Aboveground Productivity and Floristic Structure of a High Subalpine Herbaceous Meadow

Abstract

The aboveground primary productivity within each of four areas, differing in length of the snow-free season, was determined in a high subalpine (3380 m) herbaceous meadow in Colorado. Net productivity, minus losses to herbivores, ranged from 114 g • m~2 • yr" and Senecio crassulus, the only dominant forb species common to all four areas, showed differing patterns of productivity within and between areas. Domestic sheep may have removed up to 38% of the peak standing crop within the study area during 6 h of grazing. Variation in dominance-diversity curves among the four areas suggests that the effect of snow cover in controlling the length of the growing season may be less important than its influence on moisture availability in determining the overall structure of this subalpine community.

Understorey plant community structure in lower montane and subalpine forests, Grand Canyon National Park, USA

“…Snow‐pack location is strongly correlated with topography (Billings, 1973), and the persistence of winter snow pack strongly influences plant community structure in subalpine forests (Fonda & Bliss, 1969; Kuramoto & Bliss, 1970; Douglas, 1972; Canaday & Fonda, 1974; Knight et al. , 1977; Anderson et al. , 1979).…”

“…Warmer, southern exposures harboured more species than cooler, northern exposures. Snow-pack location is strongly correlated with topography (Billings, 1973), and the persistence of winter snow pack strongly influences plant community structure in subalpine forests (Fonda & Bliss, 1969;Kuramoto & Bliss, 1970;Douglas, 1972;Canaday & Fonda, 1974;Knight et al, 1977;Anderson et al, 1979). Although we did not measure snow pack on these sites, the Kaibab Plateau receives an average of 3.56 m snow each winter, and snow depths of 1-3 m have been recorded (Merkle, 1962).…”

“…Topography can affect community structure in the region because of increased insolation on southern slopes and prolonged snow packs on northern slopes (Fonda & Bliss, 1969;Kuramoto & Bliss, 1970;Douglas, 1972;Canaday & Fonda, 1974;Anderson et al, 1979). Increased insolation on southern exposures raises soil temperatures and evaporation rates, and reduces the duration of the winter snow pack (Patten, 1963).…”

“…Topography can affect community structure in the region because of increased insolation on southern slopes and prolonged snow packs on northern slopes (Fonda & Bliss, 1969; Kuramoto & Bliss, 1970; Douglas, 1972; Canaday & Fonda, 1974; Anderson et al. , 1979).…”

Subalpine forests

“…Other excellent recent summaries of the world production characteristics can be found in Rodin and Bazilevich (1968), which also includes accumulation and dynamics of ash elements and nitrogen for various vegetation types, including conifer foreststopics beyond our purview. Parenthetically, we note that despite the above generalization, certain subalpine forests of northwestern North America and possibly Japan are more productive than most boreal forests, and most show productivity values greater than the 5-10 mt ha-1 yr-1 considered an upper limit for subalpine meadows (Andersen et al, 1979).…”