Experimental warming and drought treatments reduce physiological activities and increase mortality of Pinus koraiensis seedlings

摘要: This study was conducted to investigate physiological responses and mortality of P. koraiensis seedlings under warming drought treatments. In May 2016, 90 (aged 2 years) were planted in each plot (n = 20), exposed a combination + 3 °C − 30% drought, with 5 replicates. Net photosynthetic rate (A), stomatal conductance (gs), transpiration (E), maximal photochemical efficiency photosystem II (Fv/Fm) measured from April 2017 December 2018. Seedling eight times during the period at irregular intervals. A, gs, E decreased by − 21.99%, − 34.58%, − 33.6% treatment, − 5.82%, − 11.03%, − 8.56% respectively, response decreasing soil water content increasing leaf temperature. There no significant difference overall Fv/Fm The long-term reduction photosynthesis treatment might cause carbon starvation, resulting 7.43-fold increase seedling mortality. Moreover, unaffected since its effects on A occasional small as compared treatment. Due unusually high temperature summer 2018, 38.28 °C above 45 °C for 10.7 h August 2018 sharply − 11.79% increased 15.31-fold summer, Thus, damage severe heat stress may have triggered rapid