates of K (0, 100, 200, 300, and 400 kg K ha -1 ). Total 4-yr dry matter (DM) yields averaged 74.9 Mg ha -1 without diff erences between K fertilizer rates, although the unfertilized control produced the lowest DM yields. Th e 4-yr crop uptake of K reached 1738 kg ha -1 with the application of 400 kg K ha -1 yr -1 , and 756 kg K ha -1 for the 0 K fertilization. Th e removal was greater than the K applied. Th e results suggest that large amounts of K should not be applied to alfalfa because the crop uses excess K without increasing yield. Soil K e concentrations decreased every year for all K rates except for the highest treatment of 400 kg K ha -1 yr -1 . Lack of K fertilization did not aff ect stand density but the shoot weight was the yield component most closely related to K fertilization. * Signifi cant at the 0.05 level; ns, not signifi cant. ** Signifi cant at the 0.01 level. † Year and K rate main effects and the Year × K rate interaction for the period (2002-2005) were signifi cant at the 0.01 level. ‡ LSD(0.05) value for the year effect is 0.55 Mg ha -1 . * Signifi cant at the 0.05 level; ns, not signifi cant. ** Signifi cant at the 0.01 level. † Year and K rate main effects and the Year × K rate interaction for the period 2003-2005 were signifi cant at the 0.01 level. ‡ LSD(0.05) for year effect on K concentration is 1.0 g kg -1 and for K removal is 23 kg ha -1 .