The effect of nitrogen on mycorrhizal colonization associated

with Populus grandidentata

Megan McLinBartlett Experimental ForestMELNHE Project

Bartlett, NH

The MELHNE project-studying N and P acquisition and limitation through a

series of nutrient manipulations in northern hardwood forests

Mycorrhizal Fungi

Background: Mycorrhiza the root fungus

• Symbiotic Fungi

• Crucial link between root system and

soil

• Creates surface area

• Releases enzymes in soil to

to break down nutrientsEgli, S.; Brunner, I. (2011): Mykorrhiza. Eine faszinierende Lebensgemeinschaft im Wald. 3. Aufl. Merkbl. Prax. 35 8 S

Nitrogen Deposition

Nitrogen Deposition: Questions?

• Will nitrogen exceed the nutritional needs of the ecosystem causing a decrease in mycorrhizal abundance?

• Studies have shown that ecosystems have been susceptible to decline in response to nitrogen deposition. (Bevege, 102)

Arbuscular vs Ecto Mycorrhizae

Arbuscular vs Ecto Mycorrhizae

• Ecto can be seen within the naked eye or dissecting microscope 10x-50x magnification

• Arbuscular can be seen with high magnification 200x magnification

• In spite of their profound morphological and taxonomic differences,some of the effects of AM fungi and ECM fungi on host physiology are similar (Tinker, Jones & Durall,1992).

Bigtooth Aspen

Methods

• Mycorrhizal colonization will be measured by directly

collecting Populus grandidentata roots. Both AM and

EM mycorrhizal colonization will be quantified on each

root with a microscope and staining techniques.

Field Methods

• The collection of the roots came from nitrogen plot.

• Three treatment trees and three control trees were sampled

• Control trees were sampled outside buffer and also on same slope

• Organic horizon depth was used to root trace

Field Methods cont.

• Tree DBH was taken for trees as well as nearby neighbors

• Four Cardinal directions for root tracing

• Tree roots were placed in corresponding test tubes

Lab Methods: Ectomycorrhizal

• Roots were separated from soil.

• Cut into 5 mm sections

• Examined under dissecting microscope

• The portion of ectomycorrhizal root tips were calculated

Lab Methods: Ectomycorrhizal

Gridline intersect method(Figure 4.5A in Brundrett et al. 1996).

Lab Methods: Arbuscular

Figure 4.4B in Brundrett et al. 1996).

Figure 4.4B in Brundrett et al. 1996).

Results

Data

Control Ecto Quantifying

Treatment Ecto Quantifying

Data cont.

Conclusion

• Nitrogen decreases mycorrhizal colonization

• Control showed more mycorrhizal activity

• Treatment trees showed more DSE hyphae

• Different staining technique

Future Work

• Continue work with senior thesis

• Molecular work

• Trying different staining techniques

Cited sourcesBevege DI. 1968. A rapid technique for

clearing tannins and staining intact roots

for detection of mycorrhizas caused by

Endogone spp. and some records of

infection in Australasian plants.

Transactions of the British Mycological

Society 51: 808- 810.

Cripps, C. L. 2001. Mycorrhizae of Aspen

Forests: ecology and potential

application. In: Sustaining Aspen in

Western Landscapes: Proceedings of the

Symposium on Western Aspen Forests,

Grand Junction, CO, June 2000. pp. 285-

298.

Acknowledgments

The Shoestring crew

Ruth Yanai

Craig See

Adam Wild

Franklin Diggs

Tougaloo College