Mini Field Day! (2/21/13)

With Austin as our MC on Thursday we started the day with a recap discussion of Ian Pearse’s talk on Tuesday. There was discussion of the two seasonal oak gall communities, but it was determined that this will not be an issue for our experiment because our timescale will not span the seasonality of these two communities. Concerns were raised over insect taxonomy and it was decided that it is going to be difficult, but as we identify more insects, it will become easier. Sorting first by morpho-type will help in the identification process. Ian mentioned that when collecting galls, you need to be careful not to destroy them when they are knocked off the tree. One of the main insights from this discussion is that we need to have an in depth discussion of our treatment groups.

After this, we divided into groups to conquer our goals/missions for our trip to our field site (oak grove near Russell Ranch) and develop our protocol for Tuesday. Brief mission statements for the teams and are below:

Survey Team (Austin, Wenbo, Melissa and Esther)

Find, count and flag/tag oak trees, measure height and dbh

Gall Counting Team (Nuray and Carolyn)

Count the number of galls per tree

Collecting Team (Ivana and Kyle)

Collect galls and insects from non-experimental oak trees for baseline data

Materials and Methods Testing Team i.e. Team Destruction (Jenn and Robyn)

Experiment with different methods of removing galls and bagging branches

When we felt we had discussed our protocol enough in our groups, we unleashed ourselves on campus to practice them in a more realistic setting. While I cannot speak for other groups, the Collecting Team and Team Destruction had an especially fun time practicing the protocol. Together we shared some special moments:

reaching for the galls

insect and gall collection

standing on one foot while doing field work

When we returned from the field we discussed any problems or issues we ran into while practicing. The Gall Counting team was concerned with what exactly is considered a gall because there were a couple that were very small and some that appeared to be growing very close or on top of each other. When counting galls we need to consider what about the galls is most important. Do we just want the number of galls? Or do we want to find a way to measure gall volume and/or surface area? Answers to these questions likely depend on how organisms are using the galls. The Survey team had a little difficulty attaching flags/tags to some of the trees because the branches were high up on the tree. They were concerned about figuring out a maximum and minimum height for experimental trees. This is something that our trip to our field site might help resolve. Team Destruction (as their name implies) destroyed a large trash bag while attempting to bag a branch. It was decided that thicker bags were greatly needed. Team Destruction felt confident in their ability to remove galls with the fruit picker being especially effective. Finally, the Collecting team needs a beat sheet to improve their (already amazing) insect collecting skills.

After this discussion, we began writing down all the different hypotheses we could think of for this experiment.

H’s about changes in abundances/population sizes
H1: Galls increase the number of spiders on trees by providing domatia which increase adult survival–>more adults
H1: Galls increase the number of spiders on trees by providing domatia which increase adult reproduction or increase spiderling survival–>more spiderlings
H1A(tree): Spiders decrease the number of immobile (relative to size of tree) herbivore insects through consumption
H1B(branch): Spiders decrease the number of herbivore insects through consumption of immobile (relative to size of branch) and emigration of mobile prey

H2: Galls increase the number of herbivore insects on trees by providing domatia
H2A(tree): Herbivores will decrease leaf foliage area and decrease shoot elongation through consumption and increase spider number by providing more prey
H2B(tree): Herbivores will decrease leaf foliage area and decrease shoot elongation through consumption and decrease spider number by taking refuge in galls (decreasing available prey to spiders)

H’s about changes in species richness
H3: Galls increase species richness by providing more niches (food, shelter, etc)

H4: Galls don’t influence the number of any potential secondary users

H5: Galls influence detritvores (earwigs).
H6: Galls increase both spider and herbivore abundance by providing domatia for both
H7: Parasitoids.

After working on this for a while, we began creating a long term timeline for the class. This is not yet finished, but will be soon. This will keep us thinking about our long term goals through out the course.

Since this is going to be our project, it would be beneficial for everyone to read two papers from the readings folder for this project. If we could all have that done by Tuesday we will have a better understanding of what we are observing in the field.

On a final note, it is important to remember that when in the field, everything takes much longer than expected. Most likely we will not finish gathering all of the data we need on Tuesday, so expect another field day on Thursday if it is necessary.


900-940: Gather materials and drive out to field site.

940-1000: Work through the protocol on the first tree together as a team

1000-1125: Split into groups to collect data

1125-1150: Return to campus

One response to “Mini Field Day! (2/21/13)

  1. possible H7s: Galls promote parasitoids by increasing concentrations/abundances of host species /vs./ Galls limit parasitoids by increasing (protective) domatia for hosts /vs./ Galls have no effect on parasitoids…

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