Monday, July 26, 2010

In Case You Were Wondering...

I realized that I haven't really explained what the project here is or what exactly I'm doing this summer. I'll try to make sure this isn't too boring/scientific. The project we're working on is a 7-year project (that started last summer) with Tad Fukami from the Stanford Bio Department (who Jenny and I are working for this summer) as one of the principal investigators (PIs). The goal of the project is to examine how the invasive species Rattus rattus (the common rat in case you were wondering) affects food web structures of native forests in Hawaii.

Our work site is the perfect spot to study these effects because it contains about 30 patches of native forest, called kipuka (example above), ranging in size from less than one hectare to more than 10 hectares. The long-term goal of the project is to exclude (that is kill) rats from certain kipuka, see how these forests respond over 4-5 years, and then compare the results to the kipuka where rats were not eliminated to see more accurately what rats do to native forests. To examine the effects that rats have on food webs, the study is specifically looking at birds and insects.
The first five weeks of our work (the end of June through next week) have been spent gathering baseline data about insect diversity and abundance in the kipuka and in the area between the kipuka, the lava fields (known as the matrix). Twice a week, Jenny, Devin (the head field technician here), Bernice (another field tech who helps us out), and I head out to one of the two locations where the kipuka are located and gather branch clippings in garbage bags. Devin and Bernice get samples from the tops of trees inside the kipuka (they have the fun job, see Devin below), while Jenny and I get the branch clippings from the matrix (see below Devin), two in the matrix and one to two inside the kipuka per kipuka we visit.

We then return to the lab where we engage in certainly the most scientifically rigorous aspect of this project; I call it the whack-the-branch-on-the-table-until-all-the-insects-come-out method. We beat the branches on the table to shake the insects off while another person gathers then with an aspirator- a breath-powered vacuum cleaner basically (I worry that some of the insects are smaller than the screen that prevents them from simply being sucked into my mouth...). The branches from each sample are then dried and sorted and the leaf mass is measured to provide an index for insect diversity and abundance (since our sample sizes all vary). Eventually the insects will be identified by a trained entomologist (definitely not me). By the end of this week we will have gathered samples from all 32 kipuka; this work will be done again at the end of the study to help determine how removing rats has affected the food web.

Since this post is so epic, I'll leave a description of our work for weeks 6-10 for another time (I KNOW you can't wait, right?).

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