Luo Z.-S.,Sichuan Academy of Forestry |
Xiang C.-H.,Sichuan Academy of Forestry |
Zhang L.,Sichuan Institute of Forest Inventory and Planning |
Xie D.-J.,Sichuan Academy of Forestry |
Luo X.-H.,Sichuan Academy of Forestry
Beijing Linye Daxue Xuebao/Journal of Beijing Forestry University | Year: 2010
Fine root biomass distribution is usually used as a main competition indicator for fruit trees and crops and a basis for species selection and system design in agroforestry systems. To achieve a rational intercrop selection and density arrangement in the model shifting of Chinese prickly ash (Zanthoxylum bungenum) plantations, the fine root biomass distribution of Chinese prickly ash and interplanted weeds throughout the soil profiles was measured by an entrenchment method. The underground competition index between Chinese prickly ash and weeds was measured by the niche overlap formula from Levins (1968). The results show that: 1) the average fine root (≤1 mm) biomass of Chinese prickly ash and weeds were 0.40 and 0.97 mg/cm3, respectively and the amount of weed roots was 242.0% of that of Chinese prickly ash roots; 2) the fine root biomass of Chinese prickly ash and weeds presented a even distribution with distances from trees at 30 cm, 60 cm, 90 cm, 120 cm and 150 cm (P > 0.05), but the amount of fine roots of weeds at all distances was more than that of Chinese prickly ash (P < 0.05), and the competition index of weeds for Chinese prickly ash at all distances was significantly higher than that of Chinese prickly ash for weeds at 0.05 levels except for the distance at 30 cm; 3) at soil depths of 0-5 cm, 5-10 cm, 10-15 cm, 20-25 cm and 25-30 cm, the fine root biomass of Chinese prickly ash was evenly distributed (P > 0.05), but those of weeds decreased with increasing depths. The fine root of weeds throughout the soil profiles were grouped into two areas according to the distribution of fine weed root biomass: the main area at 0-15 cm depth where fine root biomass occupied 81.1% of total fine root of weeds and the other at 15-30 cm where fine root biomass occupied 18.9%. The competition index of weeds for Chinese prickly ash at each soil layer was clearly higher than that of Chinese prickly ash for weeds at 0.05 levels except for at 25-30 cm depth. Based on the distribution of fine root biomass of Chinese prickly ash and weeds and the underground competition index between them, the intercrops selection, the pattern of density arrangement as well as nutrient and water management were discussed for the model shifting of Chinese prickly ash plantation in the conversion of cropland to forests in the hilly region of the Sichuan Basin.