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1.
Glob Chang Biol ; 30(1): e17064, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38273565

RESUMO

Climate change is pushing species towards and potentially beyond their critical thermal limits. The extent to which species can cope with temperatures exceeding their critical thermal limits is still uncertain. To better assess species' responses to warming, we compute the warming tolerance (ΔTniche ) as a thermal vulnerability index, using species' upper thermal limits (the temperature at the warm limit of their distribution range) minus the local habitat temperature actually experienced at a given location. This metric is useful to predict how much more warming species can tolerate before negative impacts are expected to occur. Here we set up a cross-continental transplant experiment involving five regions distributed along a latitudinal gradient across Europe (43° N-61° N). Transplant sites were located in dense and open forests stands, and at forest edges and in interiors. We estimated the warming tolerance for 12 understory plant species common in European temperate forests. During 3 years, we examined the effects of the warming tolerance of each species across all transplanted locations on local plant performance, in terms of survival, height, ground cover, flowering probabilities and flower number. We found that the warming tolerance (ΔTniche ) of the 12 studied understory species was significantly different across Europe and varied by up to 8°C. In general, ΔTniche were smaller (less positive) towards the forest edge and in open stands. Plant performance (growth and reproduction) increased with increasing ΔTniche across all 12 species. Our study demonstrated that ΔTniche of understory plant species varied with macroclimatic differences among regions across Europe, as well as in response to forest microclimates, albeit to a lesser extent. Our findings support the hypothesis that plant performance across species decreases in terms of growth and reproduction as local temperature conditions reach or exceed the warm limit of the focal species.


Assuntos
Mudança Climática , Florestas , Ecossistema , Europa (Continente) , Flores , Temperatura , Plantas
2.
New Phytol ; 233(1): 219-235, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34664731

RESUMO

Forests harbour large spatiotemporal heterogeneity in canopy structure. This variation drives the microclimate and light availability at the forest floor. So far, we do not know how light availability and sub-canopy temperature interactively mediate the impact of macroclimate warming on understorey communities. We therefore assessed the functional response of understorey plant communities to warming and light addition in a full factorial experiment installed in temperate deciduous forests across Europe along natural microclimate, light and macroclimate gradients. Furthermore, we related these functional responses to the species' life-history syndromes and thermal niches. We found no significant community responses to the warming treatment. The light treatment, however, had a stronger impact on communities, mainly due to responses by fast-colonizing generalists and not by slow-colonizing forest specialists. The forest structure strongly mediated the response to light addition and also had a clear impact on functional traits and total plant cover. The effects of short-term experimental warming were small and suggest a time-lag in the response of understorey species to climate change. Canopy disturbance, for instance due to drought, pests or logging, has a strong and immediate impact and particularly favours generalists in the understorey in structurally complex forests.


Assuntos
Florestas , Microclima , Mudança Climática , Plantas , Temperatura , Árvores
3.
Glob Ecol Biogeogr ; 31(9): 1877-1893, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36246451

RESUMO

Aim: The amount of forest edges is increasing globally due to forest fragmentation and land-use changes. However, edge effects on the soil seed bank of temperate forests are still poorly understood. Here, we assessed edge effects at contrasting spatial scales across Europe and quantified the extent to which edges can preserve the seeds of forest specialist plants. Location: Temperate European deciduous forests along a 2,300-km latitudinal gradient. Time period: 2018-2021. Major taxa studied: Vascular plants. Methods: Through a greenhouse germination experiment, we studied how edge effects alter the density, diversity, composition and functionality of forest soil seed banks in 90 plots along different latitudes, elevations and forest management types. We also assessed which environmental conditions drive the seed bank responses at the forest edge versus interior and looked at the relationship between the seed bank and the herb layer species richness. Results: Overall, 10,108 seedlings of 250 species emerged from the soil seed bank. Seed density and species richness of generalists (species not only associated with forests) were higher at edges compared to interiors, with a negative influence of C : N ratio and litter quality. Conversely, forest specialist species richness did not decline from the interior to the edge. Also, edges were compositionally, but not functionally, different from interiors. The correlation between the seed bank and the herb layer species richness was positive and affected by microclimate. Main conclusions: Our results underpin how edge effects shape species diversity and composition of soil seed banks in ancient forests, especially increasing the proportion of generalist species and thus potentially favouring a shift in community composition. However, the presence of many forest specialists suggests that soil seed banks still play a key role in understorey species persistence and could support the resilience of our fragmented forests.

