Fig. 4From: Boreal trees in the Mediterranean: recruitment of downy birch (Betula alba) at its southern range limitVariation of seed density with distance in 2005 and 2006 in three downy birch populations of central Spain. Values of seed density at each distance were computed as the mean number of seeds fallen in five traps. Note the logarithmic scale on the vertical axis. HO Honduras, NO Nogaledas, CM Casas del MonteBack to article page