12 November 2004

Storm damage

Jim Hannon

Jim Hannon sent this photo of a large elm tree (genus Ulmus) downed by a wind storm around 2:00 AM on 23 May 2004 in Linn County, Iowa. Jim writes, "Some of the other elm trees on the property are dying, maybe from Dutch elm disease. Besides this tree, three cottonwood trees over 60 cm (2 ft) in diameter were pushed over into the neighbor's bean field. The maple trees did not get uprooted, but some had their tops ripped off."

Uprooted trees such as this one provide an important opportunity for serious amateur naturalists, for the scientific literature has considerably more papers about the trunks of trees than about their branches and roots. The canopy branches of downed trees (scroll down to "Tree rings and sunlight") provide an opportunity to compare their leaves, bark, wood and annual growth ring features with branches closer to the ground. The exposed roots permit their size and growth rings to be studied. They also permit the study of the beneficial mycorrhizal fungi (.pdf) that are associated with the roots of virtually all trees.