A new species of Contarinia (Diptera: Cecidomyiidae) from flower galls on the relict tree Zelkova abelicea (Ulmaceae) endemic to Crete (Greece).

Contarinia ampelitsiae n. sp. Dorchin & Fazan is described as a newly discovered gall-midge species (Diptera: Cecidoymiidae) forming galls in flowers of Zelkova abelicea (Ulmaceae), a tree species endemic to the Mediterranean island of Crete (Greece). Larvae develop within modified filaments of male flowers, contrary to many Contarinia species that develop freely in flowers or in simple flower galls. The species has one generation per year, and its galls are sometimes found in great numbers on individual trees, thus affecting both fruit quantity and weight. This is the first report of a gall midge from Zelkova and the first record of Contarinia from Ulmaceae. Based on its host-plant association and on the barcoding section of the mtCOI gene, this species has no obvious relatives within Contarinia.

A multifaceted field sampling approach for the management of extremely narrow endemic vascular plant species.

Extremely narrow endemic plant species (ENEs) are generally connected with microrefugia characterized by particular environmental conditions. In-depth knowledge of the ecological requirements of ENEs is fundamental to plan appropriate conservation measures. Using cross-cutting technology, this paper gives a multifaceted approach to collect on-site data on the ecology of ENEs, defines the protocols for a correct sampling design and describes the type of equipment, the time and expenditure needed. Our sampling approach is based on two orthogonal transects, long enough to extrapolate the whole ecological gradient across the area of occupancy of the target species. Microclimatic data are recorded all along the transects through iButton technology, plus a weather station installed at the intersection of the transects. Microtopographic data are recorded with high-resolution digital elevation model and sub-metric GPS. Edaphic data are recorded along the transects through standard soil analyses and on-site evaluation of the seasonal decomposition rate of organic matter. Additionally, vegetation sampling in 4 m2 plots and on-site germination tests allow to collect data on auto- and synecological factors that regulate the life cycle of the target species. Our approach has proved to be cost-effective and efficient in terms of time spent in the field against the data collected. The most demanding activities were the establishment of the transects and the vegetation sampling. The time spent downloading microclimatic data and testing seed germination was relatively short. Our sampling design allows: (i) to catch as much micro-topographic variability as possible, both within and out of the tolerance range of the target species, (ii) to minimize the risk of recording identical micro-topographic conditions compared with a random sampling scheme, and (iii) to ensure quick and relatively easy retrieval of the plots and the equipment both on a multi-seasonal and multi-annual basis.

Biogeographic Overview of Ulmaceae: Diversity, Distribution, Ecological Preferences, and Conservation Status.

The elm family (Ulmaceae) is a woody plant group with important scientific, societal, and economic value. We aim to present the first biogeographic synthesis investigating the global diversity, distribution, ecological preferences, and the conservation status of Ulmaceae. A literature review was performed to explore the available data for all extant species. Our study made it possible to map the actual global distribution of Ulmaceae with high precision, and to elucidate the centers of diversity, located mainly in China and in the southeastern USA. A detailed comparative analysis of the macroclimatic niche for each species was produced, which shows the general biogeographic pattern of the family and pinpoints the outlier species. The results corroborate recent molecular analyses and support the division of Ulmaceae into two taxonomically, biogeographically, and ecologically well-differentiated groups: the so-called temperate clade with 4 genera and 43 species and the tropical clade with 3 genera and 13 species. The elm family is often described as a typical temperate plant group, however the diversity peak of all Ulmaceae is located in the subtropical zone, and a non-negligible part of the family is exclusively distributed in the tropics. We also noticed that a high proportion of Ulmaceae is linked to humid macro- or microhabitats. Finally, we highlighted that nearly 25% of all Ulmaceae are threatened. Fieldwork, conservation efforts, and research activities are still necessary for this family, particularly for the tropical members and the most endangered species.

From glacial refugia to hydrological microrefugia: Factors and processes driving the persistence of the climate relict tree Zelkova sicula.

