陕北水蚀风蚀交错带柠条适应不同生境的形态和生理可塑性

以陕北水蚀风蚀交错带4个不同坡位与土壤质地生境沟底+坝淤绵沙土(A)、梁坡+红黄土(B)、坡顶+绵沙土(C)、坡顶+风沙土盖绵沙土(D)]中生长的柠条为研究对象,研究了其生长、光合和水力性状的可塑性变化,以揭示柠条对不同生境的适应机制。结果表明:(1)生境D和生境A样地1~3m和3m土层的平均含水量明显高于生境B和C;(2)与生境B和C相比,生境A和D中生长的柠条冠幅、株高和新枝长显著增加,叶厚度减小,正午叶水势、净光合速率、气孔导度和蒸腾速率亦显著增加,但不同生境中柠条枝比导水率、Huber值和栓塞程度无显著差异;(3)柠条各测定指标中,新枝长、净光合速率、气孔导度和蒸腾速率表现出较大的可塑性。研究认为,柠条可能主要通过新枝长或光合生理特征的改变来适应不同的水分生境。

Plasticity of Morphological and Physiological Traits in Caragana korshinskii under Different Habitats of Water Wind Erosion Crisscross Region of the Loess Plateau

The plasticity of plant morphological and physiological traits is the foundation to probe species adaptation.Hence,the plasticity of growth,photosynthetic and hydraulic traits of Caragana korshinskii growing under different slope positions with different soil texture,including A:gully channel+loessial soil,B:slope+loessial soil,C:slope top+loessial soil and D:slope top+layered soil,were studied in order to explore the mechanism of the extensive distribution of this species under fragmented landscapes on the Loess Plateau.The results indicated that:(1)the soil moisture within 1-3 m and 3 m layer under habitat D and A were higher than those under habitat B and C.(2)C.korshinskii growing under habitat A and D had relatively larger canopy size,plant height and current year twig length and thinner leaf thickness than those plants under habitat B and C.The midday leaf water potential,net photosynthetic rate,stomatal conductance and transpirational rate were also increased,but no difference existed for specific hydraulic conductivity,Huber value and midday native embolism.(3)Among those measured plant traits,current year twig length,net photosynthetic rate,stomatal conductance and transpirational rate showed relative larger plasticity,indicting C.korshinskii mainly depend on variation of current year twig length and photosynthetic traits to adapt to different water habitats.