Abstract
Under ongoing global climate change, drought periods are predicted to increase in frequency and intensity in the future. Under these circumstances, it is crucial for tree's survival to recover their restricted functionalities quickly after drought release. To elucidate the recovery of carbon (C) transport rates in c. 70-year-old Norway spruce (Picea abies [L.] KARST.) after 5years of recurrent summer droughts, we conducted a continuous whole-tree 13 C labeling experiment in parallel with watering. We determined the arrival time of current photoassimilates in major C sinks by tracing the 13 C label in stem and soil CO2 efflux, and tips of living fine roots. In the first week after watering, aboveground C transport rates (CTR) from crown to trunk base were still 50% lower in previously drought-stressed trees (0.16±0.01mh-1 ) compared to controls (0.30±0.06mh-1 ). Conversely, CTR below ground, that is, from the trunk base to soil CO2 efflux were already similar between treatments (c. 0.03mh-1 ). Two weeks after watering, aboveground C transport of previously drought-stressed trees recovered to the level of the controls. Furthermore, regrowth of water-absorbing fine roots upon watering was supported by faster incorporation of 13 C label in previously drought-stressed (within 12±10h upon arrival at trunk base) compared to control trees (73±10h). Thus, the whole-tree C transport system from the crown to soil CO2 efflux fully recovered within 2weeks after drought release, and hence showed high resilience to recurrent summer droughts in mature Norway spruce forests. This high resilience of the C transport system is an important prerequisite for the recovery of other tree functionalities and productivity.
Highlights
Global climate change has been causing significant and mostly negative impacts on forest ecosystem carbon (C) cycling such as reduced productivity (Ciais et al, 2005; Collins et al, 2013)
We show for the first time the resilience of the whole- tree C transport after repeated summer droughts in a highly productive Norway spruce forest stand of great ecological and economic relevance in central Europe (Caudullo et al, 2016)
As the third transport process, we show how fast the current photoassimilates are incorporated in fine roots after drought release
Summary
Global climate change has been causing significant and mostly negative impacts on forest ecosystem carbon (C) cycling such as reduced productivity (Ciais et al, 2005; Collins et al, 2013). Drought is one of the most influential drivers of tree mortality (Allen et al, 2010; 2015; McDowell et al, 2008; van Mantgem et al, 2009) and it is predicted to occur more frequently and for longer durations in the future (IPCC, 2007, 2014). Under these circumstances, tree survival primarily depends on the extent to which tree functionality is impaired by drought (i.e., resistance, Lloret et al, 2011). C limitation in sink tissues can occur if the C transport would not recover fast enough to meet the sink demands (Hartmann et al, 2013; Hartmann et al, 2013; Sevanto, 2014; Winkler & Oberhuber, 2017), but knowledge on mature trees is scarce (Gao et al, 2021)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
