Macroecology of global alpine vegetation

Gli ecosistemi alpini, ossia gli habitat di alta quota al di sopra della linea degli alberi, sono essenziali per il sostentamento umano e sono tra gli ambienti più minacciati dal cambiamento climatico di origine antropica. Nonostante il consenso generale sulla distribuzione e le caratteristiche ecologiche dei biomi terrestri, l'effettiva estensione e le caratteristiche bioclimatiche degli ecosistemi alpini globali sono ancora incerte. Inoltre, i pattern e le cause della diversità vegetale e del funzionamento degli ecosistemi alpini globali sono in gran parte sconosciuti. Questo lavoro rappresenta un punto di partenza per la delineazione dei pattern macroecologici dei biomi alpini globali. In primo luogo, ho creato una mappa delle aree alpine globali modellando le quote altimetriche regionali della linea degli alberi ad alta risoluzione spaziale, utilizzando dataset globali di copertura forestale. Ho usato questa mappa in combinazione con altri dataset digitali per valutare le caratteristiche climatiche degli ecosistemi alpini e determinarne i pattern di produttività primaria. In secondo luogo, ho analizzato i pattern globali di ricchezza delle specie vegetali negli ecosistemi alpini e l’influenza di fattori ambientali, geografici e storici a diverse scale spaziali. Per fare ciò, ho messo insieme un dataset globale della vegetazione alpina composto da oltre 8.900 plot, ho valutato i pattern latitudinali di ricchezza regionale e a livello di singole comunità vegetali, e li ho modellati rispetto a diversi predittori, stimati utilizzando raster globali. Infine, ho analizzato la variazione funzionale della vegetazione alpina in rapporto alla storia evolutiva e al macroclima. Per fare ciò, ho ulteriormente selezionato il suddetto dataset di plot di vegetazione alpina in base alla disponibilità di tratti funzionali e dati filogenetici. Ho valutato le strategie funzionali delle diverse specie di piante alpine e la dissimilarità funzionale della vegetazione tra grandi unità geografiche caratterizzate da diversa vegetazione planiziale dominante, macroclima e storia evolutiva. Infine, ho modellato la dissimilarità funzionale rispetto alle dissimilarità ambientale e filogenetica. Dalle analisi effettuate, è emerso che i biomi alpini coprono quasi il 3% delle terre emerse al di fuori dell'Antartide. Nonostante le differenze di temperatura tra le diverse latitudini, questi ecosistemi convergono al di sotto di una soglia di 5,9 °C di temperatura media annua e verso l'estremità più fredda dello spazio climatico globale. Al di sotto di tale soglia di temperatura, gli ecosistemi alpini sono influenzati da un gradiente latitudinale di temperatura media annua e sono differenziati dal punto di vista climatico per stagionalità e continentalità. Questo gradiente distingue lo spazio climatico dei biomi alpini globali da quello dei biomi temperati, boreali e della tundra. Sebbene i biomi alpini siano similmente caratterizzati da aree scarsamente vegetate, le ecoregioni mondiali mostrano forti differenze nella produttività della loro fascia alpina indipendentemente dalle principali zone climatiche. Inoltre, in contrasto con il ben noto gradiente di diversità latitudinale, la ricchezza di specie vegetali alpine di alcune regioni temperate dell'Eurasia è paragonabile a quella degli ecosistemi alpini tropicali. Questo pattern è principalmente spiegato dall'estensione attuale e passata delle aree alpine, dall'isolamento e dalla variazione del pH del suolo tra le diverse regioni, mentre la ricchezza delle comunità vegetali dipende da fattori ambientali locali. Infine, le specie vegetali delle aree alpine sembrano riflettere la variazione funzionale globale di tutte le piante e sono principalmente differenziate per le loro strategie di utilizzo delle risorse. Il macroclima attuale esercita un effetto limitato sulla vegetazione alpina, agendo per lo più a livello delle singole comunità vegetali e in combinazione con la storia evolutiva. Inoltre, la vegetazione alpina globale è funzionalmente indipendente dalle zone di vegetazione in cui è integrata, mostrando una forte convergenza funzionale. Nel complesso, nonostante la loro distribuzione globale e