降水变化对红砂-珍珠碳、氮、磷化学计量特征的影响

以荒漠C3植物红砂(Reaumuria soongarica)和C4植物珍珠(Salsola passerina)为材料,在西北干旱荒漠区沿自然降水梯度,对不同降水条件下单生和混生红砂与珍珠根、茎、叶器官碳、氮、磷化学计量指标进行测定,分析其在不同生境下化学计量特征对种间关系及环境胁迫的响应规律。结果表明:(1)随干旱胁迫程度增加(降水量的减少),红砂各器官C含量平均升高7.73%,N、P含量分别平均降低6.20%、10.61%;珍珠各器官C含量平均升高7.36%,N、P含量分别平均降低5.93%、14.03%。两种植物叶片C含量升高表明其光合速率较低,生长缓慢,但对外界不利环境的防御能力增强,能更好地适应干旱环境。(2)干旱胁迫改变了红砂和珍珠的N、P含量在各器官的分配模式,两种植物N、P含量在叶部高于根部,在根、叶中N/P明显高于茎,表明两种植物不同器官受到的养分限制不同。(3)红砂各器官C、N、P含量高于珍珠,说明红砂防御能力较强,生长速率高,对资源的竞争和利用能力较珍珠强;珍珠C/N和C/P均高于红砂,表明珍珠比红砂有较强的碳同化能力和较高的营养利用效率。(4)在干旱胁迫条件下,红砂和珍珠均表现为碳素积累、氮磷素限制的格局,它们对于氮和磷的养分利用不活跃,受到氮和磷养分的限制较为均衡。

Effect of Precipitation on the Stoichiometric Characteristics of Carbon, Nitrogen and Phosphorus of Reaumuria soongarica and Salsola passerina

Using desert C₃ plant Reaumuria soongarica and C₄ plant Salsola passerina as materials, along the natural precipitation gradient in the arid desert region of Northwest China, the solitary and mixed R. soongarica and S. passerina roots, stems and leaf organs under different precipitation conditions we measured carbon, nitrogen, and phosphorus stoichiometry indicators, and analyzed their stoichiometric characteristics in different habitats in response to interspecific relationships and environmental stress. The results showed that: (1) with the increase of drought stress (decrease in precipitation), the C content of various organs of R. soongarica increased by 7.73% on average, and the N and P contents decreased by 6.20% and 10.61%, respectively; the C content of S. passerina increased by 7.36% on average, and the N and P contents decreased by 5.93% and 14.03%, respectively. The increased C content in the leaves of the two plants indicates that their photosynthetic rate is low and their growth is slow. However, they have a strong defense ability against the adverse external environment and can better adapt to the drought environment. (2) Drought stress changed the distribution patterns of C, N and P in different organs of R.soongarica and S. passerina, and the N content and N/P ratio were higher in leaves than that in roots. The N/P of R. soongarica and S. passerina was significantly higher in roots and leaves than that of stems, indicating different nutrient limitation in different organs of the two plants. (3) The contents of C, N and P in R. soongarica are higher than that in S. passerina, which indicates that R. soongarica has strong defensive ability, fast growth rate and strong ability to compete and utilize resources. C/N and C/P of S. passerina were higher than those of R. soongarica, indicating that S. passerina had stronger carbon assimilation ability and higher nutrient use efficiency. (4) Under drought stress condition, both R. soongarica and S. passerina showed a pattern of carbon accumulation and nitrogen and phosphorus limitation. They were inactive in nitrogen and phosphorus nutrient utilization, and were more balanced by the nitrogen and phosphorus limitation.