Autecology of Kobresia bellardii: Why Winter Snow Accumulation Limits Local Distribution

Abstract

In the Colorado Front Range Kobresia bellardii distribution is restricted to alpine meadows which are neither extremely wind exposed nor buried under snow in winter. This study examined reasons for such a limited distribution by comparing the behavior of undisturbed Kobresia with that of transplants into alpine habitats with less and more winter snow accumulation. Kobresia's success in snow—free meadows was related to rapid summer growth and to its use of an extended period for development, from about 1 April to 20 October. New leaves began elongation in the autumn and completed growth the following summer. Most carbohydrates were stored as oligosaccharides in the shoots. During periods of relatively warm weather (>—4°C) in winter, when soil water potential (ψs) rose above —2.0 MPa, leaves elongated slightly; they died back when cold, windy weather resumed. Kobresia did not survive in a fellfield primarily because of mechanical damage by windblown snow and sand. Low ψs led to leaf wilting in summer and winter. Shallow snow cover (°15 cm) that melted early permitted extensive April leaf elongation in saturated soils. The prematurely developed leaves apparently lost frost hardiness and were injured in late spring freezes. In sites of moderate (°75 cm) and deep (°140 cm) snow accumulations, autumn dieback was incomplete when drifts first formed in September and October. Winter freezing destroyed the apparently unhardened leaf tissues and meristems, resulting in loss of carbohydrate reserves. In the moderate snow accumulation sites, leaf elongation was delayed until snowmelt was complete in late June or early July. Interspecific competition appeared unimportant in determining Kobresia distribution. Flower and seed production were reduced up to 99% by habitat alteration. Kobresia may not be reproducing by seed in the Front Range at the present time.

Ground Temperatures under Ski Pistes with Artificial and Natural Snow

“…Wipf et al (in press) found indicator species for snowbeds (alpine depressions with a long-lasting snow cover [Ellenberg, 1988;Körner, 1999]) to be more frequent on pistes with artificial snow compared to off-piste control plots. This finding is in line with other studies where snow-covered time was experimentally extended: A delay in the start of the growing season due to an artificially increased snow cover caused extensive dying of Kobresia myosuroides, a species that is adapted to thin winter snow cover (Bell and Bliss, 1979;Walker et al, 1999). In a snow-manipulation experiment at a snowbed site, the snowbed specialist Sibbaldia procumbens responded in cover to late snowmelt according to its historical snow depth gradient (Galen and Stanton, 1995).…”

Damage of alpine vegetation by the 2009 fire on Mt. Shirouma, central Japan: comparison between herbaceous vegetation and Pinus pumila scrub

“…Most alpine perennial plants store carbon dioxide fixed during a growing season as nonstructural carbohydrates in roots before overwintering, and then these plants grow in the next year by using the nonstructural carbohydrates (Moony and Billings 1960;Bell and Bliss 1979;Kanai and Masuzawa 1993;Shibata and Nishida 1993;Tolsma et al 2007). High concentration of carbohydrates also contributes to frost resistance in winter (Sakai 1960;Yoshida and Sakai 1967;Zachhuber and Larcher 1978).…”

Variation in timing and abundance of flowering by Delphinium barbeyi Huth (Ranunculaceae): the roles of snowpack, frost, and La Niña, in the context of climate change

“…Snowpack has been shown, through both natural variation (e.g., Kudo 1993) and experimental manipulation of snowpack, using both shoveling snow (e.g., Stanton 1993, 1995;Dunne 2000) and drift fences (e.g., Weaver and Collins 1977;Sturges 1989;Scott and Rouse 1995), to have a variety of effects on vegetation and flowering. These include protection from frost (Bell and Bliss 1979), effects on subalpine meadow community pattern (Weaver 1974;Sturges 1989;Evans and Fonda 1990), change in developmental time (Holway and Ward 1963) and productivity (Billings and Bliss 1959;Weaver 1974), variation in percent cover and seed mass through changes in growing-season length Stanton 1993, 1995), phenology (Weaver and Collins 1977;Kudo 1992;Morton 1994;Walker et al 1995), seed set, and mating system (Kudo 1993). Leaf life-span, leaf mass per area (LMA), and leaf nitrogen concentration (Kudo et al 1999) have also been demonstrated to respond to variation in snowpack.…”