三江源区高寒草地根系-土壤C、N、P生态化学计量特征

Root-soil ecological stoichiometric characteristics of alpine grassland in the source area of three rivers

植物生态化学计量学及内稳性特征对于研究C、N、P元素与植物生长之间的关系、限制性养分的判断、生态系统的稳定性等方面有重要意义,但对高寒草地生态系统的相关研究报道较少,鉴于此,以三江源区4类高寒草地为研究对象,测定并分析了根系与土壤C、N、P生态化学计量关系特征以及根系生态化学内稳性特征。结果表明,不同类型高寒草地0~20 cm植物根系C含量平均为27.42%~44.8%;0~20cm根系全N含量平均为1%~1.68%;0~20cm根系全P含量平均为0.07%~0.16%。高寒草原植物根系各指标均具有内稳性特征;高寒草甸植物根系C∶N属于弱内稳态;沼泽草甸植物根系P属于敏感态,N∶P是弱内稳态;人工草地植物根系N是弱敏感态,根系P是敏感态。说明高寒草原植物根系具有相对较高的内稳性,可能是其能适应极端环境胁迫的原因;高寒草甸植物根系C、N含量受土壤环境的影响较大,沼泽草甸和人工草地植物根系N、P含量受土壤环境影响较大。高寒草原、高寒草甸、沼泽草甸、人工草地根系C∶N分别为19.35、20.68、19.7、46.02;根系C∶P分别为443.03、208.08、183.71、360.29,根系N∶P分别为23.14、10.17、9.28、7.77;高寒草地根系C∶N和C∶P均低于全球植物根系平均水平48.25和1158.00,说明三江源区草地N、P元素利用效率较高;高寒草原植物根系N∶P高于全国平均水平13.5,其他3类高寒草地均低于全国平均水平13.5,此结果为各类草地后续进行植物生长限制因子的判断提供重要的科学依据。

Eco-chemometrics and internal stability characteristics of plants are of great significance for studying the relationship between C,N,P elements and plant growth,judgment of limiting nutrients,stability of ecosystems,etc.However,there are few reports on alpine grassland ecosystems.In this paper,four types of alpine grasslands in the source region of three rivers were taken as the research object,and the ecological stoichiometric relationship between roots and soil C,N and P as well as the ecological chemical internal stability of roots were measured and analyzed.The results showed as follows:1.The average root C content of 0~20 cm plants in different types of alpine grassland was 27.42%~44.8%;The average content of total N in 0~20 cm roots was 1%~1.68%.The average content of total P in 0~20 cm roots was 0.07%~0.16%.2.The root C,N,P,C∶N,C∶P and N∶P in alpine steppe had the characteristics of internal stability;The roots C∶N of alpine meadow plants belonged to weak homeostasis.Root P of marsh meadow plant was sensitive state,N∶P was weak homeostasis.Root N was a weak sensitive state,and root P was a sensitive state.These results indicated that the root system of alpine steppe had relatively high internal stability,which may be the reason for its adaptability to extreme environmental stress.The contents of C and N in the roots of plants in alpine meadow were significantly affected by the soil environment,while the contents of N and P in the roots of plants in swamp meadow and artificial grassland were significantly affected by the soil environment.3.The root C∶N of alpine steppe,alpine meadow,swamp meadow and artificial grassland were 19.35,20.68,19.7 and 46.02 respectively;Root C∶P were 443.03,208.08,183.71 and 360.29 respectively,and root N∶P were 23.14,10.17,9.28 and 7.77 respectively;The root C∶N and C∶P of all alpine grasslands were lower than the global average level of plant roots(48.25 and 1158.00),indicating that the utilization efficiency of N and P elements in grasslands in the source area of three rivers were high.The N∶P of plant roots in alpine steppe was higher than the national average level of 13.5,and the other three types of alpine grasslands were lower than the national average level of 13.5.This result provided an important scientific basis for the subsequent judgment of plant growth limiting factors in various grasslands.