Phosphorus uptake and toxicity are delimited by mycorrhizal symbiosis in P-sensitive but not in P-tolerant .

Many plant species from regions with ancient, highly weathered nutrient-depleted soils have specialized adaptations for acquiring phosphorus (P) and are sensitive to excess P supply. Mycorrhizal associations may regulate P uptake at high external P concentrations, potentially reducing P toxicity. We predicted that excess P application will negatively impact species from the nutrient-depleted Jarrah forest of Western Australia and that mycorrhizal inoculation will reduce P toxicity by regulating P uptake.

Climate drives patterns of seed traits in Quercus species across China.

Traits enabling seeds to survive post-dispersal desiccation and subsequently germinate are important aspects of plant regeneration for species with desiccation-sensitive seeds. However, how desiccation and germination-related traits co-vary and relate to patterns of climate variation are unknown. We investigated physiological traits related to desiccation and germination of desiccation-sensitive seeds from 19 Quercus species, which typically dominate subalpine, subtropical and temperate forests in China.

Thermal buffering capacity of the germination phenotype across the environmental envelope of the Cactaceae.

Recruitment from seeds is among the most vulnerable stage for plants as global temperatures change. While germination is the means by which the vast majority of the world's flora regenerate naturally, a framework for accurately predicting which species are at greatest risk of germination failure during environmental perturbation is lacking. Taking a physiological approach, we assess how one family, the Cactaceae, may respond to global temperature change based on the thermal buffering capacity of the germination phenotype.

Management-driven evolution in a domesticated ecosystem.

Millennia of human land-use have resulted in the widespread occurrence of what have been coined 'domesticated ecosystems'. The anthropogenic imprints on diversity, composition, structure and functioning of such systems are well documented. However, evolutionary consequences of human activities in these ecosystems are enigmatic.

Campanulaceae: a family with small seeds that require light for germination.

Background And Aims: The Campanulaceae is a large cosmopolitan family, but is understudied in terms of germination, and seed biology in general. Small seed mass (usually in the range 10-200 µg) is a noteworthy trait of the family, and having small seeds is commonly associated with a light requirement. Thus, the purpose of this study was to investigate the effect of light on germination in 131 taxa of the Campanulaceae family, from all five continents of its distribution.

Conditional cold avoidance drives between-population variation in germination behaviour in Calluna vulgaris.

Background And Aims: Across their range, widely distributed species are exposed to a variety of climatic and other environmental conditions, and accordingly may display variation in life history strategies. For seed germination in cold climates, two contrasting responses to variation in winter temperature have been documented: first, an increased ability to germinate at low temperatures (cold tolerance) as winter temperatures decrease, and secondly a reduced ability to germinate at low temperatures (cold avoidance) that concentrates germination towards the warmer parts of the season.

Methods: Germination responses were tested for Calluna vulgaris, the dominant species of European heathlands, from ten populations collected along broad-scale bioclimatic gradients (latitude, altitude) in Norway, covering a substantial fraction of the species' climatic range.

Physical dormancy in seeds: a game of hide and seek?

Historically, 'physical dormancy', or 'hard seededness', where seeds are prevented from germinating by a water-impermeable seed coat, is viewed as a dormancy mechanism. However, upon water uptake, resumption of metabolism leads to the unavoidable release of volatile by-products, olfactory cues that are perceived by seed predators. Here, we examine the hypothesis that hard seeds are an anti-predator trait that evolved in response to powerful selection by small mammal seed predators.

Rates of water loss and uptake in recalcitrant fruits of Quercus species are determined by pericarp anatomy.

Desiccation-sensitive recalcitrant seeds and fruits are killed by the loss of even moderate quantities of water. Consequently, minimizing the rate of water loss may be an important ecological factor and evolutionary driver by reducing the risk of mortality during post-dispersal dry-spells. For recalcitrant fruits of a range of Quercus species, prolonged drying times have been observed previously.

The role of botanic gardens in the science and practice of ecological restoration.

Many of the skills and resources associated with botanic gardens and arboreta, including plant taxonomy, horticulture, and seed bank management, are fundamental to ecological restoration efforts, yet few of the world's botanic gardens are involved in the science or practice of restoration. Thus, we examined the potential role of botanic gardens in these emerging fields. We believe a reorientation of certain existing institutional strengths, such as plant-based research and knowledge transfer, would enable many more botanic gardens worldwide to provide effective science-based support to restoration efforts.

Ecological correlates of ex situ seed longevity: a comparative study on 195 species.

Background And Aims: Extended seed longevity in the dry state is the basis for the ex situ conservation of 'orthodox' seeds. However, even under identical storage conditions there is wide variation in seed life-span between species. Here, the effects of seed traits and environmental conditions at the site of collection on seed longevity is explored for195 wild species from 71 families from environments ranging from cold deserts to tropical forests.

Germination responses to water potential in neotropical pioneers suggest large-seeded species take more risks.

Background And Aims: In neotropical forests, very small-seeded pioneer species (<0.1 mg seed mass) recruit preferentially in small tree fall gaps and at gap edges, but large-seeded pioneers do not. Since water availability is related to gap size, these differences in microsite preference may reflect in part species-specific differences in germination at reduced water potentials.

The development and limits of freezing tolerance in Acer pseudoplatanus fruits across Europe is dependent on provenance.

The effects of fruit maturity, at the time of natural dispersal, on subsequent desiccation tolerance and sub-zero storage was investigated in three lots of Acer pseudoplatanus (sycamore) collected from northern to southern Europe. Fruits from the native plant distribution range in Italy had significantly higher desiccation tolerance (0.16 g water per g DW) than those from England (0.

Pre- and post-harvest influences on seed dormancy status of an Australian Goodeniaceae species, Goodenia fascicularis.

Background And Aims: The period during which seeds develop on the parent plant has been found to affect many seed characteristics, including dormancy, through interactions with the environment. Goodenia fascicularis (Goodeniaceae) seeds were used to investigate whether seeds of an Australian native forb, harvested from different environments and produced at different stages of the reproductive period, differ in dormancy status.

Methods: During the reproductive phase, plants were grown ex situ in warm (39/21 degrees C) or cool (26/13 degrees C) conditions, with adequate or limited water availability.

Allometric relationships between seed mass and seedling characteristics reveal trade-offs for neotropical gap-dependent species.

A seed size-seed number trade-off exists because smaller seeds are produced in greater number but have a lower probability of establishment. This reduced establishment success of smaller-seeded species may be determined by biophysical constraints imposed by scaling rules. Root and shoot diameter, root growth extension rate (RGER) and shoot length at death for dark-grown seedlings are predicted to scale with the cube root of seed embryo and endosperm mass (m).

Variable desiccation tolerance in Acer pseudoplatanus seeds in relation to developmental conditions: a case of phenotypic recalcitrance?

Nine seedlots of the widely planted southern and central European native tree species Acer pseudoplatanus L. were collected along a north-south gradient spanning 21° of latitude in Europe. We investigated how the heat sum during seed development influences seed maturity as assessed by physical, physiological and biochemical traits.

Ecological correlates of seed desiccation tolerance in tropical African dryland trees.

In the tropics, species with recalcitrant or desiccation-sensitive, Type III seeds are largely restricted to regions with comparatively high rainfall, because desiccation-induced seed death will be minimal in these environments. However, species with recalcitrant seeds do occur in drylands, although little is known about ecological adaptations to minimize seed death in these environments. Here we present data for the seed desiccation tolerance of 10 African dryland species and examine the relationships between seed size, rainfall at the time of seed shed, and desiccation tolerance for these and a further 70 species from the scientific literature.