4.
Planta ; 252(6): 99, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33170944

RESUMO

MAIN CONCLUSION: Odontarrhena is a highly diverse genus of Ni-hyperaccumulators. Here, we demonstrate substantial inability to accumulate Ni in the facultative serpentinophyte O. sibirica, which seems a unique case among the numerous species of the genus that grow on ultramafic soils. Odontarrhena is the most diverse genus of Ni-accumulating plants in W Eurasia, with most taxa growing obligatorily or facultatively on ultramafic soils. A notable exception may be O. sibirica, a facultative serpentinophyte from the E Mediterranean and W Asia in which accumulation ability is still enigmatic. We addressed this issue using observational and experimental methods. Atomic Absorption Analysis of 33 herbarium specimens and plant and soil samples from seven ultramafic and non-ultramafic sites in Greece revealed shoot Ni values always much lower than 1000 µg g-1, non-significant differences between plants from the two soil types and no relationship with soil pH. Only two Turkish specimens from waste mines had shoot Ni concentration > 1000 µg g-1. The reasons for this deviating result remain obscure, but may be associated with inherent peculiarities of the local populations. When cultivated together with congeneric Ni-accumulating species on the same natural ultramafic soil, only O. sibirica was unable to accumulate the metal. Although plant growth was stimulated in hydroponics at relatively low NiSO4 levels (50-150 µM), as typical for hyperaccumulators, Ni-accumulation occurred only at higher concentrations which had a toxic effect. This peculiar combination of Ni-response traits could be the result of a partial evolutionary loss of ability with respect to all other Ni-accumulating congeneric species. For this, O. sibirica could represent a unique model system for further studies on the evolutionary dynamics, physiological mechanisms and genetic control of metal accumulation and homeostasis.


Assuntos
Brassicaceae , Níquel , Poluentes do Solo , Ásia , Brassicaceae/metabolismo , Níquel/metabolismo , Solo/química , Poluentes do Solo/metabolismo
5.
Mol Phylogenet Evol ; 141: 106626, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31526848

RESUMO

Studies about the drivers of angiosperm clade diversifications have revealed how the environment continuously alters the species chances to adapt or to go extinct. This process depends on complex interactions between abiotic and biotic factors, conditioned to the geological and tectonic settings, the genetic variability of species and the rate at which speciation occurs. In this study, we aim to elucidate the timing of diversification of the Lithospermeae, the second largest tribe within Boraginaceae, and to identify the possible morphological and ecological characters associated with shifts in diversification rates of the most species-rich clades. Lithospermeae includes ca. 470 species and 26 genera, among which are some of the largest genera of the family such as Onosma (150 spp.), Echium (60 spp.), and Lithospermum (80 spp.). An exhaustive study of the whole clade is not available to date and its evolutionary history and diversification rates are incompletely known. In the present study, we provide the most comprehensive phylogeny of the group so far, sampling 242 species and all 26 genera. We found that crown-groups and diversification rates of Lithospermeae largely date back to the Mid-Miocene, with high diversification rates in the largest genera, though only significantly high in Onosma. Our analysis fails to associate any of the functional or morphological traits considered with significant shifts in diversification rates. The timing of the diversification of the species-rich clades corresponds with Miocene tectonic events and global climate changes increasing aridity across Eurasia and western North America. These results suggest a causal link between known ecological features of Lithospermeae (i.e., pre-adaptation to arid, open habitats, and mineral soils) and their diversification. Future studies should expand the sampling of individual subclades and detailed functional analyses to identify the contribution of adaptations to arid conditions and pollinator shifts.


