Thursday, July 31, 2014

Canopy shape and tree spacing

    Back in 1995 we established a block of seedling trees that we later grafted to Kanza. The original tree spacing was  30 ft. x 30 ft. and  by 2012 the branches of some adjacent trees were starting to touch. In 2012, we developed a tree thinning plan that called for the removal of trees over several years starting in areas of the orchard that were showing signs of overcrowding. You can review this thinning plan and follow the history of tree removal in this orchard by viewing my post from last March.

     Today, I went out to our Kanza block to check on this year's crop load crop.  While walking through the orchard, I was struck by how different the tree canopies  looked between thinned and un-thinned areas. I took a couple of photos that I hope illustrate what I'm talking about.
    The photo at right shows the portion of our Kanza block that has not been thinned. The trees in the photo look really close together because I took the snapshot on the diagonal from the 30 ft. by 30 ft. tree rows. These trees are starting to touch and I'll need to thin trees from this area next winter. But what I really wanted you to see is the shape of each tree's canopy. Trees in the un-thinned area appear tall and columnar. The only pruning we do in this grove of trees is to remove low hanging branches or wind-broken limbs. So ultimately, the distinctive shape of these trees was determined by inter-tree competition for sunlight. To impact tree shape so dramatically, competition  for sunlight had to have started long before the branches of adjacent trees started to touch.

    So what happens when trees are thinned from the grove and sunlight streams down onto the sides of remaining trees.  The photo at right shows the portion of the Kanza block grove that was thinned in February of 2012. This photo was taken in the same diagonal direction as the photo of the un-thinned portion of the block. The trees in this area are now spaced 42 ft. x 42 ft.
    With only three years of new shoot growth, you can see how quickly the sides of these trees have grown out to take advantage of increased sunlight penetration into the orchard. Note how the tree canopies have changed shape to become more rounded. I'm also seeing more nut production on lower limbs in this portion of the orchard as compared to the un-thinned areas.
   This winter we will be cutting more trees out of this orchard according to our tree thinning plan. The number of trees we will remove in February of 2015 is yet to be determined but I keep you posted.