Seasonality and moisture regime control soil respiration, enzyme activities, and soil microbial biomass carbon in a semi-arid forest of Delhi, India

Abstract

Abstract Soil respiration, soil enzymes, and microbial biomass are important in carbon cycling in the terrestrial ecosystem which is generally limited by environmental factors and soil carbon availability. Hence, we tried to assess the factors affecting the functional aspects of these processes in a semi-arid climate. We monitored soil respiration (surface) using a portable infrared gas analyzer (Q-Box SR1LP Soil Respiration Package, Qubit Systems, Canada) equipped with a soil respiration chamber (Model: G 180). Soil respiration was measured at midday during each season throughout the study period. Soil enzymatic activities and microbial biomass carbon (MBC) were analyzed following the standard protocol for a year during peak time in four seasons at 0–10 cm and 10–20 cm depth. Soil respiration shows significant variation with highest in monsoon (3.31 μmol CO2 m−2 s−1) and lowest in winter (0.57 μmol CO2 m−2 s−1). Similarly, β-glucosidase, dehydrogenase, and phenol oxidase activity ranged from 11.15 to 212.59 μg PNP g−1 DW h−1, 0.11 to 16.47 μg TPF g−1 DW h−1, and 4102.95 to 10187.55 μmol ABTS+ g−1 DW min−1, respectively. MBC ranged from 17.08 to 484.5 μg C g−1. Besides, soil respiration, soil enzymes (except β-glucosidase), and MBC were significantly correlated with soil moisture. Seasonality, optimum moisture and temperature played a significant role in determining variations in soil microbiological processes (except β-glucosidase activity); the carbon cycling in the study area is assisted by enzyme activity; dehydrogenase and phenol oxidase played a significant role in soil respiration; hence, this landscape is sensitive to environmental changes.

Keywords

• Soil respiration
• Enzyme activities
• Microbial biomass carbon
• Seasons
• Semi-arid forest