A systematic review of nurse objects as safe sites for seedling establishment and implications for restoration.

Direct human activity and global climatic changes are threatening the existence of many vegetated habitats. Seedling establishment, one of the riskiest plant life stages, must be successful for such habitats to persist. The establishment of seedlings is known to be enhanced by nurse effects, but most studies to date have looked at the nursing effects of plants while sidelining inanimate objects.

Inter-generational consistency of the ectomycorrhizal fungal community in a mixed pine-cedar post-fire stand.

The mutualistic interaction between trees and ectomycorrhizal fungi (EMF) can have a major effect on forest dynamics and specifically on seedling establishment. Here, we compared the EMF community composition associated with the roots of young saplings and mature trees of two co-habiting Pinaceae: Pinus halepensis and Cedrus deodara growing together in a post-fire forest plot, using fungal ITS metabarcoding. We found that the differences in the EMF community between the two sapling groups were mostly attributed to changes in the relative abundance of specific fungal species, with little species turnover.

Context-dependent benefits of forest soil addition on Aleppo pine seedling performance under drought and grass competition.

Seedling establishment under natural conditions is limited by numerous interacting factors. Here, we tested the combined effects of drought, herbaceous competition, and ectomycorrhizal inoculation on the performance of Aleppo pine seedlings grown in a net-house. The roots of all pine seedlings were strongly dominated by Geopora, a fungal genus known to colonize seedlings in dry habitats.

A non-linear effect of the spatial structure of the soil ectomycorrhizal spore bank on the performance of pine seedlings.

The spatial structure of the environment is known to affect ecological processes. Unlike the spatial structure of negative interactions, such as competition and predation, the role of spatial structure in positive interaction has received less attention. We tested how the spatial structure of spores of ectomycorrhizal fungi (EMF) in the soil affects the growth of Aleppo pine (Pinus halepensis) seedlings.

High resilience of the mycorrhizal community to prescribed seasonal burnings in eastern Mediterranean woodlands.

Fire effects on ecosystems range from destruction of aboveground vegetation to direct and indirect effects on belowground microorganisms. Although variation in such effects is expected to be related to fire severity, another potentially important and poorly understood factor is the effect of fire seasonality on soil microorganisms. We carried out a large-scale field experiment examining the effects of spring (early-dry season) versus autumn (late-dry- season) burns on the community composition of soil fungi in a typical Mediterranean woodland.

Small-scale spatial variability in the distribution of ectomycorrhizal fungi affects plant performance and fungal diversity.

The effects of spatial heterogeneity in negative biological interactions on individual performance and species diversity have been studied extensively. However, little is known about the respective effects involving positive biological interactions, including the symbiosis between plants and ectomycorrhizal (EM) fungi. Using a greenhouse bioassay, we explored how spatial heterogeneity of natural soil inoculum influences the performance of pine seedlings and composition of their root-associated EM fungi.

Wild boars as spore dispersal agents of ectomycorrhizal fungi: consequences for community composition at different habitat types.

The success of dispersal events depend on the organism's ability to reach and establish in a new habitat. In symbiotic organisms, establishment also depends on the presence of their symbiont partner in the new habitat. For instance, the establishment of obligate ectomycorrhizal (EM) trees outside the forest is largely limited by the presence of EM fungi in soil.

Pea Plants Show Risk Sensitivity.

Sensitivity to variability in resources has been documented in humans, primates, birds, and social insects, but the fit between empirical results and the predictions of risk sensitivity theory (RST), which aims to explain this sensitivity in adaptive terms, is weak [1]. RST predicts that agents should switch between risk proneness and risk aversion depending on state and circumstances, especially according to the richness of the least variable option [2]. Unrealistic assumptions about agents' information processing mechanisms and poor knowledge of the extent to which variability imposes specific selection in nature are strong candidates to explain the gap between theory and data.

Architectural plasticity in a Mediterranean winter annual.

Size variability in plants may be underlain by overlooked components of architectural plasticity. In annual plants, organ sizes are expected to depend on the availability and reliability of resources and developmental time. Given sufficient resources and developmental time, plants are expected to develop a greater number of large branches, which would maximize fitness in the long run.

The effect of steepness of temporal resource gradients on spatial root allocation.

Plants are able to discriminately allocate greater biomass to organs that grow under higher resource levels. Recent evidence demonstrates that split-root plants also discriminately allocate more resources to roots that grow under dynamically improving nutrient levels, even when their other roots grow in richer patches. Here, we further tested whether, besides their responsiveness to the direction of resource gradients, plants are also sensitive to the steepness of environmental trajectories.

Anticipating future conditions via trajectory sensitivity.

Plants are known to be highly responsive to environmental heterogeneity and normally allocate more biomass to organs which grow in richer patches. However, recent evidence demonstrates that plants can discriminately allocate more resources to roots that develop in patches with increasing nutrient levels, even when their other roots develop in richer patches. Responsiveness to the direction and steepness of spatial and temporal trajectories of environmental variables might enable plants to increase their performance by improving their readiness to anticipated resource availabilities in their immediate proximity.

The effects of nutrient dynamics on root patch choice.

Plants have been recognized to be capable of allocating more roots to rich patches in the soil. We tested the hypothesis that in addition to their sensitivity to absolute differences in nutrient availability, plants are also responsive to temporal changes in nutrient availability. Different roots of the same Pisum sativum plants were subjected to variable homogeneous and heterogeneous temporally - dynamic and static nutrient regimes.

Factors affecting mercury release from dental amalgam exposed to carbamide peroxide bleaching agent.

Purpose: To assess, in vitro, the effects of aging and surface polishing on mercury release from dental amalgams exposed to 10% carbamide peroxide at two pH levels.

Methods: Samples of fresh and aged amalgam, polished and unpolished, were treated with 10% carbamide peroxide at pH 4.5 and at pH 6.