Assuntos
Biodiversidade , Boraginaceae/classificação , Filogenia , Filogeografia , Sequência de Bases , Boraginaceae/anatomia & histologia , DNA de Cloroplastos/genética , DNA Espaçador Ribossômico/genética , América do Norte , Especificidade da Espécie , Fatores de Tempo
6.
Proc Natl Acad Sci U S A ; 113(13): 3557-62, 2016 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-26979952

RESUMO

Many experiments have shown that local biodiversity loss impairs the ability of ecosystems to maintain multiple ecosystem functions at high levels (multifunctionality). In contrast, the role of biodiversity in driving ecosystem multifunctionality at landscape scales remains unresolved. We used a comprehensive pan-European dataset, including 16 ecosystem functions measured in 209 forest plots across six European countries, and performed simulations to investigate how local plot-scale richness of tree species (α-diversity) and their turnover between plots (ß-diversity) are related to landscape-scale multifunctionality. After accounting for variation in environmental conditions, we found that relationships between α-diversity and landscape-scale multifunctionality varied from positive to negative depending on the multifunctionality metric used. In contrast, when significant, relationships between ß-diversity and landscape-scale multifunctionality were always positive, because a high spatial turnover in species composition was closely related to a high spatial turnover in functions that were supported at high levels. Our findings have major implications for forest management and indicate that biotic homogenization can have previously unrecognized and negative consequences for large-scale ecosystem multifunctionality.


Assuntos
Biodiversidade , Florestas , Simulação por Computador , Bases de Dados Factuais , Ecossistema , Europa (Continente) , Agricultura Florestal , Modelos Biológicos , Árvores
7.
Retina ; 37(10): 1931-1941, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28033235

RESUMO

PURPOSE: To identify the prognostic variables relative to myopic choroidal neovascularization (CNV) treated with intravitreal ranibizumab/bevacizumab. METHODS: Forty-eight patients with myopic CNV were enrolled in a prospective, interventional, non-randomized 12-month study. Intravitreal ranibizumab/bevacizumab was administered in a pro-re-nata regimen and re-treatment was performed in the presence of angiographic leakage, intraretinal/subretinal fluid on optical coherence tomography, new hemorrhages, five-letter decrease and increased metamorphosia. The primary outcome measures were the identification of the predictive value of symptom duration, patient's age, refractive error, best-corrected visual acuity (BCVA), central macular thickness (CMT), CNV area, CNV location, retinal hemorrhages, atrophy, lacquer cracks, and CNV-fundus autofluorescence pattern (hyper-fundus autofluorescence/patchy pattern). The secondary outcomes were patients requiring either one or two injections to achieve CNV stabilization. RESULTS: The mean BCVA improved from 0.49 ± 0.30 (logarithm of minimal angle resolution, Snellen equivalent 20/63) to 0.39 ± 0.32 (20/49) at 1-year follow-up (P = 0.043). Univariate and multiple stepwise linear regression analysis identified baseline BCVA (P = 0.0003), symptom duration (P = 0.005), CMT (P = 0.02), and fundus autofluorescence pattern (P = 0.005) as the explanatory variables on the final BCVA and the change in the mean BCVA. Overall, patients with better baseline BCVA, early diagnosis, lower CMT, or disclosing a hyperfundus autofluorescence CNV pattern achieved better visual outcomes. Patients responding with just one to two intravitreal injections (45.8%) obtained better visual outcomes compared with patients receiving three or more injections, and this group consisted of younger patients with lesser CMT, smaller CNV area, and fewer baseline hemorrhages. CONCLUSION: Ranibizumab/bevacizumab therapy was effective in improving and maintaining visual acuity in myopic choroidal neovascularization. Early diagnosis, better baseline BCVA, and hyperfundus autofluorescence CNV pattern were strongly associated with better functional outcomes. Moreover, CNV distinguished by its small size and low CMT responded more favorably, achieving a better visual outcome.


