Scholarly Work - Ecology
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8716
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Item Distribution of Exotic Plants in the N. Rocky Mountains by Environmental Type and Disturbance Condition(Montana State Univeristy, 1989-06) Weaver, T.; Gustafson, D.; Lichthardt, J.; Woods, B.This report lists seventy-three exotic species found in a systematic sampling of major environmental zones of the Rocky Mountains between the Canadian border and central Wyoming. For each exotic it states the regional distribution, the environmental types (HTs) it occupies (% constancy), the disturbance conditions (DCs) it occupies (% constancy), and its dominance (in terms of% frequency and% cover) in each cell of the HT x DC matrix. Park managers need to develop policy with respect to legally noxious weeds, forage grasses (eg Phleum pratense, Poa pratensis, Bromus inermis, and Dactylis glomerata), and forage legumes (eg Melilotus and Trifolium spp).Item Cone production in Pinus albicaulis Forests(Inland Mountain West Symposium, 1985-08) Weaver, T.; Forcella, FWhitebark pine cone production was estimated for a 6 to 8 year period in each of 29 stands widespread in.the northern.Rocky Mountains. 1) One-time sampling was possible since the estimate was m2de by multiplying the number of branches perm by an estimate of annual cone production made from counts' of cone lets, mature cones, or cone scars on successively older annual increments of those branches. 2) Average cone production ranged from 0.3 to 3.6 cones·m^-2 ·yr^1 and from 22-270 seeds·m^-2·year^-1 . 3) Regression analysis was used to relate the variance observed to time and place. a) Year-to-year variation in the cone yield of branches, trees, and stands in a region appears to be both internally and externally controlled. Internal control is suggested by the fact that good cone years were usually preceded by poor cone years. While external control is indicated by significant correlations between growth and weather conditions, control is not dominated by the effect of any one factor or any particular developmental stage. b) Although cone production of the average branch varied significantly within 30 percent of the trees and within 48 percent of the stands observed, it did not vary significantly among stands. c) Regressions relating stand cone production to easily measured stand characteristics such as canopy cover, fallen cones, and/or stand size explain no more than 50 percent of the variance among stands.Item Bibliography of Montana vegetation description(1988) Burgeron, P.; Kratz, A.; Weaver, T.; Weidman, N.Listed in alphabetical order by author are 549 references to literature that describes the native vegetation of Montana. This updates the 1965 list of Habeck and Hartley. A keyword subject index is included.