Welcome to Acta Prataculturae Sinica ! Today is Share:

Acta Prataculturae Sinica ›› 2024, Vol. 33 ›› Issue (5): 183-195.DOI: 10.11686/cyxb2023232

Previous Articles    

Variations in soil inorganic nitrogen content under canopies of two shrubs in the Junggar Desert

Si-yao PAN(), Yu-chuan SONG, Ru-yi YUAN, Sheng-tong HOU, Jun-ge CAI, Bing CHEN, Jun-hui CHENG()   

  1. College of Resources and Environment of Xinjiang Agricultural University,Xinjiang Key Laboratory of Soil and Plant Ecological Processes,Urumqi 830052,China
  • Received:2023-07-05 Revised:2023-08-04 Online:2024-05-20 Published:2024-02-03
  • Contact: Jun-hui CHENG

Abstract:

As a direct nitrogen source for plant absorption and utilization, the soil inorganic nitrogen content (SINC) reflects the nitrogen-supply capacity of soil. Many studies have revealed that in desert ecosystems, SINC is significantly affected by the shrub species, but also by the position of the sampling site. However, there is still limited knowledge about the impact of sampling direction on SINC. In this study, we selected two dominant shrubs (Haloxylon ammodendron and Kalidium caspicum) that are widely distributed in the Junggar Desert, and collected soil samples at 0-10 cm and 10-20 cm soil depths under plants in four size classes (large, medium, small, and very small) at four spatial positions (shrub center, shrub middle, shrub edge, and shrub outside) and for four sampling directions (east, south, west and north). We then measured the nitrate nitrogen content (NNC) and ammonium nitrogen content (ANC) in the soil samples, and calculated the ratio of ammonium nitrogen content (RAN) to nitrate nitrogen. These analyses allowed us to determine the main and interactive effects of shrub size, spatial position, and sampling direction on SINC. It was found that: 1) Shrub size significantly affected SINC. In particular, NNC was higher under canopies of large individuals than under canopies of smaller individuals of both H. ammodendron and K. caspicum. However, ANC and RAN were lowest under canopies of large individuals of H. ammodendron but highest under canopies of large individuals of K. caspicum, suggesting that the variation in SINC was dependent on shrub size. 2) NNC and ANC were significantly higher in the 0-10 cm soil depth than in the 10-20 cm soil depth under canopies of H. ammodendron and K. caspicum, indicating that shrubs had a stronger effect on SINC in the topsoil layer. 3) SINC under canopies of H. ammodendron was affected by interactive effects between shrub size and sampling direction, and a SINC enrichment phenomenon was observed at the east and south directions under canopies of H. ammodendron. 4) SINC under canopies of K. caspicum was influenced by the interactive effect between spatial position and sampling direction. SINC was generally higher at the shrub center that at the other three positions at the east and south directions. These findings demonstrate that in desert ecosystems, SINC under shrub canopies varies among shrub species and is affected by shrub size, spatial position, and sampling direction.

Key words: soil inorganic nitrogen, individual sizes of shrubs, spatial positions, sampling direction, desert ecosystem