For a follow-up to our juniper project for the field ecology class, we went back out near Strawberry Crater yesterday and camped out overnight. We brought a pressure chamber device called a "pressure bomb" to measure the water potential in juniper stems that contained gymnocarpy (cones that are not fully-formed around the seeds) vs. those that did not have gymnocarpy. Basically, you put a stem in the chamber and apply compressed air to it and look through a magnifying glass at the stem until you see water seeping out of the cut. Then you see how many "bars" the meter reads to give you the negative potential water pressure. We thought that trees growing on more stressed sites with less water would be more susceptible to insect larvae causing gymnocarpy in the cones. For this test, we collected stems in the mid afternoon yesterday and pre-dawn today to measure differences in water potential (this changes in the trees at different times of the day). Our results were mixed and seem to suggest that gymnocarpy was higher on stems with more water potential. So, we are going to do some carbon tests as a follow-up later on to help figure out what's going on. It was cool to use the pressure bomb though!
While collecting samples of juniper twigs, we also looked inside some of the gymnocarpous cones to see if larvae were present. We did find a few that had larvae:
Again we found some cool stuff while collecting data. The area has several ancient indian sites and pottery shards were everywhere. Here are some of the various decorations/designs on the shards:
We came across another instance where a Loggerhead Shrike (a predatory songbird) had impaled a grasshopper, this time on a juniper stem, for later eating:
A Sage Thrasher singing its heart out near our campsite:
There were remains of some large mammal near our campsite too. It looked like the skeleton of maybe a pronghorn or mule deer (?). One of my group member's dogs is posing near the skeleton in the 2nd photo for a size comparison. The last photo shows that some hair was still clinging to the bone.
A shot of the juniper-grassland ecotone where we camped:
No comments:
Post a Comment