The impact of recreational trampling and vehicular traffic on sandhill communities
Heath, Judith Y.
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The study investigated the effects of pedestrian trampling and vehicular traffic on two sites of the Dundurn sandhills in southern Saskatchewan, where soils are loamy sand to sandy loam in texture. Experimental trampling was conducted at 0, 10, 50 and 100 passes/week for 10 weeks of the summer (June - August) in 1979 and 1980 on native Stipa-Koeleria prairie, seeded Bromus-Agropyron prairie and Populus tremuloides understorey. Treatments were designed to compare the effects of one and two summers of trampling and the extent of community recovery in the year following one summer of trampling. The woodland comnunity was most affected by trampling but the vegetation recovered relatively well during 1980 after trampling had ceased. Of the prairies, the seeded cover was slightly less tolerant than the native cover, but recovery was relatively slow on both. Existing paths also indicated that grassland cover was more resistant than woodland cover. Plant height was reduced in the prairies, and litter depth was reduced in the woodland by trampling, but both recovered slightly during 1980 after trampling ceased. Soil penetrometer resistance increased with increased trampling intensity in all communities, and recovered slightly in the woodland and seeded prairie. Bulk density was not significantly affected by trampling at these levels, except in the woodland. Relative importance of species was affected slightly by trampling in the prairies, and greatly affected in the woodland. In the woodland, the total number of species decreased greatly after 50 and 100 passes/week, and graminoid species became more important. Although plant cover was nearly restored in the recovery year, species composition remained altered. Trampling at 0, 10, 20, 30, 40, 50 and 100 passes/week for one summer, showed that cover decreased with increasing trampling intensity in an approximately linear fashion on both prairies. Shoe type (hiking boots, flat soled shoes, heeled shoes) did not affect trampling damage at 250 passes/summer. Juniperus horizontalis was more tolerant to trampling than woodland plants, and more tolerant than prairie plants after 10 passes/week but less tolerant than the seeded prairie after 30 passes/ week. Abandoned vehicle tracks suggested that plant cover recovery in lightly and medium used tracks occurred within 5 - 6 years, but soil compaction persisted for a longer period. Recovery of heavily used tracks was slower, and invasion of native species appeared to follow colonisation by weeds and exotic species. Heavily used cart tracks, abandoned for 60 years had recovered native plant cover, but soil compaction persisted.