Abstract: A study on fine root characters of a 17-year-old populus tomentosa Carr. Shelterbelt composed of one row in each roadside without root-trench was carried out. The averaged root characters per-unit soil volume for the farmland range of 5.0m from shelterbelt and the depth of 100cm are as follows: root weight is 92.20g/m³, root length 641.01m/m³, root surface area 1.0588m²/m³, root volume 103.7cm³/m³ and fine root tips 301481 tip/m³. The root characters in farmland decrease with the increase of the distance from the shelterbelt, firstly increase and then decrease with the soil depth. Higher values are mostly distributed in the 20-40cm or 40-60cm soil depth within the range of less than 1.5m from the shelterbelt. The root characters decrease rapidly or obviously in the range from 1.5m to 3.0m. In the farmland 3.0m or 5.0m away from the shelterbelt, the root characters decrease slowly with the distance from the shelterbelt, and the maximum values of root characters rise to the soil layer of 10-20cm. The most competitive zone for crops may be the range within 3m away from the shelterbelt.

Key words: shelterbelt, populus tomentosa Carr., fine root, biomass, root system