Afforestation of low-productivity peatlands in Sweden - the potential of natural seeding

In 1971, a series of five afforestation trials were established along a nor th-south gradient on open peatlands in Sweden. All areas were drained, fert ilized and planted with Scots pine (Pinus sylvestris). Survival and height of the planted trees as well as the amount of natural establishment, i.e. d owny birch (Betula pubescens), silver birch (Betula pendula), Norway spruce (Picea abies (L.) Karst.), Scots pine (Pinus sylvestris L.), and other dec iduous species: (e.g. Salix sp., Sorbus aucuparia), by seeding from nearby forests were measured 18-22 years later. The amount of naturally establishe d trees exceeded the number of living planted trees in all five areas. Next to downy birch, Scots pine was the most common naturally established speci es. Large variations in both amount and height of natural establishment wer e found along the climatic gradient. Planted trees were taller than natural ly established trees, except for the northernmost area. Number and height o f naturally established trees correlated positively to closeness to nearest forest and to nearest ditch. These trees also responded positively to PK f ertilization in the three southernmost areas. In the two northernmost areas no such response was found. It was concluded that natural seeding from nei ghbouring forests can be counted on and recommended in afforestation of low -productive peatlands in Sweden, provided that downy birch is accepted as a dominant tree species.