Ode to oaks

One of the pleasures of comparative biology is exploring new places to find the organisms that are the focus of your research. During my postdoctoral research at the University of California, Berkeley I was fortunate to find myself in a position where I could explore the western part of North America in an attempt to better characterize the drought tolerance of temperate woody angiosperm trees. My study group was the wonderfully diverse oaks of North America. Nineteen species of oaks occur in the western part of the region (see Figure 1) and my goal was to figure out how they varied in capacity to withstand embolism (which I have written about previously).

Figure 1: Nineteen species of oaks (Quercus spp.) from western North America. A. Q. kelloggii (black oak); B. Q. agrifolia (live oak); C. Q. parvula; D. Q. wislizenii (interior live oak) E. Q. palmeri F. Q. chrysolepis (golden cup oak) G. Q. vacciniifolia H. Q. tomentella I. Q. sadleriana J. Q. gambelii K. Q. lobata (valley oak) L. Q. garryana M. Q. durata N. Q. berberidifolia (scrub oak) O. Q. pacifica P. Q. john-tuckeri Q. Q. douglasii (blue oak) R. Q. cornelius-mulleri S. Q. dumosa T. Notholithocarpus densiflorus (tan oak; not an actual oak, but a closely-related species)

As you would expect just by looking at the leaves of the different oaks, many of these species occur in vastly different habitats, including moist temperate rainforest (e.g. Quercus sadleriana; note the moisture on the leaves in the photo) and semi-arid desert scrub or chaparral (e.g. Q. berberidifolia) (see Figure 2). This meant that I had to sample species ranging from the pacific northwest close to the border between Oregon and California to the deserts of southern California close to San Diego.

The measurements that I was taking on each species involved drying the plants down from a hydrated state and visually capturing the point at which they fail (i.e. emoblise) using repeat photographs taken of the xylem. A key part of this measurement process is ensuring that the plants are hydrated when the measurements start. To ensure this I was required to collect the plants in the early hours of the morning, and then place them in a bag to prevent them from drying out. I also needed to take the measurements as quickly as possible from the time when I first collected the plants. The best way to ensure this was to make the hydraulics lab mobile! So, I packed up all the gear into my trusty steed (including scanners, pole pruners, pressure chambers, stem psychrometers and a whole bunch of other equipment) and hit the road (see Figure 3).

“I went to the desert on a horse with no name; it felt good to be out of the rain” [Americas]

On my travels I was accompanied by several incredible assistants, companions and collaborators. Together, we sampled oaks from all sorts of exotic locations. We sampled species in the high elevation deserts in southern California (note the snow), the pristine Channel Islands (we got there by ferry) and slow moving Los Angeles. It was very special to see exciting and diverse habitats and to meet many wonderful people along the way.

You will have to wait to see what we found…as that is a post for another day! One exciting initial finding though is the discovery that science moves at about the same pace as the traffic in Los Angeles (see Figure below)…

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s