| Ecological stoichiometry is a science that studies the energy balance and chemical element balance of ecosystem,which is mainly reflected in the process of the influence of carbon,nitrogen and phosphorus element balance on ecological interaction.Studying the ecological stoichiometry of carbon,nitrogen and phosphorus in wetland plants is of great significance for understanding the spatial pattern of wetland ecosystem,the cycle and balance mechanism of carbon,nitrogen and phosphorus,revealing the availability of nutrients and predicting future trends.Taking Dunhuang Yangguan wetland as the research object in this study,30 representative sample sites were selected to collect samples of subterraneous stem,stems,leaves and flowers of the dominant species reed during its vigorous growth period,and soil samples were collected in layers(0～20,20～40 and 40～60 cm).The contents of carbon,nitrogen and phosphorus in different organs of reed and the soil physical and chemical factors(soil moisture,salinity,p H,bulk density,organic carbon,total nitrogen,alkali-hydrolyzed nitrogen,total phosphorus and available phosphorus)in different soil layers were determined.The ecological stoichiometry characteristics of carbon,nitrogen and phosphorus in different organs and the response of ecological stoichiometry of carbon,nitrogen and phosphorus in the subterraneous stem,stems,leaves and flowers of reed to soil physical and chemical factors were analyzed.The main results are as follows:(1)The average values of soil moisture of 0～20,20～40 and 40～60 cm soil layers were 15.22,18.36 and 22.32%in the study area,respectively,and the moisture increased with the increase of soil depth;the average salinity of each soil layer was 7.67,3.66 and 2.69 g/kg,respectively,which decreased with the increase of soil depth;compared with other soil physical and chemical factors,the moisture and salinity of different soil layers were significantly different(P<0.05).The average values of soil p H were 8.49,8.48 and 8.43,which decreased with the increase of soil depth.The average values of soil bulk density were1.11,1.12 and 1.08 g/cm~3,which increased first and then decreased with the increase of soil depth.Alkali-hydrolyzed nitrogen increased with the increase of soil depth(41.29,42.55,47.87 mg/kg),while available phosphorus was the opposite(4.97,4.61,3.73 mg/kg).The variation ranges of organic carbon,total nitrogen and total phosphorus were 1.61～18.34 g/kg,0.17～1.55 g/kg and 0.36～0.71 g/kg,respectively.The vertical variation trend of organic carbon and total nitrogen content was the same,which decreased first and then increased with the increase of soil depth,and reached the highest level in 40～60 cm.while total phosphorus is the opposite.(2)The contents of C,N and P of reed subterraneous stem were 395.95,3.08 and 0.41g/kg,the contents of C,N and P of reed stems were 421.03,5.32 and 0.60 g/kg,the contents of C,N and P of reed leaves were 433.39,18.80 and 0.95 g/kg,and the contents of C,N and P of reed flowers were 429.00,11.88 and 1.07 g/kg,respectively.C content in each organ was leaf>flower>subterraneous stem>stem,N content in each organ was leaf>flower>stem>subterraneous stem,P content in each organ was flower>leaf>subterraneous stem>stem.(3)Relative to the C and P elements,there was a good correlation between N content in organs,it shows a positive correlation except that there was no significant correlation between stem N and flower N,subterraneous stem N was negatively correlated with stem C and subterraneous stem P(P<0.05),and positively correlated with leaf C(P<0.05).subterraneous stem and stem P were significantly positively correlated(P<0.01).(4)C/N,C/P and N/P of reed subterraneous stem were 159.11,1203.95 and 7.68 in the study area,respectively,C/N,C/P and N/P of reed stems were 99.85,997.67 and 12.76respectively,C/N,C/P and N/P of reed leaves were 23.93,475.04 and 20.76 respectively,and C/N,C/P and N/P of reed flowers were 37.23,435.98 and 11.92 respectively.The average C/N of each organ was subterraneous stem>stem>flower>leaf,the average C/P was stem>subterraneous stem>leaf>flower,and the average N/P was leaf>stem>flower>subterraneous stem.(5)The C/N and C/P of the organs of reed in this study were significantly higher than other studies,showing higher carbon sequestration advantages and nutrient use efficiency.There is a good correlation between N,C/N and N/P of various organs and N of various organs,subterraneous stem P,soil moisture and salinity.Generally speaking,the effect of reed organs on C,N,P and their stoichiometric ratios was higher than that of soil physical and chemical factors.There are significant differences in soil moisture and salinity in different soil layers,and the contents of C,N,P and their stoichiometric ratios in different organs are affected.Compared with C and N elements in soil,P element has greater influence on them,In particular,the soil available phosphorus content is much lower than that of alkali-hydrolyzed nitrogen,and the degree of influence is higher than that of alkali-hydrolyzed nitrogen.(6)The effect of soil chemical elements on the eco-chemometric characteristics of reed organs is P>N>C.Among them,the effect of soil N element on reed flowers is higher,while that of P element on reed stems and leaves are higher. |
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