Assuntos
Bevacizumab/administração & dosagem , Neovascularização de Coroide/tratamento farmacológico , Miopia Degenerativa/complicações , Ranibizumab/administração & dosagem , Acuidade Visual/efeitos dos fármacos , Adulto , Idoso , Idoso de 80 Anos ou mais , Inibidores da Angiogênese , Neovascularização de Coroide/diagnóstico , Neovascularização de Coroide/fisiopatologia , Feminino , Angiofluoresceinografia , Seguimentos , Fundo de Olho , Humanos , Injeções Intravítreas , Masculino , Pessoa de Meia-Idade , Miopia Degenerativa/fisiopatologia , Prognóstico , Estudos Prospectivos , Refração Ocular , Fatores de Tempo , Tomografia de Coerência Óptica , Resultado do Tratamento , Fator A de Crescimento do Endotélio Vascular
8.
Sci Total Environ ; 918: 170531, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38309368

RESUMO

Coppicing is one of the oldest silvicultural practices and is still widely applied to produce renewable energy from broadleaf forests. However, the consequences on microclimate and understorey vegetation are still poorly understood, especially in Mediterranean oak forests. With the ongoing changes in the climate system and global biodiversity loss, a better understanding of how the forest temperature buffering capacity and below-canopy plant community are impacted by coppicing is crucial. Here we quantify microclimate and understorey vegetation changes in adjacent ancient coppice-with-standards and high forest stands dominated by oaks in Italy, where these systems have been applied for a long time. Air and soil temperatures were recorded for 2.5 years, and nested vegetation plots were used to analyse coppicing effects on species composition, taxonomic, phylogenetic, and functional diversity. Coppicing significantly reduced the forest temperature buffering capacity. The mean of the daily maximum temperatures over the entire period was 1.45 °C higher in the coppiced sites, whereas the mean of the daily minimum temperatures was 0.62 °C lower than in the high forest. Coppicing increased understorey species richness by favouring generalist taxa, but significantly decreased the proportion of forest specialists. The understorey community in coppiced forests consisted of more warm-adapted species. Moreover, coppicing also led to a loss of phylogenetic evenness and to shifts in diversity and community weighted mean Leaf Dry Matter content, pointing to habitat filtering and acclimation processes. In sum, we show that coppicing affects microclimate and understory vegetation in a direction that can exacerbate the effects of climate change, negatively affecting the oak forest specialist flora and its phylogenetic evenness.


Assuntos
Quercus , Microclima , Filogenia , Florestas , Ecossistema , Biodiversidade
9.
Nat Ecol Evol ; 8(5): 880-887, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38424266

RESUMO

Forest biodiversity and ecosystem services are hitherto predominantly quantified in forest interiors, well away from edges. However, these edges also represent a substantial proportion of the global forest cover. Here we quantified plant biodiversity and ecosystem service indicators in 225 plots along forest edge-to-interior transects across Europe. We found strong trade-offs: phylogenetic diversity (evolutionary measure of biodiversity), proportion of forest specialists, decomposition and heatwave buffering increased towards the interior, whereas species richness, nectar production potential, stemwood biomass and tree regeneration decreased. These trade-offs were mainly driven by edge-to-interior structural differences. As fragmentation continues, recognizing the role of forest edges is crucial for integrating biodiversity and ecosystem service considerations into sustainable forest management and policy.


Assuntos
Biodiversidade , Florestas , Europa (Continente) , Conservação dos Recursos Naturais , Árvores , Filogenia
10.
Mol Phylogenet Evol ; 68(3): 604-18, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23608129

