呼伦贝尔草地植物群落与土壤化学计量学特征沿经度梯度变化

Abstract

In large scale,plant stoichiometry is mainly affected by latitude and longitude.Many works has have been done to study the effects of temperature on plant stoichiometry along the latitude gradient,while researches on the precipitation along the longitude gradient are rare.In this research,we studied the stoichiometry characteristics of grassland communities along the longitude gradient in Hulunbeir.The results showed as follow: 1)the range of leaf carbon was 440.76—452.72 mg/g,leaf nitrogen was 17.79—30.88 mg/g,and leaf phosphorous was 1.31—1.71 mg/g.Both the leaf carbon and C/N ratio significantly increased with the increasing longitude.Leaf nitrogen significantly decreased with the increasing longitude,and leaf phosphorous showed an increasing tendency,however,the relationship between leaf phosphorous and longitude was not significant.The amount of carbon,nitrogen and phosphorous of grassland communities significantly increased with the increasing longitude.2)For the 0—10cm soil depth,total carbon,total nitrogen,total phosphorus and organic carbon were significantly affected by precipitation and increased with longitude;however,soil ammonium nitrogen(NH+4-N) and nitrate nitrogen(NH-3-N) were less affected by precipitation and didn′t change significantly with longitude.3)Soil total carbon,organic carbon,total nitrogen,total phosphorus and available phosphorus did not have significant effects on plant leave carbon,nitrogen and phosphorus,but had a significant effects on the amount of carbon,nitrogen and phosphorous of grassland communities.In this studied region,soil available phosphorus was 8.13 mg/ kg,which was higher than the Global Average Value(7.65 mg/kg),but the average leaf phosphorous was 1.5 mg/g and lower than the Global Average Value(1.77 mg/kg).Our research suggested that variation in leaf carbon,leaf nitrogen and leaf phosphorus concentration and its strong correlation with precipitation reveal that,to some extent,stoichiometry characteristics at the community level are adaptive to local precipitation condition.The amount of carbon,nitrogen and phosphorus of grassland communities have a high relationship with the local precipitation,and have a significant correlation with soil total carbon,total nitrogen,total phosphorus.The shortage in soil available phosphorus is not the major factor for the low plant leaf phosphorus concentration in our studied region,and the low plant leaf phosphorus is a result of adaptation.