黄土丘陵区草本群落生物量空间分布格局及其影响因素

Distribution of herbaceous community biomass and its relationship with influencing factors in the Loess Hilly Region

草地是干旱半干旱地区黄土高原植被组成的主体,而草本植物作为草地生态系统的优势群落,在黄土高原恢复植被和水土保持建设方面存在着不可替代的优势。因此本试验选取黄土丘陵区不同纬度下的草本群落为研究对象,分析草本群落地上、地下生物量的空间分布特征及其影响因素,同时并验证等速生长关系,以期为黄土丘陵区恢复植被、改善生态建设方面提供理论指导。结果表明:(1)在纬度梯度35.95°~38.36°N变化范围内,黄土丘陵区不同植被带草本群落地上生物量变化范围为54.60~204.32g·m^(-2),平均值156.968g·m^(-2),变异系数为27.83%;地下生物量变化范围为78.88~829.64g·m^(-2),平均值469.21g·m^(-2),变异系数为48.87%;草本群落地下/地上生物量变化范围为0.93~4.49,平均值2.89,变异系数为39.18%。草本群落生物量(地下、地上)大小顺序均为:森林-草原带>草原带>森林带>草原-荒漠带,且地上、地下生物量随纬度梯度变化规律均呈现出"先增加后减少"的单峰型变化趋势。(2)草本群落地下与地上生物量呈极显著正相关(P<0.01),决定系数达到0.59,且符合等速生长关系。(3)草本群落地下生物量与年均降水、年均温、土壤有机碳、全氮、全磷含量之间均呈显著相关。气候因子和土壤理化性质对地下生物量都具有重要影响作用,其影响机理还需进一步结合植物生物学和生理生态方面的综合研究才能做出准确结论。

Grassland is the main vegetation type in arid and semiarid areas of the Loess Plateau.Herbs,as the dominant community in the grassland ecosystem,have an irreplaceable advantage in the restoration of vegetation and in the conservation of soil and water on the Loess Plateau.In this study,we analyzed the spatial distribution characteristics of aboveground and belowground biomass and their influencing factors in herbaceous plant communities at different latitudes in the Loess Hilly Region.In addition,isokinetic growth was statistically analyzed to provide theoretical guidance for the restoration of vegetation and improvement of ecological management strategies for the Loess Hilly Region.The results showed that:(1)in the range of 35.95°to 38.36°N,the aboveground biomass of the herbaceous plant community in the Loess Hilly Region ranged from 54.60 to 204.32 g·m-2(average,156.968 g·m-2;coefficient of variation,27.83%).Belowground biomass ranged from 78.88 to 829.64 g·m-2(average,469.21 g·m-2;coefficient of variation,48.87%).The change in the belowground/aboveground biomass of the herbaceous plant community was 0.93-4.49(average,2.89;coefficient of variation,39.18%).The communities were ranked,from highest biomass(belowground+aboveground)to lowest,as follows:forest-grassland belt>grassland belt>forest belt>grassland-desert belt.The aboveground and belowground biomass showed a“single peak”trend along the latitudinal gradient,first increasing and then decreasing with increasing latitude.(2)There was a significant positive correlation between belowground biomass and aboveground biomass(P<0.01;coefficient of determination,0.59),and this relationship was consistent with isokinetic growth.(3)The belowground biomass of the herbaceous plant community was positively correlated with mean annual precipitation,mean annual temperature,soil organic carbon,soil total nitrogen,and soil total phosphorus.Both climatic factors and soil physico-chemical properties had important effects on belowground biomass.To draw accurate conclusions about the effects of climatic and soil physico-chemical properties on plant communities,further plant biology and eco-physiology research should be undertaken to explore the mechanisms underlying plants’responses.