Soil microclimate is a potentially important regulator of the composition of plant-associated fungal communities in climates with significant drought periods. Here, we investigated the ...spatio-temporal dynamics of soil fungal communities in a Mediterranean Pinus pinaster forest in relation to soil moisture and temperature.
Fungal communities in 336 soil samples collected monthly over 1 year from 28 long-term experimental plots were assessed by PacBio sequencing of ITS2 amplicons. Total fungal biomass was estimated by analysing ergosterol. Community changes were analysed in the context of functional traits.
Soil fungal biomass was lowest during summer and late winter and highest during autumn, concurrent with a greater relative abundance of mycorrhizal species. Intra-annual spatiotemporal changes in community composition correlated significantly with soil moisture and temperature. Mycorrhizal fungi were less affected by summer drought than free-living fungi. In particular, mycorrhizal species of the short-distance exploration type increased in relative abundance under dry conditions, whereas species of the long-distance exploration type were more abundant under wetter conditions.
Our observations demonstrate a potential for compositional and functional shifts in fungal communities in response to changing climatic conditions. Free-living fungi and mycorrhizal species with extensive mycelia may be negatively affected by increasing drought periods in Mediterranean forest ecosystems.
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.
Vital for human consumption, water is a scarce resource, particularly in the arid environments of Patagonia. In this study we analysed local perspectives and the use of different water sources, based ...on two case studies in rural communities of Mapuche and Creole ancestry inhabiting extra-Andean Patagonia in Chubut, Argentina. Water quality was evaluated using an ethnolimnological, interdisciplinary approach, taking into account local perspectives and scientific contributions. In addition, we analysed appropriation strategies, management and local organoleptic characteristics. The work was based on semi-structured interviews, tours guided by informants, and physicochemical and microbiological analysis of water sources. It was found that 92% of local inhabitants mainly used superficial and subterranean sources of water for consumption, among which stood out: river, streams, springs, wells, and boreholes. Differences were observed between local and scientific perspectives in terms of water quality (chemical and microbiological). Most water sources used by inhabitants presented water of deficient quality for human consumption (61%), whereas locals considered the water to be fresh, delicious, and transparent. Nevertheless, some points of agreement were found in terms of organoleptic characteristics (e.g., odour, colour) and physicochemical parameters in certain water sources. In general, locals do not recognise the deterioration of their water supply, but the importance of organoleptic characteristics in local perception should be highlighted. These aspects speak of a need to promote opportunities for dialogue, and implement effective health measures, taking local perspectives into account.
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•Patagonian rural communities largely depend on surface and subterranean water.•Most water sources are not suitable for human consumption.•Organoleptic attributes play an important role in the perception of water quality.•Poor-quality water is not perceived locally as a health risk.•Local and scientific perspectives differ with respect to water quality.
Forest restoration has become one of the most important challenges for restoration ecology in the recent years. In this regard, soil fungi are fundamental drivers of forest ecosystem processes, with ...significant implications for plant growth and survival. However, the post-disturbance recovery of belowground communities has been rarely assessed, especially in highly degraded systems such as mines. Our aim was to compare forests and mined systems for biomass and structure of fungal communities in soil during early stages of tree establishment after disturbance. We performed ergosterol analysis and PacBio and Illumina sequencing of internal transcribed spacer 2 amplicons across soil layers in P. sylvestris, Q. robur and Q. ilex (holm oak) forests and naturally revegetated mined sites. In pine forests, total fungal biomass was significantly higher in litter and humus compared to mineral layers, with dominance of the mycorrhizal genera Tomentella, Inocybe and Tricholoma. Conversely, in oak forests the most abundant mycorrhizal genera were Tomentella, Cortinarius and Sebacina, but the biomass of saprotrophic fungi was greater in the litter layer compared to mycorrhizal fungi, with the genus Preussia being the most abundant. In the revegetated mined sites, ectomycorrhizal fungi dominated in the humus and mineral layers, with the mycorrhizal genus Oidiodendron being dominant. In contrast, in holm oak forests saprotrophic fungi dominated both soil humus and mineral layers, with the genera of Alternaria, Bovista and Mycena dominating the soil humus forest layer, while the genus Cadophora dominated the mineral layer. The habitat-specific differences in soil fungal community composition and putative functions suggest that an understanding of soil–plant–microbial interactions for different tree species and use of specific soil/litter inoculum upon planting/seeding might help to increase the effectiveness of tree restoration strategies in Mediterranean degraded sites.
