Research On The Effect Of Freezing Disaster On Eucalyptus Plantation

The object of this thesis is to evaluate the disaster situation of different ages of eucalyptus plantation in Huanjiang Branch of Huangmian Stated Forestry Farm,Guangxi province,China.Through the investigation of standard plots,the disaster situation of different ages of eucalyptus plantation in this region was assessed.The factors,such as age,DBH,height,elevation,slope,slope position and aspect were selected as the influencing factors of damage to eucalyptus plantation by using the regression analysis.It provided scientific basis for the sustainable development of eucalyptus production in Huangmian Stated Forestry Farm.The results showed that:(1)Under the influence of low temperature and freezing weather around New Year's Day in 2019,eucalyptus plantations of 1-8 years old in Huangmian Stated Forestry Farm were all suffered from disasters.The main damage of the plantation trees were breaking,falling down and bending mechanical damage,but no freeze injury.(2)1 to 8 years old eucalyptus man-made forests were seriously affected except the 53.3 hm~2 part of 6 years old eucalyptus plantation.The damage rate of most of them was greater than 60%.The order of damage rate was 1a>2a>4a>7a=8a>5a>3a>6a;There was no significant difference in the loss ratio between one-year and two-year eucalyptus plantations,but it was significantly different comparing with other plantation age eucalyptus plantations.There was no significant difference in the damage proportion of eucalyptus plantations in three years,four years,five years,seven years and eight years.(3)In 1 to 8 years old eucalyptus man-made forests,the damage areas of young and overmature forests were large;while,the damage areas of medium and mature forests were a little small.(4)According to the estimation,the economic loss of eucalyptus plantation in 1-8 years was 5a>1 a>7 a>8 a>3 a>2 a>6 a>4 a.The total economic loss was 85,353,000 yuan(RMB).The man-made forest of 5 years old eucalyptus which was in the felling period was seriously affected.The rotation felling period could be shortened to reduce the effect of freezing disaster on eucalyptus plantation.(5)In this ice freezing natural disaster,the age of the forest,DBH and height of the tree were obviously relative to the disaster situation of eucalyptus man-made forests.The damage rate decreased and then increased with the increase of forest age.The survey indicated that the disaster resistances of young and over-mature forests were weaker than that of medium and near-mature forests.With the increase of DBH,the damaged eucalyptus plantation in different age groups(medium age forest,near mature forest and over mature forest)showed a decreasing trend of different degrees.And the smaller DBH,the easier damage.Damage rate was negatively correlated with tree height.(6)There was a negative correlation between the damage rate of eucalyptus and the altitude.And the damage rate of eucalyptus was slightly higher in the foothills at lower altitudes than in the stands at higher altitudes.The influence of slope direction,slope position and slope on eucalyptus was not obviously.