It's always tempting to focus on the extremely fast growth of many tree species in tree tubes. It's hard not to focus on it when you see crabapple trees start the year as six inch seedlings and emerge from 4 and 5 foot treeshelters before the end of summer!
But it's important to remember that fast growth in tree tubes is really just a means to an end - and that end is simply the long term survival of the tree.
All too many tree planting projects end in failure due to low seedling survival. Deer browse, competing vegetation, drought, wind and moisture stress and other factors all play a part. For most tree planters the bottom line is survival, which simply means: not having to plant that same piece of ground again. Fast growth is nice, and it's something to brag about to your neighbors and friends, but the main thing is simply success.
That's why this article is so great (follow the link and then click View Document). This studied tracked survival rates of four species, baldcypress (yes! baldcypress grows great in tree tubes!), water tupelo, swamp blackgum and green ash over five years, in 4 different types of sites and in the face of severe herbivory from beavers. Some interesting results:
Baldcypress, planted in a willow area,
With tree shelters: 97% survival
Without tree shelters: 45% survival
Green ash, planted in a grassy area,
With tree shelters: 90% survival
Without tree shelters: 8% survival
Green ash, planted in a a willow area,
With tree shelters: 88% survival
Without tree shelters: 2% survival
No, not all of the results were this dramatic, and I'm "cherry picking" the most compelling results the way that all salesmen tend to do.
But almost across the board the results tell one story: Success (with tree tubes) versus Replant (without tree tubes).