For more than 30 years, Arbor Age magazine has been covering new and innovative products, services, technology and research vital to tree care companies, municipal arborists and utility right-of-way maintenance companies
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PLANT HEALTH CARE All photos provided by Rainbow Treecare Scientific Advancements Cherry flowering has been recorded in Japan for centuries Olde timey gardeners are full of all sorts of useful advice. Plant tomatoes when lily-of-the-valley blooms. Plant peppers when the iris bloom. Plant corn when oak leaves are the size of a squirrel's ear. People have been observing and recording these coinciding events going back thousands of years.The Chinese have the earliest written records of these arrival dates, dating to around 974 B.C., and the timing of peak cherry blossom bloom have been recorded every year for the past twelve centuries in Japan.Who knew your grandpa was passing along ancient knowledge when he vociferated you with "corn should be knee-high by the Fourth of July"? Today, powered by the Internet and smartphones, these provincial observations have evolved into a global network of data with tens of thousands of professional and amateur contributors.What were once just farmers' colloquiums are now under the umbrella of phenology. Literally meaning "the science of appearance," phenology studies the timing of life cycles in all living things.The date of bud break, sighting of the first spring flowers, insect emergence, bird migrations, and first leaf turning red in the fall are all observations recorded by phenologists. What are we learning from this information at the global scale and, more importantly to us, how do we use it to improve how we do tree care? 20 Arbor Age / September 2013 The measurement of phenology Your grandpa may know to plant peppers when iris bloom, but when exactly is that? Plants don't have calendars to know when spring has sprung, and, regardless what the calendar says, the first day of spring happens significantly earlier in Atlanta than it does in Minneapolis.Although one aspect of phenology is observing the coinciding events such as what flowers are blooming when this butterfly appears, another aspect of it tries to predict the date on which this will occur. Not only is it difficult to predict an occurrence date across latitudes, it is difficult to predict year to year.Where I live in Minnesota, the spring of 2012 started in mid-March, but in 2013 there was nearly a foot of snow on the ground at the beginning of May. Humans may mark the vernal equinox as the first day of spring each year,but nature's rhythms are less reliable.To try and get a more predictable date, several different phenological indexes track temperature changes and other phenomena, and these can be used to key in when certain events may take place. On the global scale, remote sensing using satellites can give us indications of changes in vegetation at the ecosystem level.The commonly used indicator Normalized DifferenceVegetation Index (NDVI) measures the amount of near-infrared (NIR) light reflected by plants.As the cellular structure of leaves naturally bounces NIR light back into space, measuring this can give a pretty good indication of the vegetative growth www.arborage.com