l'apparente eterogeneità, gli ambienti alpini formano un gruppo distinto di biomi funzionalmente convergenti, fortemente disaccoppiati dagli ambienti di pianura e con una storia biogeografica varia, la cui eredità può ancora essere osservata sugli attuali pattern di diversità che sono ulteriormente rifiniti da fattori locali.Alpine ecosystems, namely high-elevation habitats above the climatic treeline, are essential to human livelihoods and are among the environments with the highest vulnerability to anthropogenic climate change. Despite the overall agreement on the distribution and ecological features of terrestrial biomes, the actual extent and bioclimatic characteristics of alpine ecosystems worldwide are still uncertain. Furthermore, the patterns and drivers of plant diversity and functioning in alpine ecosystems are largely unknown at the global scale. This work represents a novel contribution to the delineation of macroecological patterns of global alpine biomes. First, I created a map of global alpine areas by modelling regional treeline elevations at high spatial resolution using global forest cover data. I used this map in combination with global digital datasets to assess the climatic characteristics of alpine ecosystems and to evaluate patterns of primary productivity. Second, I assessed the global patterns of plant species richness in alpine ecosystems and the relative effect of environmental, geographical and historical factors at different spatial scales. To do so, I compiled a global dataset of alpine vegetation consisting of more than 8,900 plots, evaluated latitudinal patterns of regional and community richness and modelled them against different predictors estimated using global raster layers. Third, I assessed the functional variation of alpine vegetation and its relationship with evolutionary history and macroclimate. I filtered the abovementioned dataset of alpine vegetation plots based on the availability of functional trait and phylogenetic data. I assessed the functional trade-offs of alpine plant species and the functional dissimilarity of alpine vegetation across large geographic units with different dominant lowland vegetation, macroclimate, and evolutionary history. Finally, I modelled functional dissimilarity against environmental and phylogenetic dissimilarity. I found that alpine biomes cover almost 3% of land outside Antarctica. Despite temperature differences across latitudes, these ecosystems converge below a sharp threshold of 5.9 °C and towards the colder end of the global climatic space. Below that temperature threshold, alpine ecosystems are influenced by a latitudinal gradient of mean annual temperature and are climatically differentiated by seasonality and continentality. This gradient delineates a climatic envelope of global alpine biomes. Although alpine biomes are similarly dominated by poorly vegetated areas, world ecoregions show strong differences in the productivity of their alpine belt irrespectively of major climate zones. Furthermore, in contrast with the well-known latitudinal diversity gradient, plant species richness of some temperate alpine regions in Eurasia is comparable to that of hyper-diverse tropical alpine ecosystems. This pattern is mainly explained by the current and past alpine area, isolation, and variation in soil pH among regions, while community richness depends on local environmental factors. Finally, plant species in alpine areas seemingly reflect the global variation of plant function and are mainly differentiated for their resource-use strategies. The current macroclimate exerts a limited effect on alpine vegetation, mostly acting at the community level in combination with evolutionary history. Alpine vegetation is also functionally independent from the vegetation zones in which it is embedded, exhibiting strong functional convergence at the global scale. Overall, despite their global distribution and apparent heterogeneity, alpine environments form a distinct group of functionally convergent biomes, strongly decoupled from lowland environments, and with a varied biogeographic history, whose legacy can still be observed on current diversity patterns which are locally refined by fine-scale factors

