Improving Inner-Cities: What You Can Do and What You Can’t

Ok, we shall take this title in reverse.

We will first discuss what must be accepted in inner-city neighborhoods.  One person said that trees keep neighborhoods out of “the ghetto.”  But trees are not an absolute concern to the quality of a urban block, and I will prove this with some botany.

Remember, the diameter of tree trunk depends on its age.  Wood, properly, is solely the xylem of the plant, the central structure which is dead at maturity. Xylem is responsible for transpiration, the gravity-defying, gradient-based water transport from the roots and into the air. The rest of the trunk, that is, its peripheral structure, is collectively called the bark, which includes the phloem (which carries sugars, etc.) and the dead external cork.

In a tree trunk, a tissue called the cambium divides cells both ways, phloem to the outside and xylem towards the center. This is secondary growth, a horizontal process which generates tree trunks, as opposed to primary growth, which is vertical.

Much more xylem is produced than phloem.  Now here it gets interesting. In spring and early summer, secondary xylem cells have a wide diameter, thanks to water from the recent snow melt and the minerals it contains. However, as it continues to absorb minerals and water, they are depleted, and much water is lost throughout the summer. Also, come fall, the days progressively shorten and temperatures drop. Therefore, cells are much narrower in the radial (i.e., toward the center) dimension when generated later in the season.  No growth occurs in winter, and thus the tree acquires a new growth ring.

Tree cross-section.  (Koning)

Since some older houses were built in a environment without trees, it is not always a matter of the presence or absence of such, but the actual condition of the homes play a role as well.  Of course, I am not saying that trees are not a beautiful addition to a block.  They sure are!  But it would not be practical to add trees when non-existent.  In fact, another beauty can fill in:  an open and sunny look that trees would intercept.

If houses are run-down, unless they are totally uninhabitable (thus doomed to demolition), they should be repaired, both inside and out.  This includes things such as painting chipped structures, pointing bricks, and other tasks.

So whether choosing houses or fixing them up, as for the trees on the block, just take it or leave it.

Koning, Ross E. 1994. Secondary Growth. Plant Physiology Information Website. (3-4-2017).