Model construction and application of effective freeze-thaw injury in poplar

  Objective  Since 2000, poplar in Liaoning Province of northeastern China has suffered five serious overwintering injuries, resulting in huge economic and ecological losses. The construction of an effective freeze-thaw injury（EFTI）model can provide a basis for the prevention and control of poplar overwintering injuries.

  Method  On the basis of clarifying the mechanism of poplar overwintering injury and putting forward the hypothesis of cumulative effect of EFTI, this paper selects the days of effective freeze-thaw, the daily minimum temperature of effective freeze-thaw, tree health index and frost free period as parameters, constructs and tests the EFTI model of poplar.

  Result  The minimum required days of frost free period for fast-growing poplar of Sect. Aigeiros were 170 d. During the cold resistance exercise period and off exercise period, when the daily minimum temperature was ≤− 3 ℃, the daily maximum temperature was > 0 ℃ and the daily range was ≥ 12 ℃, the fast-growing poplar of Sect. Aigeiros will have effective freeze-thaw injury. The greater the effective freeze-thaw injury risk index (Rio) was, the greater the risk of overwintering injury was. The model was applied to draw the overwintering injury risk assessment map of fast-growing poplar of Sect. Aigeiros in Liaoning Province. The model test results showed that the accuracy of the model for overwintering injury assessment of fast-growing poplar of Sect. Aigeiros was 75%.

  Conclusion  The model has great practical value. The development of EFTI model of poplar lays a foundation for preventing and reducing overwintering injury of poplar in Liaoning Province and other provinces. It provides reference for poplar afforestation and forest management in northern China.