Microbiological Indication of Soils in Forest Plantations of the Shirinskaya Steppe

摘要

To control soil degradation and desertification, sustainable long-term protective forest plantations that perform water and soil protection functions are commonly used on the erosion-prone lands of steppe ecosystems. In the Shirinskaya dry lake-basin steppe (Khakassia) in the coastal zone of Lake Shira, the staff of the Sukachev Institute of Forest, Siberian Branch, Russian Academy of Sciences, has created artificial plantings of forest cultures (Pinus sylvestris L., Larix sibirica L., and Ulmus humilis L.) and provenance trials (P. sibirica Du Tour and P. sylvestris). A wildfire damaged the coastal 40-year-old forest cultures in 2015; the surface soil layer was burnt out. Agrotechnical soil cultivation for planting provenance trials (2017) and wildfire in forest cultures affected the state of soil microbiomes. The aim of the research is to assess the rate of recovery and formation of biological soil properties in forest plantations after disturbances (wildfire and agrotechnical influences) in the coastal dry-steppe zone of Lake Shira using microbiological indicators. The research objects are the Burnt Areas (postfire and postconflagration areas) and Provenance TrialPlantation sites. The use of microbial indicators shows that the soil microbiomes on the burnt sites are restored with different intensities. The recovery of soil microbiomes on the postfire sites is much faster than in the postconflagration sites, as is evidenced by the high values of the total number of microorganisms (TNM), microbial biomass (MB), enzymatic activity (EA), and humification coefficient (C-h), which are close to the control values. Specific microbial respiration (qCO(2)) is within the range of natural variability. The burnt soil is characterized by an increased proportion of hydrolytic microorganisms actively participating in the decomposition of half-burnt plant residues. On the provenance trial sites under the pine seedlings, specific rhizosphere microbiomes are forming due to the influence of the root exudates of climatypes. The values of TNM, ETGM, MB, EA, and qCO(2) change either upwards or downwards; the state of microbial communities has not reached its ecophysiological norm.