If you garden for birds you know that what you plant has a huge effect on the variety of birds in your yard.  This applies on a larger scale as well.

In recent years our government has encouraged the development and manufacture of biofuels to replace our dependence on foreign oil.  The typical method is to grow corn and refine it into ethanol.  This has spawned a debate on the wisdom of converting valuable farmland into acreage devoted to fuel instead of food and using the corn supply to feed our cars. 

But corn, a labor intensive crop that must be planted every year, is not the only source of biofuel.  Perennial grasses like switchgrass work as well.

When our government provides subsidies to grow biofuel feedstock, even marginal land will be converted to this purpose.  Does it matter what we plant?  Indeed, it does.

Last month two researchers from the University of Wisconsin-Madison published a study on the effect of bioenergy crops on bird diversity in the Upper Midwest.  Using bird surveys and land use maps, Claudio Gratton and Tim Meehan calculated the change in bird diversity when marginal land is planted in annual monocultures (corn) versus a mixture of perennial prairie plants and grasses.

Their results are shown in the maps above.  Brown is bad — species decline up to 50%.  Blue is good — species increase up to 200%. 

Can you guess which map is which? 

The lefthand map shows bird diversity declines up to 50% if we plant monocultures of corn for biofuel.  The righthand map shows that bird diversity doubles if we plant diverse grasslands.

It’s no surprise that monocultures are bad but the results are frightening.   Click here to read more about this in Science Daily.

(image linked from Science Daily.  Click on the image to read the article.)