Ghazoul Jaboury

Post-fire ectomycorrhizal fungi and their role for Pinus sylvestris L. seedling growth

Project Number: Parcs Data Center 9937 / 4D CH-4827
Project Type: Dissertation
Project Duration: 05/01/2007 - 06/30/2010 project completed
Funding Source: WSL ,
Leading Institution: ETH Zürich
Project Leader: Prof. Jaboury Ghazoul
Institut für Terrestrische Ökosysteme (ITES)
ETH Zürich
ETH Zentrum CHN G 74.1
Universitätstrasse 16
8092 Zürich
Phone: +41 (0) 44 632 86 27 ; +41 (0) 44 633 60 63
FAX: +41 (0) 44 633 11 23
e-Mail: jaboury.ghazoul(at)env.ethz.ch
http://www.ito.ethz.ch

related to this project.
for which the project has a relevance.


Research Areas:
Biodiversity

Disciplines:
environmental sciences
forestry

Keywords:
Cenococcum geophilum Fr., ectomycorrhizal fungi, fire disturbance, heat, Pinus sylvestris L., Rhizopogon roseolus (Corda) Th. Fr., resilience, resistance, recruitment, Scots pine, biomass, drought, diversity, extracellular enzyme activity, mutualism, sampling effect, species richness, Suillus granulatus (L.) Roussel, symbiosis

Abstract:
Forest fires are among the most important disturbances in many forested landscapes, and climate change is likely to enhance their relevance because of predicted warmer conditions and shifts in precipitation patterns. In the dry inner-alpine valleys of Central Europe, the frequency of extreme fire events is expected to increase. Today already, regeneration of Pinus sylvestris L. (Scots pine) on forest fire sites in these regions is sparse or even missing. Ectomycorrhiza, the symbiosis between fungi and woody plants, is suggested to be an important biotic factor for successful tree recruitment because the fungi enhance plant growth and improve the water status of their host. Yet, little is known about their ability to resist fire and to recover from fire disturbance. In this thesis, the following two questions are addressed: 1) How resistant and resilient are ectomycorrhizal fungal communities to forest fire? 2) If ectomycorrhizal fungal communities are altered due to forest fire and diversity is reduced, what are the consequences for seedling growth under drought stress?


In chapter 1, an experiment that examines the susceptibility of ectomycorrhizal fungi to heat is reported. Soil samples were collected from a P. sylvestris stand in the Valais (Switzerland) and experimentally heated to three different temperature levels (45, 60 and 70 °C). Surviving ectomycorrhizal fungi were assessed using a bioassay with P. sylvestris as an experimental host plant, and identified by a combination of morphotyping and DNA sequencing. Heating at 60 and 70 °C caused a reduction in mean species number, and species composition changed due to heat. While some ectomycorrhizal fungal species did not survive, a considerable number was also found in the heated samples, indicating their resistance to high temperatures.


Chapter 2 presents an investigation of the post-fire recovery of ectomycorrhizal fungi. On a chronosequence (1990-2006) of 12 sites located in the Val d’Aosta (Italy) and the Valais (Switzerland), soil samples were taken along transects on both, burnt and adjacent non- burnt forest sites. Ectomycorrhizal fungal communities were assessed via a bioassay and subsequent morphotyping and DNA sequencing. Samples from burnt sites were species- poorer than those from non-burnt forest, but the species number increased with time since fire. Fire disturbance altered composition of ectomycorrhizal fungal communities, and there was no apparent tendency for community composition from burnt sites and non-burnt forest to become more similar over time. This indicates resilience of ectomycorrhizal fungi in terms of species richness, but not in terms of species composition.


In chapter 3, the effect of ectomycorrhizal fungal community composition on host performance is addressed. Sterile P. sylvestris seedlings were inoculated with four selected ectomycorrhizal fungal species (Cenococcum geophilum Fr., Paxillus involutus (Batsch) Fr., Rhizopogon roseolus (Corda) Th. Fr. and Suillus granulatus (L.) Roussel.), either in monoculture or in different species mixtures. Seedlings were cultivated in a growth chamber under two different watering regimes (moist vs. dry). Presence of S. granulatus enhanced shoot growth, whereas seedlings inoculated with any other fungus did not differ from non- mycorrhizal ones. However, the positive effect of S. granulatus was attenuated by drought. These findings provide evidence that ectomycorrhizal fungal species composition has a strong effect on seedling performance measured as biomass, since one fungus considerably increased seedling growth, whereas the others did not.


The results of this thesis contribute to our knowledge about ectomycorrhizal fungal communities on forest fire sites in the Central Alps. Ectomycorrhizal inoculum was not completely missing on these sites, but species composition remained altered for at least two decades. The inoculation experiment suggests that not only the presence, but also the species identity of ectomycorrhizal fungi is important for seedling growth. Consequently, this study proposes that fungal species composition plays an important role for seedling performance.

Leading questions:
  • How resistant and resilient are ectomycorrhizal fungal communities to forest fire?

  • If ectomycorrhizal fungal communities are altered due to forest fire and diversity is reduced, what are the consequences for seedling growth under drought stress?


    URL: http://e-collection.library.ethz.ch/eserv/eth:2462/eth-2462-01.pdf

    Publications:
    Kipfer, Tabea. 2010. POST-FIRE ECTOMYCORRHIZAL FUNGI AND THEIR ROLE FOR PINUS SYLVESTRIS L. SEEDLING GROWTH. Dissertation, ETH Zürich.
    PDF Dissertation


    Last update: 4/5/22
    Source of data: ProClim- Research InfoSystem (1993-2024)
    Update the data of project: CH-4827

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