Analysis of Fine Root Production Features in High Mountain Communities by Ingrowth Method using Filter Balls

The investigation of belowground plant production and its determining factors is critical for better understanding carbon turnover in the biosphere. The measurement of fine root production is a methodical and difficult task. To reveal factors determining fine root production in mountain ecosystems, we introduced a new modification of ingrowth method with the use of filter balls (tea strainers). We studied root production in 16 communities from upper forest to subnival belts in the range of 2184–3069 m a.s.l. in the Teberda Reserve, Northwestern Caucasus, Russia. The filter balls were filled with sifted soil (without roots or stones) and buried in the soil 7–8 cm deep. The mass of root ingrowth was measured after two months of incubation under natural conditions. Mixed-effect models were applied to test the relationships between root mass, elevation, soil moisture, organic matter content, and pH. The highest root production was observed in an alpine snowbed (247 mg per filter ball in 60 days), the lowest was in forest and subnival communities (3–20 mg per filter ball in 60 days). The communities with woody dominants had lower production than herb communities. It increased with soil moisture, which was the most important factor. In herb communities the production of roots tended to decrease with the elevation. Soil organic matter as a separate factor had a positive relationship with root production in herb communities. There were no links between root ingrowth and soil pH. The method introduced presently both allows for the comparison of plant communities by their root production and reveals factors determining it.