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This work was supported by the Spanish Ministry of Economy and Competitivity (MINECO) (grant number AGL2015‐66001‐C3). C.C. received support from the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya through the program of Doctorats Industrials, funded by the European Union and the European Social Fund. J.G.A. was supported by Juan de la Cierva (Grant number IJCI‐2014‐21393) and Ramon y Cajal fellowships (RYC‐2016‐20528) and J.A.B. benefits from the Serra‐Hunter Fellowship.

This research was funded by the Project INNOVATRUF (PECT El bosc, el primer recurs de l’economia verda—Fons Europeu de Desenvolupament Regional de la Unió Europea-Programa operatiu FEDER de Catalunya 2014-2020) and by the project UdL-Impuls. Y.P. acknowledges the support of University of Lleida for her contract (UdL-Impuls), J.G.A. was supported by the Ramon y Cajal fellowship (RYC-2016-20528), D.O. received support from the ‘Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya’ through the program of ‘Doctorats Industrials’, F.B.’s salary was partially funded by the Ministry of Science, Innovation and Universities through the National Agency of Research (PTA2017-14041-I) and J.A.B. benefitted from a Serra-Húnter Fellowship provided by the Generalitat of Catalunya.

Calluna vulgaris-dominated heathlands are a priority habitat type in Annex I of the Habitats Directive (92/43/ECC, habitat code 4060). In the Iberian Peninsula, the landscape of the Cantabrian Mountain range has great heterogeneity due to human management during the last 10,000 years. Another factor that can affect these communities is the increase in human-induced atmospheric nitrogen (N) deposition. During the last century, there has been a dramatic increase in N deposition rates. For all these reasons, it is important to know the regeneration dynamics of the heathlands in the context of the disturbances that these communities currently face (i.e., N deposition, fire, and decrease in sheep grazing) in the Cantabrian Mountain range. In this study, we characterized the plant species composition and soil seed bank after prescribed burning in three heathlands on their southern distribution limit in Spain, to gain insights into regenerative capacity and conservation of these communities. The results obtained suggest that the post-burn soil seed bank could restore Calluna-dominated vegetation in these habitats, indicating that the restoration potential from the soil seed bank after wildfires of these habitats is high. Our results also suggest that, in the short term after burning, the main characteristic species such as Calluna and Erica are recovered, which is fundamental to maintain the heathland community structure.

Pteridium aquilinum is one of the most widespread, invasive species in the world, frequently invading disturbed land where it often reduces biodiversity, crop yield, and economic value. Most research on P. aquilinum has been conducted in temperate climates, with limited information available on the spread of the species in areas with semi-arid or Mediterranean climates. Here, we present a regional assessment of the growth of P. aquilinum in Mazandaran Province, northern Iran. P. aquilinum frond and rhizome growth was assessed at 15 sites covering its regional geographic range and a range of elevations, climate types, soil properties and land-uses. Frond phenological change over the growing season was also measured at three sites at different elevations. Results showed that P. aquilinum invasion is not restricted by land-use, elevation, and climate type. P. aquilinum produced 23–42 fronds m −2 with a height of between 78 and 275 cm and 4 to 21 t ha −1 frond biomass and 1.3–18 t ha −1 rhizome biomass. Sites at high elevation had the greatest dormant bud number indicating a potentially greater resistance to control treatment. A novel result was that P. aquilinum biomass produced a bimodal response for soil carbon, nitrogen and pH, but soil phosphorus produced greatest biomass at low concentrations. Phenological analysis of fronds showed a site-dependent, non-linear, sigmoidal pattern for biomass and frond height; asymptotes for frond biomass and frond height reached 1700 g m −2 and 110 cm and became stable after 170 and 180 Julian days, respectively. The phenological results indicate that treatments targeting fronds to control P. aquilinum invasion should be applied after 180 Julian days when maximum transfer of resources from fronds to rhizomes occur. These results provide for the first-time information on the spread of P. aquilinum in northern Iran from a growth and phenological perspective of both fronds and rhizomes and indicate that any human changes in natural ecosystems up to an elevation of 2100 m could facilitate further invasion.

This project was supported financially by the BiodivERsA FIREMAN program (NERC/Defra: NE/G002096/1), the Ecological Continuity Trust and the Heather Trust. VMS was supported by ªBeatriu de PinoÂsº fellowship (2014BP-B 00056) from the Generalitat de Catalunya. JGA was supported by Juan de la Cierva-fellowship (IJCI- 2014-21393).

