干旱半干旱区降水量梯度下植物群落的叶、茎属性特征

Leaf and stem traits of plant communities along rainfall gradient in arid and semi-arid areas

通过对沿年均降水量减少的兰州、白银、景泰和临泽4个试验点不同科属植物进行野外调查与室内分析,试图明确干旱区降水量梯度下植物叶、茎属性〔比叶重(LMA)、单位面积氮含量(Narea)和单位面积叶绿素含量(Chlarea)〕的变化并探讨其对渐进干旱胁迫的适应规律。结果表明:降雨量梯度下叶、茎利用不同属性特征应对干旱胁迫,LMA和Narea含量随干旱胁迫的加剧而增大,Chlarea含量随干旱胁迫的加剧而降低,这在一定程度上体现了研究区域植物对干旱胁迫加强的适应规律。另外随年均降水量的减少,临泽、景泰、白银、兰州其物种的绿色茎枝/叶生物量比依次减小。即随干旱胁迫的加剧,干旱区植物绿色茎枝与叶片生物量的比例逐渐增大。

Plant leaf and stem traits include the leaf mass per areas（LMA）,leaf life span（LL）,nitrogen content per unit area（Narea） and the chlorophyll content per unit area（Chlarea）.These features, directly affecting the properties of carbon sequestration capacity of plants,are the adaptation strategies of plants resistant to the environment in the long process of production in order to obtain maximum photosynthetic formation.This study is to identify plant leaf and stems traits（LMA,Narea and Chlarea） and explore the changes of adapting to progressive drought stress along rainfall gradient in arid and semi-arid areas.The results show that different families and genera of plants distributed in Lanzhou,Baiyin,Jingtai and Linze experimental sites take different attributes of leaf,stem or branch response characteristics against drought stress with annual mean precipitation reducing.The LMA and content of Narea increase with intensification of drought stress and Chlarea content increases with the decline of drought stress,which reflects the strengthening of plant adaptation to drought stress in some extent.In addition,green stem or branch/leaf biomass ratio in Linze species is the largest with annual mean precipitation reducing,followed by Jingtai species,even Baiyin species,whereas Lanzhou species is the smallest.With the increase of drought stress,the biomass ratio of green stem or branch/leaf is gradually increasing in dry areas.