Influence of stand density, thinning and elevated CO₂ on stem wood density of spruce

Abstract

Stem wood density (SWD) of young Norway spruce trees (Picea abies [L.] Karst.) growing at ambient (A variant, 350 µmol(CO 2 )/mol) and elevated (E variant, A + 350 µmol(CO 2 )/mol) atmospheric CO 2 concentration inside of the glass domes with adjustable windows was estimated after six and eight years of the cultivation. Stand density of two subvariants (s -sparse with ca 5,000 trees/ha and d -dense with ca 10,000 trees/ha) and thinning impact (intensity of 27%) on SWD and its variation along the stem vertical profile were investigated. After six years of CO 2 fumigation, stems of sparse subvariant had about 10% lower values of SWD comparing to dense ones, although the difference was not statistically significant. In 2004 (two years after thinning), the SWD values were higher in all subvariants along the whole stem vertical profile. This increase was more obvious in E variant (about 6% in d subvariant and only 3% in s subvariant). The highest increase of SWD values was found in Ed subvariant, particularly in the middle stem part (about 8%, statistically significant increase).Keywords: elevated CO 2 ; Picea abies; stand density; stem wood density; thinning J. FOR. SCI., 53, 2007 (9): 400-405 401 may imply improvements in wood strength properties. Variations in environmental conditions induce unequal response of wood density to elevated CO 2 . For example, at ambient temperatures, approximately 60% increase of the air's CO 2 concentration significantly enhance latewood density (by 27%) and maximum wood density (by 11%), while elevatedtemperature conditions enhance less significantly latewood density (by 25%) and, in contrary, more significantly maximum wood density (by 15%) (Beismann et al. 2002). These changes lead to mean overall CO 2 -induced wood density increases of 2.8% at the ambient-temperature and 5.6% at the elevated-temperature (Beismann et al. 2002). Furthermore, elevated atmospheric CO 2 concentration increase wood toughness of spruce seedlings grown on acidic soils by 12 and 18% under low and high levels of nitrogen deposition, respectively. Elevated atmospheric CO 2 also increase the same mechanical wood properties in spruce seedlings grown on calcareous soils by about 17 and 14% under low and high levels of nitrogen deposition (Beismann et al. 2002).The objectives of this study were: (a) to evaluate an influence of elevated atmospheric CO 2 concentration on SWD, (b) to describe the changes of SWD values along the stem vertical profile, (c) to investigate changes of SWD with respect to stand density and thinning. , and in the one tenth of tree height (Ht 1/10 ) ( Table 1). Fresh stem discs volume was measured as a volume of cylinder. Afterwards, stem discs were dried for 48 hours in 105°C. After drying, dry weight was precisely estimated (balance model 1405 B MP8-1, Sartorius, Germany). Then, SWD was calculated using the common formula for basic wood density calculation (Roderick 2001). SWD of the stem disc t 3 was assorted to block of internodial sections from the tree top to the t 3 secti...

Variation of Selected Macrostructure Features and Density Wood of the European Spruce (Picea abies (L.) Karst.) in the Cross-Section of Trees over 90-Years-Old in Poland

“…Research plots located in mountain areas (No. [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] were located at an altitude of 400 to 1200 m above sea level.…”

“…Some researchers, however, found inverse correlations, especially regarding the density of spruce wood of various provenances, in studies conducted within experimental plots [10][11][12]. The structure and density of wood are often influenced by its location on the trunk, both along the length of the trunk and within its cross-section [4,13]. The widest growth rings are found in the root collar because it is necessary for the formation of the butt swell at the base of the trunk, where the wind produces the greatest bending moment.…”