Soil Microbial Community Structure and Metabolic Activity of Pinus elliottii Plantations across Different Stand Ages in a Subtropical Area

Abstract

Soil microbes play an essential role in the forest ecosystem as an active component. This study examined the hypothesis that soil microbial community structure and metabolic activity would vary with the increasing stand ages in long-term pure plantations of Pinus elliottii. The phospholipid fatty acids (PLFA) combined with community level physiological profiles (CLPP) method was used to assess these characteristics in the rhizospheric soils of P. elliottii. We found that the soil microbial communities were significantly different among different stand ages of P. elliottii plantations. The PLFA analysis indicated that the bacterial biomass was higher than the actinomycic and fungal biomass in all stand ages. However, the bacterial biomass decreased with the increasing stand ages, while the fungal biomass increased. The four maximum biomarker concentrations in rhizospheric soils of P. elliottii for all stand ages were 18:1ω9c, 16:1ω7c, 18:3ω6c (6,9,12) and cy19:0, representing measures of fungal and gram negative bacterial biomass. In addition, CLPP analysis revealed that the utilization rate of amino acids, polymers, phenolic acids, and carbohydrates of soil microbial community gradually decreased with increasing stand ages, though this pattern was not observed for carboxylic acids and amines. Microbial community diversity, as determined by the Simpson index, Shannon-Wiener index, Richness index and McIntosh index, significantly decreased as stand age increased. Overall, both the PLFA and CLPP illustrated that the long-term pure plantation pattern exacerbated the microecological imbalance previously described in the rhizospheric soils of P. elliottii, and markedly decreased the soil microbial community diversity and metabolic activity. Based on the correlation analysis, we concluded that the soil nutrient and C/N ratio most significantly contributed to the variation of soil microbial community structure and metabolic activity in different stand ages of P. elliottii plantations.

Changes in rhizosphere bacterial and fungal community composition with vegetation restoration in planted forests

“…tabulaeformis , Quercus liaotungensis , and Populus davidiana . Wu et al () also observed a decline in soil nutrient concentration after a peak in Pinus elliottii and further supports that soil nutrients reach an upper asymtote at a certain stage during secondary succession. Interestingly, we found that both total nitrogen and total phosphorus increased from 10 to 40 years along the successional gradient, whereas available nitrogen and phosphorus decreased over time.…”

“…Our findings aligned with a study in P . elliottii forests (Wu et al, ). However, another study of abandoned farmland on the Loess Plateau revealed that soil bacterial richness and diversity increased during natural succession (Zhang et al, ).…”

Similar soil microbial community structure across different environments after long‐term succession: evidence from volcanoes of different ages

“…This finding was different from the results of the present study. The difference was mainly caused by the following reasons: most evidence was drawn from studies focused on disturbed soil, such as farmland, grazing grassland, polluted or recovered soil . In these soils, soil properties must change due to external disturbance and start succession anew .…”

“…However, most of the evidence was obtained over short time scales: no more than 100 years . In the few long‐term studies, soil microbes were always surveyed along with plants in succession, and changes in soil microbes were mainly explained as being influenced by the variations of plants . Although direct evidence has been found that temporal factors act to structure soil microbial communities in a long‐term chronosequence , our understanding of the processes driving microbial patterns over large temporal scales remains limited .…”

Effects of Continuous Tomato Monoculture on Soil Microbial Properties and Enzyme Activities in a Solar Greenhouse

“…The seedling age was assumed to be an important influence on the microbial activity and diversity in the rhizosphere soil of plants [38]. Corneo et al indicated that the most abundant and balanceable type of microflora in healthy soils was bacteria, followed by actinomycetes, and then fungi [39].…”