Ecology

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The department's teaching and research addresses critical ecological and natural resources issues for Montana, but also tackles fundamental and applied questions around the globe. Undergraduate programs within the department include Fish & Wildlife Management and Ecology, Conservation Biology and Ecology, Organismal Biology, and Biology Teaching. Graduate programs (M.S. and P.hD.) include Fish & Wildlife Management or Biology and Biological Sciences and an intercollege PhD in Ecology and Environmental Sciences.

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1974 - 197921980 - 19901

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Author: search.filters.author.Dale, D.

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    Trampling Effects on Vegetation of the Trail Corridors of North Rocky Mountain Forests
    (1974-08) Dale, D.; Weaver, T.
    The management of trails should be based on knowledge of the effects of humans on them; most of the available information has been reviewed by Speight (1973), Stankey & Lime (1973), and Liddle (1975). Observations of existing trails suggest the following conclusions. (1) Vegetation cover is reduced by trampling and some plants are more resistant to trampling than others (Speight 1973; Liddle 1975; Dale & Weaver 1974; Davidson & Fox 1974). (2) Trail width increases linearly with increasing slope, wetness, roughness and the logarithm of the number of users (Bayfield 1973; Dale & Weaver 1974), but decreases linearly with the logarithm of the roughness of trailside vegetation and terrain (Bayfield 1973). Vegetation more than 2 m from the edge of a trail is often little effected (Dale & Weaver 1974). (3) Trail depths depend on compaction and erosion and therefore on climate, vegetation type, soil and substrate type, slope, and type of user (Helgath 1975; Dale & Weaver 1974). (4) Soil compaction is usually greater, i.e. bulk densities average 02-06 g cm-3 greater, in trampled areas than in untrampled areas. Several experimental studies .have shown the quantitative effects of wear on vegetation (Bell & Bliss 1973; Liddle 1975; Liddle & Greig-Smith 1975; Rogova 1976) but there has been no experimental comparison of the effects of different modes of trail travel. The experiments reported below compare the effects of hiker, motorcycle, and horse trampling on level and sloping sites in both a meadow and a forest with a dwarf shrub understorey.
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    Pinus albicaulis in Central Montana: Environment, Vegetation and Production
    (1974-07) Weaver, T.; Dale, D.
    Nineteen apparently climax, non-krumholz, whitebark pine (Pinus albicaulis) forests were sampled at 2490-2930 m in the Rocky Mountains of S-Central Montana. The understory of these forests is strongly dominated by Vaccinium scoparium (median cover 40% +). Mature stands (200 + years old), with trees 12 m high, had basal areas of 14-24 m2/ha and had merchantable volumes of 195 m3/ha. Whitebark stands usually occur on soils of igneous origin. The growing season in a typical stand has 3 wet months with over 80 mm of rain and 3 dry months with less than 50 mm of rain; average maximum temperatures in this period rose to 20 C while average minimum temperatures Jell below 0 C.
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    Stand development in whitebark pine woodlands
    (1990) Weaver, T.; Forcella, F.; Dale, D.
    Analysis of density data from stands in the Northern Rocky Mountains shows that, while seedlings establish at the rate of over 1,000 I ha x year in whitebark pine-grouse whortleberry (Pinus albicaulis-Vaccinium scoparium) forests of all ages, stem numbers in the canopy thin to 400 at 30 years, 150 at 200 years, and 100 at 300 to 600 years. Indices of productive potential, cover, and total circumference rise to an asymptote at about 100 years. Total basal area rises from 0 to 60 m21 ha at about 200 years, the aggregate basal area of trees with diameters over 20 em rises from 0 to 40 m21 ha at about 250 years, and tree height maximizes (12 m) at 200 years. It is hypothesized that further growth in productive potential (that is leaf and I or root area) is prevented by limited supplies of water or a nutrient, further growth in basal area is prevented by lack of a nutrient (probably not carbon, hydrogen, oxygen, or nitrogen) and further growth in height is prevented by scarcity of water.
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