Naphthalene exerts non-target effects on the abundance of active fungi by stimulating basidiomycete abundance

As an arthropod biocide,naphthalene has been used in studies of the ecological functions of soil fauna for decades.However,its potential non-target effects on soil microorganisms may affect soil mineralization and litter decomposition processes.Therefore,we conducted an experiment with naphthalene adding to soil surface at a rate of 100 g·m-2 per month to examine the potential non-target effects of this treatment on soil fungal phospholipid fatty acids(PLFAs),18 S rDNA gene copy numbers and community diversity in a subalpine forest of western Sichuan,China.The results showed that naphthalene addition significantly increased fungal PLFAs but did not significantly alter fungal gene copy numbers.A total of 16 phyla,62 genera and 147 Operational taxonomic units(OTUs)were identified through Illumina Mi Seq sequencing analysis.Basidiomycota and Ascomycota were the most abundant phyla in both the control and naphthalene addition plots.Naphthalene addition did not affect the diversity or structure of the soil fungal community,but the increase in some genera of Basidiomycota might contribute to the increase in fungal PLFAs in the naphthalene addition plots.These results suggest that naphthalene exerts non-target effects on the active fungal abundance by stimulating the abundance of specific taxa in subalpine forest soils.The non-target effects of naphthalene on the fungal community should be taken into consideration when it is used to exclude soil fauna.

Degree of Humification in Fresh Litter from a Subtropical Mixed Plantation Forest in Southwest China

The humification degree of fresh litter directly controls the accumulation of soil humus derived from plant litter,but very little information on this process is available.Planted forests are well known to restrict soil fertility,which is often indicated by the soil humus level.In this study,fresh litter was collected during different plant phenological stages during 2016 and 2017 in a mixed plantation in Southwest China.The values of hue coefficientΔlogK(absorbance ratio of 400 nm and 600 nm on a logarithmic scale),optical density E4/E6(absorbance ratio of 400 nm and 600 nm)and A600/C(absorbance at 600 mm per mg of carbon per ml of extraction)and the concentration of extractable humus carbon(HC)were determined in four litter components(foliar,twigs,reproductive organs and miscellaneous)of the dominant species(Pterocarya stenoptera,Quercus acutissima,Cunninghamia lanceolata and Toxicodendron vernicifluum).All of the litter components exhibited obvious humification characteristics,and showed the highest concentration of extractable HC during the leaf maturation period.The miscellaneous and foliar litters showed greater humification than the other litter types.The components of Pterocarya stenoptera litter exhibited greater degrees of humification than those of the other species,with lowerΔlogK and E4/E6 values and higher A600/C values.The litter from coniferous and evergreen species showed lower humification than that from broad-leaf and deciduous species regardless of the litter component examined.The present results provide new insights into the management of plantations and theoretical data to accurately improve the quality of plantations and maintain soil fertility under a global change.