Resistance Of Birch From Different Geographical Origins Against Mountain Hare (Lepus Timidus) Browsing

Comparative study of the resistance of plant against mammalian browsing in a large geographical scale is a prevailing topic and the study now is in the period of exploring and discussing. In this thesis, international applied methods were used to compare the resistance of birch form different geographical origin(four from China, White Birch, Betula platyphylla and four from Finland, European White Birch, Betula pendula) against mountain hares(Lepus timidus) browsing. The birches were planted in the same condition all the time for seven months from seed sowing to seedling harvesting. Some features that related to birch resistance, such as resin droplet density and percent content of NDF, ADF, ADL, were determined and the percent content of total phenol were determined for the first time. Regarding the experiment animals, encaged mountain hares caught from wild field were used. The result shows that, there are some differences on seedling height, base diameter, fresh weight, resin droplet density, percent content of NDF, ADF, ADL, total phenol between White Birch and European White Birch. Hares were selective browsing when they fed to different birch seedlings. Four original White Birches grew better than European White Birches, they were higher and heavier and have bigger density of reason droplet and percent content of NDF, ADF, ADL. European White Birches were smaller, but they have higher content of total phenol. In the feeding experiment, hares selected all original birches, but preferred to White Birch obviously which does not support the hypothesis raised by Euramerican scholars. The experiment also indicates that the distribution of contents of total phenol was opposite: in white birch, lower parts were higher and in European White Birch, upper parts were higher. AH factors in the experiment were divided into two groups by factor analysis: content of total phenol was a group and the left were the other group. A negative correlation exists between relative consumption and total phenol and the total phenol may be the main factor influencing hare's browsing in this experiment. The results of this experiment were different from previous study which suggests that the study on plant chemical defense in large geography scale is difficult and the results may be affected by the background of seedlings and experimental animals and the measured features. So that, more experiments should be carried on in the future.