Tree Troubles

Before heading out to Montana de Oro I had some idea of the terrain we would be working in, but not a complete picture. From what I understood, the trees had been uniformly planted decades ago, with the intention of cutting them down to use for railroad ties.  I believed that the area was going to be flat and easy to traverse, it just seemed like it would be logical to plant the trees somewhere that would be easy to harvest them.

The evenly spaced trees

The reality partially matched my expectations. The trees were evenly spaced but the ground was not easy to cover as all of the trees were planted on a steep slope. Some areas of the plot were impossible to cover because of fallen trees and other areas were littered with poison oak. We made it out to Montana de Oro around 8AM and by 10 the weather started to heat up, only making it harder to climb up and down the slope.

We had planned to do transect sampling to get a population estimate, but three samples in and our stamina started to give out. After two more samples we decided that we needed to try another method. We weren’t getting the kind of accuracy we needed out of our transect measurements. Our GPS wasn’t accurate enough to keep us on track for the entire length of a transect and the difficult terrain meant we had to wander off track occasionally.

Jefferson and I decided to break off from the transect group and give spot counting a try. We chose a random set of GPS coordinates in the area and measured out a circle with a 15 meter radius. From there we counted every tree inside the circle. We did this twice and compared our data to the transect counted trees. 

The area of the transects was roughly 715m² while the circles measured 707m².  The transect counted trees averaged between 36-49 per plotted area, the spot counted trees were counted as 49 and 41. The methods provide similar data, but the spot counting was substantially easier to do. In the future we will go out to Montana de Oro again and do a more intensive series of spot counting.

My main takeaway from the whole event was that, before deciding on a population estimate method, you need to strongly familiarize yourself with the area you plan on working in. We could have finished our data collection if we had done spot counts from the beginning.

Team Transect feat, Jefferson