空间格局和物种组合对三个植物种行为的影响

Effects of spatial pattern and species combination on the performance of three plant species.

以青藏高原东部高寒草甸弃耕地种子大小不同的3个常见物种:2个1年生物种鼬瓣花(Galeopsis bifida)和菊叶香藜(Chenopodium foetidum)及1个2年生物种四数獐牙菜(Swertia tetraptera)为试验材料,通过单播、2个、3个物种的混播,分别以2个密度(高密度和低密度),按照随机或者种内积聚的空间格局形式播种,研究空间格局、物种组合对不同种子大小植物行为的影响。结果表明:1)空间格局和物种组合对3物种的出苗率没有显著影响,但在一定程度上影响着物种竞争能力等级,大种子鼬瓣花在种间竞争中占据着优势地位,小种子菊叶香藜在种内集聚格局下获益;四数獐牙菜的种子大小介于二者之间,其种间竞争的结果表现复杂;2)集聚格局下菊叶香藜的幼苗死亡率低,地上生物量比随机格局下显著高;集聚格局下鼬瓣花死亡率高,通过密度-格局作用,高密集聚下的地上生物量才表现显著较低;3)与其他物种混播相比,鼬瓣花单播下死亡率高,地上生物量低;当混播中存在四数獐牙菜时,菊叶香藜的死亡率比单播下高,物种组合对其地上生物量没有显著影响;四数獐牙菜与鼬瓣花混播时死亡率最低,3个物种混播时其死亡率最高。

Taking the common three plant species with different seed size （two annuals Galeopsis bifida and Chenopodiumfoetidum 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 （monocuhure vs. mix-culture）. The results showed that spatial pattern and species combination had no significant effects on the emergence rate, but affected the competition 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. tetraptera, whose seed size was between that of G. bifida and C. foetidum, showed complexity in interspecific competition. For C. foetidum, its seedling 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 significantly lower in high density and aggregated pattern. The seedling mortality rate of G. bifida was higher and its aboveground biomass was lower in monocuhure than in mix-cuhure. For C. foetidum, its seedling mortality rate was higher in mix-culture with S. tetraptera than in monocuhure, but there was no significant 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.