CollectHomepage AdvertisementContact usMessage

Arid Land Geography ›› 2020, Vol. 43 ›› Issue (6): 1523-1533.doi: 10.12118/j.issn.1000-6060.2020.06.13

Previous Articles     Next Articles

Fine root characteristics of degraded artificial forest under community structure adjustment in semiarid loess hilly region

LI Hao1, 2, HU Chan-juan2, FENG De-xian2, ZHAO Rong-qin1, GUO Lei2, MAN Zhou1   

  1. 1 School of Surveying and Geo-informatics, North China University of Water Resource and Electric Power, Zhengzhou 450045, Henan, China; 2 Institute of Geography Science, Henan Academy of Sciences, Zhengzhou 450052, Henan, China
  • Online:2020-11-25 Published:2020-11-25

Abstract: This study was conducted in Longtan watershed, Chankou Town, Dingxi City, Gansu Province, China in order to reveal the fine roots distribution characteristics of different plantation restoration patterns. Two typical degraded artificial forests in this study area included Populus tomentosa and Armeniaca sibirica, and their adjusted mixed forests included Populus tomentosa with 5- year- old Pinus tabuliformis, Populus tomentosa with 10- year- old Pinus tabuliformis, Armeniaca sibirica with Picea asperata, and Armeniaca sibirica with Pinus sylvestris. The root length density, root area, root biomass density, specific root length and specific root area of fine roots of the mentioned forests were compared in different soil depth and diameter degree. The roots of different soil layers in sampling plots were collected by root-drilling method. In the lab, the roots were scanned by a root scanner and were classified by WinRHIZO software. Excel 2003 and SPSS 24 software were used for data analysis. One-way ANOVA and LSD method were used to compare the significant differences of various indicators between vegetation restoration patterns and different soil layers. In a 0- to 10- cm soil layer, results showed that the mixed restoration model played a positive role in the increase of the growth of plant roots, root area density, and root biomass density of most mixed forests in the surface soil layer compared with that of the pure forest. Specifically, the root length density of Armeniaca sibirica with Picea asperata and Armeniaca sibirica with Pinus sylvestris were 2.85 cm ? cm- 3 and 2.08 cm?cm-3, respectively, which were higher than that of Armeniaca sibirica (1.65 cm?cm-3). Similarly, higher root area densities were observed with the two mixed forests (27.48 cm2 ? cm- 3 and 20.00 cm2 ? cm- 3, respectively) compared to that of Armeniaca sibirica (16.21 cm2 ? cm- 3). Finally, the root biomass density of the two mixed forests were 1.25 mg?cm-3 and 1.36 mg?cm-3, respectively, which were higher than that of Armeniaca sibirica (1.03 mg?cm-3). The root length density, root area density, and root biomass density of Populus tomentosa with 5- year- old Pinus tabuliformis and Populus tomentosa with 10- year- old Pinus tabuliformis were 1.52 cm ? cm- 3 and 2.11 cm ? cm- 3, 18.16 cm2 ?cm- 3 and 26.46 cm2 ?cm- 3, and 1.23 mg?cm- 3 and 1.82 mg?cm- 3, respectively. The root length density, root area density, and root biomass density of Populus tomentosa were 1.68 cm2?cm-3, 17.66 cm2?cm-3, and 1.41 mg? cm- 3, respectively. The mixed forest of Populus tomentosa with 10-year-old Pinus tabuliformis had the highest root length density, root area density, and root biomass density in the surface soil layer. In a 1- m deep soil layer, the average root biomass density of Populus tomentosa, Populus tomentosa with 5- year- old Pinus tabuliformis, and Populus tomentosa with 10- year- old Pinus tabuliformis were 0.58 mg ? cm- 3, 0.66 mg ? cm- 3, and 0.82 mg ? cm- 3, respectively. The root biomass density of Populus tomentosa and Pinus tabuliformis mixed forests were higher than that of the pure forest and were found to increase with increased restoration years. The average root length density and root area density of Armeniaca sibirica with Picea asperata and Armeniaca sibirica with Pinus sylvestris mixed forests were observed to be higher than that of Armeniaca sibirica in a 1-m soil layer. From the vertical soil profile, the root length density, root area density, and root biomass density of fine roots in all restoration patterns showed obvious surface aggregation phenomenon. The mixed restoration patterns increased the proportion of fine roots in the surface layer and increased with increased restoration years. The correlation analysis between the root indexes and the soil physiochemical indexes showed that the fine root length density, root area density, and root biomass density were significantly positively correlated with soil total carbon, total nitrogen, water content, and organic carbon. Specific root length and specific root area also had a positive relationship with soil total carbon, soil total nitrogen, and organic carbon.

Key words: loess hilly region, mixed forest, fine root, restoration patterns