内蒙古典型草原8种优势植物养分回收特征

选取内蒙古典型草原优势植物羊草(Leymus chinensis)、大针茅(Stipa grandis)和冷蒿(Artemisia frigida)等8种植物,通过在夏秋季节每隔15天采样,重复测定其地上部分氮(N)和磷(P)浓度变化,确定不同植物的氮和磷养分回收特征。结果显示:每种植物的氮和磷回收过程基本同步,但不同植物的回收时间存在差异;羊草和大针茅的养分回收起始时间最早(7月15日~7月30日),而冷蒿最晚(8月30日),这与不同植物种的物候期相对应。在植物群落水平,氮和磷的回收起始时间均为7月30日。植物氮回收效率范围为41%~70%,磷回收效率范围为52%~84%;羊草养分回收效率最高,大针茅和小叶锦鸡儿(Caragana microphylla)次之,糙隐子草(Cleistogenes squarrosa)和冷蒿最低。羊草和大针茅的较强的养分回收能力可能是其在典型草原保持优势地位的重要因素之一。根据植物养分回收时间,确定草场年度终牧时间是保持草原植物活力、生态系统健康和可持续利用的基础。

Plant Nutrients Resorption Characteristics of Eight Dominant Species in Typical Steppe of Inner Mongolia

In order to determine the characteristics of nitrogen(N)and phosphorus(P)resorption of eight dominant plants(Leymus chinensis,Stipa grandis,Agropyron cristatum,Carex duriuscula,Cleistogenes squarrosa,Potentilla bifurca,Artemisia frigida and Caragana microphylla)in Inner Mongolia typical steppe,the nitrogen and phosphorus concentrations of aboveground parts of different plants were measured repeatedly every 15 days in summer and autumn.The results showed that the nitrogen and phosphorus resorption process of eight species was basically synchronous,though the starting time of nutrient resorption differed among species.The nutrient resorption of L.chinensis and S.grandis was the earliest(July 15^th~30^th),and that of A.frigida was the latest(August 30^th),which corresponded to the phenological development of different plant species.At the plant community level,the average starting time of nitrogen and phosphorus resorption was from July 30 th.The plant N resorption efficiency ranged from 41%to 70%,and P resorption efficiency ranged from 52%to 84%.The nutrient resorption efficiency of L.chinensis was the highest,followed by S.grandis and C.microphylla,and that of C.squarrosa and A.frigida was the lowest.In conclusion,the greater nutrient resorption efficiency of L.chinensis and S.grandis may be one of the important factors contributing to their dominance in the typical steppe.According to the plant nutrient recovery time,determining the grassland annual end of grazing time is the basis of maintaining plant vitality,ecosystem health and sustainable production.