[Biomass and morphological characteristics of fine roots and their affecting factors in diffe-rent vegetation restoration stages in depressions between karst hills].

This study focused on four vegetation restoration stages of grasslands, shrublands, secondary forests and primary forests in the typical karst peak-cluster depression. The soil core method was used to collect fine roots with 2 mm or less in diameter in three layers (0-10, 10-20, 20-30 cm). The biomass, morphological characteristics of fine roots and their relationship with soil properties were analyzed. The results showed that fine root biomass ranged between 194.63 and 255.19 g·cm in different vegetation restoration stages. Most of fine roots distributed in the surface soil of 0-10 cm, which accounted for more than 60% of the total biomass in the soil layer of 0-30 cm. No significant difference was found among different stages in fine root biomass. There was significant difference among different stages in the specific root length and specific surface area of fine roots. Both parameters were gradually decreased with vegetation forward restoration from grassland to primary forest. More than 66% root length and 64% root area were distributed in the surface soil of 0-10 cm. The length and area of most of the fine root were in the diameter class of 0-0.5 mm and 0.5-1mm, respectively. These two levels of the root length and root area accounted for more than 87% and 72% of the total amount, respectively. Results from the redundancy analysis showed that there were different correlations between karst peak-cluster depression vegetation community characteristics and soil properties, with soil organic carbon, available potassium, and total nitrogen having a great influence on the characteristics of fine roots. It is an effective strategy for plants to better adapt to the habitats.