RESUMO

Recent studies all indicated that both the affinities and subdivision of Boraginaceae s.str. are unsatisfactorily resolved. Major open issues are the placement and affinities of Boraginaceae s.str. in Boraginales and the major clades of the family, with especially the large tribes Cynoglosseae and Eritrichieae repeatedly retrieved as non-monophyletic groups, and the doubtful monophyly of several larger genera, especially Cynoglossum and Omphalodes. The present study addresses and solves these questions using two plastid markers (trnL-trnF, rps16) on the basis of a sampling including 16 outgroup taxa and 172 ingroup species from 65 genera. The phylogeny shows high statistical support for most nodes on the backbone and on the individual clades. Boraginaceae s.str. are sister to African Wellstediaceae, Wellstediaceae-Boraginaceae s.str. is sister to African Codonaceae. Echiochileae are retrieved as sister to the remainder of Boraginaceae s.str., which, in turn, fall into two major clades, the Boragineae-Lithospermeae (in a well-supported sister relationship) and the Cynoglosseae s.l. (including Eritrichieae). Cynoglosseae s.l. is highly resolved, with Trichodesmeae (incl. Microcaryum, Lasiocaryum) as sister to the remainder of the group. Eritrichieae s.str. (Eritrichium, Hackelia, Lappula) are resolved on a poorly supported polytomy together with the Omphalodes-clade (incl. Myosotidium, Cynoglossum p.p.), and the Mertensia-clade (incl. O. scorpioides, Asperugo). The Myosotideae (Myosotis, Trigonotis, Pseudomertensia) are retrieved in a well-supported sister-relationship to the core-Cynoglosseae, the latter comprising all other genera sampled. Cynoglossum is retrieved as highly para- and polyphyletic, with a large range of generic segregates embedded in Cynoglossum, but other species of Cynoglossum are sister to Microula or to the American "Eritrichieae" (Cryptantha and allied genera). Representatives of the genus Cynoglossum in its current definition are segregated onto six independent lineages, members of Omphalodes onto three independent lineages. At least 11 of the genera here sampled are deeply nested in other genera. The data show that individual details of nutlet morphology (e.g., winged margins, glochidia) are highly homoplasious. Conversely, a complex of nutlet characters (e.g., characters of the gynobase and cicatrix together with nutlet orientation and sculpturing) tends to circumscribe natural units. Geographical distribution of major clades suggests that the family originated in Africa and western Asia and radiated to eastern Eurasia, with several independent dispersal events into Australia and the New World.


Assuntos
Boraginaceae/classificação , Boraginaceae/genética , Fenótipo , Filogenia , Filogeografia , Plastídeos/genética , Sementes/genética
11.
PhytoKeys ; 227: 123-134, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37325450

RESUMO

The new species Sileneisabellae is described and illustrated from the Skënderbëut mountain range of central Albania. It grows on the ultramafic mountain slopes around Qafë Shtamë, in the understorey of open Pinusnigra forests and in the rocky grasslands above the forest belt, at 1000-1600 m a.s.l. Sileneisabellae is a serpentine endemic likely belonging to section Elisanthe (Fenzl ex Endl.) Ledeb. and shows affinities with the widespread European species S.noctiflora L. It is sharply distinct from the latter species in habit, stem and leaf pubescence, morphology, and biology of the flowers and length of the carpophore. Moreover, the ecology of the two taxa is also contrasting, being S.noctiflora a synanthropic-ruderal, mostly in lowlands. Weaker similarities were also observed with the south European subalpine taxa of the group of S.vallesia L. of section Auriculatae (Boiss.) Schischk., though these are not likely to reflect a real systematic affinity.

12.
Plant Physiol Biochem ; 176: 9-20, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35182963

RESUMO

Nickel-induced changes in photosynthetic activity were investigated in three Ni-hyperaccumulating Odontarrhena species with increasing Ni tolerance and accumulation capacity, O. muralis, O. moravensis, and O. chalcidica. Plantlets were grown in hydroponics at increasing NiSO4 concentrations (0, 0.25, and 1 mM) for one week, and the effects of Ni on growth, metal accumulation, photosynthesis, and nitrogen (N) allocation to components of the photosynthetic apparatus were analysed. Nickel treatments in O. chalcidica, and O. moravensis to a lesser extent, increased not only the photochemical efficiency of photosystem II (PSII) and the CO2 assimilation rate, but also CO2 diffusion from the atmosphere to the carboxylation sites. These two species displayed a specific increase and/or rearrangement of the photosynthetic pigments and a higher leaf N allocation to the photosynthetic components in the presence of the metal. Odontarrhena muralis displayed a decrease in photosynthetic performance at the lowest Ni concentration due to a combination of both stomatal and non-stomatal limitations. Our data represent the first complete investigation of the effects of Ni on the photosynthetic machinery in Ni hyperaccumulating plants. Our findings clearly indicate a stimulatory, hormetic-like, effect of the metal on both biophysics and biochemistry of photosynthesis in the species with the highest hyperaccumulation capacity.


