Understanding the effects of elevated atmospheric CO2 on carbon (C) relations of mature forest trees is central to understanding ecosystem C fluxes and pools in a future high-CO2 world. Here, we investigated the CO2-induced photosynthetic enhancement and the diurnal variation in shoot carbon assimilation, stem CO2 efflux and soil respiration associated with ca. 110-year-old and 37 m tall Norway spruce trees (Picea abies (L.) H. Karst.) growing under free air CO2 enrichment (FACE) in a mixed, near-natural forest in Northern Switzerland. Diurnal measurements of these major C fluxes were conducted simultaneously on three occasions: one week before and after the start of CO2 enrichment, and one year later. Under controlled leaf chamber conditions, an increase in the atmospheric CO2 concentration of ca. 150 ppm above ambient stimulated light-saturated rates of photosynthesis in previous- and current-year upper-canopy shoots equally by 73 ± 2%. In the course of the day such large differences in C assimilation between trees growing under elevated CO2 (eCO2) and ambient conditions (aCO2) only occurred around midday under non-limiting light conditions. The CO2 efflux rates from spruce stems (CEstem) and surrounding soil (Rsoil) shared a similar range during night- and daytime (3–5 μmol m−2 s−1) but were not stimulated by eCO2. Both CEstem stem and Rsoil were still rising when photosynthesis approached evening light compensation potentially reflecting the time lag in assimilate allocation to stem tissue and fine roots. Our findings suggest a strong photosynthetic enhancement during the initial CO2 enrichment phase but provide no evidence for an overall or daytime-dependent stimulation of respiratory CO2 fluxes indicating that the extra C was not quickly returned to the atmosphere through respiratory processes in spruce stems or surrounding soil.
from #AlexandrosSfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/2iLnQCG
via IFTTT
Εγγραφή σε:
Σχόλια ανάρτησης (Atom)
Δημοφιλείς αναρτήσεις
-
Publication date: Available online 4 January 2018 Source: European Journal of Radiology Author(s): Peiyao Zhang, Jing Wang, Qin Xu, Zhen...
-
Medicine by Alexandros G. Sfakianakis,Anapafseos 5 Agios Nikolaos 72100 Crete Greece,00302841026182, Butyric Acid from Probiotic Staphyloco...
-
Does CBD Oil Lower Blood Pressure? This article was originally published at SundayScaries." Madeline Taylor POSTED ON January 13, 20...
-
Medicine by Alexandros G. Sfakianakis,Αλέξανδρος Γ. Σφακιανάκης A Novel Technique for Endoscopic Repair of Large Anterior Skull Base Defect...
-
2016-11-22T07-55-59Z Source: International Journal of Medical Science and Public Health Banothu Srinivas, Madhu Mohan Reddy B. Backgrou...
-
2016-10-15T06-30-01Z Source: The Southeast Asian Journal of Case Report and Review Sangita Deepak Kamath, Neeraj Jain, Saurabh Pathak, Ba...
-
BACKGROUND AND PURPOSE: Lesion load is a common biomarker in multiple sclerosis, yet it has historically shown modest association with cl...
-
Abstract The development of focused ion beam-scanning electron microscopy (FIB-SEM) techniques has allowed high-resolution 3D imaging of n...
-
Vol.48 No.2 from #AlexandrosSfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/1S2Z7n2 via IFTTT
Δεν υπάρχουν σχόλια:
Δημοσίευση σχολίου