The Onion Park Research Natural Area (RNA) lies on the eastern most extension of the Tenderfoot Creek Experimental Forest. This minimally disturbed 1209 acre sub-watershed is used for monitoring natural ecological change such as plant succession and stream dynamics. Baseline information (see Botanical and Ecological Resources Inventory, Mapping and Analysis) collected within the RNA is useful to assess the effectiveness of management activities performed on similar sites.
The Onion Park RNA contains several important features:
- A 73 acre subalpine mesic meadow with high forb diversity, named for the presence of three species of onion (Allium spp.). Onion Park also contains pink agoseris (Agoseris lackschewitzii), a sensitive species for the Northern Region.
- The headwaters of Tenderfoot Creek, a major tributary of the Smith and Missouri rivers.
- Subalpine forests characterized by overstory dominance of lodgepole pine (Pinus contorta) and classified as the subalpine fir/grouse whortleberry and subalpine fir/bluejoint reedgrass habitat type.
- Quartzite Ridge, a talus/scree slope with scattered lodgepole pine and whitebark pine (Pinus albicaulis).