Assuntos
Brassicaceae , Clorofila , Níquel/farmacologia , Fotossíntese , Complexo de Proteína do Fotossistema II , Folhas de Planta
13.
Sci Total Environ ; 812: 152560, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-34952080

RESUMO

Tree species diversity promotes multiple ecosystem functions and services. However, little is known about how above- and belowground resource availability (light, nutrients, and water) and resource uptake capacity mediate tree species diversity effects on aboveground wood productivity and temporal stability of productivity in European forests and whether the effects differ between humid and arid regions. We used the data from six major European forest types along a latitudinal gradient to address those two questions. We found that neither leaf area index (a proxy for light uptake capacity), nor fine root biomass (a proxy for soil nutrient and water uptake capacity) was related to tree species richness. Leaf area index did, however, enhance productivity, but negatively affected stability. Productivity was further promoted by soil nutrient availability, while stability was enhanced by fine root biomass. We only found a positive effect of tree species richness on productivity in arid regions and a positive effect on stability in humid regions. This indicates a possible disconnection between productivity and stability regarding tree species richness effects. In other words, the mechanisms that drive the positive effects of tree species richness on productivity do not per se benefit stability simultaneously. Our findings therefore suggest that tree species richness effects are largely mediated by differences in climatic conditions rather than by differences in above- and belowground resource availability and uptake capacity at the regional scales.


Assuntos
Ecossistema , Árvores , Biodiversidade , Biomassa , Florestas , Solo
14.
Plants (Basel) ; 10(2)2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33671132

RESUMO

Trichome biomineralization is widespread in plants but detailed chemical patterns and a possible influence of soil chemistry are poorly known. We explored this issue by investigating trichome biomineralization in 36 species of Mediterranean Brassicaceae from ultramafic and calcareous soils. Our aims were to chemically characterize biomineralization of different taxa, including metallophytes, under natural conditions and to investigate whether divergent Ca, Mg, Si and P-levels in the soil are reflected in trichome biomineralization and whether the elevated heavy metal concentrations lead to their integration into the mineralized cell walls. Forty-two samples were collected in the wild while a total of 6 taxa were brought into cultivation and grown in ultramafic, calcareous and standard potting soils in order to investigate an effect of soil composition on biomineralization. The sampling included numerous known hyperaccumulators of Ni. EDX microanalysis showed CaCO3 to be the dominant biomineral, often associated with considerable proportions of Mg-independent of soil type and wild versus cultivated samples. Across 6 of the 9 genera studied, trichome tips were mineralized with calcium phosphate, in Bornmuellera emarginata the P to Ca-ratio was close to that of pure apatite-calcium phosphate (Ca5(PO4)3OH). A few samples also showed biomineralization with Si, either only at the trichome tips or all over the trichome. Additionally, we found traces of Mn co-localized with calcium phosphate in Bornmuellera emarginata and traces of Ni were detected in trichomes of the Ni-hyperaccumulator Odontarrhena chalcidica. Our data from wild and cultivated plants could not confirm any major effect of soil chemistry on the chemistry of trichome biominerals. Hyperaccumulation of Ni in the plants is not mirrored in high levels of Ni in the trichomes, nor do we find large amounts of Mn. A comparison based on plants from cultivation (normal, calcareous and serpentine soils, Mg:Ca-ratios ca 1:2 to 1:20) shows at best a very weak reflection of different Mg:Ca-ratios in the mineralized trichomes. The plants studied seem to be able to maintain highly conserved biomineralization patterns across a wide range of soil chemistries.

