2001 THE MICHIGAN BOTANIST 3 THE RARE PLANTS OF FORT MCCOY MILITARY RESERVATION, MONROE COUNTY, WISCONSIN Mark K. Leach The Nature Conservancy, Wisconsin Field Office 333 West Mifflin Street Madison, Wisconsin 53703 ABSTRACT Fort McCoy Military Reservation is a 24,180 ha United States Army training facility in west-cen- tral Wisconsin. In 1991 and 1992 I conducted the first extensive survey at the fort for rare vascular plants, documenting 89 stations of 14 species including four Wisconsin threatened and 10 Wisconsin watch-list species. Two species, bog bluegrass (Poa paludigena) and fame flower (Talinum ru- gospermum), were also listed as United States Fish and Wildlife Service Category 2; large popula- tions of these grow at the fort. One formerly documented species, the Wisconsin endangered rough white lettuce (Prenanthes aspera), was apparently extirpated. I briefly describe my observations on population size, habitat and apparent threats. For convenience of reporting, the rare plants are dis- cussed in an upland group (Artemisia dracunculus, Asclepias ovalifolia, Gentiana flavida, Opuntia fragilis, Polytaenia nuttallii, Solidago sciaphila, and Talinum rugospermum) and a lowland (or wet- land) group (Bartonia virginica, Carex folliculata, Poa paludigena, Polygala cruciata, Rhexia vir- ginica, Scleria triglomerata, and Thelypteris simulata). Generally, rare plant conservation appears to be compatible with military training: both benefit from restoring and maintaining semi-open, sa- vanna-like upland landscapes and preventing activities which would damage wetlands. INTRODUCTION Fort McCoy Military Reservation is an installation of the United States Army located in Monroe County, Wisconsin (Figure 1). The primary mission of the Fort is to serve as a facility for military training. Training first began on Major General Robert Bruce McCoy’s ranch in 1905. The army bought 5,750 ha in 1909 and has since used the facility more or less constantly. Currently more than 100,000 people train there annually. The fort now occupies 24,180 ha, of which 23,358 ha are classified as “unimproved.” The facility lies south of the Tension Zone (Curtis 1959) within the Driftless Area (Figure 1), an unglaciated region of geologically ancient, highly eroded, steep-sloped, sandstone hills with narrow ridges and broad valleys. Prior to Euro-American settlement, the generally thin upland soils supported vegetation described by Hole & Germain (1994) as “largely oak savanna, with patches of oak forest. Some white pine (Pinus strobus) and red pine (P. resinosa) were pre- sent on favorable exposures and on coarse-textured soils. The savanna was com- posed of bur, white, black, and Hill’s oaks (Quercus macrocarpa, Q. alba, Q. ve- lutina, and Q. ellipsoidalis) in a matrix of prairie grasses and forbs.” The Present address: University of Wisconsin-Madison Arboretum, 1207 Seminole Highway, Madison WI 53711-3728. E-mail: [email protected] 4 THE MICHIGAN BOTANIST Vol. 40 FIGURE 1. Fort McCoy Military Reservation (black) is located in Monroe County, Wisconsin within the Driftless Area (dotted lines), west of the ancient bed of Glacial Lake Wis- consin (gray), and south of the Tension Zone (dashed lines; Curtis 1959). The size of the fort averages about 25 km north to south and 8 to 10 km east to west, Latitude 43° 54’ to 44° 9′ North, Longitude 90° 36′ to 90° 46′ West. nutrient-poor drought-prone soil, the short growing season, and common wild fires combine to maintain much of the savanna-like character of the uplands. However, many areas now are presumably more densely timbered than at settle- ment. Some of the valleys contain extensive wetlands on soils varying from sand to muck. Existing wetland communities include hardwood swamp, wet prairie, 2001 THE MICHIGAN BOTANIST 5 sedge meadow, Sphagnum bog, shrub-carr, tamarack (Larix laricina) swamp, and emergent aquatic marsh. The fort contains 10 major and 10 tributary streams, totaling 17.7 km in length. They are cold, fast-flowing, spring-fed, and sandy-bottomed. Trainers restrict military equipment, for the most part, from wetlands and streams. Annual normal precipitation is 79 cm (Fort McCoy 1983). The Mauston weather station, which is about 48 km east-southeast of Fort McCoy, reports 84 cm of mean average annual precipitation, with most falling in summer (30 cm). They also report that the area has an average summer temperature of 20° C and average winter temperature of –8° C, with extremes of 39° C to –38° C. Median last and first frost dates are May 15 and September 26. The year-to-year varia- tion of weather parameters is considerable. Like many other military installa- tions, Fort McCoy has preserved rare species and communities, including what is likely the largest metapopulation of the federally endangered Karner blue but- terfly (Lycaeides melissa samuelis; Leach 1993a, Bleser 1993). Other rare ani- mals found at the fort include the phlox moth (Shinia indiana; Maxwell & Ferge 1994, Kirk 1994) and the slender glass lizard (Ophisaurua attenuatus; Nedrelo 1994). Fort McCoy’s Natural Resource Management