Photo by lrargerich via Flickr Creative Commons
What are city trees really worth? Just how much of a contribution do they make to cityscapes, and how can we calculate the pricetag? A software program called i-Tree helps to save urban trees by pinpointing their value. Created by the US Forest Service, the program hammers out cost-benefit calculations to quantify the contribution trees make in urban environments.The software program is in part a way to save trees by pointing out the contribution they make to cities and towns. Too often trees are invisible, or worse, viewed as a problem because of their root structures impacting pipe systems or their overhanging branches causing any number of issues. However, they do indeed have value, and the US Forest Service wants to show numbers and place tangible values on contributions like cleaning our air, filtering our water, providing habitat to important animal species, and so on.
Gizmag notes that the latest version 3.0 has two analysis tools, and three assessment programs:
As the weather warms and days lengthen, adjust your irrigation timer to water more frequently. Be sure to run your system long enough to wet the top two feet of soil. Deep, infrequent watering is much better than a daily sprinkle.
Tree water use, desert types being the exception, increases rapidly during this period of leafing out and gradually higher air temperatures.
Allow your wildflowers to go to seed. They will produce a natural healthy feast for birds as well as reseeding themselves to come up again in your yard next year.
Make plans for Arbor Day, The Last Friday in April
Climate Information for April in Phoenix, Arizona
Average: 0.22 inches
Record: 3.4 inches (1926)
Temperature (degrees F):
Average High: 84.5 degrees
Lowest High: 52 degrees
Record High: 105 degrees (1989, 1992) Average Low: 55.3 degrees
Highest Low: 77 degrees
Record Low: 35 degrees (1922)
Climate Information for March
in Phoenix, Arizona
Average: 0.9 inches
Record: 4.9 inches (1941)Temperature (degrees F):
Average High: 75.5 degrees
Lowest High: 49 degrees (1915)
Record High: 100 degrees (1988)
Average Low: 48.8 degrees
Highest Low: 74 degrees (1986)
Record Low: 25 degrees (1966)
PLANTS MOST SUSCEPTIBLE: Citrus trees
Leaves turn yellow and fall off
CAUSES & MANAGEMENT:
Some leaf drop is normal for citrus particularly in the late winter/early spring as new leaves are pushing out. Heavy leaf drop could be due to a variety of circumstances:
- CAUSE: Over fertilization
Prevent by following fertilizer application instructions on the product. Treat by watering heavily to flush the fertilizer below the root zone.
- CAUSE: Inappropriate watering strategy, too much, or not enough
As a general rule citrus need a deep watering once a month in the winter and once a week in the summer. Apply water to the entire root zone, well out beyond the drip line. Apply enough water to wet the soil at least a foot below the surface. Check the depth of the irrigation with a long handled screw driver, you will only be able to push the screw driver as deep as the water has gone.
- CAUSE: Citrus Mesophyll Collapse: Grapefruits are particularly susceptible but any citrus may be affected. It is not uncommon for grapefruit trees to be affected and other nearby citrus to be fine. Leaves and fruit of citrus trees dry up and drop. Stems and branches remain green and living. Rarely is the whole tree affected. Mesophyll collapse occurs when there are unseasonable weather changes. For example if it gets abnormally cold in October for several days and then heats back up above average temperature in November. This fluctuation stresses the trees as they kick into and out of and then back into their winter slow down. It is especially stressful after a dry summer.MANAGEMENT:
Remove fallen fruit to prevent attracting fungal and bacterial diseases. Continue to water the tree on its normal cycle and it will leaf-out again in the spring. Do not prune out the defoliated branches until spring, and then only after the tree has completely leafed out.
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James Haley is a certified playground safety inspector