Background The oasis farmland shelterbelt plays an important role in carbon sequestration. The existing biomass models are mostly flaky forest structures, with large differences between species, small DBH, lack of representativeness, and flaky forest easy degradation forming a little old tree. Uprooting to be difficult and complex, the study on the root biomass of narrow forest belt is not deep enough.Long-term observation is difficult, and the annual biomass survey reduces the benefits of forest belt conservation, wind protection, carbon sequestration, and age modeling and actual discrepancies, uprooting damage infrastructure, etc.In order to solve these problems, a model of root biomass is used to study the distribution of root biomass and its variation in different soil layers of forest belts, which provided a reference for the study of carbon storage of shelterbelt roots in narrow forest belts.

Methods The experimental area was based on the Dengkou oasis of the Ulan Buh Desert in China, and two rows of narrow shelterbelt were selected as the water-saving structure.The space was used instead of the time to carry out the root biomass survey of the 20 target trees according to DBH. Used the fixed sample method, width, length, depth of the sample were respectively 2.3 m, 2.5 m, 2 m, and were divided into four layers each layer of 50 cm. The fresh weight of root was weighed, and the sampling was calculated according to the dry-to-sale ratio and biomass in the sample. Based on lateral root biomass inside the sample to calculate outside, the total biomass was the sum of the biomass inside and outside the sample plot. The model was established and analyzed by SPSS from the root biomass of each diameter to analyze the simulated biomass growth process.

Results The study found that there were 20 growth models of root biomass and distribution of DBH and tree height in narrow forest belts, and the proportions of 0-50 cm, 50-100 cm, 100-150 cm and 150-200 cm eaverage root biomass were 59.32%, 38.68%, 1.82%, and 0.18% respectively, and the 0-100 cm soil layer contained 98% of the root biomass. The Main root was 2/3 root biomass, which increases with DBH, and the proportion of each layer increased with the exception of 0-50 cm soil layer. The lateral root was a 2-layer structure, distributed in 0-50 cm and 50-100 cm soil layer, and also increaseed with DBH, the proportion of 0-50 cm soil layer increased, and the proportion of others decreases.

Conclusions The experiment achieved the expected results.Root biomass of oasis shelterbelt is inverted pyramid shape and distributed in shallow soil layer with Main space decreasing layer by layer and increases with increasing DBH, and distribution proportion being relatively constant.The results of this study have important reference significance for the calculation of root biomass and carbon storage in the oasis farmland shelterbelt in the arid zone and even the Three North Region.