Lake-level records from Italy suggest that patterns of precipitation in the central Mediterranean during the Holocene were divided between the north and south, but a scarcity of reliable palaeoclimatic records in the north and central-southern Mediterranean means new evidence is needed to validate this hypothesis. We provide robust quantitative estimates of Holocene climate in the Mediterranean region using four high-resolution pollen records from northern (Lakes Ledro and Accesa) and southern (Lakes Trifoglietti and Pergusa) Italy. Multiple methods are used to provide an improved assessment of the palaeoclimatic reconstruction uncertainty. The multi-method approach uses the pollenbased weighted averaging, weighted-average partial leastsquares regression, modern analogue technique, and the nonmetric multidimensional scaling/generalized additive model methods. We use independent lake-level data to validate the precipitation reconstructions. Our results support a climatic partition between northern and southern Italy during the Holocene, confirming the hypothesis of opposing mid-Holocene summer precipitation regimes in the Mediterranean. The northern sites (Ledro, Accesa) are characterized by minima for summer precipitation and lake levels during the early to midHolocene, while the southern sites (Trifoglietti, Pergusa) are marked by maxima for precipitation and lake levels at the same time. Both pollen-inferred precipitation and lake levels indicate the opposite pattern during the late Holocene, a maximum in northern Italy and a minimum in southern Italy/Sicily. Summer temperatures show the same partitioning, with warm conditions in northern Italy and cool conditions in Sicily during the early/mid-Holocene, and a reversal during the late Holocene. Comparison with marine cores from the Aegean Sea suggests that climate trends and gradients observed in Italy show strong similarities with those recognized from the Aegean Sea, and more generally speaking in the eastern Mediterranean

Aim To elucidate the phylogeographical patterns in three Cenozoic relict species: Zelkova sicula, Z. abelicea and Z. carpinifolia (Ulmaceae).Location Sicily, Crete and Transcaucasia.Methods Two chloroplast loci (trnH-psbA and trnL) and the nuclear ribosomal markers ITS1 and ITS2 were sequenced for 154 samples collected from 14 populations of Z. abelicea, 16 populations of Z. carpinifolia, and the two known populations of Z. sicula. We obtained georeferenced data, calculated median joining networks and carried out diversity analyses. A few ex situ samples collected from botanical gardens, of the East Asian species Zelkova serrata, Z. schneideriana and Z. sinica, were also analysed for comparative purposes.Results High levels of variability were found in the chloroplast markers within Z. carpinifolia (15 haplotypes) and Z. abelicea (33 haplotypes), in association with strong phylogeographical structure. Conversely, Z. sicula was characterized by low diversity, with each population exhibiting a single haplotype. Lower variability was found for ITS1 and ITS2 within Z. carpinifolia and Z. abelicea (13 and 7 ribotypes per species, respectively), with Z. carpinifolia showing a high proportion of populations with no intragenomic polymorphism. In the triploid and clonal Z. sicula, all individuals displayed intragenomic polymorphism and seven ribotypes were identified.Main conclusions The chloroplast diversity of Z. abelicea and Z. carpinifolia suggests a very ancient history of diversification and structuring, with footprints of past expansions and more recent bottlenecks. Zelkova sicula has had a history of severe isolation and is likely to be of hybrid origin.

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Relict species provide a unique opportunity to understand past and recent biogeographical and evolutionary processes. Zelkova abelicea (Ulmaceae), which is endemic to the island of Crete (Greece), is one of the most prominent Tertiary relict trees of the Mediterranean region. We collected distribution, threat and population structure data by reviewing literature and herbaria and through field surveys at 14 study plots throughout the range of the species. The present distribution of Z. abelicea is extremely fragmented. Although the total estimated number of individuals is relatively high, the populations are dominated by dwarf, severely browsed, non-flowering individuals. The population structure is asymmetric. At most, 5% of a plot's trees are large and fruit-bearing. The asymmetric structure is particularly pronounced in isolated and small populations. Based on its limited geographical range, the fragmented spatial pattern, and data on distribution and population structure, our study confirms that Z. abelicea is a threatened species (IUCN category Endangered). Our research aim is to promote the development of new approaches for the improvement of conservation strategies for Tertiary relict trees characterized by major local disjunctions.

Zelkova, with six extant species in Eurasiathree in East Asia (2. schneideriana, 2. serrata, 2. sinica), one in south-western Asia ( 2 . carpinifolia) and two in southern Europe (2. abelicea, 2. sicula) -was investigated with respect to leaf architecture and epidermal characters by LM and SEM. The leaf venation of Zelkova is relatively uniform, while leaf size and shape are highly variable. Characters such as teeth and epidermal cells, trichomes and stomata provide useful specific distinctions. Beginning in the Miocene, increasing aridity in Central Asia would appear t o have been responsible for isolating the eastern Asiatic species from their Europeadwestern Asiatic counterparts. The European range underwent further changes in response to Quaternary climatic oscillations. 0 2001 The Linnean Society of London ADDITIONAL KEY WORDS: stomatateethtrichomeswax.

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A study on the impact of silvicultural practices on the water balance was carried out in a watershed in Calabria, southern Italy, the prevalent cover of which is Calabrian pine stands. A thinning was carried out in 1993, which removed 50% of the total number of trees (about 30% of the basal area), and the catchment hydrological response before and after the intervention was compared. After thinning, differences were observed in yearly runoff, with a significant increase in groundwater flow during spring and summer. In light of this evidence, we assume that silvicultural interventions can contribute significantly to improve water resources management, particularly in regions with a long dry season, as in the Mediterranean area.Key words: Pinus laricio, runoff, small catchment, thinning, water resources management L'impact des interventions sylvicoles sur le bilan hydriques a été étudié en un bassin-versant boisé, en Calabre (Italie méridionale), dominé par des peuplements de pin laricio. En 1993 un élagage fut effectué, emportant l'élimination de 50% du nombre total des arbres (correspondant à environ 30% de la surface terrière) et la réponse hydrologique du bassin fut comparée avant et après l'intervention. Les résultats ont montré que l'élagage a induit quelques différences significatives sur le ruissellement annuel, avec une augmentation assez remarquable de l'écoulement souterrain surtout au printemps et en été. Sur la base de cette évidence, il est très vraisemblable que les interventions sylvicoles peuvent notablement contribuer à l'amélioration de l'aménagement des ressources hydriques, surtout dans des régions caractérisées par une longue saison sèche comme la région méditerranéenne.