Investigation on the freeze-damaged trees by twice uttermost microtherm encountered once in one hundred or fifty years in FujJan

Fujian encountered twice uttermost microtherm at an interval of 8 years in the nineties of 20th century．The uttermost lowest temperature were -7～-l3℃ at north Fujian(Guangze)and under 2℃ at south Fujian，breaking the lowest record of the same period in the century，on the 29 December 1991．The uttermost lowest temperature were -7～-l0℃ at north Fujian(Jianning)and about 1℃ at south Fujian，reaching lowest temperature within fifty years，on the 23 December 1999．The species coming from tropic or sub-tropic and planted in the middle sub-tropic section had gotten the graveness of freezing damage in twice microtherm ．According to two investigated results，the trees suffering from the different degrees frostbite were 180 species in Fujian．According to the information investigated in the microtherm of December 1999，the trees encountering graveness frostbite(grade I～III)were 105 species in Fujian；the most graveness is in the northern region of Fujian．For the sake of reducing loss，it is necessary to choose carefully the species of virescence and forestation parting districts．