Using the methods introduced by Bier, X.H., Buchinock, Wang Jing-wen, Shi Rihe et al., different varieties of poplar (poplar-Mei譗ing, Poplar-A100, Poplar-Xiaohe14 et al.) were inoculated with poplar ice nucleation active (INA) bacteria respec-tively in 1997-1999. The water content, relative turgidity, lignin content, phenylalanine ammonialyase (PAL) activity, electrolyte effusion rate, and inorganic element content of poplar bark were measured before and after inoculating. The results showed that after the poplar trees were inoculated with INA bacteria, the moisture content of bark decreased but relative turgidity increased, electrolyte effusion rate increased and had a peak at temperatures of 4 and 5 C, lignin content increased and positively cor-related with poplars disease-resistance, and the plenylalanine ammonialyase activity increased and also showed a significant positive correlation with poplars disease-resistance. For the contents of inorganic element, Cu and Fe decreased but K and Zn increased obviously, while Mn, Ca and Mg changed little.
We studied winter food-habits of wild boars (Sus scrofa) by using micro-histological fecal analyses in combination with field surveys of feeding sign in the Wulong Hunting area of Tonghe,Heilongjiang Province, during the winters of 2000 and 2001. The major winter foods of wild boars included Pteridophytes and the fruits,branches and leaves of other plants. Equisetum hiemale was the main food and accounted for 41.7%. Other food components, such as Pinus koraiensis, Populus spp., Juglans mandshurica, Quercus mongolica, Padus asiatica, and Corylus heterophlla accounted for 10.5%, 10.2%, 9.3%, 5.3%, 4.0%, and 4.0%, respectively. The concentrations of crude fat and crude protein of the food plants showed a peak in November, then decreased and became lowest in February, then increased slightly in March. The mean concentrations of crude fat and crude protein were 9.6% and 10.2%,respectively.
