Effect of grassland restoration duration on plant-soil ecological stoichiometry characteristics in a typical steppe

RAO Li-Xian;SHEN Yan;NIE Ming-He;Agriculture College in Ningxia University;Key Laboratory of Restoration and Rehabilitation of Degraded Ecosystem in Northwestern China,Ningxia University;

typical steppe in Ningxia;;abandoned grassland;;soil;;dominant plant;;C,N,P stoichiometry

To determine the influence of restoration period on the stoichiometry of dominant plant species and soil C,N,P of typical steppe in Ningxia,China,the stoichiometric characteristics of dominant plant species and soil C,N,P in grassland abandoned for periods of 0,1,3,5,6,8,11,15 and 20 years.The total nitrogen content of individual plants showed that the aboveground portion is greater than the belowground portion; the total nitrogen content of Artemisia scoparia was higher than other species.Similarly the total P content of plants was dominated by the above ground portion with the exception of Leymus secalinus plants.The organic carbon in grassland abandoned for 1 year Setaria viridis and 3 years L.secalinus was greater in the underground portion; for remaining abandonment periods the aboveground portion was greater than underground portion.The highest C∶N,C∶P,N∶P ratio's in dominant plants in 20 year grassland occurred in S.bungeana and the lowest in L.secalinus and A.scoparia.Abandonment periods between 6 and20 years resulted in soil organic carbon content layer decreasing from the surface with increasing depth while abandonment periods between 0-6 years resulted in fluctuating changes in soil N.The response of total P to abandonment period was similar to that of total N.The soil C∶N ration varied from 7.08-19.62,C∶P ranged from 6.60 to 35.25,N∶P varied from 0.82 to 2.17; the mean soil C∶N ration ranged from 11.18 to 15.03 in different soil layers,C∶P from14.09 to 24.55 and N∶P from 1.06 to 1.98; The soil C∶P and N∶P ratio's were generally lower than those typically found in other regions of China while the C∶N ration was similar to typical values in China.There was no correlation between soil C∶N and soil organic carbon but there was a negative correlation with total N,meaning that C ∶N was mainly controlled by N; the C∶P ratio was significantly positively correlated with organic carbon but not with total P.There was a significant positive correlation between soil N∶P and total soil N,indicating this ration is primarily controlled by N.Total soil N showed a fluctuating upward trend with increasing abandonment period.There was a strong correlation between total plant P and total soil P(P<0.01); soil organic C was also correlated with N∶P(P<0.05).