There is broad consensus on restoration of native woodlands in places where intensive forestry is nowadays not profitable. However, this consensus is lost when stakeholders need to implement forest management practices as restoration tool, especially because there is a substantial lack of empirical evidence about its feasibility. In this context, we assess the impact of two different harvest treatments on understorey plant species composition of Pinus radiata plantations as tools to recover native woodland vegetation in northern Iberian Peninsula. Here, common clear-cut treatment and restoration-clear-cut where only pine trees were removed (i.e. reducing the disturbance effect over understorey vegetation) were compared against understorey plant species composition of young and old plantations and restored tracks. The aim was to identify which treatment is more suitable to recover native woodland vegetation. The results reveal that both clear-cuts maintained species composition plus important understorey native species, some of them being restoration targets. However, both clear-cuts showed diversity reductions compared with old plantations, although there were not apparent retention effects on compositional change towards native communities at least two years after harvest. It seems that the remaining vegetation established by natural succession after both clear-cut treatments could be used to achieve initial restoration objectives for some native tree and understorey plant species at relatively low costs. In any case, it would be interesting to implement supplementary management measures to accelerate this conversion, such as invasive species elimination or target species seeding, to maintain local biodiversity and introduce native woodland species not present in the area.

Understanding whether the occurrences of ectomycorrhizal species in a given tree host arephylogenetically determined can help in assessing different conservational needs for each fungalspecies. In this study, we characterized ectomycorrhizal phylogenetic composition and phylogeneticstructure in 42 plots with five different Mediterranean pine forests: i.e., pure forests dominated byP.nigra,P. halepensis, andP. sylvestris, and mixed forests ofP. nigra-P. halepensisandP. nigra-P. sylvestris,and tested whether the phylogenetic structure of ectomycorrhizal communities differs among these.We found that ectomycorrhizal communities were not different among pine tree hosts neither inphylogenetic composition nor in structure and phylogenetic diversity. Moreover, we detected a weakabiotic filtering effect (4%), with pH being the only significant variable influencing the phylogeneticectomycorrhizal community, while the phylogenetic structure was slightly influenced by the sharedeffect of stand structure, soil, and geographic distance. However, the phylogenetic communitysimilarity increased at lower pH values, supporting that fewer, closely related species were found atlower pH values. Also, no phylogenetic signal was detected among exploration types, although shortand contact were the most abundant types in these forest ecosystems. Our results demonstrate thatpH but not tree host, acts as a strong abiotic filter on ectomycorrhizal phylogenetic communities inMediterranean pine forests at a local scale. Finally, our study shed light on dominant ectomycorrhizalforaging strategies in drought-prone ecosystems such as Mediterranean forests.

Evapotranspiration is a major component of the water cycle, yet only daytime transpiration is currently considered in Earth system and agricultural sciences. This contrasts with physiological studies where 25% or more of water losses have been reported to occur occurring overnight at leaf and plant scales. This gap probably arose from limitations in techniques to measure nocturnal water fluxes at ecosystem scales, a gap we bridge here by using lysimeters under controlled environmental conditions. The magnitude of the nocturnal water losses (12-23% of daytime water losses) in rowcrop monocultures of bean (annual herb) and cotton (woody shrub) would be globally an order of magnitude higher than documented responses of global evapotranspiration to climate change (51-98 vs. 7-8 mm yr(-1)). Contrary to daytime responses and to conventional wisdom, nocturnal transpiration was not affected by previous radiation loads or carbon uptake, and showed a temporal pattern independent of vapour pressure deficit or temperature, because of endogenous controls on stomatal conductance via circadian regulation. Our results have important implications from largescale ecosystem modelling to crop production: homeostatic water losses justify simple empirical predictive functions, and circadian controls show a fine-tune control that minimizes water loss while potentially increasing posterior carbon uptake.

This project has received funding from the European Union’s H2020 research and innovation programme under Marie Sklodowska-Curie grant agreement No 801586. This work was supported by the Spanish Ministry of Science, Innovation and Universities, grants RTI2018-099315-AI00. I.A. was supported by a H2020-Marie Slodowska Curie Action Cofund fellowship (801596) and J.G.A. was supported by Ramon y Cajal fellowship (RYC-2016-20528).

Background Molecular clocks drive oscillations in leaf photosynthesis, stomatal conductance, and other cell and leaf-level processes over ~24 h under controlled laboratory conditions. The influence of such circadian regulation over whole-canopy fluxes remains uncertain; diurnal CO2 and H2O vapor flux dynamics in the field are currently interpreted as resulting almost exclusively from direct physiological responses to variations in light, temperature and other environmental factors. We tested whether circadian regulation would affect plant and canopy gas exchange at the Montpellier European Ecotron. Canopy and leaf-level fluxes were constantly monitored under field-like environmental conditions, and under constant environmental conditions (no variation in temperature, radiation, or other environmental cues). Results We show direct experimental evidence at canopy scales of the circadian regulation of daytime gas exchange: 20-79 % of the daily variation range in CO2 and H2O fluxes occurred under circadian entrainment in canopies of an annual herb (bean) and of a perennial shrub (cotton). We also observed that considering circadian regulation improved performance by 8-17 % in commonly used stomatal conductance models. Conclusions Our results show that circadian controls affect diurnal CO2 and H2O flux patterns in entire canopies in field-like conditions, and its consideration significantly improves model performance. Circadian controls act as a 'memory' of the past conditions experienced by the plant, which synchronizes metabolism across entire plant canopies.