Post 00934
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The majority of parks or meadow gardens which decorate the forests of the Rocky Mountains probably owe their existence to fire. Trees and grass are endlessly contending for the possession of the earth. In this incessant silent struggle a sweeping fire is generally of advantage to the grass. Trees suffer more from fire than does grass. It is probable that repeated fires enable the grass to hold the plains and prairies against the encroachments of the trees. Each forest fire commonly gives the grass possession of a part of the area formerly dominated by the forest. Usually both grass and trees are prompt to seize any fire-cleared area. The grass may be first to come, or some space may be wet or in some other way unfavorable to tree seed but encouraging to grass seed.
While forest fires bring many of these parks, others are glacier meadows, lake-basins which time has filled with sediment and sodded with grass. Many are due to the presence of water, either outspreading surface water or an excess of underground water just beneath the surface,–to streams visible or invisible. A few result from boggy places which result from impaired drainage caused by landslips or fallen trees. Thousands were made by beaver dams,–are old beaver ponds that filled with sediment and then grassed over.
Most parks that owe their origin to forest fires have charcoal beneath the surface. A little digging commonly reveals charred logs or roots. Occasionally, too, a blackened tree-snag stands suggestively in these treeless gardens. In the competition for this territory, in which grass, spruces, aspens, and kinnikinick compete, grass was successful. Just what conditions may have been favorable to grass cannot be told, though probably one point was the abundance of moisture. Possibly the fire destroyed all near-by seed trees, or trees not destroyed may not have borne seed until the year following the fire. Anyway, grass often seizes and covers fire-cleared areas so thickly and so continuously with sod that tree seeds find no opening, and grass thus holds possession for decades, and, in favorable places, possibly for a century.