Research Highlights: Mycorrhizal helper bacteria (MHB) promote mycorrhization processes and are commonly found in the mycorrhizosphere of fungi, such as the edible hypogeous fungus Tuber melanosporum ...Vittad. Background and Objectives: The effectiveness of MHB in promoting the mycorrhization process and the root development of Portuguese oak (Quercus faginea Lam.) seedlings destined for truffle plantations has not been determined. The main aim of this study was to shed light on the effect of bacterial inoculation on fungal root tip colonization and seedling root traits. Material and methods: We performed a co-inoculation trial using three bacteria naturally present in the T. melanosporum niche (i.e., Pseudomonas fluorescens, Pseudomonas putida, and Bacillus amyloliquefaciens) and two different bacterial inoculation times (one month and nine months after fungal inoculation) under glasshouse conditions. Results: Only P. fluorescens had a significant mycorrhizal promoter effect, increasing the truffle inoculation rates of root tips by more than 10% compared with seedlings that received non-bacterial inoculation treatments. Simultaneously, the co-inoculation of P. fluorescens with T. melanosporum improved seedling root growth parameters compared with those of seedlings that received non-bacterial inoculation treatments. The different bacterial inoculation times and applications of uninoculated bacterial growth media did not affect the root traits analyzed or the root mycorrhization rates. Conclusions: These results suggest that P. fluorescens bacteria have a potential commercial application as a treatment for truffle-inoculated seedlings to improve both seedling quality and mycorrhizal colonization under nursery conditions.
There is increasing evidence that the circadian clock is a significant driver of photosynthesis that becomes apparent when environmental cues are experimentally held constant. We studied whether the ...composition of photosynthetic pigments is under circadian regulation, and whether pigment oscillations lead to rhythmic changes in photochemical efficiency. To address these questions, we maintained canopies of bean and cotton, after an entrainment phase, under constant (light or darkness) conditions for 30–48 h. Photosynthesis and quantum yield peaked at subjective noon, and non‐photochemical quenching peaked at night. These oscillations were not associated with parallel changes in carbohydrate content or xanthophyll cycle activity. We observed robust oscillations of Chl a/b during constant light in both species, and also under constant darkness in bean, peaking when it would have been night during the entrainment (subjective nights). These oscillations could be attributed to the synthesis and/or degradation of trimeric light‐harvesting complex II (reflected by the rhythmic changes in Chl a/b), with the antenna size minimal at night and maximal around subjective noon. Considering together the oscillations of pigments and photochemistry, the observed pattern of changes is counterintuitive if we assume that the plant strategy is to avoid photodamage, but consistent with a strategy where non‐stressed plants maximize photosynthesis.
From chloroplasts to ecosystems, the circadian clock is a significant driver of photosynthesis, which becomes apparent when environmental cues are experimentally held constant over a few days. In the present study, we have investigated whether the composition of photosynthetic pigments is under circadian regulation. We show that carbon assimilation, stomatal conductance and quantum yield oscillated with a frequency close to 24 h, peaking around subjective noon. These changes were paralleled by robust oscillations of chlorophyll a/b both under constant light or darkness, indicating a rhythmic pattern of antenna‐size adjustment (minimal at night and maximal around noon). These results have important implications for future studies on pigment dynamics, particularly when using remote‐sensing platforms.
The identification of the factors controlling the understory species distribution and abundance is essential to understand the ecology and dynamics of natural forests and their management response. ...We assess the relationships between environmental gradients and shrub functional groups distribution patterns and niche characteristics in a transitional area between the Eurosiberian and Mediterranean biogeographic regions in Northern Spain. Here, 772 plots from the 3rd Spanish National Forest Inventory were used. Shrub functional groups respond to the same complex environmental gradients as trees, i.e., the north-south climatic gradient and a slope gradient. Unimodal response curves of shrub functional groups and families dominate along both gradients, providing evidence of successful functional turnover. Similar to tree species, the niche location of functionally related shrubs is close. Functional groups occupying environments with sharp contrast or transitional environments have the broadest niches, whereas those specialized functional groups occupying localized habitats showed the narrowest niches. The knowledge of shrub species distributions and niche characteristics along complex environmental gradients will improve our ability to discuss potential conservation management goals or threats due to land-use changes and future climate change.
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.
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