5 Conclusions
The conversion from natural forest to monoculture plantations decreased
C and N contents and related enzymes activities (such as sucrase, acid
protease, urease, glutaminase, acid and alkaline phosphatase
activities), thereby reducing soil quality. The conversion resulted in
markedly differences in the structure of the fungal community between
Forest and plantations, and increased microbial α-diversity. According
to the life history classification system based on functional traits -
Grime’s C-S-R (competitor, stress-tolerator, ruderal) life history
framework, forest conversion decreased the abundance of dominant fungal
taxa including Basidiomycota (C-strategists), but increased that in
Ascomycota (S-strategists) and Zygomycota (R-strategists). The decrease
of C-strategists Basidiomycota indicated that forest conversion had a
negative impact on the fungal lignin decomposition ability and
competitive intensity, especially for oligotrophic taxa. The increase of
S-strategists Ascomycota and R-strategists Zygomycota demonstrated that
some taxa with stress-tolerating and ruderal survival strategies, such
as copiotrophic fungi, maximize occupation and exploitation of available
resources after conversion. Correspondingly, Pseudophialophora,
Rhytisma and other genera (mostly belonging to Ascomycota) increased,
while Russula (mostly belonging to Basidiomycota) decreased.
Correlation analysis showed that, in addition to soil pH, the key
indicators of SQI, including organic carbon, glutaminase, and
phosphorus, were main drivers for fungal community characteristics in
subtropical forest conversion. To conclude, forest conversion to
monoculture plantations decreased soil quality, but increased the
dominance of S and R strategists in a more diverse fungal community,
retarding lignin decomposition and increasing the depletion of available
resources.