Explanation of beta diversity in European alpine grasslands changes with scale

The importance of environmental difference among sites and dispersal limitations of species to the explanation of diversity differs among biological systems and geographical regions. We hypothesized that climate and then dispersal limitation will predominantly explain the similarity of alpine vegetation at increasing distances between pairs of regions at subcontinental extent. We computed the similarity of all pairs of 23 European mountain regions below 50 degrees N after dividing the species lists of each region by calcareous or siliceous substrates. Distance decay in similarity was better fitted by a cubic polynomial than a negative exponential function, and the fit was better on calcareous than on siliceous substrate. Commonality analysis revealed that the proportion of explanation of beta diversity by climatic difference had unimodal patterns on a gradient of increasing distance between regions, while explanation by dispersal limitation had consistently rising patterns on both substrates. On siliceous substrate, dispersal limitation explained more of the variation in beta diversity only at longer distances, but it was predominant at all distances on calcareous substrate. The steeper response to distance at 2600 km may indicate dispersal limitation at different temporal scales, and the uptick in the response to distance at the longest distances may reflect how isolated some regions have been before and since the last glacial maximum

Global patterns and drivers of alpine plant species richness

Aim Alpine ecosystems differ in area, macroenvironment and biogeographical history across the Earth, but the relationship between these factors and plant species richness is still unexplored. Here, we assess the global patterns of plant species richness in alpine ecosystems and their association with environmental, geographical and historical factors at regional and community scales. Location Global. Time period Data collected between 1923 and 2019. Major taxa studied Vascular plants. Methods We used a dataset representative of global alpine vegetation, consisting of 8,928 plots sampled within 26 ecoregions and six biogeographical realms, to estimate regional richness using sample‐based rarefaction and extrapolation. Then, we evaluated latitudinal patterns of regional and community richness with generalized additive models. Using environmental, geographical and historical predictors from global raster layers, we modelled regional and community richness in a mixed‐effect modelling framework. Results The latitudinal pattern of regional richness peaked around the equator and at mid‐latitudes, in response to current and past alpine area, isolation and the variation in soil pH among regions. At the community level, species richness peaked at mid‐latitudes of the Northern Hemisphere, despite a considerable within‐region variation. Community richness was related to macroclimate and historical predictors, with strong effects of other spatially structured factors. Main conclusions In contrast to the well‐known latitudinal diversity gradient, the alpine plant species richness of some temperate regions in Eurasia was comparable to that of hyperdiverse tropical ecosystems, such as the páramo. The species richness of these putative hotspot regions is explained mainly by the extent of alpine area and their glacial history, whereas community richness depends on local environmental factors. Our results highlight hotspots of species richness at mid‐latitudes, indicating that the diversity of alpine plants is linked to regional idiosyncrasies and to the historical prevalence of alpine ecosystems, rather than current macroclimatic gradients

Post-glacial determinants of regional species pools in alpine grasslands

[Aim] Alpine habitats support unique biodiversity confined to high-elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups.[Location] European mountains below 50° N.[Time period] Between 1928 and 2019.[Major taxa studied] Vascular plants.[Methods] We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non-alpines. We used species–area relationships to test the influence of the extent of alpine areas on regional richness, and mixed-effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions.[Results] Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non-alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non-alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions.[Main conclusions] Besides area effects, edaphic, topographic and spatio-temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post-glacial environmental filtering, while non-alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.The authors thank Daniela Gaspar for support in GIS analyses. B.J.-A. thanks the Marie Curie Clarín-COFUND program of the Principality of Asturias-EU (ACB17-26), the regional grant IDI/2018/000151, and the Spanish Research Agency grant AEI/ 10.13039/501100011033. J.V.R.-D. was supported by the ACA17-02FP7 Marie Curie COFUND-Clarín grant. G.P.M. was funded by US National Science Foundation award 1853665. C.M. was funded by grant no. 19-28491 of the Czech Science Foundation.Peer reviewe

A major QTL controlling apple skin russeting maps on the linkage group 12 of 'Renetta Grigia di Torriana'

Background: Russeting is a disorder developed by apple fruits that consists of cuticle cracking followed by the replacement of the epidermis by a corky layer that protects the fruit surface from water loss and pathogens. Although influenced by many environmental conditions and orchard management practices, russeting is under genetic control. The difficulty in classifying offspring and consequent variable segregation ratios have led several authors to conclude that more than one genetic determinant could be involved, although some evidence favours a major gene (Ru). Results: In this study we report the mapping of a major genetic russeting determinant on linkage group 12 of apple as inferred from the phenotypic observation in a segregating progeny derived from 'Renetta Grigia di Torriana', the construction of a 20 K Illumina SNP chip based genetic map, and QTL analysis. Recombination analysis in two mapping populations restricted the region of interest to approximately 400 Kb. Of the 58 genes predicted from the Golden Delicious sequence, a putative ABCG family transporter has been identified. Within a small set of russeted cultivars tested with markers of the region, only six showed the same haplotype of 'Renetta Grigia di Torriana'. Conclusions: A major determinant (Ru_RGT) for russeting development putatively involved in cuticle organization is proposed as a candidate for controlling the trait. SNP and SSR markers tightly co-segregating with the Ru_RGT locus may assist the breeder selection. The observed segregations and the analysis of the 'Renetta Grigia di Torriana' haplotypic region in a panel of russeted and non-russeted cultivars may suggest the presence of other determinants for russeting in apple

