Forest Investment Account (FIA) - Forest Science Program
FIA Project Y073064

    Ectomycorrhizae and networks: their role in facilitating Douglas-fir regeneration under water, site and climatic stresses
 
Project lead: Simard, Suzanne
Contributing Authors: Simard, Suzanne W.; Teste, Francois P.; Karst, Justine; Jones, Melanie D.; Durall, Daniel M.; Hagerman, Shannon M.; Sachs, Donald L.; Heineman, Jean L.; Mather, W. Jean; Vyse, Alan
Imprint: Vancouver, B.C. : University of British Columbia, 2007
Subject: Forest Investment Account (FIA), Ectomycorrhizae, Pseudotsuga Menziesii, Reproduction, British Columbia, Interior, Growth
Series: Forest Investment Account (FIA) - Forest Science Program
Description:
This project fits the FSP 'Timber Growth and Value' program, '1.0 Basic Research on tree growth and stand development' theme and '1.1 Complex stands' topic. This project investigates the role of ectomycorrhizae (ECM) and common mycorrhizal networks (CMNs) in facilitating Douglas-fir regeneration, growth and young stand development in the Interior Cedar Hemlock and Interior Douglas-fir zones of British Columbia. It includes four graduate student studies under the joint supervision of the core team members. Study 1: The role of common mycelial networks in facilitating artificial and natural regeneration of Douglas-fir This study is being carried out as part of François Teste’s PhD research under the supervision of Simard, Durall, Jones, and Berch. The specific objectives are: (1) to examine the influence of green tree size and proximity on Douglas-fir regeneration, and (2) to determine whether the importance of the common mycorrhizal network to Douglas-fir establishment increases with site disturbance. To meet objective 1 in Study 1, Douglas-fir was planted and seeded into forest gaps in the neighbourhood of (1) advance regeneration that varied in size, or (2) retained trees that varied in proximity. The size study is being conducted in a clearcut opening, and the proximity study in six separate Douglas-fir openings north of Kamloops, BC. Non-mycorrhizal (NM) Douglas-fir seedlings grown at UBC were out-planted in April, 2004, along with seed in treatments with and without mesh barriers that restricted ECM hyphae (to separate CMN from non-CMN effects). In each experiment the following treatments were applied: (1) size effects - located in the neighbourhood of different sized advance Douglas-fir regeneration; and (2) proximity effects - located at different distances from mature Douglas-fir trees. Over the next two growing seasons, we will measure seedling water stress, photosynthesis, transpiration, and relative growth rate. After the third growing season, we will apply dual isotope (13C/14C) labeling to quantify bi-directional transfer between Douglas-fir and neighbours. We will harvest the remaining replicates for biomass, nutrient content, wood NA 13C, root morphology, and ECM using morphological and molecular techniques. Data will be analyzed using the regression and model selection approaches. For objective 2 in Study 1, we are using the Long-Term Soil Productivity Study (LTSP) to test CMN effects on seedling establishment across levels of soil disturbance in a drought-limited environment. Seedlings, with and without CMN-restricting mesh, were planted into three treatments: (a) no compaction (C)/no forest floor removal (FFR), (b) no C/FFR, (c) no C/FFR and mineral soil removed, representing gradients of increasing organic matter removal. In May, 2004, NM Douglas-fir were out-planted into these treatments near (0.5 m) transplanted advance Douglas-fir. Near the end of each of two growing seasons, we will assess seedling water stress, foliar nutrients, and growth. We will then quantify bi-directional C transfer using 13C/14C as above, and the remaining pairs will be harvested for biomass, nutrient content, wood NA 13C, root morphology, and ECM using morphological and molecular techniques. Data will be analysed using Mixed Model Procedure for a split-plot design. Study 2: The role of ectomycorrhizal fungi in interspecific carbon transfer between birch and Douglas-fir This study is being carried out as part of Leanne Philip’s PhD research under the supervision of Drs. Simard and Jones. The specific objectives are: (1) To determine the importance of hyphal pathways relative to other pathways in the transfer of carbon between paper birch and Douglas-fir in the lab and field, (2) To determine whether the magnitude and direction of carbon transfer between paper birch and Douglas-fir changes with the phenology of the tree species. Achieving these objectives involved two lab studies, one where two-way carbon transfer was examined between connected and unconnected seedlings, and the second where one-way transfer was examined along different mycorrhizal pathways. A field experiment