Two days ago, the Iowa Department of Natural Resources reported that 950,000 trees along the Iowa side of the Missouri River are likely to die as a consequence of the Great Flood of 2011. How the Iowa DNR came up with that figure is anyone’s guess. I think the figure of 1 million trees would have been a more impressive number, or maybe 2 million. The reality is that no one knows how many trees are going to die in the months and years ahead. But it is apparent that astronomical numbers of trees will die.
In the past, before the construction of the Dakota and Montana dams, the river annually experienced an April and June rise. On average, neither of those rises lasted longer than a few weeks. The biggest flood of the year occurred in June. But it was rare for a June rise to last longer than a month – although it did happen on occasion. Because floods during the pre-dam era were of shorter duration, valley vegetation inundated by high water usually survived the deluges. However, this year’s flood represents a hydrological anomaly in the river’s history. High water remained atop the valley floor for three months. Trees that had adapted to the river’s past hydrological regime did not evolve to survive an extended period underwater. Thus, countless trees are now dead and still more will die in the future. Dead trees are visible everywhere along the river’s banks in the Sioux City area. The trees closest to the river’s edge experienced the longest period beneath the dark water and thus have suffered the highest loss rates. Yet, even trees further back from the river will die.
The loss of timber will have dire consequences for birds and mammals. Songbirds, already hard-pressed in the United States from the human destruction of their habitat and from cat-induced mortality (yes, your lovable kitty is a natural born bird killer), will decline further with the loss of vast tracts of Missouri Valley forest habitat. Populations of white-tailed deer, raccoons, turkeys, beaver, and possums will also diminish over the next several years as valley timber disappears. But that isn’t even the whole story. Valley timber tracts act as buffer strips, keeping farm pollutants out of the Missouri. With the trees gone, herbicides, pesticides, fungicides, and animal waste will more quickly pass into the river – which will harm fish – and potentially the humans who consume those fish. Healthy trees served as obstacles to surface runoff which in-turn slowed or stopped water from entering the big stream. As the trees die, more rainwater and snowmelt will move off of farm fields and into the Missouri, forcing it to rise higher faster. Trees act as natural reservoirs too. They capture rainwater in their leaves, branches, trunks, and root systems. Without valley timber, even more water will find its way to the Missouri. And lets mention the roots. Tree roots hold soil together. As the trees die, soil will be more apt to erode off the land into the river. Riverside trees even stabilize the Missouri’s banks. Without bank side trees, the river will be more prone to cut into its banks and cart the soil off to the Mississippi.
The loss of valley timber can be mitigated with concerted government action. The federal government should initiate a large-scale tree-planting program within the Missouri’s floodplain right now! We cannot wait. And the species in the valley cannot wait. To wait is to increase the costs of this year’s disaster. Planting trees will save the public untold millions in preserved soil fertility, continued hunting opportunities, bank erosion prevention, and water quality control. The Tea Party-controlled House of Representatives needs to pass an appropriations bill for such a program this fall. Otherwise, the party’s fiscal fanaticism will cost us all far more over the long-term.