Mortality of western larch seedlings in relation to seedbed characteristics at the dry end of its ecological range

Journal Article

Development

The effects of different seedbeds on westem larch (Larix occidentalis Nutt.) germination and seedling mortality were assessed in a grand fir/ninebark (Abies grandis ((Dougl. ex. D.Don) Lindl.))/(Physocarpus malvaceus ((Greene) Kuntze)) habitat type in northem Idaho, U.S.A. Two plots were established on each of four sites, and 150 westem larch seeds (66% viable) were distributed on each of 16 randomly applied seedbed modification combinations (bumed or mechanical scarified, mineral soil or duff, shaded or non-shaded, caged or non-caged for protection from predation). Germination percentages and seedling development were significantly greater (4 - 10 times) on caged units than on uncaged units by mid-July. Shading did not significantly affect germination percentage or initial seedling establishment. No significant differences occurred in germination or initial seedling establishment between bumed and unbumed treatments. Mortality of seedlings, most likely caused by a month-long dry period with high temperatures, resulted in no significant differences in seedling numbers among treatments by mid-August the first year after seed dispersal. On the dry end of this species' range, there does not appear to be any difference in seedling survival from seedbed modification.