Aim
Species–area relationships (SARs) are fundamental scaling laws in ecology although their shape is still disputed. At larger areas, power laws best represent SARs. Yet, it remains unclear whether ...SARs follow other shapes at finer spatial grains in continuous vegetation. We asked which function describes SARs best at small grains and explored how sampling methodology or the environment influence SAR shape.
Location
Palaearctic grasslands and other non‐forested habitats.
Taxa
Vascular plants, bryophytes and lichens.
Methods
We used the GrassPlot database, containing standardized vegetation‐plot data from vascular plants, bryophytes and lichens spanning a wide range of grassland types throughout the Palaearctic and including 2,057 nested‐plot series with at least seven grain sizes ranging from 1 cm2 to 1,024 m2. Using nonlinear regression, we assessed the appropriateness of different SAR functions (power, power quadratic, power breakpoint, logarithmic, Michaelis–Menten). Based on AICc, we tested whether the ranking of functions differed among taxonomic groups, methodological settings, biomes or vegetation types.
Results
The power function was the most suitable function across the studied taxonomic groups. The superiority of this function increased from lichens to bryophytes to vascular plants to all three taxonomic groups together. The sampling method was highly influential as rooted presence sampling decreased the performance of the power function. By contrast, biome and vegetation type had practically no influence on the superiority of the power law.
Main conclusions
We conclude that SARs of sessile organisms at smaller spatial grains are best approximated by a power function. This coincides with several other comprehensive studies of SARs at different grain sizes and for different taxa, thus supporting the general appropriateness of the power function for modelling species diversity over a wide range of grain sizes. The poor performance of the Michaelis–Menten function demonstrates that richness within plant communities generally does not approach any saturation, thus calling into question the concept of minimal area.
Similarly to other Mediterranean regions, Italy is expected to experience dramatic climatic changes in the coming decades. Do to their poikilohydric nature, lichens are among the most sensitive ...organisms to climate change and species requiring temperate-humid conditions may rapidly decline in Italy, such in the case of the epiphytic Lobaria species that are confined to humid forests. Our study, based on ecological niche modelling of occurrence data of three Lobaria species, revealed that in the next decades climate change will impact their distribution range across Italy, predicting a steep gradient of increasing range loss across time slices. Lobaria species are therefore facing a high extinction risk associated with reduction of their range. The current patterns indicate that only L. pulmonaria still has a continuous distribution across Italy, with potential contact between Apennine and Alpine populations. This situation is consistent with the wider climatic niche of this species, still offering a major opportunity for its successful long-term conservation. Results (a) support the inclusion of the three Lobaria species in European conservation policies, such as the Habitat Directive, and (b) warn against an over-estimation of the indicator power of single flagship species to establish conservation priorities for lichens, indicating that even lichens with peculiar and similar climatic envelopes may fail to co-occur within a given forest stand. A multiple indicator approach could provide more useful tools for a community-based conservation strategy for epiphytes.
•Lichens are among the most sensitive organisms to climate change.•Climate change will impact the distribution range of Lobaria species across Italy.•Lobaria species are facing extinction risk due to range reduction.•Lobaria species should be included in European conservation policies.•A multiple indicator approach could support conservation priorities for lichens.
The fragmentation of the natural habitat is a process that is exponentially increasing worldwide and represents one of the biggest threats to biological diversity. Habitat destruction and ...fragmentation have a major impact on landscapes and may also affect ecosystems, populations, and species. The ongoing anthropogenic process can result in habitat loss for some species, habitat creation for others, reduced patch size, and increased distance between patches, which may lead to local extinction. We analyzed the effects of patch size and isolation on lichens in Quercus pubescens woods surrounding the city of Potenza (south Italy). We randomly sampled 11 forest patches with homogeneous environmental variables using circular plots with a 10 m radius; the patches ranged from 0.3 to 30 ha. For each plot, we collected data about presence and abundance of epiphytic lichens. We performed the analyses at the patch level using linear regression and multivariate analysis, searching for effects on species richness, life forms, and community compositions. Multivariate analyses were used to study the effect of fragmentation on the structure of lichen vegetation. We investigated the main predictor of lichen species richness in habitat fragmentations and concluded that patch area per se is an important (positive) driver of lichen species richness in Mediterranean peri-urban forests.
Marketable yield is the main objective in tomato production, but fair values for quality parameters are also becoming very important. A research project was undertaken for two years to assess the ...impact of water-saving techniques on yield, fruit quality and water use efficiency (WUE) of processing tomato (cv. Pullrex) in the Mediterranean environment. Additionally, to better understand how irrigation may affect tomato traits, different statistical techniques were applied to the results. Total yield was reduced by 37% on average in both years when half of the crop evapotranspiration (ET) was restored, and maximum marketable tomato yield was obtained under irrigation when 100% of the crop ET was restored. Irrigation cut at tomato veraison (irrigation cutback treatment) did not affect the yield, enhanced fruit quality and maximised WUE, thus contributing to water saving. Through the application of irrigation cutback toward the end of the tomato cycle, there is a possibility to improve tomato quality and, at the same time, save irrigation water. Principal component analysis confirmed that the cutback of irrigation was well correlated with tomato quality.
