藏北高原两种典型毒草空间分布特征

Spatial distribution characteristics of two typicalpoisonous weeds along the altitude and slopeon the north Tibetan plateau

摘要:

为揭示藏北高原高寒退化草地毒草的空间分布特征,以该区典型的毒草—瑞香狼毒和镰形棘豆为研究对象,于2018年8月采用样方调查法对其沿海拔和坡向的生物量和群落特征进行观测。结果表明:两种毒草的分布受到了海拔,坡向单独作用及交互作用的显著影响(P＜0.05)。在坡向上,瑞香狼毒和镰形棘豆主要分布于南坡与西坡,其平均生物量在南坡、西坡、北坡分别为25.5,15.6和0.06 g/m²和2.7,2.2和0.03 g/m²;在海拔梯度上,瑞香狼毒的高度在南坡低海拔梯度最高,为22.6 cm,生物量和相对盖度在北坡高海拔梯度最高,分别为37.4 g/m²和72.6%,镰形棘豆的生物量、密度和相对盖度均是南坡的山底梯度最高,分别为5.8 g/m²,0.3株/m2和17.9%。相关分析表明,瑞香狼毒的生物量以及镰形棘豆的生物量、高度、密度、相对盖度与土壤温度呈显著的正相关关系(P＜0.05),瑞香狼毒的生物量和相对盖度与土壤含水量呈显著的负相关关系(P＜0.05)。

Abstract:

In order to reveal the spatial distribution characteristics of poisonous grasses (Stellera chamaejasme and Oxytropis falcata) in the degraded alpine grassland of the northern Tibetan plateau,the biomass and community characteristics along the altitude and slope were investigated in August 2018 by using the field quadrat survey method.The results showed that the distribution of the two poisonous weeds was significantly affected by altitude and slope direction (P＜0.05).On the slope gradient,S.chamaejasme and O.alcata were mainly distributed on the south and west slopes,and its average biomass was 25.5,15.6,0.06g/m and 2.7,2.2,0.03 g/m on the south,west and north slopes,respectively.On the altitude gradient,the height of S.chamaejasme was the highest at the bottom of the south slope (22.6 cm),and the biomass and relative coverage were the highest at the north slope (37.4 g/m and 72.6%,respectively).The biomass,density and relative coverage of O.falcata were the highest in the bottom of south slope,(5.8 g/m,0.3 plant/m² and 17.9%,respectively).The correlation analysis showed that the biomass of S.chamaejasme and the height,density and relative coverage of O.alcata were significantly positively correlated with soil temperature (P＜0.05),while the biomass and relative coverage of S.chamaejasme were significantly negatively correlated with soil water content (P＜0.05).In conclusion,S.chamaejasme and O.alcata were suitable for growing in a warm and dry environment.