Plant community structure in relation to grazing and environmental changes along a north-south transect in the western Kalahari

Sixteen vegetation types were described from a north-south transect in the western Kalahari. Pronounced differences were found between communities on the nutrient poor red Kalahari sand, covering most of the area and those on fine soils and white calcareous sand. Syntaxa resulting from severe overgrazing by livestock were in most cases clearly distinguished from the less disturbed vegetation. The communities on red sand consisted mainly of shrub savanna dominated by perennial tufted grasses, whereas in the vegetation on calcareous material and on overgrazed land, forbs, dwarf shrubs and shrubs played a more important role. The major communities on red sand showed a clear geographical zonation roughly corresponding to the gradient in mean annual rainfall and its interannual variation. In the northern and central Kalahari these syntaxa were dominated by species of Sudano-Zambezian origin and in the southern Kalahari by species showing Karoo-Namib affinities.     

A new Spanish species of the genus Ononis L.(Fabaceae)

The name Ononis rentonarensis is proposed for a new Spanish species belonging to Ononis section Matrix subsection Rhodanlhae, whose distribution is restricted to a few localities in northeastern Alicante Province (E.Spain). Its morphological features, ecology and main relationships and differences with other Spanish species in the subsection are discussed.     

Environmental and human factors influencing rare plant local occurrence, extinction and persistence: a 115-year study in the Mediterranean region

Aim Assessing whether environmental and human factors influenced the spatial distribution and the dynamics of regionally rare plant species since the late nineteenth century, and whether these spatial and temporal patterns of rare species occurrences differ according to their chorology (level of endemism and biogeographic affinity). Location An area extending over 6250 km² in the French Mediterranean Region. Methods We used two botanical surveys achieved in 1886 and in 2001, and considered species rare if occurring in only one or two sites in the study area. Each rare species was assigned to a group of endemism level (restricted endemic, non‐endemic), and of biogeographic affinity (Mediterranean, South/Central European, Mountain, Eurosiberian). A 1 × 1 km grid was applied to the study zone. Generalized linear models were developed to study the spatial distribution and the fate of rare species occurrences (local extinction vs. local persistence between 1886 and 2001), as a function of environmental and human variables. Multivariate analyses were used to test whether the spatial distribution and the fate of rare species occurrences differed according to their chorology. Results In 2001, rare species as a whole tended to occur at higher altitude, in zones dominated by semi‐natural open habitats, and where cultivated area had decreased in the last 30 years. Between 1886 and 2001, rare species were the most prone to local extinction in zones where human population density, cultivated area and livestock density had increased the most. Between 1886 and 2001, rare species had a higher probability of local persistence in zones of high altitude and steep slope, on basic bedrocks and with low cultivated area. Rare species with Mountain and Eurosiberian affinities occurred in marginal habitats in the study region, i.e. on gneiss‐micaschist bedrocks and at high altitudes, whereas Mediterranean and South/Central European rare species occupied more varied environmental conditions. Between 1886 and 2001, Eurosiberian rare species showed high rates of local extinction whereas Mediterranean rare species had a significantly higher probability of local persistence. Restricted endemic species mostly occurred in zones of high slope, low human population density, and where cultivated area had decreased in the last 30 years. Occurrences of restricted endemics remained significantly stable between 1886 and 2001. Main conclusions Environmental and land‐use changes that occurred over the twentieth century in the Mediterranean Basin had significant impacts on the spatial distribution and on the long‐term dynamics of rare species occurrences. Urbanization and recent agriculture intensification, occurring mainly in coastal plains and littoral zones, caused most local extinctions of rare species from 1886 to 2001. Local populations of Eurosiberian species, which reach their range limits in marginal zones of the Mediterranean, also appear to be highly vulnerable. Conversely, most restricted endemic species occur in habitats with harsh topography and low human disturbance and have a higher potential of local persistence.     

Atlas versus range maps: robustness of chorological relationships to distribution data types in European mammals

Aim Chorological relationships describe the patterns of distributional overlap among species. In addition to revealing biogeographical structure, the resulting clusters of species with similar geographical distributions can serve as natural units in conservation planning. Here, we assess the extent to which temporal, methodological and taxonomical differences in the source of species’ distribution data can affect the relationships that are found. Location Western Europe. Methods We used two data sets – the Atlas of European mammals and polygon range maps from the IUCN Global Mammal Assessment – both as presence–absence data for UTM 50 km × 50 km squares. We performed pairwise comparisons among 156 species for each data set to build matrices of the similarity in distribution across species, using both Jaccard’s and Baroni‐Urbani & Buser’s indices. We then compared these similarity matrices (chorological relationships), as well as the species richness and occurrence patterns from the two data sets. Results As expected, range maps increased both the mean prevalence per species and mean species richness per grid cell in comparison to atlas data, reflecting the general view that these data types respectively over‐ and underestimate species occurrence. However, species richness and occurrence patterns in atlas and range map data were positively associated and, most importantly, the chorological relationships underlying the two data sets were highly similar. Main conclusions Despite many methodological, temporal and taxonomical differences between atlas data and range maps, the chorological relationships encountered between species were similar for both data sets. Chorological analyses can thus be robust to the data source used and provide a solid basis for analytical biogeographical studies, even over broad spatial scales.     

