What a difference a week makes! But this being Minnesota, that’s not surprising. I am photographing this little bur oak seedling in a Tubex Tree Tube every Monday. I wish I had waited until the afternoon today, because I have a feeling it will grow an inch by then.
Last Monday (actually it was Tuesday with the holiday) I was nearly tipping over when taking the photo, with 30-40mph winds buffeting – and desiccating – all young seedlings not inside of tree tubes.
Today I took the photo at about 9am and already it’s steamy and hot, heading for a high well above 90.
Last week the bur oak seedling was glad to be safe inside its tree tube, sheltered from the drying winds.
Today the seedling is happy to be shielded from the scalding sun, and have its leaves continuously enveloped in moist air.
The question is often asked: Don’t tree seedlings get too hot in tree tubes? The answer: No! From the seedling’s perspective it is actually much cooler inside a tree tube. Let’s look at 2 factors: Light & evaporative cooling.
The amount of solar radiation striking the leaves is reduced. Trees achieve peak photosynthesis at a relatively low % of full sunlight. Anything beyond that simply causes stress. Tree tubes reduce the level of solar radiation incident upon the leaves, reducing stress while allowing leaves enough sunlight for peak photosynthesis.
Anyone who has ever stood on a hot day on a section of lawn that was recently water knows that evaporation is a cooling process. Evaporation of moisture from leaves – transpiration – is a cooling process. It is also a process that is limited by the amount of moisture available to a seedling’s limited root system. At a certain point, when the evaporative demand necessary to keep leaves cool enough to photosynthesize efficiently would dangerously tax the seeding’s moisture reserves, the seedling instead closes its stomata (pores) and stops growing.
Not in a tree tube. In a tree tube evaporative demand is lower because the leaves are continuously enveloped in humid air, and the amount of available moisture is increased as the humidity inside the tubes condenses as air cools in the evening and trickles back into the soil to be absorbs again.
Yes tree tubes recycle water, and your trees get more photosynthesis and growth out of every drop available. That comes in handy on days like today.