Post-glacial determinants of regional species pools in alpine grasslands

Aim Alpine habitats support unique biodiversity confined to high-elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups. Location European mountains below 50 degrees N. Time period Between 1928 and 2019. Major taxa studied Vascular plants. Methods We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non-alpines. We used species-area relationships to test the influence of the extent of alpine areas on regional richness, and mixed-effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions. Results Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non-alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non-alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions. Main conclusions Besides area effects, edaphic, topographic and spatio-temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post-glacial environmental filtering, while non-alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.Gobierno del Principado de AsturiasAgencia Nacional de Investigación e InnovaciónFundación para el Fomento en Asturias de la Investigación Científica Aplicada y la TecnologíaPrograma Clarín COFUNDDepto. de Farmacología, Farmacognosia y BotánicaFac. de FarmaciaTRUEpu

Citizen science data to measure human use of green areas and forests in European cities

Understanding and explaining the use of green spaces and forests is challenging for sustainable urban planning. In recent years there has been increasing demand for novel approaches to investigate urban green infrastructure by capitalizing on large databases from existing citizen science tools. In this study, we analyzed iNaturalist data to perform an assessment of the intentional use of these urban spaces for their value and to understand the main drivers. We retrieved the total number of observations obtained across a set of 672 European cities and focused on reporting from mapped green areas and forests. We used two separate multivariate explanatory models to investigate which factors explained variations in the number of observations for green areas and forests. We found a relatively heterogeneous use of these two urban green spaces. Gross domestic product was important in explaining the number of visits. Availability and accessibility also had positive relationships with the use of green areas and forests in cities, respectively. This study paves the way for better integration of citizen science data in assessing cultural services provided by urban green infrastructure and therefore in supporting the evaluation of spatial planning policies for the sustainable development of urban areas

Citizen science data to measure human use of green areas and forests in European cities

Detecting and quantifying the use of green spaces and forests is paramount for sustainable urban planning. The increasing availability of large databases from existing citizen science tools can contribute to developing novel approaches to investigate urban green infrastructure. Using the iNaturalist database – a citizen science initiative on collecting the occurrences of plant and animal species worldwide – we estimated the intentional use of these urban spaces by people for their value and to understand the main drivers. We retrieved the total number of observations obtained across 672 European cities and focused on reporting from mapped green areas and forests. We used two separate multivariate explanatory models to investigate which factors explained variations in the number of observations for green areas and forests. We found a relatively heterogeneous use of these two types of urban green spaces. Gross domestic product (GDP) was important in explaining the number of visits. Availability and accessibility also had positive relationships with green areas and forests in cities, respectively. This study paves the way for better integration of citizen science data in assessing cultural landscape services provided by urban green infrastructure and, therefore, supporting the evaluation of spatial planning policies for the sustainable development of urban area

Ecological Characterization of Syzygium (Myrtaceae) in Papua New Guinea

Syzygium is the largest woody genus of flowering plants in the world and one of the most important components of the forest vegetation in Papua New Guinea (PNG). Although the systematics of the genus is improving, a comprehensive appraisal of the environmental features and gradients of its species is still lacking. Our work aims to fill this gap by analyzing the georeferenced specimens collected at the Lae National Herbarium of PNG. A data set of 1,563 records of 131 species was used to assess their altitudinal gradients and the correspondence with the main vegetation types and to model their spatial ecological niche with respect to climatic, topographical, and pedological variables. Several species were found to be widely distributed throughout the region, while other species were restricted to narrow altitudinal belts or only occurred in specific vegetation types. Overall, the genus is also characterized by an increasing altitudinal turnover likely due to topography-driven isolation. The improved knowledge of the ecological requirements of Syzygium assists in the elaboration of effective conservation strategies and improves in situ species identification of this taxonomically difficult group