It's the Carbon Stupid!

Question: “Interesting, you make and sell tree tubes. So what does a Tree Tube do?”

That is a stressful question at a party. Spouses of those of us in the tree tube industry get a look of alarm when we are asked the simple and innocent question, “What does a tree tube do?” The reason is that a tree tube seemingly does many things and there is no obvious end to the monologue. Where do we begin? Here is a partial list:

A Tree tube:

1. Is used on tree seedlings, acorns, nuts, tissue culture plantlets, grafted grape vines, and etc.

2. Protects the plant from deer, rabbits and other animals

3. Shields from herbicide spray

4. Blocks the wind

5. Conserves moisture

6. Trains the plant to a single

7. Modifies the quality, quantity and wavelength composition of the light hitting the seedling

8. Has photomorphogenic effects

9. Is not a season extender

10. Affects CO2 uptake

11. Protects against mechanical damage

12. Makes it possible to find a plant in the forest to take care of it

13. Works best with small plants

14. Prevents side branching

15. Saves training labor

16. Is made of translucent polyolefin

17. Is tubular

18. Must be the equivalent of 3.5 inch OD in cross-section

19. Prevent seasonal buck rub

20. Discourages rodents

21. Ad infinitum…

I could go on indefinitely.

For over twenty years, my colleagues and I have searched for understanding of what it is a treeshelter or tree tube does to makes trees grow so magnificently. The answer is complex and involves a great deal of plant physiology. What is the simplest way to express what a tree tube does? Around 1pm on Friday afternoon (19 June 2009), it dawned on me. It is possible in three or four words to express the purpose and function of a tree tube. A tree tube does Carbon Acquisition and Retention (CARe) CARe is all a tree tube does. Plantra Tree Tubes CARe!

Everything about a tube flows from these concepts. So here is the answer I have been looking for – with some attempts at developing a useful acronym.

Answer: A tree tube is a Carbon Acquisition and Retention Device (CARD for short) Acronyms help us hold and retrieve knowledge. CARD is not a helpful acronym for what a tree tube does. A better acronym would spell a metaphor. Hmm… CARE or CARe meets that test. So my answer could be “A tree tube is for Carbon Acquisition and Retention (CARe).” Just thought of a third acronym - metaphor. The answer could also be, “The purpose of a tree tube is Acquisition and Retention of Carbon (ARC)” I know Noah’s ark has a “K” and not a “C”, but it is highly suggestive of the notion of saving a species. The Plantra Tree ARC has a ring to it!

The short story is that a Plantra Tree Tube does two things. First, it helps the plant acquire more carbon than it would without the tube and then the tube helps the plant retain the carbon by preventing browsing animals from removing carbon in the form of leaves, buds and twigs.

CARBON ACQUISITION

Since water is most often used as the electron donor in oxygenic photosynthesis, the equation for this process is:

CO₂ + 2 H₂O + photons → (CH₂O)_n + H₂O + O₂

carbon dioxide + water + light energy → carbohydrate + oxygen + water

Every fan of science fiction has heard the expression that Earth based life forms – plants and animals – are carbon based. Life on Earth is fueled and made possible by Chlorophyll in leaves. Chlorophyll takes energy from sunlight to chemically convert water and carbon dioxide into sugar (carbohydrate), water and oxygen. Sugar is the fuel of life for both plants and animals. Animals consume plants to get sugar. Oxygen is consumed to “burn” the sugar fuel. When animals release the energy in the plant sugar, water and carbon dioxide are the byproducts. Therefore, animals produce the CO₂ & H₂O that plants consume to produce sugar and O₂ that animals consume in a never-ending cycle. It is all about moving the carbon from plant to animal and back to the plant.

So exactly how does a grow tube help the leaf take in more CO2 than an unaided plant? The carbon used in photosynthesis must enter the leaf through open stoma or stomata. The stoma is a pore in the leaf that opens and closes with the action of two guard cells. The problem is that water vapor escapes out the stoma when open (so does O₂, but that is not a problem). To conserve water the stoma only open when conditions are right for photosynthesis and it is not too dry or windy. If it is too dry or too windy, the loss of water is too great for the plant to remain turgid (not wilted) and the stoma close the guard cells. Closed stoma means no CO₂ and no CO₂ means no photosynthesis. The microenvironment in a tube is humid and still – no wind. There is little evaporative demand in the tube, so there is little loss of water when the stomas are open. Therefore, the stoma stays open continuously. (Bergez Dupraz 1997) There is no interruption in the supply of carbon (CO2) unless the plant depletes the CO2 in the tube. That will happen in an unvented tube on a sunny day that is otherwise ideal for photosynthesis. Without venting the CO2 level in the tube drop below a level that sustains photosynthesis and the plant goes into photorespiration and starts giving off CO2. Venting replenishes the CO₂ supply available to the leaf.

It is only a slight exaggeration to say that life on earth is about move carbon into plants, then animals and back. Plantra Tree Tubes move carbon.

CARBON RETENTION

This is the easy part. Plantra Tree Tubes prevent browsing up to the height of the tree. The tube is a visual and physical barrier. The animals can’t see the plant. The animals can’t get to the plant.