The discovery of few isolated populations of
Gymnospermium scipetarum
(since now considered as an amphi-Adriatic endemic) in the S-Apennines prompted to investigate, also for conservation purposes, ...some aspects of its reproductive biology. We aim: (1) to determine if insects play an important role in pollination; (2) to describe the pollinator community; (3) to detect floral scent composition. Experiments of insect exclusion were carried out in the field using 24 flowering individuals: one raceme was capped whereas the nearest one was used as control to ascertain differences in seed set. Pollinator community was detected during the blooming phase of two consecutive flowering seasons by visual observation; insect identification was made at the highest possible taxonomic resolution with the help of digital photographs. In order to determine the chemical composition of the volatiles, we used SPME sampling of cultivated plants. Mann–Whitney U test reveals significant differences for treatment in mean seed set with very low values for capped flowers, thus clearly indicating as insects are crucial for successful pollination. During the 42 h of observations we detected 326 visitors belonging to only three guilds: 79% were Diptera, 20% Hymenoptera and 1% Coleoptera. We identified overall 36 floral organic compounds with only two compounds common to the other studied Berberidaceae. Ambrox was never identified before in the floral scents of any angiosperm. The presence in the scent of several aldehydes and one ketone (benzophenone) could be related to the detected dominance of muscoid flies as pollinators. Floral morphology and composition of the pollinators community indicate a generalist pollination behaviour probably related to its phenology and habitat preference. The possibility of being pollinated also by muscoid flies can be considered an advantage for the reproductive fitness of the species, since these Diptera are abundant in the mountain pastures surrounding the forest habitat of
Gymnospermium
.
Despite the importance for scientific and conservation purposes, the knowledge of the Italian territory is far from exhaustive. New chorological data for 87 vascular taxa regarding the ...central-southern part of Italy and its two main islands (Sicilia and Sardegna) are presented. Among these taxa, Epilobium nummularifolium, Metrosideros excelsa, and Salvinia minima are recorded as casual aliens for the first time in Europe (excluding Azores and Madeira for M. excelsa), while Cyclamen balearicum and Polygala rupestris are reported for the first time and confirmed for Italian native flora, respectively. Furthermore, several taxa are new or confirmed at regional level. Finally, Lathyrus cirrhosus, Urginea fugax, and Linum tenuifolium are excluded from Italy, continental and peninsular Italy, and Sardegna, respectively.
Despite the wide amount of scientific contributions published on alien plant species, their diffusion dynamics, and their interactions with native taxa, it is increasingly difficult to slow down ...their spreading and their negative impact on habitats. Last recent years, in fact, a sharp rise in the number of new alien plant taxa introduced in Italy and Europe has been recorded. The aim of this work is to investigate most of the Italian territory in order to verify whether this alarming trend is still underway. Specimen collections and/or observations of alien plants have been performed in as many as 12 Italian regions. All the collected specimens are stored in public or private herbaria. Taxa have been identified according to the literature from the countries of origin of the investigated taxa, while the nomenclature followed the current international references. Updates on 106 taxa are reported. In particular, among 117 new records, 89 are first records, 27 are changes to status and there is 1 extinction. Seven new taxa for Italian alien flora are reported, two of which are new to Europe. The administrative regions with the highest number of records are Calabria (48), Sardegna (17) and Sicilia (15). Five of the surveyed taxa, for the first time, have been considered invasive aliens to Italian territory. The unfrequent amount of original results provided by this work, over the simple importance of data itself, proves how floristic investigation, still today, represents one of the most effective tools in broadening the current knowledge about alien taxa and their dynamics.
In this contribution, new data concerning algae, bryophytes, fungi and lichens of the Italian flora are presented. It includes new records and confirmations for the algal genera Chara and Nitella , ...the bryophyte genera Brachythecium , Didymodon , Fissidens , Physcomitrium , and Riccia , the fungal genera Biatoropsis , Cantharellus , Coprinellus , Dacrymyces , Inosperma , Nigropuncta , Urocystis , and Xanthoriicola , and the lichen genera Arthonia , Bellemerea , Circinaria , Lecania , Lecanora , Lecidella , Mycobilimbia , Naetrocymbe , Parmelia , Peltigera , Porpidia , Scytinium , and Usnea .
In this contribution, new data concerning algae, bryophytes, fungi and lichens of the Italian flora are presented. It includes new records and confirmations for the algal genera
Acetabularia
,
...Nitella
, and
Nitellopsis
for the bryophyte genera
Drepanocladus
,
Fissidens
,
Hookeria
, and
Weissia
, the fungal genera
Alnicola
,
Arthonia
,
Cortinarius, Inocybe
,
Leucoagaricus
,
Neohygrocybe
, and
Puccinia
and the lichen genera
Bacidina
,
Chaenotheca
,
Flavoplaca
,
Gyalecta
,
Heterodermia
,
Rinodina
,
Scytinium
, and
Squamarina
.
In this contribution, new data concerning the distribution of native vascular flora in Italy are presented. It includes new records, confirmations, and exclusions to the Italian administrative ...regions. Nomenclatural and distribution updates, published elsewhere, and corrigenda are provided as supplementary material.
PDF
