Never mind zombies; invasion of the Tamarisk trees is officially here

By Nicolette Smith - 07 Mar 2011 18:44:30 GMT
Never mind zombies; invasion of the Tamarisk trees is officially here

If you combined 'Invasion of the Bodysnatchers' and 'Day of the Triffids', what would you have?

I'll give you a clue; you would have something rather similar to recent scientific study published by the U.S. Department of Agriculture (DoA) and the U.S. Geological Survey (GS). A species of tree – the Tamarisk, too be exact – is swiftly invading the American eco-system and taking over the land. Luckily, we have a natural biological hero in the form of the Tamarisk Leaf Beetle (Diorhabda Carinulata), an Asian Beetle.

The Tamarisk Leaf Beetle is inadvertently battling one of the greatest threats to the U.S. water reserves… by eating it. The Tamarisk Tree, which survives by absorbing river water in a sponge-like manner, has met its nemesis in the Tamarisk Leaf Beetle, an insect whose favourite food of choice is Tamarisk Tree leaf. Two Scientists from University College, working with the DoA ad the GS, have monitored the controlling effect that the Tamarisk Leaf Beetle has on the invasive Tamarisk Tree.

The study, published in the ecological industry Journal Oecologia, investigated the water savings brought into effect by the Beetle's eating habits. Professor Carla D'Antonio, Professor of Environmental Studies at UCSB, said of the collaborative project: "Widespread growth of this tree is a critical issue in arid regions facing greater social water demands. It happens at a time when water supplies may be reduced as a consequence of climate change. Additionally, society is increasingly concerned about wildlife species that depend on these wetland ecosystems."

The Tamarisk Tree – also known as 'Saltceder' - is in the process of taking over US riverside shrubland in western North America; over one million acres are currently dominated by the water-sapping tree, and without the Tamarisk Leaf Beetle the affected waterways would be in serious danger. The shrub as originally introduced into the US eco-system only 100 years ago, and has rapidy taken over. The dangers of the Saltceder shrub don't just run to the monopolisation of water sources, secondary knock-on effects include the displacement of woodland areas, increased erosion and sedimentation problems, the devaluation of the surrounding habitat for animal lifeforms, and is a serious fire hazard due to its dry, brittle composition.

The study, which was part of an agricultural initiative to manage invasive plant movements, saw researchers analysing the Great Basin of Nevada – an area covering approximately 4,500 acres of Tamarisk Tree undergrowth - to see how the mass Tamarisk defoliation by the Tamarisk Beetle affected water dispersement.  The results showed than in only a one-year period, over 2,500 acre-feet of water remained untapped, compared with the results had the Tamarisk tree flourished n the absence of the helpful little Beetle.

To put the utility of the Tamarisk Lea Beetle into perspective; the amount of water saved in the test area is equivalent to the water required to irrigate over 1000 acres over a year, or the annual water requirements of 5,000-10,000 households. Research team member Tom Dudley summarised the results by confirming: "It suggests that the biocontrol of weedy tamarisk across the Western U.S. could play an important role in conserving limited water resources."