15.
Sci Total Environ ; 798: 149373, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34375232

RESUMO

Despite the crucial role of the seed bank in forest conservation and dynamics, the effects of forest edge microclimate and climate warming on germination responses from the forest seed bank are still almost unknown. Here, we investigated edge effects on the realised seed bank and seedling community in two types of European temperate deciduous forest, one in the Oceanic and one in the Mediterranean climatic region. Responses in terms of seedling density, diversity, species composition and functional type of the seed bank at the forest edge and interior were examined along latitudinal, elevational and stand structural gradients by means of soil translocation experiments. Moreover, we translocated soil samples from high to low elevation forests in the two regions, thus performing a warming simulation. Density, species diversity and mortality of the seedlings varied with region and elevation. Seedling density also differed between forest edge and interior position, while seedling cover mainly depended on forest structure. Both the edge and interior forest seed bank contained a high proportion of generalist species. In Belgium, a more homogeneous seed bank was found at the forest edge and interior, while in Italy compositional and ecological differences were larger: at the forest edge, more light and less moisture demanding seedling communities developed, with a higher proportion of generalists compared to the interior. In both regions, the upland-to-lowland translocation experiment revealed effects of warming on forest seed banks with thermophilization of the realised communities. Moreover, edge conditions shifted the seedling composition towards more light-demanding communities. The establishment of more light and warm-adapted species from the seed bank could in the long term alter the aboveground vegetation composition, with communities becoming progressively richer in light-demanding generalists and poorer in forest specialists.


Assuntos
Banco de Sementes , Solo , Florestas , Microclima , Plântula , Sementes , Árvores
16.
Sci Total Environ ; 759: 143497, 2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33246733

RESUMO

Forests play a key role in global carbon cycling and sequestration. However, the potential for carbon drawdown is affected by forest fragmentation and resulting changes in microclimate, nutrient inputs, disturbance and productivity near edges. Up to 20% of the global forested area lies within 100 m of an edge and, even in temperate forests, knowledge on how edge conditions affect carbon stocks and how far this influence penetrates into forest interiors is scarce. Here we studied carbon stocks in the aboveground biomass, forest floor and the mineral topsoil in 225 plots in deciduous forest edges across Europe and tested the impact of macroclimate, nitrogen deposition and smaller-grained drivers (e.g. microclimate) on these stocks. Total carbon and carbon in the aboveground biomass stock were on average 39% and 95% higher at the forest edge than 100 m into the interior. The increase in the aboveground biomass stock close to the edge was mainly related to enhanced nitrogen deposition. No edge influence was found for stocks in the mineral topsoil. Edge-to-interior gradients in forest floor carbon changed across latitude: carbon stocks in the forest floor were higher near the edge in southern Europe. Forest floor carbon decreased with increasing litter quality (i.e. high decomposition rate) and decreasing plant area index, whereas higher soil temperatures negatively affected the mineral topsoil carbon. Based on high-resolution forest fragmentation maps, we estimate that the additional carbon stored in deciduous forest edges across Europe amounts to not less than 183 Tg carbon, which is equivalent to the storage capacity of 1 million ha of additional forest. This study underpins the importance of including edge influences when quantifying the carbon stocks in temperate forests and stresses the importance of preserving natural forest edges and small forest patches with a high edge-to-interior surface area.

17.
Ann Bot ; 106(5): 751-67, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20724306

RESUMO

BACKGROUND AND AIMS: Nickel (Ni) hyperaccumulation is a rare form of physiological specialization shared by a small number of angiosperms growing on ultramafic soils. The evolutionary patterns of this feature among European members of tribe Alysseae (Brassicaceae) are investigated using a phylogenetic approach to assess relationships among Ni hyperaccumulators at the genus, species and below-species level. METHODS: Internal transcribed spacer (ITS) sequences were generated for multiple accessions of Alysseae. Phylogenetic trees were obtained for the genera of the tribe and Alyssum sect. Odontarrhena. All accessions and additional herbarium material were tested for Ni hyperaccumulation with the dimethylglyoxime colorimetric method. KEY RESULTS: Molecular data strongly support the poorly known hyperaccumulator endemic Leptoplax (Peltaria) emarginata as sister to hyperaccumulator species of Bornmuellera within Alysseae. This is contrary to current assumptions of affinity between L. emarginata and the non-hyperaccumulator Peltaria in Thlaspideae. The lineage Bornmuellera-Leptoplax is, in turn, sister to the two non-hyperaccumulator Mediterranean endemics Ptilotrichum rupestre and P. cyclocarpum. Low ITS sequence variation was found within the monophyletic Alyssum sect. Odontarrhena and especially in A. murale sensu lato. Nickel hyperaccumulation was not monophyletic in any of three main clades retrieved, each consisting of hyperaccumulators and non-hyperaccumulators of different geographical origin. CONCLUSIONS: Nickel hyperaccumulation in Alysseae has a double origin, but it did not evolve in Thlaspideae. In Bornmuellera-Leptoplax it represents an early synapomorphy inherited from an ancestor shared with the calcicolous, sister clade of Mediterranean Ptilotrichum. In Alyssum sect. Odontarrhena it has multiple origins even within the three European clades recognized. Lack of geographical cohesion suggests that accumulation ability has been lost or gained over the different serpentine areas of south Europe through independent events of microevolutionary adaptation and selection. Genetic continuity and strong phenotypic plasticity in the A. murale complex call for a reduction of the number of Ni hyperaccumulator taxa formally recognized.


