摘要:为了探明荒漠生态系统优势种白刺的生存和生长策略，以便更好地服务于退化生态系统恢复及荒漠化治理。根据空气相对湿度选取阿拉善地区3个典型白刺群落样点，研究白刺根、茎、叶中非结构性碳水化合物（NSCs）的积累及分配和碳：氮：磷（C：N：P）计量比特征的变化，并分析相应区域的土壤有机质、全N、全P含量。结果表明：（1）随干旱程度加剧，白刺根、茎、叶中NSCs绝对含量减小，可溶性糖先增加后降低，淀粉先降低后增加；白刺叶片中N、P含量先增加后降低，C：N和C：P先降低后增加，在最为干旱的Plot3样点叶片N：P>16。（2）在Plot1样点，器官间根系可溶性糖显著高于茎干和叶片，根系淀粉含量显著低于茎干和叶片，在Plot3样点叶片可溶性糖含量显著高于茎干和根系，根系中淀粉含量显著高于叶片和茎干；白刺根、茎全C含量显著高于叶片，叶片N含量显著 > 根系 > 茎干；在Plot1和PLot2样点叶片P含量显著大于根系和茎干，在Plot3样点根系 > 茎干 > 叶片。（3） NSCs及构成与C：N：P计量比间关系表明叶片N、P含量与茎、叶可溶性糖含量正相关和淀粉含量负相关，根中P含量与根中淀粉含量正相关和可溶性糖含量负相关。以上结果表明，随干旱加剧白刺的生长受到水分和P的双重限制，白刺通过调整器官间NSCs积累及分配和提高N、P利用效率的策略来适应干旱生境，P含量的变化影响器官间可溶性糖和淀粉的相互转化，对NSCs构成和含量的波动起着调节作用。



Abstract:Studies on the survival and growth strategies of the dominant species Nitraria tangutorum in desert ecosystem can help serving ecological restoration and soil desertification prevention. The N. tangutorum samples were collected from three plots where differed in relative moisture and drought degree showed as Plot1 < Plot2 < Plot3, to explore the C ∶ N ∶ P stoichiometry and non-structural carbohydrate (NSCs) accumulation and allocation in organs of roots, stems and leaves. Meanwhile, the concentrations of soil organic matter, total nitrogen and phosphorous were analyzed in the same sites. The results showed that: (1) with increasing drought stress, NSCs concentrations decreased, while soluble sugar (SS) concentrations increased first and then decreased, and starch (ST) concentrations decreased first and then increased in N. tangutorum organs of leaves, stems and roots. The total N and P concentrations in leaves significantly increased and then decreased with increasing drought stress, C ∶ N ratios and C ∶ P ratios showed the opposite trend and the N ∶ P ratios in leaves were greater than 16 in Plot3. (2) The SS concentrations in roots were higher, while ST contents in roots were lower, than those in stems and leaves in Plot1 sampling site. In Plot3 sampling site, the SS concentrations were higher in leaves than in stems and roots, while ST concentrations were higher in roots than in leaves and stems. Carbon contents in roots and stems of N. tangutorum were significantly higher than those in leaves. Except for P concentrations in Plot3 sampling site, total N and P contents in leaves were higher than those in stems and roots among all three sampling sites. (3) The N and P concentrations in leaves were positively correlated with SS concentrations but negatively correlated with ST concentrations in stems and leaves respectively, and P concentrations were positively correlated with ST concentrations but negatively correlated with SS concentrations in roots. Based on these results, we speculated that water and phosphorous were the limiting factors for the growth of N. tangutorum under drought stress. N. tangutorum adapted to drought by allocating NSCs among organs, and by increasing nitrogen and phosphorous use efficiency. P played an important role in inter-converting of SS and ST, and regulating NSCs composition.





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