The Quercus petraea-dominated communities in Italy: Floristic,coenological and chorological diversity in an European perspective

In Italy, woods dominated by Quercus petraea are well documented within local and regional phytosociological studies but a critical revision of their principal ecological-floristic components based on a comprehensive Italian data set was missing. We gathered 209 published and unpublished Italian phytosociological relevés, where Q. petraea was dominant, that were investigated by means of multivariate analysis. The ecological requirements of the resulting groups were indirectly calculated by means of Ellenberg indicator value, and a chorological analysis was performed. The fidelity coefficient (phi) for the diagnostic species of each group was calculated. According to our analysis, five different types of Q. petraea woods were found to be present in Italy. Each group was characterized by means of its floristic, ecological and chorological components. These resulting five groups were further compared with similar Q. petraea-dominated woods recorded in other European locations, as to the floristic and chorological components. We collected 57 synoptic tables of Q. petraea communities coming from all over Europe. This data set, together with the Italian relevés, was submitted to exploratory multivariate analysis using also the chorological information. According to these analyses, the Italian woods dominated by Q. petraea can be subdivided in two main clusters: the communities belonging to It-1 group (Alps) fell within the central European communities, distinguished by the predominance of large distribution and European chorotypes. All the other Italian groups of relevés resulted to be positioned in the cluster which includes central southern, central eastern and eastern European Q. petraea communities. From the syntaxonomical point of view, the results of this analysis allow to attribute the Italian Q. petraea woods to seven alliances of three different orders. The ecological similarities between Erythronio-Quercion petraeae and Erythronio-Carpinion betuli are highlighted and the distribution of Erythronio-Quercion petraeae is limited to northern Apennines, in particular, to slopes facing the Po Valley.     

Floristic relationship between plant communities of corresponding habitats in southeast Greenland and alpine Scandinavia

Barkman's similarity coefficiënts have been calculated for twelve ecologically related communities of southeast Greenland (SEG) and alpine Scandinavia (SCA). Comparisons were made between corresponding saxicolous lichen communities, dwarf shrub communities, snow bed communities and herb and Salix shrub communities. The corresponding SEG and SCA communities of extreme habitats have the same faithful taxa or the same dominant taxa, relatively few or no area-differential (ArD) taxa and they are floristically strongly related. They should be classified in one single association; the geographical variation is expressed in terms of geographical races. Corresponding vegetation types of mesic habitats have low floristic similarity coefficiënts, many ArD taxa and the same dominant taxa, or different faithful taxa. The geographical variation should be expressed here on the association level.     

An Iranian floristic link with Socotra inHypericum (Hypericaceae)

Hypericum dogonbadanicum Assadi, a local species from theQuercus brandtii forests of the Zagros Mountains in south-western Iran, belongs to sect.Campylosporus (Spach)R. Keller and is most closely related to a Socotran endemic,H. socotranum Good subsp.smithii N. Robson. Despite the inclusion of these forests in the Irano-Turanian Element of the Iran flora byZohary (1963),H. dogonbadanicum appears to belong rather to the Mediterranean dwarf-shrub maquis type of community and therefore to be a member ofZohary's (1963) Mediterranean/Irano-Turanian group of Iranian species.—The key position of the Socotran endemics to the understanding of the inter-sectional relationships is discussed.Dedicated to Prof.K. H. Rechinger on the occasion of his 80th birthday.     

Saxifraga depressa and Saxifragetum depressae: an endemic species and association of the western Dolomites (Italy)

Saxifraga depressa grows only on the summits of eleven siliceous massives in the western Dolomites. It is restricted to the habitat of steep N-faced screes lying above 2000 m. Syntaxonomically, Saxifraga depressa characterizes the association Saxifragetum depressae which is here described for the first time with two subassociations. With respect to the closely allied Oxyrietum digynae, the Saxifragetum depressae colonizes debris richer in fine material. The soil pH in the habitats of the Saxifragetum depressae varies from acid to slightly basic, mainly as a result of lithological differences in the parent rocks. The habitats having a subneutral or basic soil are colonized by a well-defined subassociation of the Saxifragetum depressae, which is differentiated by some basiphilous species.     

