Seasonal adjustment of primary and secondary growth in maritime pine under simulated climatic changes

Abstract

& Key message Reducing irrigation by up to 75% in spring decreased primary and secondary growth in Pinus pinaster Aiton saplings, whereas an extra irrigation in September prompted secondary growth, confirming the high plasticity of xylogenesis in this species. & Context Water availability is the main limiting factor for plant growth and forest productivity in drought-prone environments, such as the Mediterranean region. Future scenarios for this region predict an increase in spring drought and in autumn precipitation. Understanding how tree growth responds to these conditions is imperative to anticipate forest productivity shifts under future climate change scenarios. & Aims We simulated the expected climatic conditions for the Mediterranean region in order to study the response of primary and secondary growth in maritime pine (Pinus pinaster Aiton) saplings. & Methods In February 2017, 2-year-old maritime pine saplings (n = 512) were subjected to a water manipulation experiment in a tunnel greenhouse. Saplings were randomly divided into four groups: control, exclusion, irrigation and exclusion-irrigation. Between May and August, saplings in the exclusion and exclusion-irrigation groups received 50 to 75% less water than saplings in the control and irrigation groups. In September, saplings in the irrigation groups received an extra irrigation. From February 2017 to February 2018, primary (height) and secondary growth (diameter and wood formation) were monitored. Seasonal dynamics of cambial activity and wood formation were monitored monthly through destructive sampling. & Results Primary and secondary growth were reduced in exclusion saplings. The extra irrigation in September triggered the production of tracheids with wider lumen diameter at the end of the tree ring. & Conclusion Maritime pine saplings survived an intense spring drought, despite primary and secondary growth reduction. The extra irrigation in September triggered a rapid increase in cambial activity, demonstrating the high plasticity of xylogenesis in this species.

Tree Growth Under Climate Change: Evidence From Xylogenesis Timings and Kinetics

“…It is an economically important species (e.g., pulp, wood, resin), representing about 2% of the Portuguese National Gross Domestic Product. In Portugal, the response of maritime pine to increased spring drought has already been studied under field (Vieira et al, 2017) and greenhouse conditions (Garcia-Forner et al, 2019;Vieira et al, 2019). The rain exclusion experiment carried out in the field revealed that the rate of cell production and tracheid differentiation was reduced by the simulated drought (Vieira et al, 2017).…”

Extreme Growth Increments Reveal Local and Regional Climatic Signals in Two Pinus pinaster Populations

“…The identified negative convergent event years correspond to extreme drought years and were also detected in other studies analyzing extreme growth reduction in the Iberian Peninsula ( Gazol et al, 2018 ; Sánchez-Salguero et al, 2018 ). Low water availability limits tree growth directly by reducing the rate of cambial cell division ( Vieira et al, 2017b , 2019 , 2020 ) and indirectly by reducing photosynthesis and the soluble sugars available for secondary growth ( Cartenì et al, 2018 ). Low water availability associated with warmer temperatures can trigger stomatal closure ( Roman et al, 2015 ) in isohydric species such as P. pinaster ( Ripullone et al, 2007 ).…”

“…Changes in temperature and precipitation regimes may increase drought risk, which can negatively affect trees’ physiological performance ( Garcia-Forner et al, 2019 ), carbon allocation ( Cartenì et al, 2018 ), and growth ( Vieira et al, 2019 ). In fact, changes in intensity, duration, and frequency of droughts are responsible for many observed shifts on vegetation and forest dieback ( DeSoto et al, 2020 ).…”

The Analysis of Pinus pinaster SnRKs Reveals Clues of the Evolution of This Family and a New Set of Abiotic Stress Resistance Biomarkers

“…Pinus pinaster is a gymnosperm species with a key environmental and forestry relevance into the northwestern Mediterranean area, where it is used for afforestation due to its fast growth, high phenotypic plasticity and stress tolerance, soil stabilization capacity and the quality of its timber and oleoresins [5,6]. Moreover, this species is also a good example of the climate-associated reductions in plant biomass yield related to regional climatic changes, increasing abiotic-heat and drought-and biotic stress pressure, which are also a main constraint for other Pinus species [7][8][9][10].…”