Lignin and Cellulose Contents in Chinese Red Pine (Pinus tabuliformis Carr.) Plantations Varied in Stand Structure, Soil Property, and Regional Climate

Abstract

The reserve of litter is expected to be reduced on the forest floors of pine plantations dually for the prevention of high risks of forest fires and with a more practical probability of reuse. Lignin and cellulose are the two key constitutive components in litter residues that account for the highest proportion of carbon but are the last to be fully decomposed. The existing trials started examining the mechanisms behind decomposing these two components in response to the combined driving forces of microclimatic factors, forest structure, and stand properties. However, the results were mostly limited to a local-scale ecosystem, and the evidence was reported to be highly scattered across varied conditions globally. Awareness about the combined effects of the driving forces behind the lignin and cellulose contents in the litter of plantations on a large scale is still scarce. In this study, a total of 60 Pinus tabuliformis Carr. plantations (40-year-old) were investigated for their litter quality, regional meteorological factors, soil properties, and stand structure in a provincial area across Liaoning, northeast China. High lignin (40%–43%) and cellulose contents (15%–20%) were found to be located mainly in stands around the biggest city of Shenyang. Rainfall was a key factor that determined the decomposition, but neither the forest structure nor soil nutrient content generated direct effects on the two litter components. The combined factors of low soil pH (~5.8) and high rainfall (~3.0 mm per day) together mainly accounted for the promotion of natural litter decomposition.