Assuntos
Brassicaceae/genética , Brassicaceae/metabolismo , DNA de Plantas/genética , DNA Espaçador Ribossômico/genética , Evolução Molecular , Níquel/metabolismo , Brassicaceae/classificação , Filogenia
19.
Plants (Basel) ; 9(12)2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-33271845

RESUMO

Albanian taxa and populations of the genus Odontarrhena are most promising candidates for research on metal tolerance and Ni-agromining, but their genetic structure remains unknown. We investigated phylogenetic relationships and genetic differentiation in relation to distribution and ploidy of the taxa, anthropic site disturbance, elevation, soil type, and trace metals at each population site. After performing DNA sequencing of selected accessions, we applied DNA-fingerprinting to analyze the genetic structure of 32 populations from ultramafic and non-ultramafic outcrops across Albania. Low sequence divergence resulted in poorly resolved phylograms, but supported affinity between the two diploid serpentine endemics O. moravensis and O. rigida. Analysis of molecular variance (AMOVA) revealed significant population differentiation, but no isolation by distance. Among-population variation was higher in polyploids than in diploids, in which genetic distances were lower. Genetic admixing at population and individual level occurred especially in the polyploids O. chalcidica, O. decipiens, and O. smolikana. Admixing increased with site disturbance. Outlier loci were higher in serpentine populations but decreased along altitude with lower drought and heat stress. Genetic variability gained by gene flow and hybridization at contact zones with "resident" species of primary ultramafic habitats promoted expansion of the tetraploid O. chalcidica across anthropogenic sites.

20.
BMJ Open Ophthalmol ; 5(1): e000497, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33083552

RESUMO

OBJECTIVE: To evaluate objective and subjective outcomes after bilateral implantation of two different multifocal intraocular lenses, which correct pseudophakic presbyopia in an adequate and homogeneous population court. METHODS AND ANALYSIS: Fifty patients were evaluated at 3 months after bilateral implantation, at the Eye Clinic of University of Verona and at the Carones Ophthalmology Center Milano, as follows: Tecnis Symfony (25 patients), Alcon PanOptix (25 patients). Main outcomes were uncorrected and best-corrected distance visual acuity (UDVA and BCVA) at 4 m, 60 cm (best distance corrected intermediate visual acuity (BDCIVA) and uncorrected intermediate visual acuity), 40 cm (best distance corrected near visual acuity (BDCNVA) and uncorrected near visual acuity (UNVA)), objective refractive outcome, defocus curve, contrast sensitivity (Modulation Transfer Function (MTF) cut-off), optical quality (Strehl ratio), aberrometry (root mean square RMS 4 mm), subjective quality of life (National Eye Institute Refractive Error Quality of Life score (NEI-RQL-42 score) test). RESULTS: Symfony and PanOptix showed BCVA and UDVA comparable results. Symfony presented significant better outcomes at BDCIVA (p=0.001), while PanOptix showed better performances at BDCNVA and UNVA (p=0.01). Symfony achieved better results in RMS 4 mm (p=0.024) and in MTF cut-off (p=0.041). In the questionnaire NEI-RQL-42, PanOptix presented better scores in 'near vision' and 'spectacles independence', whereas Symfony in 'symptoms' and 'clarity of vision'. CONCLUSION: Both intraocular lenses are valid options to avoid pseudophakic presbyopia, even though they present different features which make them unique. Symfony allows patients to achieve a better objective and subjective quality of vision and contrast sensitivity; PanOptix provides better outcomes in near vision and spectacles independence requirements.

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