Over the past century tree encroachment has occurred in North American subalpine meadows. Causes of tree establishment have been related to climate influences and exclusion of fire, but very few studies have looked at the consequence of tree encroachment on meadow vegetation. Within the southern Canadian Rocky Mountains, Waterton Lakes National Park and Castle Special Management Area, 14 meadows were randomly selected at wet and dry sites. Nonmetric multidimensional scaling showed that species composition changed during the transition of open meadow to forest for both wet and dry habitats. There were no significant differences in these two management areas in terms of conifer encroachment and the effects on meadow species. Results of this study show that conifer encroachment has increased over the last century with the consequences of loss in meadow species through a decrease in abundance, richness and diversity. Wet sites were significantly more sensitive to conifer encroachment than dry sites. The greatest inhibitory effects of trees on meadow vegetation within the ecotone occurred when trees were 54-72 years old for wet sites and 77-112 years old for dry sites. Ecological restoration of these meadows is important for ongoing habitat conservation, maintaining species and landscape diversity and ecosystem resilience.

The structural integrity of fire-dependent ecosystems, such as ponderosa pine (<i>Pinus ponderosa </i> Dougl.) and Interior Douglas-fir (<i>Pseudotsuga menziesii </i> (Mirb.) Franco) biogeoclimatic zones in Interior British Columbia (BC) is changing. The problems within these ecosystems include decreased rangeland area, reduced carrying capacity and loss of biodiversity due to tree encroachment and forest ingrowth caused mainly by fire suppression. The goal of this study was to determine the effect of burning and thinning on understory vegetation of grassland and forested sites. The burning experiment took place at Dew Drop (Tranquille Ecological Reserve) located 20 km northwest of Kamloops, BC. Thinning was done at two upper grassland sites near Cache Creek, BC; Coal Mine Pasture and Gladys Lake Pasture. Species evenness and values of the Shannon-Weiner Diversity Index (H) were reduced (13 and 27%, respectively) within three years following burning (P = 0.014 and P = 0.038, respectively). Burning reduced canopy cover of shrubs on grassland sites (P = 0.005) and it reduced graminoid cover on forest sites (P = 0.014) immediately after the treatment (1999) but both functional groups had recovered by 2002. Litter depth and total canopy cover of plants were reduced in grasslands and forests immediately following burning (1999) but litter depth and canopy cover had recovered by 2002. Litter cover and litter depth beneath the tree canopy were reduced by burning (P = 0.037 and P = 0.009, respectively). Trends in the data indicate forb standing crop increased and total understory standing crop increased following burning in the grassland compared to the control. Graminoid standing crop was reduced 47% by burning in the forests (P = 0.049). Thinning reduced species richness in the first (P = 0.033) and fourth (P = 0.030) years, and H in the first year (P = 0.037) following the thinning at Coal Mine Pasture. Trends in the data suggest understory standing crop increased at Coal Mine and Gladys Lake Pastures following thinning. At both locations, thinning reduced litter depth. Therefore, burning and thinning kills trees, reduces fuel loads, and increases standing crop of the understory.

The structural integrity of fire-dependent ecosystems, such as ponderosa pine (<i>Pinus ponderosa </i> Dougl.) and Interior Douglas-fir (<i>Pseudotsuga menziesii </i> (Mirb.) Franco) biogeoclimatic zones in Interior British Columbia (BC) is changing. The problems within these ecosystems include decreased rangeland area, reduced carrying capacity and loss of biodiversity due to tree encroachment and forest ingrowth caused mainly by fire suppression. The goal of this study was to determine the effect of burning and thinning on understory vegetation of grassland and forested sites. The burning experiment took place at Dew Drop (Tranquille Ecological Reserve) located 20 km northwest of Kamloops, BC. Thinning was done at two upper grassland sites near Cache Creek, BC; Coal Mine Pasture and Gladys Lake Pasture. Species evenness and values of the Shannon-Weiner Diversity Index (H) were reduced (13 and 27%, respectively) within three years following burning (P = 0.014 and P = 0.038, respectively). Burning reduced canopy cover of shrubs on grassland sites (P = 0.005) and it reduced graminoid cover on forest sites (P = 0.014) immediately after the treatment (1999) but both functional groups had recovered by 2002. Litter depth and total canopy cover of plants were reduced in grasslands and forests immediately following burning (1999) but litter depth and canopy cover had recovered by 2002. Litter cover and litter depth beneath the tree canopy were reduced by burning (P = 0.037 and P = 0.009, respectively). Trends in the data indicate forb standing crop increased and total understory standing crop increased following burning in the grassland compared to the control. Graminoid standing crop was reduced 47% by burning in the forests (P = 0.049). Thinning reduced species richness in the first (P = 0.033) and fourth (P = 0.030) years, and H in the first year (P = 0.037) following the thinning at Coal Mine Pasture. Trends in the data suggest understory standing crop increased at Coal Mine and Gladys Lake Pastures following thinning. At both locations, thinning reduced litter depth. Therefore, burning and thinning kills trees, reduces fuel loads, and increases standing crop of the understory.

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