5年模拟增温后矮嵩草草甸群落结构及生产量的变化

5年模拟增温后观察表明,植物生长期4～9月暖室内10cm、20cm地下土壤平均增温1.86℃,10cm、20cm地上空气平均增温1.15℃,地表0cm平均增温1.87℃,且增温在植物生长初期大于生长末期及枯黄期。在模拟增温初期年生物量比对照高,增温5年后生物量反而有所下降。增温使禾草类植物种增加,杂草减少。从表面来看,增温可使植物生长期延长,利于增大生物量,实际受热效应作用,植物发育生长速率加快,植物成熟过程提早,生长期反而缩短,加之玻璃纤维的存在使暖室内外温度交换减缓,减少了温度日变化,限制干物质积累,终久导致生物量减少。这说明小气候的作用,环境条件诱发土壤结构变化,植被的种群结构也随之改变,甚至出现演替的过程,全球变暖不仅对植物的生物生产力影响较大,而且对植被类型的演替有着不可忽视的作用。

Effects of a 5-years mimic Temperature Increase to the structure and productivity of kobresia humilis meadow

A mimic 5-year temperature increased in a greenhouse raised the soil temperature of 10 and 20 cm depth 1.86℃ higher than that in the open, the 10 and 20 cm above ground air temperature 1.15℃ higher, and the soil surface temperature 1.87℃ higher than that in the open respectively, The extent of temperature increase was generally greater in the early plant growing season than in the later stage and the plant withering period.The result showed that in the first few years of the 5-year experiment, the yearly biomass from the greenhouse is weightier than that of the control in the open.However, after the 5-year period,the yearly biomass form the greenhouse decreased and became less than of the control. Though higher temperature increased the number of grass species, prevented weeds from teeming the land,and apparently extended the plant growing period,and raised the biomass,the heat accelerated the growth and maturing of plants, thus shortening the growing period actually.Moreover, the glass of the greenhouse retarded the fluctuation of temperature of daytime and the night time,and restricted the accumulation of dry matter.all this leads to the decrease of biomass in the greenhouse.The micro-climatic change of soil structure which also changes the structure of the plant species and leads to the species succession process.Consequently,global warming not only affects the plant productivity,but the succession of plant types as well.