With only two tiny populations, the climate relict Zelkova sicula (Sicily, Italy) is one of the rarest trees in the world. It also represents the most marginal member of genus Zelkova that was widespread in the broadleaved forests thriving in warm-temperate climates throughout Eurasia until the Last Glacial Age. Occurring at the westernmost range of the genus under typical Mediterranean climate, the micro-topographic settings have always appeared crucial for the survival of this relict. However, the factors and processes actually involved in its persistence in the current refugia, as well as the response of similar relict trees in arid environments, are poorly understood worldwide. In the aim to elucidate these aspects, in the two sites hosting Z. sicula analyses of topographical attributes were combined with investigations on soil moisture dynamics. Additionally, plants' growth and spatial distribution patterns were analyzed to detect fine-scale differences between populations and assess the possible ecological amplitude of the species. Results revealed that convergent topographies are basic determinants of microrefugia in arid environments. Within the investigated sites, underground moisture never decreases below 25%, buffering seasonal rainfall fluctuations. Therefore, hydrological microrefugia play a key role in decoupling from regional climate, supporting the target species in coping with an unsuitable climatic envelope. Additionally, the inter-population variability of biometric attributes showed that individual growth is site-dependent and the species retains a relative ecological plasticity, whereas the strongly clumped spatial patterns confirmed the common clonal growth. On one hand, deeply incised landforms have acted as effective hydrologic microrefugia, on the other clonality coupled with triploidy supposedly improved the resistance of Z. sicula to harsh environments, though entailing inability to reproduce sexually. Most likely, sterility and environmental/physical barriers that have existed for millennia have prevented this relict from leaving the last suitable microrefugia, resulting in the two current rear edge populations.

Velocity of the falling dispersal units in Zelkova abelicea: remarkable evolutionary conservation within the relict tree genus.

PREMISE: Seed dispersal is extremely important for the recovery and restoration of forest communities. Relict tree genus Zelkova possesses a unique dispersal mechanism: mature fruits fall with the entire twig, and the dried leaves that are still attached function as a drag-enhancing appendage, carrying the fruits away from the parent tree. This singular adaptation has never been investigated in Z. abelicea. METHODS: Drop tests with dispersal units and individual fruits of Z. abelicea were performed in controlled conditions to measure their dispersal velocity and to define their flight mode. RESULTS: Zelkova abelicea uses both slowly falling dispersal units with chaotic motion, as well as fast falling individual fruits using a straight path. The falling velocity of Z. abelicea dispersal units is 1.53 m s-1 , which is virtually identical to that of the East Asiatic Z. serrata (1.51 m s-1 ). In contrast, the falling velocity of individual fruits was 2.74 m s-1 (Z. serrata: 5.36 m s-1 ). CONCLUSIONS: Members of the genus Zelkova, growing today in distant regions, show remarkable evolutionary conservation of the velocity and flight mechanics of their dispersal units. This is surprising because the Mediterranean and East Asiatic Zelkova species have been separated at least 15-20 mya. Zelkova abelicea, although growing in the Mediterranean with completely different forest structure and composition, still uses the same dispersal mechanism. The dispersal capacity of the genus Zelkova is less efficient than that of other wind dispersed trees, and it presumably evolved for short-distance ecological spread and not for long-distance biogeographical dispersal.

The Woody Planet: From Past Triumph to Manmade Decline.

Woodiness evolved in land plants approximately 400 Mya, and very soon after this evolutionary invention, enormous terrestrial surfaces on Earth were covered by dense and luxurious forests. Forests store close to 80% of the biosphere's biomass, and more than 60% of the global biomass is made of wood (trunks, branches and roots). Among the total number of ca. 374,000 plant species worldwide, approximately 45% (138,500) are woody species-e.g., trees, shrubs or lianas. Furthermore, among all 453 described vascular plant families, 191 are entirely woody (42%). However, recent estimations demonstrate that the woody domination of our planet was even greater before the development of human civilization: 1.4 trillion trees, comprising more than 45% of forest biomass, and 35% of forest cover disappeared during the last few thousands of years of human dominance on our planet. The decline in the woody cover of Planet Earth did not decelerate during the last few centuries or decades. Ongoing overexploitation, land use and climate change have pushed ten thousand woody species to the brink of extinction. Our review highlights the importance, origin and past triumph of woody species and summarizes the unprecedented recent decline in woody species on our planet.

Imprisoned in the Cretan mountains: How relict Zelkova abelicea (Ulmaceae) trees cope with Mediterranean climate.

We investigate the sensitivity of the relict, endemic Cretan tree species Zelkova abelicea (Lam.) Boiss. (Ulmaceae) to several climate variables (temperature, precipitation and drought). For this purpose, we establish the first centennial tree-ring chronology for the species, and the first ever tree-ring chronology for a broadleaved species on Crete. We demonstrate the strong sensitivity of Z. abelicea towards precipitation and drought in late spring to early summer and the absence of a significant response to abundant precipitation occurring during winter or early spring. Whereas the late spring sensitivity is strong and consistent through time, the species seems to be experiencing a loss of signal towards early summer conditions since the 1970s, interpreted as an earlier cessation of cambial activity due to the increase in summer drought conditions on Crete. However, despite a reduced vegetative period, no significant decrease in radial growth of Z. abelicea was observed in the tree-ring series for the last decades, thus highlighting the capacity of Z. abelicea to withstand changing environmental conditions.