Study on Zymometric Properties of Soil Aggregates in Pure and Mixed Eucalyptus Forest

This study examines the activity and stoichiometric ratios of carbon, nitrogen, and phosphorus acquiring enzymes(β−glucosidase, β−N−acetylglucosaminidase, leucine aminopeptidase, and acid phosphatase) in soil aggregates of different particle sizes (> 2 mm, 2–1 mm, < 1–0.25 mm, and < 0.25 mm) across 3 types of plantation forests: pure Eucalyptus, E. × Mytilaria laosensis mixed, and E. × Michelia macclurei mixed plantations. It explores the enzymatic stoichiometric characteristics and interactions within both pure Eucalyptus and mixed plantations. The results showed that the activities of soil-acquired enzymes were higher in Eucalyptus mixed forests than in Eucalyptus pure forests, and all 3 forests had the highest enzyme activities in agglomerates < 0.25 mm, while the enzyme activities were lower in large-size agglomerates > 2 mm, and that there were correlations between the enzyme activities and stoichiometric characteristics of agglomerates and the pH, organic carbon and total nitrogen of the soils. The results of zymometric characterization reflected that soil microorganisms in 3 types of Eucalyptus plantations were more severely restricted by C and P than by N. Among the 3 forests, soil microorganisms in the mixed forests were more restricted. Mixed Eucalyptus and broad forests can improve the soil structure, increase the organic matter content and microbial activity, and increase the efficiency of nutrient transportation, which is conducive to the enhancement of soil enzyme activity, but at the same time, it will aggravate the microbial limitation by C and P.