Micromorphological and ultrastructural investigations of the lichen–soil interface

Asta, J.; Orry, F.; Toutain, F.; Souchier, B.; Villemin, G.

doi:10.1016/s0038-0717(00)00143-7

Cited by 29 publications

(14 citation statements)

References 13 publications

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“…Previous studies of the Pellafol site have described soil microclimate as the main factor controlling the distribution of plant communities (Lambert 1967;Garti 1980). Air circulations between the limestone blocks create a paraglacial pedoclimate with seasonal soil frost in PF and EC (Lambert 1967;Asta et al 2001). Respective mean annual soil temperature in Ah horizon at 30 cm depth (Ts) of PF and EC are -0.2°C and +0.5°C (Figure 1), as measured by data loggers (Hobo, Onset Corporation).…”

Section: Site Descriptionmentioning

confidence: 99%

Soil macroaggregate dynamics in a mountain spatial climate gradient

Cécillon

Mello

Danieli³

et al. 2009

Biogeochemistry

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We investigated the response of soil macroaggregate dynamics to soil temperature modification along a spatial gradient located on a forested north-facing slope in the southern French Alps, simulating long-term adjustment of soil-plant interactions to absence or occurrence of soil frost. Soil macroaggregate (> 250 µm) content of Ah horizons was strongly depleted (72%) in colder plots affected by freeze-thaw events, compared to 96% in warmer and frost-free plots (p < 0.05). A visual assessment of soil macroaggregation showed that physical processes were the main drivers of soil macroaggregation in colder plots, with 66% of the 5-12.5 mm fraction and the whole 3.15-5 mm fraction. Conversely, we found a balanced contribution of biological and physical aggregation pathways in warmer plots. All identified macroaggregate types could be classified, depending on their organic matter (OM) quality, using principal component analyses of their near infrared spectra. Such spectral classifications indicated temporal changes in OM quality of macroaggregates, from formation to colonization by fine roots, suggesting ecosystem-specific ontogenic trajectories for soil macroaggregation. Further physico-chemical characterizations of soil macroaggregates and Ah horizons showed that soil organic carbon content in the Ah horizon was constant along the gradient, whereas soil erodibility was reduced in warmer soils, which prevented the occurrence of fragile macroaggregates formed by freeze-thaw events. Our study thus suggests changes in the erodibility of mountain forest soils under changing climate. Soil erodibility could be affected either positively under warmer conditions, or negatively, under increased soil frost.

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Section: Site Descriptionmentioning

confidence: 99%

Soil macroaggregate dynamics in a mountain spatial climate gradient

Cécillon

Mello

Danieli³

et al. 2009

Biogeochemistry

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“…The existence of these exceptional stands in the Devoluy (Combe Obscure; Bertinelli et al, 1993; Bois du Sappey; Cécillon et al, 2010) and Grande Chartreuse (La Plagne cirque; Cassagne et al, 2008) massifs was associated with the circulation of cold air in scree slopes, which may locally create periglacial pedoclimatic conditions (Cécillon et al, 2010). The microclimate of cold scree slopes allows for exceptional microhabitats to develop with very thick and raw humus (Cassagne et al, 2008), forming ideal niches for various cold living plants (Bertinelli et al, 1993) and periglacial relict species of non-vascular plants (Asta et al, 2001), beetles (Molenda, 1996), spiders and mites (Zacharda et al, 2005). These microhabitats, which are older than the surrounding biological matrix, act as refugia by supporting relict communities unable to survive elsewhere in the landscape.…”

Section: Introductionmentioning

confidence: 99%

Impacts of more frequent droughts on a relict low-altitude Pinus uncinata stand in the French Alps

et al. 2015

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Cold microclimatic conditions provide exceptional microhabitats to Pinus uncinata stands occurring at abnormally low altitudes in seven relict stands of the northern French Alps. Here, P. uncinata is located at the lower bounds of its ecological limits and therefore expected to provide a sensitive indicator of climate change processes. We used dendrochronological analysis to study the growth patterns of closely spaced chronologies across an elevational transect and compare a relict low-altitude to a P. uncinata stand located at the alpine treeline. Two detrending procedures are used to reveal high-and low-frequencies embedded in annually resolved ring-width series. Growth response of P. uncinata to instrumental temperature and precipitation data is investigated by means of moving response function analyses. Results show an increase in the sensitivity of tree-ring widths to drought during previous summer in both stands. At the treeline stand, an increasing response to fall temperature is observed whereby fall temperature and radial tree growth increased in two synchronous steps around ∼1930 and from ∼1980-present. At the low-altitude stand, P. uncinata appears more drought sensitive and exhibits a sharp growth decline since the mid-1980s, coinciding with increasing summer temperatures. Growth divergence between the two stands can be observed since the mid-1980s. We argue that the positive growth trend at the high-altitude stand is due to increasing fall temperatures which would favor the formation of metabolic reserves in conjunction with atmospheric CO 2 enrichment that in turn would facilitate improved water use efficiency. At the relict low-altitude stand, in contrast, it seems that improved water use efficiency cannot compensate for the increase in summer temperatures.

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“…Vascular plant species growing out of these lichen mats is a natural occurrence on the coastal barrens of Nova Scotia and, during the trial, seedlings of trees and grasses were observed growing out of these modules, although control modules also had such seedling growth. Some lichen species also play a key role in soil development in conditions of high abiotic stress 8, 17 . If lichen inclusion on a green roof could improve the substrate properties for neighboring species, the entire system would benefit.…”

Section: Discussionmentioning

confidence: 99%

Cladonia lichens on extensive green roofs: evapotranspiration, substrate temperature, and albedo

Heim

Lundholm

2013

F1000Res

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Green roofs are constructed ecosystems that provide ecosystem services in urban environments. Shallow substrate green roofs subject the vegetation layer to desiccation and other environmental extremes, so researchers have evaluated a variety of stress-tolerant vegetation types for green roof applications. Lichens can be found in most terrestrial habitats. They are able to survive extremely harsh conditions, including frequent cycles of desiccation and rehydration, nutrient-poor soil, fluctuating temperatures, and high UV intensities. Extensive green roofs (substrate depth <20cm) exhibit these harsh conditions, making lichens possible candidates for incorporation into the vegetation layer on extensive green roofs. In a modular green roof system, we tested the effect of Cladonia lichens on substrate temperature, water loss, and albedo compared to a substrate-only control. Overall, the Cladonia modules had significantly cooler substrate temperatures during the summer and significantly warmer temperatures during the fall. Additionally, the Cladonia modules lost significantly less water than the substrate-only control. This implies that they may be able to benefit neighboring vascular plant species by reducing water loss and maintaining favorable substrate temperatures.

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Micromorphological and ultrastructural investigations of the lichen–soil interface

Cited by 29 publications

References 13 publications

Soil macroaggregate dynamics in a mountain spatial climate gradient

Soil macroaggregate dynamics in a mountain spatial climate gradient

Impacts of more frequent droughts on a relict low-altitude Pinus uncinata stand in the French Alps

Cladonia lichens on extensive green roofs: evapotranspiration, substrate temperature, and albedo

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