On Tuesday, the field school explored near the edge of Sibiloi National Park to learn more about adaptive strategies of vegetation in such an arid environment. In particular, we focused on the desert rose, Adenium obesum, a rather amazing tree. The desert rose is an incredibly slow growing tree, growing an average of 1 millimeter per year. It has a very thick trunk for water storage, a waxy coating to help retain water in such an arid environment, and produces rather few leaves and flowers per year to conserve energy. But when it does produce flowers, they are a brilliant pink, and radiate against the harsh landscape.
To find the age of a desert rose, you must find the diameter of a plant in millimeters, which roughly translates to the age in years. However, in field work, it is more accurate to measure the circumference of the plant, and to calculate the diameter afterwards.
We also measured the height, using Jacob’s staffs. While the height is less indicative of age, it is still interesting to note how these ancient trees grow.
After taking a few measurements to practice, we started our field practical. The students were divided into two groups, and each group measured out a forty meter transect, with the primary goal to measure every desert rose that fell into this transect area. Noting the surrounding plants that fell into the range of the transect is also important to accurately paint a picture of the landscape in which these desert roses are living.
Because desert roses tend to be found in relatively close proximity to other desert roses, it can be inferred that the oldest tree in an area is the “grandmother” of most, if not all of the others. One of our goals in this practical was to calculate the age of all the desert roses we measured, and determine which tree was the grandmother. Below is the data, including calculations, from the practical!
|Tree Number||Height||Circumference||Diameter||Diameter (mm)||Age||Notes|
|6||300||220||70.0||700.30||700||“grandmother” tree main trunk|
|128||40.7||407.45||407||“grandmother” tree side trunk|
|170||54.1||541.14||541||“grandmother” tree side trunk|
Later in the evening, we took a brief walk from camp to some nearby exposures to get an early peak at the geology module as well as to discuss the ancient ecology of this area. On our way back to camp, we were treated to a truly radiant sunset.