Fill planting is a common procedure following reforestation in Finland. In 1990, 13% of the total of seedlings planted was used for fill planting. The objective of this study is (i) to survey the survival of fill-in seedlings and (ii) to estimate the spatial pattern of stands to evaluate the importance of fill-in seedlings in constituting the stocking of Scots pine (Pinus sylvestris L.) stands in Central and Northern Finland.
A survey of 63 artificially regenerated Scots pine stands was conducted in 1990. Stand densities varied from 950 to 3,925 seedlings/ha. The mean densities of originally planted, fill planted and naturally regenerated seedlings were 863, 639 and 791/ha, respectively. The survival of originally planted seedlings was 36% and that of fill-in seedlings 48%. Death rate of fill-in seedlings of Scots pine increased with longer times between original and fill planting. The survival rate of Norway spruce (Picea abies) seedlings was correlated with temperature sum. Height of the fill-in seedlings was less than that of the originally planted ones. Most stands had an even spatial distribution with the exception of sparsely populated stands, which were somewhat clustered. This indicates that dying of seedlings is not randomly spread. Because of poor survival, fill planting seems to be a risky business in most cases.