Wednesday, December 12, 2012

Why do we need tree tubes?

Why do we need tree tubes in order to successfully establish seedling trees?  After all, trees managed to grow before tree tubes existed.  Why do we need tree tubes now?

There are two answers to that question.

The first is that a tree planting project is different than a naturally regenerated forest.  A naturally regenerated forest is the result of hundreds of years, billions of seeds, and a huge amount of random chance.  The odds that any one tree seed will someday become a mature tree are minute.  The accumulation of huge spans of time and huge numbers of seeds ultimately result in a forest... sometimes.  Nature has plenty of failed attempts at forest regeneration (we call these failures "prairies"). 

It takes an enormous amount of work - not to mention money - to plant trees in order to create a new forest.  And since the tree planting can't sow billions of tree seeds and doesn't have hundreds of years to wait, something has to be done to take the element of random chance out of the equation.  There are lots of ways to do this, to tip the scales of chance more in favor of success - planting species most likely to thrive in local growing conditions, properly planting high quality stock, and aggressively suppressing vegetative competition.

But the single most powerful tool to turn the odds in favor of the tree planter over random chance, if the tree tube (or treeshelter as it is known in the UK and among hardwood silviculturists in the USA).

The second reason we need tree tubes today is illustrated beautifully in this chronology given on this web page of the Oklahoma Department of Wildlife Conservation.

1900 - market and subsistence hunting virtually eliminate deer in Oklahoma

1917 - statewide deer population estimated at 500 

1944 - 379 deer harvested by hunters

2005 - 101,111 deer harvested, 40% of them does (which means wildlife managers are trying very hard to reduce the size of the herd)

This numbers are nearly the same in every state east of the Rockies.  Deer nearly wiped out by 1900, followed by reduced or banned hunting for a period of time, combined with heroic conservation efforts to restore whitetail deer, combined with changes in the landscape (creation of a patchwork with exponentially more forest edge, the preferred habitat of deer) and reduced predator populations, leading to huge deer harvests that still can't keep pace with the rate of reproduction.

Many of the natural forests we have can very likely trace their origins to that 1900 time period when deer numbers were at an all time low.

We are now trying to plant trees when the deer population is at an all time high.

There are now places in the USA where natural hardwood regeneration is seriously threatened, where there are very few young hardwood trees.  The deer simply eat them faster than they can grow.

So random chance is not an option any more.

There are other ways to protect trees from deer browse, but none as cost effective as tree tubes.

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