以红松(Pinus koraiensis Sieb. et Zucc.)和蒙古栎(Quercuss mongolica Fisch. ex Ledeb.)幼苗为研究对象,针对东北地区未来可能的干暖气候条件,利用盆栽实验进行干旱条件下两种幼苗的生长与竞争研究,分析其光合生理参数和生物量变化。一个生长季的实验结果表明:(1)干旱致使红松和蒙古栎幼苗的光合速率均下降,蒙古栎降低幅度达到显著水平,红松下降不显著。干旱使蒙古栎的水分利用效率下降而红松却显著增加。干旱还导致蒙古栎幼苗的茎叶和侧根生物量以及全株叶面积下降,但却增加了红松的细根生物量和根冠比。(2)混栽栽植处理降低了蒙古栎幼苗的最大净光合速率和水分利用效率,进而减少了其茎和侧根生物量。而对于红松幼苗,混栽同样降低了其水分利用效率,但也增加了其比叶面积和全株叶面积,因而对幼苗生长影响较小。以上结果表明,蒙古栎对干旱反应更为敏感和迅速。种间竞争中红松幼苗比蒙古栎幼苗表现出更强的竞争能力。
英文摘要:
Broad-leaved Korean pine forest is the zonal vegetation in eastern mountains of northeast China, which accounting for a third of the China's national forest. In order to understand the response of temperate dominant tree species Korean pine and main associated tree species Mongolian oak in broad-leaved Korean pine forest under future climate change conditions (air temperature rising,decrease in precipitation),a competition pot experiment of two-year old Korean pine seedlings and one-year old Mongolian oak seedlings under different soil water contents were conducted under completely random design in April 24,2012. This experiment set up four experimental treatments, with eighteen seedling replicates for each treatment. Two levels of soil water content were respectively 75 - 85 percent of the soil water-holding capacity for the high level,and 50 - 60 percent of soil water-holding capacity for the low level. The competition treatments were six same seedlings in one pot for mono culture and three seedlings for each of the two species in one pot for mixed culture. We analyzed the photosynthetic and physiological parameters and changes in biomass allocation. The experimentation of a growing season showed that : (1) Soil water deficit treatment resulted in the decreases of the maximum net photosynthetic rate in both Korean pine and Mongolian oak seedlings, the reduction rate of Mongolian oak reached a significant level, while Korean pine did not. Drought caused the decline in water use efficiency in Mongolian oak, while it increased significantly in Korean pine. Soil water deficit also led to the decreases in lateral root biomass, stem biomass, leaf biomass and whole tree leaf area in Mongolian oak seedlings, but the increases in fine root biomass and root to shoot ratio of Korean pine seedlings. (2) Mixed culture treatment reduced the maximum net photosynthetic rate and water use efficiency of Mongolian oak seedlings, thereby reduced their stem and lateral root biomass. While for the Korean pine seedlings, mixed culture treatment also reduced their water use efficiency,but it increased the specific leaf area and whole tree leaf area of Korean pine seedlings and therefore had less impact on seedling growth. These results indicate that, Mongolian oak is more sensitive and rapid response to drought. Korean pine seedlings are more competitive than Mongolian oak seedlings in interspecific competition.