Establishment of sweet birch on surface mine spoil as influenced by mycorrhizal inoculation and fertility

  • Published source details Walker R.F., McLaughlin S.B. & West D.C. (2004) Establishment of sweet birch on surface mine spoil as influenced by mycorrhizal inoculation and fertility. Restoration Ecology, 12, 8-19.


In the eastern United States, there are concerns about the use of exotics for forest restoration of surface-mined areas. Native species are preferable for nature conservation purposes but the choice of species is limited as they have to be able to establish and grow on sites with adverse soil conditions. A practice with proven benefits for conifers in reforestation efforts is ectomycorrhizal inoculation, one such mycobiont especially well adapted to surface mine sites is Pisolithus tinctorius which has both a broad host range and is able to thrive on harsh substrates. To see if sweet birch Betula lenta might be a suitable species to include in such resorations, mycorrhization of sweet birch by P.tinctorius, as influenced by substrate fertility, was evaluated for its effects on seedling growth and physiology in mine spoil.

Sweet birch Betula lenta seed collected in Campbell County, Tennessee (36°19'30'' N, 84°17'30'' W) was stratified by soaking for 24 h in cold water followed by an 8-week chilling period at 3º C. Approximately 25% of the birch seed was viable.

Sweet birch Betula lenta seedlings were grown in seed flats over a 4-5 month period, with seedlings inoculated with mycelial P.tinctorius and uninoculated seedlings subjected to three fertility regimes (see original paper for nurservy cultivation details).

Seedlings were transplanted into a mine spoil substrate, with the inoculation and nutrition treatments initiated in the preliminary phase continued throughout the remaining 30 months study period. This allowed examination of sweet birch performance in mine spoil as influenced by mycorrhization and fertilizer application, and also provided an indication of how amenable sweet birch is to planting out as bareroot stock following an initial nursery period.

High fertility suppressed P.tinctorius mycorrhizal formation but promoted that of a secondary symbiont on the roots of inoculated birch seedlings, Thelephora terrestris. Pisolithus mycorrhization induced substantial above ground and below ground birch seedling growth but favoured root over shoot growth overall. These mycorrhizae were also able in many cases to promote growth in a similar fashion to higher nutrient addition treatments. Measurements of xylem pressure potential and soil water potential indicated that P.tinctorius enhanced water uptake during two simulated drought episodes and in subsequent recovery periods.

Inoculated seedlings had higher leaf concentrations of critical nutrients, especially nitrogen, and lower concentrations of potentially phytotoxic metallic elements, particularly manganese, compared with uninoculated seedlings, although the latter response was absent in mine spoil with high fertility. Spoil analyses also revealed the influence of the nutrition regimes and reinforced the findings of the foliage analysis concerning suppression of metal uptake by P.tinctorius.

Conclusions: The results from this trial suggest that P.tinctorius mycorrhization can provide sweet birch with an array of physiological benefits that will enable it to establish on mine spoil soils.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at:

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