Lars Lundqvist

Influence of local stand basal area on density and growth of regeneration in uneven‐aged Picea abies stands

In single‐tree selection, trees removed by harvest or lost through mortality are replaced by ingrowth from the seedling/sapling bank. Because the level of ingrowth is governed not only by the recruitment rate of new seedlings, but also by mortality and growth rates within the seedling/sapling stratum, knowledge of how these processes are related to the tree stratum is important for successful application of single‐tree selection. Therefore, Norway spruce (Picea abies (L.) Karst.) regeneration (0.1 m ≤ height ≤ 2.0 m) was measured on seventy 100 m2 circular subplots at each of two sites in central and northern Sweden. Both sites had previously been selectively logged, but the time elapsed since the last harvest was at least 30 yrs. Basal area of trees of at least 2 m height within three different radii from the subplot centres was measured. Measurements on regeneration included height and leader length. Influence of local stand basal area on density and growth of regeneration was analysed by ordinary least...

Changes in the stand structure on permanent Picea abies plots managed with single‐tree selection

Eleven permanent plots, established in central and northern Sweden during the years 1913–59, were repeatedly treated with single‐tree selection for between 30 and 67 years. The plots were all dominated by Norway spruce (Picea abies (L.) Karst.), soil moisture was mesic, and the ground vegetation was dominated by Vaccinium myrtillus L. All trees higher than 1.3 m were numbered and cross‐calipered at the time of plot establishment, and at following treatments. In the study trees with DBH < 8.5 cm were excluded from the calculations. Stand densities generally decreased as a result of harvests and mortality together exceeding increment and ingrowth. The number of trees was generally declining over DBH at the time of plot establishment. Six plots maintained such distributions during the whole observation period. Changes in stand structure were mainly caused by the harvests being concentrated to trees with DBH less than 30 cm, and low levels of ingrowth. The low ingrowth was probably an effect of over cutting o...

Wind and snow damage in a thinning and fertilisation experiment in Pinus sylvestris

Damage induced by wind and snow was examined in an experimental series with thinning and fertilisation established in 34–58 years old Scots pine (Pinus sylvestris L.) stands in northern Sweden during the period 1969–83. The experiment contained six treatments and 23 replications. The treatments were 25% and 60% thinning from below, 25% thinning from above, 30% thinning from below combined with N and NP fertilisation. Percentages represent basal area harvested at the first thinning. Differences in damage level were examined at the first reinventory, 4–8 years after thinning. The level of wind and snow‐induced damage was about 1% of the basal area during the period studied. Proportion of basal area damaged was not affected by the treatments, but there was more snow damage after thinning from above than after thinning from below. The proportion of trees damaged by snow and the proportion of dead trees were affected by treatment. The densest stands, the control and 25% thinning from above, were damaged the mo...

Growth and competition in partially cut sub-alpine Norway spruce forests in northern Sweden

Abstract Three stands in northern Sweden were inventoried by a circular-plot survey (16, 14 and 19 plots, 314 m 2 ) in late summer 1983. All stands were dominated by Picea abies (L.) Karst. (approximately 90% of standing volume), with Betula pubescens Ehrh. as the major additional tree species. Stand 1 has been subjected to a partial cutting 16 years earlier, and Stands 2 and 3 10 years earlier. The harvests had removed about two-thirds of the standing volume and 50% of the trees. Diameter at breast height (dbh) and total tree height was measured on all trees with dbh of 7.5 cm or more. Tree growth was reconstructed for all measured trees using increment cores taken at breast height. The relation between standing volume on the plots and annual volume increment was approximately linear. The absolute growth rate of the individual trees also increased linearly over stem volume, but levelled at 0.3–0.4 m 3 per stem. The Gini coefficient dropped over time in all three stands. The spatial distribution of the trees became more aggregated in two stands. Together the results indicate that the competition among spruces with diameter 7.5 cm or more in 1983 had been symmetric rather than asymmetric both before and after the harvests. The question is raised whether this competitive symmetry is a result of below-ground competition, or the stand structure in combination with the shade tolerance of Norway spruce.

Some notes on the regeneration of Norway spruce on six permanent plots managed with single-tree selection

Abstract Interest in single-tree selection is today increasing in Sweden, but Swedish foresters believe that the harsh climate usually makes it impossible to achieve sufficient regeneration and ingrowth after selection cuttings. In this paper, data on abundance, height increment and ingrowth of Norway spruce seedlings on six permanent plots are presented. Methods to estimate seedling mortality and future ingrowth are also suggested. Four plots are situated in central Sweden, and two plots in southern Sweden. All plots are dominated by Norway spruce ( Picea abies (L.) Karst.). The soil is glacial till on all plots, soil moisture is mesic and the ground cover is dominated by bilberry ( Vaccinium myrtillus L.). The results show that it is possible to obtain abundant regeneration and high ingrowth rates in Norway spruce selection stands in Sweden, with high levels of standing volume and bilberry as the dominating ground vegetation. They also indicate that regeneration and ingrowth into the tree layer may not be as serious a problem as Swedish foresters have traditionally assumed.

Mechanical stress during dormancy stimulates stem growth of Scots pine seedlings

Abstract The effects of mechanical stress imposed during dormancy on stem growth were examined in 5-year-old Scots pine ( Pinus sylvestris L.) seedlings. The treatments were different degrees of manual bending, which were executed in freezing-storage (−6°C). After thawing, seedlings were reactivated and grown in a climate chamber for 8 weeks. Bending promoted a statistically significant increase in xylem width at the point of bending, but had no effect on tracheid width, indicating that the increase in xylem width was caused by a faster rate of tracheid production. The results show that Scots pine seedlings record mechanical stress during their dormant period, and respond to this during the following growth period. The ecological and silvicultural significance of this response is breifly discussed.

Damage to Residual Stand Caused by Mechanized Selection Harvest in Uneven- Aged Picea abies Dominated Stands

(L.) Karst) dominated stands in west-central Sweden. The objective was to quantify level and type of damage caused by harvesting and to quantify the difference between two treatments: T20) only skid road harvest (20 m distance between ca. 4 m wide roads), and T40) skid road harvest (40 m distance between ca. 4 m wide roads) combined with thinning between the roads. In T40, the goal was to harvest approximately the same standing volume as in T20. After harvest, two circular sample plots (radius 18 m, i.e. 1018 m