Chorology of Liliaceae (S. Str.) and Its Bearing on the Chinese Flora

The geographical distribution of Liliaceae (s. str. ) is analysed on the basis of the floristic regions proposed by Takhtajan. Some conclusions may be proposed as follows: 1.Liliaceae (s. str. ) consists of nine genera and about 513 species, distributed primarily in the north temperate zone. Statistics shows clearly that the Irano-Turanian Region is most abundant in number of species, The Eastern Asian Region with total nine genera of the family is the diversity centre of Liliaceae (s. str. ). 2. The distribution patterns of the genera may be divided into: 1 ) North temperate distribution pattern: Lloydia, Erythronium, Fritillaria and Lilium; 2) Old world temperate distribution pattern: Gagea and Tulipa; 3) West Asia to Himalayas and Southwest China distribution pattern: Notholirion; 4) East Asia distribution pattern: Cardiocrinum and Nomocharis. 3. The Sino-Himalayas is one of the key regions in studying the evolution of Liliaceae (s. str. ) All nine genera occur in the Eastern Asian Region with most species distributed in Southwest and Northwest China. Chorologically, five genera (Fritillaria, Lilium, Cardiocrinum, Nomocharis and Notholirion) of the Lilieae are overlapped each other in the Sino-Himalayas, showing its diversity centre in this region. The Lilieae is a main stock in the Liliaceae (s. str. ), The genus Nomocharis in this tribe may have been newly differentiated from Lilium in the course of the uplift of Qinghai-Xizang Plateau, a view also supported by Xie Xiao-yang et al.. The place of its origin was considered to be in the southern part of the Hengduan Mountains. 4. The distributions of some species in Liliaceae (s. str. ) seem to be significant for dividing some floristic regions: 1 ) Some species of Fritillaria (F. unibracteata Hsiao et K. C. Hsia, F. przewalski Maxim. ex Batal. , F. crassicaulis S. C. Chen, F. cirrhosa D. Don. , F. delavayi Franch. , F. dajinensis S. C. Chen, F. davidii Franch. , F. sinica S. C. Chen and F. sichuanica S. C.Chen) are only distributed in Sino-Himalayan forest subkingdom, while others (F. taiparensis P. Y. Li, F. yuzhongensis S. C. Chen, F. monantha Migo, F. anhuiensis S. C. Chen et S. F. Yin, F. thunbergii Miq. , F. maximowizii Freyn and F. ussuriensis Maxim. ) are restricted to Sino-Japan forest subkingdom. They show a clearly demarcation line between the two subkingdoms, which is identical with what proposed by Wu Cheng-yih. 2) The Eastern Asian Region can be divided into two subkingdoms on the basis of the distribution pattern of the genus Cardiocrinum; C. giganteum (Wall.) Makino and C. gigateum var. yunnanense Leichtlin ex Elwes are restricted to Sino-Himalayan forest subkingdom. C. cathayanum (Wilson) Stearn and C. cordatum (Thunb.) Makino are only found in Sino-Japan forest subkingdom. 3) The distributions of Gagea pauciflora Turcz. , G. triflora(Ledeb.) Roem. et Schult. G. hiensis Pasch, Lloydia tibetica Baker ex Oliver, L. oxycarpa Franch. and L. flavonutans Hara are indicative of a demarcation line between Irano-Turanica Region and Eastern Asian Region. 5. The genus Notholirion occurs in the Eastern Asian Region and Irano-Turanian Region, showing the relationships between the two regions and also between the Chinese flora and Ancient Mediterraneam flora.     

Biodiversity and phytogeography of the alpine flora of Iran

Iran is a mountainous country. Zagros and Alborz mountains reach altitudes of more than 4,000 m. Alpine regions are above timber-line, which is not easy to recognize, since aridity is prominent in most regions. The alpine zone in Alborz lies between 3,000 and 4,000 m, the nival zone is above 4,000 m, locally varying by some hundred meters. A first evaluation of vascular flora shows that 682 species belonging to 193 genera and 39 families are known from the alpine zone of Iran. The alpine zone is commonly characterized by many species of hemicryptophytes and thorny cushions. Species numbers decline very strongly with increasing altitude. In this paper biogeographical patterns of the alpine flora of Iran have been discussed and distribution maps of 44 species are illustrated. New data indicate a transitional situation of the Iranian mountains between Anatolia/Caucasus and the Hindu Kush, but with a strong own element with high endemism and remarkable relict species. Ca. 58% of the alpine flora of Iran are endemic and subendemic. The Zagros Mountains harbor high endemism which justify considering this area as a separate floristic province. Based on the evaluation of published data from 682 known alpine species ca. 160 species have been known only by one record, 110 species by 2–3 records and 87 endemic species have been known only based on the type location. These plants need a strong conservation and protection management since the fragile ecosystems are often very restricted, small and very isolated, nonetheless grazing and overgrazing are still common threats.