Carbon allocation dynamics in conifers and broadleaved tree species revealed by pulse labeling and mass balance

Carbon allocation to root exudates is maintained in mature temperate tree species under drought

“…In our study, the proportions of net‐C assimilation allocated to root exudation were only 0.6 ± 0.1% and 1.8 ± 0.6% in control and drought plots, respectively, which were below the 3–30% previously reported at other study sites for multiple species (Kuzyakov & Domanski, 2000; Jones et al ., 2009; Finzi et al ., 2015; Abramoff & Finzi, 2016; Gougherty et al ., 2018). Our observed exudation rates from root branches are in line with modeled or measured root exudation rates of diverse vegetation types (Finzi et al ., 2015; Dror & Klein, 2021; Rog et al ., 2021; Sell et al ., 2021), although they are at the lower end of reported values from comparable temperate forests (Tückmantel et al ., 2017; Meier et al ., 2020) and other ecosystems (summary provided by Gougherty et al . (2018).…”

Asymmetric belowground carbon transfer in a diverse tree community

“…The respiration of leaves and roots was measured during the evenings together with carbon isotopic ratio to quantify the amount of labelled carbon in the respiration of each tree. The exhaust ventilation of the IRGA module was directly interfaced to a CO 2 analyser (Picarro G2131i) which measured the ratio between 13 CO 2 and 12 CO 2 in the respired CO 2 from each sapling (more details on the setup in Rog, Jakoby, et al,2021).…”

“…This is probably due to the anatomical differences in their transport system (Liesche et al, 2015). A pulse labelling experiment on individual Mediterranean saplings showed carbon allocation to roots three days post labelling in saplings of Pinus halepensis , Cupressus sempervirens , Quercus calliprinos , Ceratonia siliqua and Pistacia lentiscus ( Rog, Jakoby, et al, 2021 ) . The partitioning of carbon to belowground compartments was 28%–38% in gymnosperms ( Pinus halepensis and Cupressus sempervirens ), and 5%–10% in angiosperms ( Quercus calliprinos , Ceratonia siliqua and Pistacia lentiscus ) (Rog, Jakoby, et al, 2021).…”

“…After reaching the roots, carbon can transfer to the rhizosphere, which is composed of the soil and the rhizosphere microbiota, including mycorrhizal fungi. Carbon is expected to further decrease while transferring to mycorrhizal fungi and to the roots of a neighbouring tree 2021. Indeed, in an experiment studying carbon transfer between paper birch and Douglas fir saplings it was shown that small amounts of 4.7% of the carbon fixed by paper birch were transferred to Douglas fir (Simard, et al, 1997).…”

Time‐varying response of fine root growth to soil temperature and soil moisture in cypress and deciduous oak forests

“…Therefore, fine root production of deciduous trees might be more limited within a certain period of the growing season than evergreens. Moreover, in the growing season, internal carbon resources assimilated via leaves might be more quickly allocated to root growth than in evergreens (Rog et al, 2021).…”