A Floristic inventory of the Salmon-Challis National Forest

Josh Irwin

Graduate Student, UW Botany Department

During two summers in east-central Idaho, I saw more mountains and desert lands than many Americans see in their entire lives. This region includes seven major mountain ranges and most of Idaho's top 100 summits. There are hundreds of miles of deep gorges along the Salmon River and its tributaries. To the north, one finds groves of grand fir and alpine larch, while to the south, one finds saltbush, greasewood and desert annuals more typical of the Great Basin. In many areas, local relief is nearly a vertical mile from valley bottom to ridgetop. Whenever I climbed to the top of a ridge or peak, I would look out in every direction where, as far as I could see . . . my study area. Since the project was funded by the Salmon-Challis National Forest, most collections (ca. 11,000) occur on US Forest Service lands. Where species were expected to occur exclusively on low elevation BLM lands, these areas were also surveyed.

Foothills of the Lost River Range;
careful driving is necessary in a 2wd.

All the numbers add up to an enormous project, leaving little time for leisure. The commitment to a floristic inventory is not to be taken lightly; 12-14 hr. work days are the norm both in the field and at the herbarium. I can remember early on in my first semester here at UWyo. I thought to myself, “wow, I just finished identifying 150 plants”. Now, at the time of this writing, I’ve identified around six thousand specimens. After awhile it becomes a routine – though each specimen is unique, the process of identification is a careful balance between speed and confidence. I was not altogether inexperienced when I first arrived at UWyo, but I had never undertaken a project of such a grand scale.

While many refer to a floristic inventory as descriptive science, there are many subtle questions which one could explore with additional time and motivation. For example, what biogeographic factors influence the occurrence and distribution of the flora? what are the patterns of diversity across environmental gradients? Between patches, localities and regions? In such an inventory, one practically expects to discover new populations of rare plants, but there is also the slight chance of finding an undiscovered species.