Abstract: Taking the common three plant species with different seed size (two an nuals Galeopsis bifida and Chenopodium foetidum and a biennial Swertia tetraptera) in abandoned fields of eastern Tibetan Plateau as test materials, this paper studied their performance under effects of different spatial pattern (aggregated vs. random distribution, and low vs. high density) and species combination (mon oculture vs. mix-culture). The results showed that spatial pattern and species c ombination had no significant effects on the emergence rate, but affected the co mpetition hierarchy of the three species to some degree. Large-seed species G . bifida exhibited dominance in interspecific competition, small-seed species C. foetidum benefited from intraspecific aggregated pattern, while S. tet raptera, whose seed size was between that of G. bifida and C. foetidum , showed complexity in interspecific competition. For C. foetidum, its seedl ing mortality rate in aggregated pattern was lower, and its aboveground biomass was significantly higher in aggregated pattern than in random pattern. For G. bifida, its seedling mortality rate in aggregated pattern was higher, and its aboveground biomass was signif icantly lower in high density and aggregated pattern. The seedling mortality rat e of G. bifida was higher and its aboveground biomass was lower in monocultu re t han in mix-culture. For C. foetidum, its seedling mortality rate was higher in m ix-culture with S. tetraptera than in monoculture, but there was no signifi cant difference in its aboveground biomass among different species combination. For S. tetraptera, its seedling mortality rate was the lowest in mix-culture with G. bifida, but the highest in mix-culture with G. bifida and C. foetidum.

Key words: Sulfate paper pulp waste liquid, Lignin, Phenol formaldehyde resin, Polyfunctional aqueous polymer isocyanate, Infrared spectrum analysis