The growth and P acquisition ofEucalyptus regnans F. Muell. seedlings in air-dried and undried forest soil in relation to seedling age and ectomycorrhizal infection

Abstract

The growth of Eucalyptus regnans seedlings in forest soil is enhanced when it has been air-dried. In undried forest soil seedlings grow poorly and develop purple coloration in the foliage, indicating P deficiency. This paper reports the results of pot experiments designed to investigate the relationship between growth and P acquisition, ectomycorrhizal infection and age of seedlings grown in air-dried and undried soil. The effect on seedling growth of their inoculation with air-dried or undried soil or with ectomycorrhizal roots from plants growing in air-dried or undried soil was also investigated. Ectomycorrhizal root tips were detected in 3-week-old E. regnans seedlings in both air-dried and undried soil, and from then on the frequency of ectomycorrhizal root tips increased rapidly. In air-dried soil, seedlings were fully ectomycorrhizal at 9 weeks, and the occurrence of maximum ectomycorrhizal infection coincided with enhanced P acquisition and the initiation of rapid seedling growth.

Arbuscular-Mycorrhizal Networks Inhibit Eucalyptus tetrodonta Seedlings in Rain Forest Soil Microcosms

“…The mechanisms of that effect are unresolved, however, and in our experiments, most suggested ashbed mechanisms played no role. No ECM [12], [13] formed, nor were pathogen effects [10] apparent (because iron fertilization resulted in seedlings in ambient soil recovering full health). We detected no fertilization effect of soil fumigation that killed microbes [8], but any release of iron–possibly because of glomalin degradation–likely would have been more important than elevation of nitrogen or phosphorus.…”

“…Although the ashbed effect has been investigated for more than half a century, its mechanisms remain ambiguous because it likely involves multiple phenomena associated with fire and soil desiccation. Those phenomena may include at different times and places, direct fertilization by ash [7], soil physical and chemical changes that diminish P adsorption [7], [8], release of mineral nutrients from heat-killed soil microorganisms [8] (but see [9]), partial soil sterilization that eliminates pathogenic microbes [10] (but see [11]), or other alterations of the soil microflora, especially ectomycorrhizal fungi [12], [13]. Notwithstanding uncertainty about the mechanisms behind the ashbed effect, empirical evidence from across Australia shows that without fire, rain forest resists invasion by savanna plant species, just as fire contributes to savannas' resistance to replacement by rain forest [4].…”

Soil chemical properties, rather than landscape context, influence woodland fungal communities along an urban‐rural gradient

“…Other research has demonstrated the link between P and ECM of eucalypts (Pampolina et al . 2002; Launonen et al . 2004), and a number of studies have shown that soil pH can have a particular effect on individual species as well as shift the ratio of saprotrophic to ECM fungi (Baroglio et al .…”

Ectomycorrhizal fungi: the symbiotic route to the root for phosphorus in forest soils

“…Although nitrogen is considered the main limiting nutrient for forest productivity, continued deposition of atmospheric nitrogen is likely to mean that P becomes more limiting in a broad range of forest ecosystems (Gradowski and Thomas 2006). ECM symbiosis can enhance P acquisition by a broad range of tree taxa, particularly, although not exclusively, when the element is limiting in soil (eg Heinrich and Patrick 1986;Bougher et al 1990;Jones et al 1990; Moyersoen et al 1998;Launonen et al 2004;Qu et al 2004;Dominguez Núñez et al 2006). In this way, although different fungal taxa differ in the extent to which they enhance host P acquisition (Dighton et al 1990), ECM fungi are central to the P nutrition of their hosts.…”