The microrelief of plant surfaces, mainly caused by epicuticular wax crystalloids, serves different purposes and often causes effective water repellency. Furthermore, the adhesion of contaminating particles is reduced. Based on experimental data carried out on microscopically smooth (Fagus sylvatica L., Gnetum gnemon L., Heliconia densiflora Verlot, Magnolia grandiflora L.) and rough water-repellent plants (Brassica oleracea L., Colocasia esculenta (L.) Schott., Mutisia decurrens Cav., Nelumbo nucifera Gaertn.), it is shown here for the first time that the interdependence between surface roughness, reduced particle adhesion and water repellency is the keystone in the self-cleaning mechanism of many biological surfaces. The plants were artificially contaminated with various particles and subsequently subjected to artificial rinsing by sprinkler or fog generator. In the case of water-repellent leaves, the particles were removed completely by water droplets that rolled off the surfaces independent of their chemical nature or size. The leaves of N. nucifera afford an impressive demonstration of this effect, which is, therefore, called the ''Lotus-Effect'' and which may be of great biological and technological importance.

The wetting and the self-cleaning properties (the latter is often called the "Lotus-Effect") of three types of superhydrophobic surfaces have been investigated: silicon wafer specimens with different regular arrays of spikes hydrophobized by chemical treatment, replicates of water-repellent leaves of plants, and commercially available metal foils which were additionally hydrophobized by means of a fluorinated agent. Water droplets rolled off easily from those silicon samples which had a microstructure consisting of rather slender spikes with narrow pitches. Such samples could be cleaned almost completely from artificial particulate contaminations by a fog consisting of water droplets (diameter range, 8-20 microm). Some metal foils and some replicates had two levels of roughening. Because of this, a complete removal of all particles was not possible using artificial fog. However, water drops with some amount of kinetic impact energy were able to clean these surfaces perfectly. A substrate where pronounced structures in the range below 5 microm were lacking could not be cleaned by means of fog because this treatment resulted in a continuous water film on the samples.

Endemism and species richness are highly relevant to the global prioritization of conservation efforts in which oceanic islands have remained relatively neglected. When compared to mainland areas, oceanic islands in general are known for their high percentage of endemic species but only moderate levels of species richness, prompting the question of their relative conservation value. Here we quantify geographic patterns of endemism-scaled richness (''endemism richness'') of vascular plants across 90 terrestrial biogeographic regions, including islands, worldwide and evaluate their congruence with terrestrial vertebrates. Endemism richness of plants and vertebrates is strongly related, and values on islands exceed those of mainland regions by a factor of 9.5 and 8.1 for plants and vertebrates, respectively. Comparisons of different measures of past and future human impact and land cover change further reveal marked differences between mainland and island regions. While island and mainland regions suffered equally from past habitat loss, we find the human impact index, a measure of current threat, to be significantly higher on islands. Projected land-cover changes for the year 2100 indicate that land-use-driven changes on islands might strongly increase in the future. Given their conservation risks, smaller land areas, and high levels of endemism richness, islands may offer particularly high returns for species conservation efforts and therefore warrant a high priority in global biodiversity conservation in this century.biodiversity ͉ conservation ͉ human impact ͉ terrestrial vertebrates ͉ vascular plants W orldwide loss of biodiversity requires global conservation priority setting to channel limited international conservation resources to regions of highest conservation value and need for action (1-5). Approaches for using biological data as a component of priority setting vary but can largely be divided into (i) algorithmbased assessments such as minimum-area sets or gap analyses (2, 6-8) and (ii) index-based assessments using indices such as endemism or species richness as surrogates for the conservation value of a region (1, 4, 9). While many theoretical arguments underpin the strengths of algorithm-based assessments (2, 8, 10, 11), they require detailed distribution data that are only available for few taxonomic groups-almost exclusively terrestrial vertebrates (6, 9, 12-15), on which systematic conservation planning has thus relied increasingly in the past years. Such detailed data are not available for the vast majority of taxonomic groups on the global scale including vascular plants. Although great effort is being made in digitizing existing data from natural history collections for conservation purposes (16, 17), biodiversity loss is arguably proceeding more rapidly than the documentation of species distributions. Hence, an inventory-based approach, which forms a main basis for the present study, is a workable solution if global conservation planning is to be informed by vascular plants (18), a group of o...