was also conducted where two-way carbon transfer between birch and fir was quantified in spring, summer and fall. When this fiscal year started, all experimental work was already completed except for the second laboratory study, which was completed in July/04. This year’s funding covered 4 months stipend for Leanne Philip to finish the last experiment, her PhD dissertation, and journal papers. Study 3: The influence of birch on the ectomycorrhizal fungal community in Douglas-fir stands of different ages This study is being carried out as part of the MSc research projects of Brendan Twieg and Denise Brooks under the supervision of Drs. Simard, Durall, Jones, Prescott, and Grayston. The objectives are: (1) to determine how long it takes for the ECM fungal community found in mixed forests to re-establish on clearcuts (addressing ecosystem recovery and whether CMN formation potential increases with time), and (2) to determine whether the Douglas-fir ECM fungi on clearcuts are better adapted to those sites than are forest fungi by comparing the uptake of P and various forms of N in stands of different ages. To meet objective 1 of Study 3, we selected 20 sites in 2002/03 and 8 more in 2004/05, representing a chronosequence of mixed Douglas-fir/paper birch forests in the ICH zone. The chronosequence consisted of four age classes (4-6, 24-27, 60-70, and 88-105 years-old). The 8 new sites allow us to compare fire with clearcut origin sites of the youngest age classes. In 2003/04, Brendan established the sampling area at each site, collected soil cores from one site per age class, processed the samples for morphotypes and molecular analysis, and collected fruiting bodies in fall 2003. In 2004/05, Brendan was to collect soil cores from the remaining replicate sites, describe the plant communities and soils, and characterize the fungal communities as described above. ANOVA and regression will be used to analyze the data. To address objective 2 of Study 3, two Plexiglas root windows were installed at each of the chronosequence sites in the summers of 2003 and 2004. Each window has a 30 X 30 cm trap door, allowing us access to the mycorrhizae and their hyphae for in situ assays of enzyme activity and nutrient uptake in 2004. To do this, we are using the soil-imprinting method (Grierson and Comerford 2000), where nitrocellulose membranes are applied directly to ectomycorrhizas and their hyphae exposed on the soil face. We will compare the five dominant fungi from each site, as determined by Brendan. The activity of the enzymes will be used as an index of the ability of ECM fungi in the young stands and in the older stands to access organic N and P. Study 4: The role of ectomycorrhizal fungi in establishment of Douglas-fir across a wide range of sites that vary in soil moisture regime. This project, while not requiring funding in 2004/05, has been integral with these studies since the project was first funded by FII in 2002. In this portion of the study, PhD student Justine Karst, under the supervision by Jones and Simard, is determining whether the breadth of sites where Douglas-fir establishes is greater when ectomycorrhizal than when non-mycorrhizal. In this study, ectomycorrhizal fungi were isolated from litter, humus, decaying wood and mineral soil from Douglas-fir roots at several IDF sites. The fungi were cultured and then used to inoculate Douglas-fir growing in pots in each of the substrates. After three months, mycorrhizas were sampled for isotopic signature of N accumulated from the different substrates, for use in subsequent experiments as a marker for N uptake. In a follow-up experiment, Douglas-fir mycorrhizal with individual fungi was planted with two of the above substrates, to see which fungus was better adapted for extracting N from one substrate over the other. Douglas-fir seedlings were then inoculated with multiple fungi and planted in heterogeneous mixtures of the substrates to see whether a greater diversity of fungi on the root system stimulated seedling establishment in heterogeneous substrates. A third experiment was conducted where soil water content effects on the ectomycorrhizal community of Douglas-fir was examined. Mycorrhizae are currently being assessed in this study. In the final study, genetically diverse seeds of pine and Douglas-fir were inoculated with different ECM fungi to determine the genetic and mycorrhizal component of variation in growth. These experiments will be finished by end of 2005/06, and the thesis finished by the end of 2007.
Related projects:  FSP_Y051064FSP_Y062064

    Deliverables:

Can. J. For. Res. 35:843-859
Can. J. For. Res. 36:2486-2496
Executive Summary (32Kb)
Mycorrhiza 17(1):51-65

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Updated August 16, 2010 

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