Locating Oak Trees

A basic map tells us that the 6,589 observed oak trees are unevenly distributed across the county. Unsurprisingly, they are most densely clustered in the block groups within and at the foot of the Angeles National Forest. There are also relatively high levels of oak species in the Santa Monica Mountains, and farther north, near Santa Clarita. These are all areas where, based on their mountainous topography and relatively low levels of development, we would expect to see oak species.

The distribution plot gives us a similar view of oak presence in the county. The narrow peak of observations, centered just over zero, emphasizes that most block groups in Los Angeles County have very few oak trees (again, according to imperfect iNaturalist data, which is collected by app users). The median number of iNaturalist-user-observed oak trees in the county is 1. 

The block group that extends farthest into the mountains is the one that has the most oak trees, 12. Though it’s not an enormous count, we can assume that the iNaturalist data, relying as it does on citizen scientists, undercounts tree presence. 

We also notice that one block group farther south has, at least descriptively, more oaks than neighboring block groups. Do any demographic or other neighborhood characteristics account for this difference? 

From the distribution plot, we see that, once again, most block groups have few oaks. Again, the median is 1. Given Altadena’s proximity to the Angeles National Forest, this is somewhat surprising.