Effects of enrichmemt planting with native tree species on bacterial community structure and potential impact on Eucalyptus plantations in southern China

Abstract

Multi-generational planting of Eucalyptus species degrades soil quality but the introduction of legumes can improve soil fertility and microbial diversity. However, the effects of introducing non-legume native tree species on soil nutrients and bacterial community structure remain poorly understood. This study investigated the impacts of the conversion of third generation monoculture Eucalyptus plantations to mixed systems including Eucalyptus urograndis with Cinnamomum camphora (EC) and E. urograndis with Castanopsis hystrix (EH), on soil chemical and biochemical properties and bacterial community structure, diversity and functions. First generation E. urophylla plantations were the control. Results show that planting the third generation Eucalyptus led to a significant decrease in pH, organic matter, nutrient content, enzyme activities (invertin, acid phosphataes, and urease), and bacterial α-diversity compare to the controls. However, the mixed planting showed significant improvement in soil chemical and biochemical attributes and bacterial α-diversity, although the E. urograndis and C. hystrix planting had no improvement. Chloroflexi (oligotrophic bacteria) were significantly enriched in third generation Eucalyptus and Eucalyptus + C. hystrix, while proteobacteria increased significantly in the E. urograndis with C. camphora plantings. The relative abundance of multiple metabolic pathways increased significantly in the third generation Eucalyptus plantations whereas membrane transport-related genes were enriched in soils of the mixed systems. The changes in bacterial community structures in the two mixed systems were driven by diversity, organic matter and acid phosphatase, while bacterial functions were affected by invertase, $${\mathrm{NO}}_{3}^{-}$$ NO 3 - -N, diversity and urease. These results suggest that the transformation of successive monoculture Eucalyptus plantations into mixed plantations reduces the depletion of soil nutrients and enhances the ecological function of soil microorganisms.

Mixing planting with native tree species reshapes soil fungal community diversity and structure in multi-generational eucalypt plantations in southern China

“…The experiment was conducted on harvested sites that had undergone two successive generations of eucalypt plantations (8 and 5 years of plantation cultivation, respectively) in the same area, so it can be assumed that eucalypt plantations and mixed plantations had similar geospatial heterogeneity before afforestation. Information on the plantations from 1990 to the beginning of this experiment can be found in Xu et al (2022).…”

“…Simultaneously, four unmanaged first-generation E. urophylla plantations in Luogangling Forest Park were selected as controls (CK). Information on forestland preparation, seedling specifications of eucalypts and native trees, and later plantation tending can be found in Xu et al (2022).…”

“…With the transition from pure to mixed plantations, microorganisms gradually shaped new community diversity, composition, and functional characteristics in response to the changing interspecific relationships, litter quality, and soil physicochemical properties (Zhang et al, 2018;Qu et al, 2022). Studies have shown that the implantation of native species such as Manglietia glauca, Castanopsis hystrix, Acacia mangium, and Cinnamomum camphora in eucalypt plantations significantly increase the soil bacterial diversity and relative abundance of copiotrophic and nitrogen cycle-associated bacteria (Xu et al, 2021b(Xu et al, , 2022. However, there are few studies addressing the effects of pure plantation transformation on soil fungal communities (Rachid et al, 2013;Wu et al, 2019;Liu et al, 2022).…”

Structural equation model was used to evaluate the effects of soil chemical environment, fertility and enzyme activity on eucalyptus biomass

“…With the rapid growth of eucalyptus plantations in southern China, Chinese society is increasingly concerned about the ecological problems caused by eucalyptus plantations [ 4 ]. Existing studies have shown that successive multi-generation planting of eucalyptus causes shortages of soil nitrogen (N), phosphorus (P) and potassium (K), as well as a decrease in enzyme activity [ 5 ], and the growth of the plants themselves is also suppressed [ 6 , 7 ], but the intrinsic drivers that cause these changes are not clear. The growth of successive planting eucalyptus plantations can be maintained to some extent by increasing the amount of fertilizer inputs, but this measure is not sustainable [ 8 ].…”

Assessment of the effects of multigenerational succession on soil chemical environment, fertility and enzyme activity in Eucalyptus plantations using structural equation modeling

“…With the rapid growth of eucalyptus plantations in southern China, Chinese society is increasingly concerned about the ecological problems caused by eucalyptus plantations [4]. Existing studies have shown that successive multi-generation planting of eucalyptus causes shortages of soil nitrogen (N), phosphorus (P), and potassium (K), as well as a decrease in enzyme activity [5], and the growth of the plants themselves is also suppressed [6][7], but the intrinsic drivers that cause these changes are not clear. The growth of high-generation eucalyptus plantations can be maintained to some extent by increasing the amount of fertilizer inputs, but this measure is not sustainable [8].…”