Division (NRMD) contracted with The Nature Conservancy-Wisconsin Field Office to survey the fort for rare plants. During the growing seasons of 1991 and 1992 I surveyed for populations of vascular plants listed by the Wisconsin Department of Natural Resources as Endangered, Threatened, or Watch and plants listed by the United States Fish and Wildlife Service as “Category Two.” State and federal agencies are consid- ering “Watch” and “Category Two” species, respectively, for protection as Threatened or Endangered. No plant species currently listed as federally endan- gered or threatened were thought to occur on the fort. Here I give a condensed and revised version of my rare plant survey report (Leach 1993b). I conclude this paper by discussing the challenges for continued plant conservation in the midst of a heavily used military training facility. METHODS Within the boundaries of Fort McCoy, I conducted status surveys for rare plant species. Fourteen such species had previously been reported as growing on the fort. I resurveyed their historic locations (if known) as well as other likely habitats. I worked full-time throughout most of the growing season in 1991 and 1992, alternating this survey with surveys for the Karner blue butterfly (Leach 1993a) and its host plant, wild lupine (Lupinus perennis). I surveyed most portions of the fort except the “hot” North Impact Area—a 2100-ha target area for live ammunition. For each population encoun- tered I mapped the location and recorded the population size, extent, habitat, associated species, and possible threats. The names of tentatively identified specimens were verified by Theodore Cochrane, Curator, University of Wisconsin Herbarium, Madison and by other herbarium staff. Robert Freckmann, Uni- versity of Wisconsin-Stevens Point, helped name numerous grass specimens. Nomenclature follows Gleason & Cronquist (1991). 6 THE MICHIGAN BOTANIST Vol. 40 RESULTS I increased the number of known rare plant stations (Table 1) from 27 to 89. Of those populations, 48 were fame flower (Talinum rugospermum). I verified the presence of thirteen previously reported rare plant species and I documented one new species: dragon’s sagewort (Artemisia dracunculus). I did not find five previously reported species: large water starwort (Callitriche heterophylla), tufted hairgrass (Deschampsia cespitosa), large-leaved avens (Geum macrophyl- lum), rough white lettuce (Prenanthes aspera), and silky willow (Salix sericea). Of these, only the record of rough white lettuce, which was made in 1981, was supported by a clearly identifiable specimen (Bever, WIS). Without good speci- mens, the other reports are questionable. For convenience, the findings are presented in two groups: upland species and lowland species (Table 1). The upland species are geographically centered on the Great Plains or the Midwest and the lowland species are geographically related to eastern North America. Each species’ summary includes a description of population size and habitat at the fort. Herbarium specimens that I collected or examined are indicated parenthetically. I. Upland Species The fort’s extensive oak and jack-pine (Pinus banksiana) savannas, dry prairies, and sandstone outcrops supported seven rare plant species. Clearly, the most widespread and abundant of the rare plants at the fort was the fame flower (Talinum rugospermum: Portulacaceae). This small, fleshy-leafed, perennial herb grows in the upper Midwest, Nebraska, Kansas, and east Texas, but is most common in western and central Wisconsin (Cochrane 1993). I found populations in four previously reported locations and in 44 new locations. It subsequently has been found elsewhere on the fort (Dave Beckmann, pers. comm.; Maxwell & Givnish 1994). At Fort McCoy, fame flower thrives in areas with apparent intermediate in- tensity disturbances (e.g., mechanical or fire) either in full sun or partial shade. It most commonly grows in small vegetation gaps (about 5 to 30 cm diameter) within a matrix of short native species, such as Pennsylvania sedge (Carex pen- sylvanica). This is consistent with Cochrane’s (1993) view that fame flower is not a typical sand prairie species, but is a specialist with a narrow ecological am- plitude and a lack of competitive ability. Habitats at the Fort were jack-pine bar- rens, sandy oak savannas, sand prairies, semi-eroded sandy slopes, sandstone outcrops, and the margins of sand blows and tank trails. I found one population of dragon’s sagewort (Artemisia dracunculus: Aster- aceae). It is a herbaceous perennial native to Eurasia and the Great Plains. The eastern limit of its North American range is in Wisconsin. The Fort McCoy pop- ulation included about 50 apparent clones, each with from five to 100 stems. These were located in full sun on a good quality bluff prairie situated on a steep (20–30 percent) southwest-facing slope (Leach 2319, WIS). This habitat is sim- ilar to the sandy bluff prairies (Mickelson & Iltis 1966) and rocky bluff prairies (Hartley 1966) described for other Wisconsin populations. 2001 THE MICHIGAN BOTANIST 7 TABLE 1.