Sequestration rates will vary depending on species, location (regional and site specific) and the planting and tending regime (if it's a plantation forest), amongst other things.
Sequestration rates change over the life of a tree as well. Eucalypts for example have high upfront seq rates but suffer from earlier senescence (i.e. they decay earlier). Fir trees grow more slowly but have a longer life span, so sequester carbon longer. Many pines fall somewhere in the middle. Again, this varies across sub species and regions.
To answer your question though. A tree that only sequesters 1 tonne doesn't sound healthy enough to last 100 years! A plantation pine tree (like those in North America or New Zealand) might sequester between 700 and 1200 tonnes over a typical 30 year rotation, prior to harvest.
Check out the look up tables published by the New Zealand Ministry of Forestry on growth rates for forests in the NZ ETS: http://www.maf.govt.nz/sustainable-forestry/ets/guide/lookup-table-guide.pdf
Yes you are right that it will depend on those factors. I have seen multiple sources say that a tree absorbs around 1 tonne of CO2 in its lifetime. Thats the rough figure.
I have found this document on how to calculate the amount of CO2 sequestered in a tree in an year. You might find it interesting - http://www.plant-trees.org/resources/Calculating%20CO2%20Sequestration%20by%20Trees.pdf
Here is some other interesting info I found that would give you a better context.
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