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Name: David H Khaliqi
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Question:
What is forest succession?
What is the first species of conifer that moves in to a disturbed ecosystem?



Replies:
I do not think one can generalize regarding a particular species moving into a disturbed ecosystem for the entire planet, the hemisphere or our country or even a part of our country. You will notice that there is a great diversity of species in the various forest types throughout the world. The actual pioneer species to move into a disturbed area will vary according to location, the indigenous species of that area, and the nature of the disturbance. One generalization that can be made: if you know which species are growing in an area, and can list them according to tolerance i.e. is the plant tolerant to shade, you can develop a pretty accurate list for that particular forest ecosystem.

For example, in my area here in southeastern Pennsylvania, our mature forests consist of oak, maple, and hickory. These are all shade tolerant species. This means they will do well in shade created by taller trees, and they therefore can compete for sunlight in a mature forest with some success. Species like birch, for example, do not like shade, and therefore cannot compete in a mature forest with more shade loving trees. After a disturbance, however, canopy is opened up (depending on how serious the disturbance is) there would now be sunlight available and species such as the birches would be able to develop in the sun. Naturally, if there are no birch trees nearby to provide seed, you wont see birches arriving. Other considerations would be available water and ground nutrition, again this would depend on the disturbance.

There are many books available which discuss forest regeneration and success succession. Let me know if you would like some book suggestions. Finally, your original question asked which conifer species might be the fir first to move into a disturbed area. If you could list the species of conifers in the ecosystem you are theorizing about, according to how aggressive they are, and whether they prefer (or require) sun or are shade tolerant, you can prepare an expected forest succession plan for that ecosystem. Some considerations: white pine likes a lot of sun when it is young but will tolerate shade when it is older. Spruces will tolerate shade at most any age.

If the forest ecosystem you are discussing has only spruces and white pines available to supply seed, I would bet on the white pine as an early colonizer. Something , finally, which might cloud the picture a bit: since spruces will tolerate shade, often you find many young spruces in the shade of a mature forest. When a disturbance happens they already have a head start in reclaiming the forest. Naturally if the disturbance is a fierce wildfire, many of them would be killed.

If, however the disturbance is a thinning operation by a logging company, the white pine seeds (assuming there are some available) might BEGIN to grow since the canopy would then be opened and allow more sunlight.

Rickru



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