围栏封育对青海湖地区芨芨草草原生物量的影响

Influences of enclosure to Achnatherum splendens steppes biomass in the Qinghai Lake Area

选择青海湖地区的芨芨草草原为研究对象,以围栏内封育和围栏外自由放牧的草地做比较,研究了围栏内外枯枝落叶量、地上生物量的季节动态变化和地下生物量的状况。结果表明：枯落物生物量的季节动态围栏内外均呈现高—低—高的变化趋势,且围栏内枯落物量大于围栏外。群落总地上生物量、禾草类、杂类草和豆类草生物量围栏内外均呈现明显单峰型生长曲线,围栏内地上总生物量和禾草类生物量均大于围栏外,杂类草和豆类草生物量则是围栏外大于围栏内。围栏内外群落的地下生物量垂直分布均呈典型的倒金字塔型,从地表向下地下生物量的空间分布呈递减趋势。地下生物量主要集中分布在0~10 cm,围栏内外分别达1 408.778 g和940.934 g,占总地下生物量比例分别是84.65%和77.12%;而在10~20 cm和20~30 cm两层无论是重量,还是所占的比例,都是围栏外大于围栏内。该地区降雨量和气温呈单峰的增长,且雨热同季,这也和植物的生长规律吻合,土壤含水量达到最高值的时间较降雨量和气温滞后。围栏外地上生物量的季节变化和月均气温、降雨量呈极显著正相关关系,围栏外月均地上生物量的累积量与土壤含水量呈显著负相关关系;地上生物量的月增长率与月均气温和降雨量呈显著正相关关系;围栏内地上生物量的增长率与月均气温呈极显著正相关关系,其他相关关系微弱。

The Sheep Breeding Pasture-Land in City Sanjiao of Qinghai Province is located on the north bank of Qinghai Lake,we choose the Achnatherum splendens steppe of abandoned field as our object,and research in the content of litter,overground biomass and underground biomass,comparing within and out of the fence.The result is as follows： the content of litter,total overground biomass and grasses within the fence is higher than out,while overground biomass of forbs and legume out of the fence is higher than within.The seasonal dynamic tendencies of litter within and out are both high-low-high.The seasonal dynamic growth curves of total overground,grasses and sedges,forbs and legume are all of similar form,which is single apex.The form of underground biomass is a typical reversed pyramid,spatial distribution descending from surface to subterranean.The underground content is mainly in 0-10 cm,and the underground biomass inside enclosure and outside are 940.934 g and 1 408.778 g,occupying 77.12% and 84.65% of each total underground biomass.The underground biomass inside is also higher than that of the outside.In 11-20 cm and 21-30 cm,underground biomass outside are higher than inside in both weight and percentage.In this region rainfall comes together with the high temperature,and growth curve of monthly mean temperature and monthly mean rainfall is a single apex.,which anastomose the discipline of plant.and as a result,the crest value of soil moisture is after monthly mean temperature and monthly mean rainfall.The seasonal dynamic of aboveground biomass out of fence has a very significant correlation with monthly mean temperature and monthly mean rainfall.Meanwhile,there is a remarkable negative correlation between seasonal dynamics of aboveground biomass out of fence and the soil moisture.At the same time,there is a closely correlation between the increasing rate of aboveground biomass out of fence and monthly mean temperature and monthly mean rainfall.The increasing rate of aboveground biomass within fence has a strong correlation with monthly mean temperature,but weak with others.