Temperature responses of growth and wood anatomy in European beech saplings grown in different carbon dioxide concentrations

Abstract

Effects of temperature on growth and wood anatomy were studied in young European beech (Fagus sylvatica L.) grown in 7-1 pots for 2.5 years in field-phytotron chambers supplied with an ambient (∼400 umol mol -1) or elevated (∼700 μmol mol-1) carbon dioxide concentration ([CO2]). Temperatures in the chambers ranged in increments of 2°C from -4°C to +4°C relative to the long-term mean monthly (day and night) air temperature in Berlin-Dahlem. Soil was not fertilized and soil water and air humidity were kept constant. Data were evaluated by regression analysis. At final harvest, stem diameter was significantly greater at increased temperature (Δ1°C: 2.4%), stems were taller (Δ1°C: 8.5%) and stem mass tree-1 (Δ1°C: 10.9%) and leaf area tree-1 (Δ1°C: 6.5%) were greater. Allocation pattern was slightly influenced by temperature: leaf mass ratio and leaf area ratio decreased with increasing temperature (Δ1°C: 2.3% and 2.2% respectively), whereas stem mass/total mass increased (Δ1°C: 2.1%). Elevated [CO2] enhanced height growth by 8.8% and decreased coarse root mass/total mass by 10.3% and root/shoot ratio by 11.7%. Additional carbon was mainly invested in aboveground growth. At final harvest a synergistic interaction between elevated [CO2] and temperature yielded trees that were 3.2% taller at -4°C and 12.7% taller at +4°C than trees in ambient [CO2]. After 2.5 seasons, cross-sectional area of the oldest stem part was ∼32% greater in the +4°C treatment than in the -4°C treatment, and in the last year ∼67% more leaf area/unit tree ring area was produced in the highest temperature regime compared with the lowest. Elevated [CO2] decreased mean vessel area of the 120 largest vessels per mm2 by 5.8%, causing a decrease in water conducting capacity. There was a positive interaction between temperature and elevated [CO2] for relative vessel area, which was ∼38% higher at +4°C than at -4°C in elevated [CO2] compared with ambient [CO2]. Overall, temperature had a greater effect on growth than [CO2], but elevated [CO2] caused quantitative changes in wood anatomy. © 2007 Heron Publishing.