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Jennifer Walker

PhD candidate, Biology, UBC O
Supervised by Melanie Jones

In my thesis I propose to investigate the structural and functional diversity of ectomycorrhizal communities in decayed wood and other microsites at a high elevation Engelmann Spruce/Subalpine Fir forest Sicamous Creek). Harvesting and downed wood manipulation took place in the winter of 1994/95, with operational planting of spruce the following year. Three replicate 10 ha. cutblocks are designated ‘A’, ‘B’, and ‘C’ and differ slightly in aspect and elevation. At each of three replicate blocks, there are three treatments: Complete removal (CWD–), Retention (CWD+), and Forest (F). In order to answer questions at a smaller scale, we have established the microsites Decay (D), Ground (G), and Hard (H), representing decayed wood, mineral soil, and hard wood respectively, on all plots.

I plan to ask whether the presence or absence of coarse woody debris influences the taxonomic and functional composition of ectomycorrhizal fungal communities at several scales. My initial work has been at the plot scale, but I will also compare ectomycorrhizal fungal communities in microsites containing decayed wood or mineral soil adjacent to or some distance from relatively intact logs. Samples will be taken from ectomycorrhizal root tips on seedlings planted in the summer or 2007 as well as from fungal hyphae trapped in buried mesh bags or extracted directly from soil and wood. I will use morphological techniques, T-RFLP and DNA sequencing in combination to characterize the communities taxonomically, and will employ measurements of extracellular enzyme activities and functional gene expression to evaluate physiological function. Relevant physiological activity includes the capacity to degrade wood, and assays will focus on cellulose and lignin degradation in addition to the use of nutrients such as nitrogen and phosphorus.

Ideally this work will bring us close to answering an intriguing question about the effectiveness of coarse woody debris retention:

'Do communities of ectomycorrhizal fungi in high elevation Engelmann Spruce/Subalpine Fir forests and clearcuts possess unique physiological attributes that allow them to extract nutrients from and persist in decaying wood?'


Last reviewed shim4/8/2015 12:42:44 PM