Belowground community responses to fire: meta‐analysis reveals contrasting responses of soil microorganisms and mesofauna

Dipterocarps are one of the most important tree families in the lowland forests of Southeast Asia and are somewhat unusual among tropical trees in that they form ectomycorrhizal (EcM) symbiotic root-inhabiting fungal associations. It has been hypothesized that dipterocarps have been partnered in this mutualistic association prior to the separation of Gondwana. Under many conditions EcMs form rapidly on dipterocarp seedlings through inocula present in the soil, although few studies have been conducted to provide evidence that they improve seedling establishment and performance. There are hundreds of EcM species associated with dipterocarps. Fungal fruit body surveys suggest that the most important families are Amanitaceae, Boletaceae, and Russulaceae, although Thelephoraceae also become numerically important when root tips are examined. EcM communities are affected by various biotic and abiotic factors, as well as anthropogenic perturbations, and the importance of these in structuring EcM communities is examined herein. © 2012 The Author(s). Journal compilation © 2012 by The Association for Tropical Biology and Conservation.

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Ectomycorrhizal Associations of the Dipterocarpaceae

Review on fire effects on ectomycorrhizal symbiosis, an unachieved work for a scalding topic

The Dipterocarpaceae, ecosystem dominants and source of forest products in South-east Asia, form ectomycorrhizas (EcMs). Important fungal families involved in this symbiosis are Amanitaceae, Boletaceae, Pisolithaceae, Russulaceae, Sclerodermataceae and Thelephoraceae. The presence of EcM fungi on the roots of dipterocarp seedlings has been shown to improve P nutrition most notably but also N, Ca and Mg nutrition and to improve access to organic forms of N. In addition, EcMs have been shown to improve seedling growth although mostly under nursery conditions. These results have led it to be suggested that seedlings should be inoculated prior to being out-planted in reforestation programmes. Current and recent inoculation schemes have focussed on the genera Pisolithus, Scleroderma and Tomentella. The most controlled method to inoculate seedlings is to apply a known amount of inoculum of an identified, aseptically cultured EcM fungal species. In situations where this has not been feasible, tabletted EcM inoculum has been applied. The simplest to inoculate seedlings is to use forest soil colonised with EcM hyphae, root fragments and spores; whilst this does not guarantee the most beneficial fungus will be dominant on the roots of the seedlings it will allow EcM formation of some kind. Before assuming that pre-inoculating seedlings will bring long-term benefits to seedlings planted in soils where EcM inoculum is already present, a number of questions need to be asked. First, does inoculation actually improve growth and survival of out-planted seedlings? If so, second, under what conditions and situations is inoculation of benefit? Finally, is colonised soil inoculum just as good as single species inoculum? However, in soils lacking inoculum (such as burnt peat swamp forest and ex agricultural land), inoculating seedlings is more likely to be of benefit to initial seedling growth and survival. Whilst EcMs have often been shown to be beneficial for seedling performance, the warning raised over 40 years ago that “mycorrhizal infection should not be taken as the ‘cure of all ills’ in the establishment of trees” still applies today.

The Importance of Ectomycorrhizas for the Growth of Dipterocarps and the Efficacy of Ectomycorrhizal Inoculation Schemes

Background: Ectomycorrhizal (EcM) associations have been reported with trees of the plant family Dipterocarpaceae. We hypothesised that a dipterocarp forest fragment, with more host species, would yield a higher diversity of associated EcM fungal species than that of a Dipterocarpus alatus monoculture plantation.Aims: To examine the above- and below-ground EcM community structure of a dry dipterocarp forest fragment and a D. alatus plantation in Thailand.Methods: Sporocarps were collected and identified, and EcM root tips were collected in the dry and wet seasons and identified by terminal restriction fragment length polymorphism and internal transcribed spacer sequencing.Results: Higher EcM fungal diversity was observed in the dry dipterocarp forest fragment than in the D. alatus plantation, with a larger number of species found in the wet seasons than the dry seasons. Sporocarp species richness was greater than root-tip EcM richness. Different dominant EcM taxa were observed in the above- and below-grou...

Community structure and dynamics of ectomycorrhizal fungi in a dipterocarp forest fragment and plantation in Thailand

The impact of forest fire in 1997 and 1998 on the mycorrhzae was studied at the dipterocarp forest in East Kalimantan, Indonesia. In unaffected forest more than half of total ectomycorrhizae distributed in the organic layer but in the fire-affected forest one and a half years after the fire, total amount of mycorrhizae was smaller and they were found in deeper soil. The number of morphotypes of mycorrhizae was also smaller in fire-affected forest. An artificial plantation established after clear cut and prescribed burn had the largest amount of ectomycorrhizae, but the diversity was smaller than the unaffected forest. After four years, mycorrhizae had not yet recovered in fire-affected forest although the organic layer had recovered. Pioneer species of mycorrhizal fungi (early-stage fungi) developed sporocarps around the surviving hosts in severely affected forest and this suggests the start of secondary succession of mycorrhizae. In moderately affected forest, the species composition of mycorrhizal fungi which fruited during the study was similar to those of unaffected forest. This fact suggests that such sites may be the refugia of symbionts and be important in reforestation.

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Ida Nurhiftisni

Papers

The Impact of the 1998 Forest Fire on Ectomycorrhizae of Dipterocarp Trees and their Recovery in Tropical Rain Forests of East Kalimantan, Indonesia