TSG Field Trip, August 2025
The TSG took a field trip to La Plata Canyon on the morning of August 22. Participating were, Elli Morris, Andy Hawk, Jim Gale, and Jeff Wagner.
The group stopped halfway to Mayday from Highway 160 to study a planting of about 10-15 Pinus aristata made by the firm Ecological Designs over a decade ago, when they were planted as 6-8 ft. trees. They have grown nicely since and now form a grove of healthy densely branched trees with mature cones that have more than doubled in height. They are well-established and have certainly benefited from supplemental irrigation, although there is no evidence of irrigation during this year’s brutal drought. This pine is exclusive to the E. Slope of the Colorado Rockies, with outlying populations in New Mexico and Arizona, but nowhere further west. It is cultivated on the Front Range, and less commonly on the Western Slope, where Pinus flexilis and P. strobiformis cf. are planted more frequently. It forms an interesting comparison with P. longeava, and P. balfouriana that both fill a near-identical ecological niche in California and in Nevada, and with similar growth patterns and longevity.
Our next stop was just past Mayday where the La Plata River exits the valley before a relatively deep canyon full of mature, large Southwest White Pine. At this spot, one can observe mature SWWP, Pseudotsuga menziesii, Acer glabrum, Populus tremuloides, Populus acuminata, Quercus gambellii, and others. There are also spectacular views of most of the La Plata Mountains that are significantly different from the other SW Colorado ranges, the San Juans, the Sangre de Christos, and the higher ranges of Utah, New Mexico, and Utah further south. The La Platas are geologically distinct from these other ranges, are roughly oriented at 90 degrees to the San Juans, and they form their own weather pattern with a unique flora in some respects.
We used the remainder of the morning on the main road to gain over a thousand feet of elevation, mostly along the river’s banks where possible, to see what we might find. There were several notable, large Picea englemannii, Abies lasiocarpa, and only a single, older, and well-formed Abies concolor, that is otherwise significantly more common in most of the rivers and creeks draining the San Juans. We also encountered Alnus incana, Sorbus scopulina, Rubus ideaeus, Symphoriocarpus, Lonicera, Salix, Paxistima, and more, although the drought has bit hard in nearly every plant community this year, and many plants were already going dormant for the season.
When the next opportunity arises, we certainly hope to have more time, and more favorable conditions to study this unique mountain range with its beautiful flora.
