关键词: 光皮桦, 优势种群, 种间联结

Abstract: The study showed that during the period from sowing to pre-wintering, the soil nitrate in highyielding wheat field moved down to deeper layers, and accumulated in the layers below 140 cm. An application rate of 96～168 kg N·hm^-2increased the nitrate content in 0～60 cm soil layer and the wheat grain yield and its protein content, and decreased the proportion of apparent N loss to applied N and the ammonia volatilization loss from basal nitrogen. Applying 240 kg N·hm^-2 promoted the downward movement of soil nitrate and its accumulation in deeper layers, increased the proportion of apparent N loss to applied N and the ammonia volatilization loss from basal nitrogen, had no significant effect on the protein content of wheat grain, but decreased the grain yield. The appropriate application rate of nitrogen on high-yielding wheat field was 132～204 kg N·hm^-2.

Key words: Betula luminifera, Dominant population, Interspecific association