Wednesday, March 20, 2013

The importance of "thinking bigger"


by Laura Ladwig (SEV)

My first summer conducting dissertation research at the Sevilleta National Wildlife Refuge I was determined to figure out the germination patterns of the dominant shrub, Larrea tridentata (creosote bush). It currently invades some grasslands at the Sevilleta, while it remains completely absent from others and I wanted to know why. Part of the investigation involved planting L. tridentata seeds in a variety of grass- and shrubland sites, then watering and monitoring them throughout the season to understand where L. tridentata could germinate.

Going into the project, I knew my freshly planted seeds would have a formidable opponent. Rodents. Abundant and diverse throughout my sites, rodents are known to eat both seeds and seedlings of L. tridentata. Always keeping these furry little critters in mind, I designed specialized seed collars to keep the rodents away from my seeds and hopeful seedlings.

 After much planning and time spent counting seeds, we deployed 800 specially crafted seed collars (see above) in long transects across my sites (see below). I was content with my rodent-free seed collar and eager to start monitoring germination.

 But the following week when I went out to water and monitor my seed collars, joy quickly turned to dispair (see below). Once organized transects of little white boxes were now messy and upturned. Seed collars crushed and others completely missing. Who knows where the seeds ended up. I never imagined such a sight and initially didn’t know who was to blaim. Then the hoof and antler marks became apparent. Pronghorn antelope. Apparently my little rodent-free capules became mere toys for the larger desert ungulate community. When planning the project, I had not even considered pronghorn disturbance.

And that was when I learned the importance of thinking bigger. Not only with regards to considering organisms that are physically larger, but also being open to diverse biotic interactions that are not initially obvious. It is easy to get preoccupied with the little things, but important to keep an eye on the big picture as well.

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