Dear all,
I am trying to form a mental picture of the effects of burned and charred
orgainc material on tree recruitment after wildfire in North American boreal
forests. I got the impression that ash and charcoal can have very different
effects and that these effects also depend of the life stage of the
individuals, i.e., germinant or seedling. Here are some effects that seem to
occur:
1) Ash is high in certain salts and can decrease the available soil water thus
decreasing germination rate in white pine.
2) Mortality rate of Allepo pine sedlings (nota bene: this is a mediterranean
species) is decreased and growth rate increased because of a supposed
fertilization effect by ash.
3) Ash tends to increase soil ph compared to pine litter, perhaps making
calcium more available for uptake.
4) Ash can form a crust on top of the soil (pers. obs.) thus potentially
decreasing rain water infiltration and soil penetration by roots.
5) Charred wood material breaks down faster than uncharred wood and may thus
release nutrients to the soil quicker.
6) Charcoal can absorb phytoxins and diminsh allelopathic effects.
However, I have a few questions:
1) Often one reads about charred organic matter, with organic matter meaning
litter (or duff) or humus in various degrees of decomposition. Is this material
more similar to ash or to charcoal?
2) If charred organic matter is neither ash nor charcoal, what are the effects
of this material on recruitment?
3) Are the effects mentioned above strong enough for tree recruitment to be
important compared to other factors like seed predation, weather etc.?
4) Are there inter-specific differences in the effects of ash and charcoal on
tree recruitment?
5) Do the the effects mentioned above also come into play at larger spatial end
temporal scales or only at the micro habitat level? In other words: can the
presence of a reasonably strong ash or charcoal layer have effects on the tree
species composition of stands several decennia after the fire?
I am loking forward to hear your opinion about these issues.
Thanks a lot, Michael Drescher
Michael Drescher
1162 Queen Street East
Unit # 5
Sault Ste. Marie
Ontario
P6A 2E3
Canada
Tel: + 1 705 946-3340
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