降水变化对红砂和珍珠叶片碳氮磷生态化学计量特征的影响

Effects of precipitation changes on the carbon,nitrogen and phosphorus ecological stoichiometry of Reaumuria soongorica and Salsola passerine leaves

为探明降水变化对荒漠植物化学计量特征的影响,以甘肃典型荒漠植物红砂和珍珠为研究对象,沿自然降水梯度测定红砂和珍珠的C、N和P质量分数,探讨C、N和P元素在2种植物叶片中的分配规律。结果表明:随干旱胁迫增加,红砂和珍珠叶片C质量分数增加7.64和6.69 g/kg,N质量分数降低0.50和1.22 g/kg,P质量分数降低0.78和1.12 g/kg,C/N、C/P和N/P均增加。相同的水分条件下,红砂叶片C、P质量分数和C/N、C/P均高于珍珠,珍珠叶片N质量分数和N/P均高于红砂,2种植物叶片C与N、P之间均未出现显著相关性,而C、N、P与C/N、C/P之间均存在强相关性,说明红砂和珍珠通过C/N、C/P来体现CN、CP的耦合关系。可见,干旱胁迫条件下红砂和珍珠均表现为C素积累,N、P元素限制的格局。在西北干旱区红砂的耐旱能力更强,对P元素的吸收能力更高,且珍珠具有较强的固N能力。

[Background]The arid area of northwest China featuring eco-environment frangibility is one of the areas sensitive to global climate change.Seasonal fluctuations about moisture variations in this area are particularly evident.Moisture,an important environmental factor restricting the growth of desert plants,can affect the metabolism and material synthesis in plants by interfering with the acquisition,transportation,distribution,and storage of elements such as C,N,and P of plants.Hence,focusing on two typical desert plants,Reaumuria soongorica and Salsola passerine,this paper was designed for studying the response of ecological stoichiometric characteristics of desert plant leaves to moisture and differences in element utilization of both plants.Offering basic parameters can verify the response of ecological stoichiometric indicators to precipitation.[Methods]Three sample squares of 50 m×50 m were established on natural communities of R.soongorica and S.passerine at three sampling points selected from Jiuquan,Wuwei,and Jingtai in the Hexi Corridor.Leaves of the three R.soongorica and S.passerine plants randomly selected from each sample square were collected using the harvesting method and put them in an envelope for bringing back to the laboratory.Leaves were first dried in an oven at 105℃for 30 min,and then at 80℃to a constant weight,after which the dried samples were crushed for determining C,N and P.Mass fractions of organic carbon,total nitrogen and total phosphorus in the leaves of R.soongorica and S.passerine were determined using potassium dichromate-oxidation heating,kjeldahl determination and vanadium molybdenum yellow colorimetric method together with the calculation of their C/N ratio,C/P ratio and N/P ratio.Excel 2010 and SPSS26.0 were adopted for data analysis,and Excel 2010 for graphing.[Results]With the drought stress increased successively from Jingtai,Wuwei and Jiuquan,C contents in the leaves of R.soongorica and S.passerine increased by 7.64 and 6.69 g/kg,the N content decreased by 0.50 and 1.22 g/kg,the P content decreased by 0.78 and 1.12 g/kg,respectively.Also,C/N,C/P and N/P increased.With consistent moisture conditions,contents of C,P,C/N,and C/P in the leaves of R.soongorica were higher than that of S.passerine,while contents of N and N/P of S.passerine were higher than that of R.soongorica.A strong correlation was observed between the contents of C,N,and P and the contents of C/N and C/P,although there is was no significant correlation among the contents of C,N,and P in the leaves of both plants.[Conclusion]Moisture decrease may accelerate the accumulation of C inthe leaves of R.soongorica and S.passerine.Moreover,R.soongorica in the arid area of northwestern China has a stronger drought tolerance and higher P absorbing capacity,whereas S.passerine possesses the stronger N-fixing ability.These results mayprovide a theoretical basis for protecting and restoring Reaumuria soongorica and Salsola passerine.