Abstract:

The growth of poplar (Populus tomentosa Carr.) was studied under intercropping systems by means of “time-space complementary” method. The results demonstrated that poplar-crop intercropping system carried out in plain farm region was a available way to increase poplar growth and cultivate large timber, for example, average volume growth of 11-year-old poplar trees under intercropping systems increased 30.3%～37.7% than that of grown in pure stand with the same site and at the same age. It also showed that intercropping practice, considering of the real need farm region, should leave enough space for crop growth so as to give farmer an incentive to carry out intensive management, including soil water and fertility maintaining, which will be advantageous to maintaining the fast growing of poplar trees. In fact, the average stem volume increased more than 80% after thinning, i.e.3m×14m to 3m×28m, in the tenth year of intercropping, at that stage the tree crown coverage rate on farmland was too high and heavy shading harmed crop developing. Poplar crown deflected, on the other hand, existed in all stands because of intercropping pattern (i.e. bigger spacing between-rows and smaller spacing in-row) and there was a positive proportion between the degree of crown defleeted and the intercropping year. The regression equation of crown deflected index (Y) and intercropping years (x) could be shown as belows:Y=0.0301x-0.0708 (r=0.89)

Key words: Tree-crop intercropping, Poplar-crop intercropping, Populus tomentosa Carr., Crown deflected