Seedling survival under conspecific and heterospecific trees: the initial stages of regeneration of Sorbus aucuparia, a temperate fleshy-fruited pioneer tree.

摘要

This study examined whether recruitment of Sorbus aucuparia under conspecifics and heterospecifics differs in: (i) seed-bank longevity, (ii) seedling emergence rate, (iii) seedling survival rate, and (iv) density-dependent mortality. I studied the first three cohorts of seedlings that emerged after the 2009 mast year using pairs of plots located under conspecific and heterospecific (Norway spruce, Picea abies) trees. The interannual pattern of seedling emergence did not follow the fruit production pattern. In 2010 and 2011, there was no difference in the density of emerged seedlings among the plots under rowans and under spruces. Survival of the 2010 and 2011 seedling cohorts was higher under spruces than under rowans. Under either tree species seedling survival was not correlated with the density of emerged seedlings. The survival pattern of rowan seedlings in subalpine spruce forest seems to follow the Janzen-Connell model in temperate forest.