Jukka Laine

Kontortamännyn alkukehitys ojitetulla karulla avosuolla

Laine J. Kontortamännyn alkukehitys ojitetulla karulla avosuolla.

English title: Initial development of Pinus contorta on a nutrient poor open bog in Finland

Tiivistelmä

The paper gives preliminary results of the initial development of lodgepole pine (P. contorta var. latifolia, provenance: Wono-won, British Columbia, Canada, 56°10'N; 121°30'W; 800—1000 m above sea level), compared with that of native Scots pine (P. sylvestris) in a planting experiment on a drained small-sedge bog nine years after planting in 1969. The experimental field is situated in Central Finland (61°50'N; 24°14'E; about 165 m above sea level). The annual rainfall is about 600 mm and that of the summer months (June-September) about 280 mm. Annual evapotranspiration is approximately 300 mm. The experimental field is divided into three areas (blocks), in which different drainage systems (ditch types) were used. In each area there are 8 sample plots, with 300 transplants in each, making a total of 24 plots and 7200 transplants of both pine species in the experiment. Area A is drained using ordinary open ditches, area B using plastic pipe drains and area C using narrow, vertical-walled ditches. Hyd-rological measurements were carried out in the areas in the years 1968—72 and the results have been previously published by Päivänen (1976). According to the results it was found out that the drainage effect of the plastic pipe drains was clearly smaller than that of the other ditch types, i.e. the water table in area B remained some 10 cm nearer the peat surface than in the two other areas. This affected the growth of the transplants so that the growth rate of both tree species studied, especially that of Scots pine, was in area B clearly slower (statistically significantly) than in areas A and C (Fig. 1). The height development of Pinus contorta during the first nine years since planting clearly exceeded that of P. sylvestris, except for area C (deep, narrow, vertical-walled ditches and seemingly slight-ly better nutrient status, because the amount of Sphagnum fuscum hummocks in this area was smaller) where Scots pine grew significantly better than in other areas (Fig. 1, Table 1). Lodgepole pine was 9 years after planting, on the average, in area A 31 %, in area B 24 % and in area C 5 % taller than Scots pine. This is in accordance with the results obtained in other studies with similar provenances (Hahl 1978). The mortality of transplants was also inventoried in summer 1978. The mortality of lodgepole pine turned out to be signi-ficantly smaller than that of Scots pine in all areas (Table 2). The proportion of dead Scots pine transplants was significantly higher in the poorly drained area B than in other areas, whereas Pinus contorta does not seem as susceptible to poor drainage. A new planting of both pine species took place in spring 1977 with the same experimental design and the mortality was inventoried in summer 1978. Table 2 shows that dying-off has been very small in both species confirming the results of the earlier planting (data group a in Table 2). The mortality of Pinus sylvestris was significantly bigger also in the latter planting (data group b in Table 2). The results of this experiment show that the early growth of suitable Pinus contorta provenances is somewhat better than that of Pinus sylvestris also in peatlands at least in circumstances described in this paper. It is also indicated (Fig. 1) that the requirements of lodgepole pine for drainage and nutrients may be smaller than those of Scots pine in peatlands.

Vastaanotettu 31.10.2017 Julkaistu 1.1.1979

Katselukerrat 1256

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