Thinning enhances ecosystem multifunctionality via increase of functional diversity in a Pinus yunnanensis natural secondary forest
Abstract Background: The impacts of thinning on ecosystem multifunctionality (EMF) remain largely unexplored. In this study, we analyzed nine variables related to four ecosystem functions (nutrient cycling, soil carbon stocks, decomposition, and wood production) under five thinning intensities. We included a control group to evaluate the shift in EMF of a Pinus yunnanensis natural secondary forest. We also assessed the relationship between above- and belowground biodiversity and EMF under these different thinning intensities. Additionally, we evaluated the effects of biotic and abiotic factors on EMF with the structural equation model (SEM). Results: We found that EMF tended to increase with thinning intensity, and that thinning significantly improved EMF except the low intensity of thinning. Individual ecosystem functions (EFs) all had a significant positive correlation with thinning intensity. Different EFs showed different patterns with the increase of thinning intensity: the nutrient cycling and the soil carbon stock of thinning three times and five times were significantly greater than other thinning intensities and control group; decomposition correlated directly to the increase of thinning intensity; the wood production of the fourth thinning was greatest. Thinning intensity had a significant positive correlation with functional diversity and soil moisture. Both functional diversity and soil moisture had a significant positive correlation with EMF, but soil fungal operational taxonomic units (OTUs) had a significant negative correlation with EMF. Based on SEM, we found that thinning improved EMF mainly by increasing functional diversity. Conclusion: Our study both demonstrates that thinning is a good management technique from an EMF perspective, and provides an input to improve management of a P. yunnanensis natural secondary forest.