科研之友
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摘要
Natural regeneration in temperate forests is known to be distributed unevenly, forming dense clumps or patches of young trees confined often to canopy gaps. However, in some studies no significant relationship between the presence of gaps and advanced regeneration was found. The analysis of the relationship between tree stand density and young trees density and growth rates was conducted to check if old-growth temperate forests with numerous canopy openings permit development of young trees throughout the forest floor, not only directly under canopy gaps.
The study was conducted in an old-growth stand of Fagus sylvatica L., Abies alba Mill. and Picea abies (L.) Karst. in the Babia Gora National Park (Western Carpathians, Poland). The elevation is 940-1010 m a.s.l., slope inclination varies from 2 to 40%, mean annual temperature for that area is 4 degrees C and annual precipitation amounts to 1300-1400 mm. Stand basal area in the study plot has increased from 38 m(2) ha(-1) in 1991 to 40.7 m(2) ha(-1) in 2004, and canopy openness has decreased from 15.6% in 1996 to 9.3% in 2003. Saplings were totally dominated by European beech; during 13 years of study sapling density has increased by 50%, along with the sum of sapling heights (from 0.79 m m(-2) to 1.59 m m(-2)) and the mean height (from 1.42 in to 2.46 m). The increase in sapling sizes strongly varied among individuals within plot and was only weakly related to the relative light intensities measured at the individual plot level (for sums of diameters T = 0.293, P > 0.05). The development of young generation of trees in the study area seems to support the "medium disturbance" hypothesis, with a non-continuous regeneration triggered by external disturbance, and several tree recruitment episodes during the lifespan of canopy trees.
- 出版日期2008
