Picea abies
not annotated - annotated - LINNAEUS only
21054435
Seasonal dynamics in the stable carbon isotope composition delta^1^3C from non-leafy branch, trunk and coarse root CO2 efflux of adult deciduous (Fagus sylvatica) and evergreen (Picea abies) trees.
Respiration is a substantial driver of carbon (C) flux in forest ecosystems and stable C isotopes provide an excellent tool for its investigation. We studied seasonal dynamics in delta^1^3C of CO2 efflux (delta^1^3C(E)) from non-leafy branches, upper and lower trunks and coarse roots of adult trees, comparing deciduous Fagus sylvatica (European beech) with evergreen Picea abies (Norway spruce). In both species, we observed strong and similar seasonal dynamics in the delta^1^3C(E) of above-ground plant components, whereas delta^1^3C(E) of coarse roots was rather stable. During summer, delta^1^3C(E) of trunks was about -28.2% (Beech) and -26.8% (Spruce). During winter dormancy, delta^1^3C(E) increased by 5.6-9.1%. The observed dynamics are likely related to a switch from growth to starch accumulation during fall and remobilization of starch, low TCA cycle activity and accumulation of malate by PEPc during winter. The seasonal delta^1^3C(E) pattern of branches of Beech and upper trunks of Spruce was less variable, probably because these organs were additionally supplied by winter photosynthesis. In view of our results and pervious studies, we conclude that the pronounced increases in delta^1^3C(E) of trunks during the winter results from interrupted access to recent photosynthates.
20840508
Hydraulic constraints limit height growth in trees at high altitude.
* Low temperatures limit the fixation of photosynthates and xylogenesis. Here, we hypothesized that reduced longitudinal growth in trees at high altitude is related to the lower hydraulic efficiency of the transport system. * Apical buds of Norway spruce (Picea abies) trees at high and low elevation were heated during 2006 and 2007. At the end of the experiment, trees were felled. Longitudinal increments and tracheid lumen areas were measured along the stem. Apical hydraulic conductivity (k) was estimated from anatomical data. * Before heating, high-altitude trees showed fewer (P = 0.002) and smaller (P = 0.008) apical conduits, and therefore reduced k (P = 0.016) and stem elongation (P < 0.0001), in comparison with trees at low elevation. After 2 yr of heating, k increased at both high (P = 0.014) and low (P = 0.047) elevation. Only high-altitude trees showed increased stem elongation, which reached the same magnitude as that of controls at low elevation (P = 0.735). Heating around the apical shoots did not appear to induce significant changes in conduit dimension along the rest of the stem. * The total number and size of xylem elements at the stem apex are strongly constrained by low temperatures. Trees at high altitude are therefore prevented from building up an efficient transport system, and their reduced longitudinal growth reflects strong hydraulic limitations.