Elevated CO2 concentration and temperature effects on the partitioning of chemical components along juvenile Scots pine stems (Pinus sylvestris L.)

Abstract

The effects of doubled ambient [CO 2 ] and different temperature levels on young Pinus sylvestris growing in phytotron chambers were studied. Five chambers were supplied with *380 ('ambient air') and five with *700 lmol mol -1 CO 2 ('elevated [CO 2 ]'). Temperature levels in the chambers ranged in increment steps of 2°C from -4°C to ?4°C relative to the long-term monthly (day and night) average air temperature levels in Berlin-Dahlem. Substrate was medium fertile; soil moisture and air humidity were kept constant. After three vegetation periods twigs and stems were harvested, weighed, homogenized, and analyzed chemically. There was no significant temperature effect on wood mass accumulation, clearest positive [CO 2 ] effect occurred in the youngest twigs. In total, wood mass increased by 28.5% at doubled ambient [CO 2 ]. N-contents (percentage) decreased at elevated [CO 2 ] in the uppermost stem sections and not in twig wood causing wider C/N ratios in total. In response to elevated temperature, N-contents decreased slightly in twigs (*0.3%). Traces of free glucose, fructose and sucrose, which decreased from the top to the bottom, were found in stem wood, in contrast to traces of starch that increased from the top to the bottom. In response to elevated [CO 2 ] only a little more (0.05%) was accumulated in the top shoot and in tendency; glucose, fructose, and sucrose contents were lower at the bottom of stems as compared to the control. There was no obvious response of these non-structural carbohydrates to elevated temperature except for starch that decreased to half of the content from the lowest to the highest temperature level. Among the hemicellulose compounds, rhamnose and arabinose declined from the top shoot to the bottom of stem, whereas 4-O-methyl-D-glucuronicacid, mannose, and xylose increased. Contents (percentage) of galactose remained approximately stable along the stem. The clearest positive effect of elevated [CO 2 ] along the whole stem was found for mannose with differences of 0.6-0.3%. In contrast to rhamnose and arabinose that showed a negative response to elevated [CO 2 ], mannose was reduced towards the uppermost stem sections. The 4-O-methyl-Dglucuronic-acid was slightly lowered at the bottom, and galactose and xylose showed no [CO 2 ] response. The only hemicellulose compound which reacted to temperature elevation was galactose. It increased slightly (*0.1% per 1°C). Cellulose and lignin (Klason) behaved oppositely: cellulose increased and lignin decreased from the top to the bottom. These structural components behaved reversely also in response to elevated [CO 2 ]. In stem parts above the bottom section, cellulose content was slightly higher at elevated [CO 2 ], and lignin content was slightly lower at the bottom. Lignin reacted to temperature elevation by a very slight increase on the average (*0.1% per one 1°C). Cellulose, however, decreased by *0.2% per 1°C temperature elevation. The importance of persistent sinks of carbon in woody plant parts is discussed in respect to the greenhous...

Phenological and Temperature Controls on the Temporal Non-Structural Carbohydrate Dynamics of Populus grandidentata and Quercus rubra

“…If growth terminates during mid-summer independent of temperature as we observed, then extending C assimilation later into autumn might augment NSC accumulation by increasing the period in which assimilated C is allocated to storage NSC rather than to growth. We did not adjust our predictions of future late season NSC accumulation for a concurrent rise in plant respiration that might occur as temperatures increase [41][42][43]; however, we suggest that lengthening of the C assimilation period and, consequently, higher gross NSC production under warmer conditions may provide an important mechanism for offsetting rising metabolic costs, which have been demonstrated to increase with temperature [5,44,45]. Interestingly, our findings suggest that rising air temperature may compound forecasted increases in tissue NSC caused by rising atmospheric CO 2 [32].…”

Carbon concentration in the world's trees across climatic gradients

“…Even multiple studies on the same species, Scots pine ( Pinus sylvestris L.), have reported different results: Kilpeläinen et al . (2005) detected no change in lignin concentrations with temperature increases of 2–6°C, Overdieck & Fenselau (2009) found lignin concentrations increased by < 0.5% with temperature increases of 2–4°C, and Kilpeläinen et al . (2003) found that lignin concentrations increased by c .…”

“…The few extant experimental studies evaluating changes in lignin concentrations (but not wood C concentrations) as a function of increasing temperatures are nearly entirely restricted to commercially important temperate gymnosperms, and results are mixed. Some studies have found statistically significant, albeit weak, increases in lignin concentrations with temperature (Kilpeläinen et al ., 2003; Overdieck & Fenselau, 2009), whereas others have shown no significant change in lignin with temperature (Kostiainen et al ., 2009). Even multiple studies on the same species, Scots pine ( Pinus sylvestris L.), have reported different results: Kilpeläinen et al .…”

“…At present, however, potential mechanisms of this relationship remain largely unidentified. Indeed, though the literature on wood formation is vast, to our knowledge there exists only a single study that has explicitly tested how wood C concentrations change in response to experimentally manipulated temperatures: Overdieck & Fenselau (2009) found no change in stem wood C concentrations of Norway spruce ( Picea abies (L.) H. Karst.)…”

Elevated CO2 and/or ozone modify lignification in the wood of poplars (Populus tremula x alba)

“…Most studies addressed lignin content and various responses were reported. Elevated CO 2 decreased lignin content in beech ( Blaschke et al , 2002 ), birch ( Kostiainen et al , 2006 ), and Scots pine ( Overdieck and Fenselau, 2009 ). Lignin content was increased in poplar subjected to elevated CO 2 ( Luo et al , 2008 ; Luo and Polle, 2009 ).…”