Ray W. Brown

Alpine Seedling Establishment: The Influence of Disturbance Type

The effects of disturbance type on seedling environment and establishment of alpine species with different physiological and life history traits were examined during a 2-yr study on the Beartooth Plateau in southwestern Montana, USA. We compared soil temperatures, water potentials, and nutrients on mineral soils of a gravel borrow area with those on highly organic soils of a Geum turf area. Seedling emergence, growth, and survival of six seeded species (Geum rossii, Artemisia scopulorum, Potentilla diversifolia, Sibbaldia procumbens, Deschampsia cespitosa, and Festuca idahoensis) and emergence and survival of five unseeded species (Draba crassifolia, Draba incerta, Cerastium arvense, Arenaria rubella, and Androsace septentrionalis) were evaluated on both areas. The effects of N and P nutrient addition and surface organic mulch on the soil environment and seedling es- tablishment were evaluated on the borrow area, while differences between uncleared turf and turf cleared of vegetation were compared on the Geum turf area. Plots cleared of vegetation on the Geum turf area had higher levels of soil N (NO3-) and P than uncleared turf and both higher levels of N (NO3- + NH4+) and P and higher soil temperatures (surface, 5, and 15 cm depths) than fertilized or not-fertilized borrow area treatments. Fertilization increased N and P on borrow area soils, but after 2 yr N had decreased significantly. Soil water potentials (5 and 15 cm depths) did not differ between cleared plots on the Geum turf area or any of the borrow area treatments and were never low enough to cause plant stress. Vegetated Geum turf had significantly lower water po- tentials than cleared plots, especially late in the growing season. Mulch had no effect on soil water potential or nutrients on the borrow area and increased soil temperatures only on clear days during the first growing season. Wind removed or redistributed the mulch over time, thus decreasing potential effects. Seedling emergence was highly dependent on soil surface stabilization and reflected species life history traits. Growth of seedlings was slow, and varied among species and treatments: 0.005-0.04 and 0.02-0.20 g total mass after the first and second growing seasons, respectively. Significantly higher total seedling mass was observed on cleared Geum turf plots than on any of the borrow area treatments, and on fertilized than on not-fertilized plots on the borrow area. Seedling mortality of most species was much lower than previously found for alpine ecosystems, rarely exceeding 50% even after 2 yr. On the borrow area mulch increased survival, probably through microenvironmental amelioration. The nu- trient pulse from fertilization increased mortality of several species, presumably by creating plant nutrient demands in excess of availability during year 2. Both disturbance characteristics and species life history and physiological traits affected seedling establishment. Pretreatment soil properties of the two disturbance types had the greatest effects on soil temperatures and nutrients and, consequently, on seedling growth and survival. Soil surface characteristics had the largest effects on seedling emergence; surface stabilization was essential for holding both soil and seed in place. Single species responses varied in magnitude but were similar on both disturbance types. In general, there were larger differences among species in emergence and growth than in survival. Thus, successful seedling establishment on different alpine disturbance types may depend more

NATURAL REESTABLISHMENT OF MYCORRHIZAE IN DISTURBED ALPINE ECOSYSTEMS

Vesicular-arbuscular mycorrhizal fungi were surveyed in several successional areas of the Beartooth Mountains in Montana. Roots were examined for percentage of mycorrhizal infection, and spores were counted in rhizosphere soils from undisturbed, - 25-yr-old seral, and 3- and 7-yr-old revegetated areas in 1983 and 1984. The three most abundant grasses of early seral areas, Deschampsia caespitosa, Agropyron trachycaulum, and Poa alpina, showed similar patterns: spore counts and percent infection of these species were generally higher in undisturbed than seral and revegetated areas in 1983, but in 1984 the spore numbers and infection were similar because the values dropped in undisturbed areas and increased in the other areas. Patterns of mycorrhizal infection varied for the other species, and Geum rossii, a late seral dominant, was heavily colonized by an unidentified nonendogonaceous fungus. Plant colonization is slow in the alpine, but once plants are established, mycorrhizal fungi apparently colonize quickly. Even the 3-yr-old revegetated area had infection equal to some of the undisturbed areas. However, only a single mycorrhizal fungal species was obtained from the revegetated areas, in contrast to more than 11 species from older areas.

A mapping table for obtaining plant population data.

Researchers and managers aliie are placing greater emphasis on understanding the life history characteristics of plants. Basic demographic data, including patterns of recruitment, reproduction, and survival, are central to understanding plant population dynamics. Such information, in combination with the proper correlative data, allows prediction of changes in plant populations in response to environment, competition, herbivory, or other factors (Schalll984). Applied uses of these data are many and varied. For example, acquiring detailed life history information on rare and endangered plants can help managers devise strategies for insuring their preservation. Mapping tables are routinely used for collecting plant demographicdata (Moore and Chapman 1986, Mackand Pyke 1983, Mack and Harper 1977), but seldom is detailed methodology presented. We describe the construction and use of an acrylic mapping table designed for obtaining basic demographic information from plant populations. Our primary objective was to design and construct a table that would allow accurate and precise relocation of mapping quadrats and plants using acetate sheets as “maps.” The table differs slightly from others that have been described: (1) It was designed so that permanent mapping quadrats were relocated from the positions of permanent corner stakes marked on acetate sheets, rather than from fitting table legs over permanently set stakes. This eliminates the necessity of precise stake locations which is often impossible in rocky soils. (2) The table was built with easy-toadjust legs so that its surface could be quickly leveled on uneven

EFFECT OF ACID MINE DRAINAGE ON A RIPARIAN AREA: ELEMENT CONCENTRATIONS IN SOILS AND PLANTS

The Stillwater River headwaters, located above Cooke City, Montana, have received acid mine drainage (AMD) from the McLaren gold mine since about 1935. To determine the cumulative effects of AMD on the · riparian zone, we collected plant leaf material and soil from the upper 15 cm of the rooting zone of Carex paysonis plants along a gradient of decreasing river water pH. Sampling locations were above the source of AMD into the river, at the source of AMD, and below tha source of AMD. Soil metal concentrations (Al, Cu, Fe, Mn, Pb, and Zn) were generally related to pH or percentage OM. Plant metal concentrations were poorly correlated with soil metal cojcentrations. Plant available metals may have been lower in highly organic soils near the AMD source due to the formation of stable complexes, or high concentrations of some metals may have resulted in toxicity and reduced plant uptake. Concentrations of Cu in plant leaves were higher than suggested maximums for plants and livestock forages at and below the source ofAMD. Additional