Effects of Predominant Tree Species Mixing on Lignin and Cellulose Degradation during Leaf Litter Decomposition in the Three Gorges Reservoir, China

Abstract

The aim of this study was to investigate the potential mixing effects on degradation of lignin and cellulose in mixed leaf litter from Pinus massoniana Lamb., Cupressus funebris Endl., and/or Quercus variabilis Bl., and elucidate the interactions with abiotic factors. The litter bag method was used in the field experiment, and the three predominant species in the Three Gorges Reservoir region were treated as single-, pair-, and tri-species combinations with equal proportions of litter mass. Lignin and cellulose losses in the litter treatments were measured, and the mixing effects were evaluated based on the sampling phase and decomposition period. At the end of the one-year decomposition period, mixing species increased lignin loss by 3.3% for the cypress + oak combination and cellulose loss by 3.9%, 1.8%, and 0.8% for the pine + oak, cypress + oak, and pine + cypress + oak combinations, respectively. The pine + oak and cypress + oak combinations exhibited greater lignin and cellulose loss than the tri-species mixture. Accelerated lignin degradation also apparently occurred in the pine + cypress combination as decomposition proceeded. Generalized linear models suggested that the investigated environmental factors (in terms of average temperature and cumulative precipitation) and changing litter quality (lignin, cellulose, and lignin/cellulose) had significant effects on nonadditive lignin loss, whereas only the changing litter quality factors significantly affected nonadditive cellulose loss. In summary, mixing two or three of the studied species alters cycling of recalcitrant substrates in plantations, and mixed planting with Quercus appears to strengthen both the lignin and cellulose degradation processes.

A comparison of lodgepole and spruce needle chemistry impacts on terrestrial biogeochemical processes during isolated decomposition

“…These observations indicate functional differences in the decomposition processes of lodgepole and spruce needles. This observation agrees with a litter decomposition study by He et al (2019) that reported periodic lignin losses associated with increases in cellulose. Lignin and cellulose decomposition processes can be controlled by climate, litter quality, and the decomposers present.…”

Leaf litter lignin degradation in response to understory vegetation removal in a Masson pine plantation

“…Furthermore, we defined a positive nonadditive effect (synergistic interaction) and negative nonadditive effect (antagonistic interaction) as occurring whenever the deviation was greater or lower than zero, respectively. In addition, path analysis with the best linear model (He et al, 2019) was conducted to examine the effects of microbial biomass nitrogen, average temperature, and lignin percentage on litter lignin degradation rate and nonadditive lignin degradation rate. The k value was estimated by the nonlinear regression equation (y = ae –kt ) according to the Olson model (Olson, 1963) based on the untransformed data (remaining mass rate).…”

“…As a recalcitrant component in plants, however, lignin not only plays a vital role in strengthening plant structure (Su et al, 2019) but also regulates the plant litter decomposition rate because it is difficult to degrade and surrounds labile litter components in the cell wall, preventing their release (Melillo, Aber, & Muratore, 1982; He et al, 2016). Assessing the plant litter decomposition process is important for understanding nutrient cycling in terrestrial ecosystems (He et al, 2019). Accordingly, the lignin degradation process in decomposing plant litter has historically been well‐studied, and the percentage or content of lignin in a given litter has been identified as a key indicator for predicting plant litter decomposition (Meentemeyer, 1978; Melillo et al, 1982; McClaugherty & Berg, 1987; Taylor, Parkinson, & Parsons, 1989; Qu et al, 2019).…”

Mixing effect on stand yield ofPinus tabulaeformisandQuercus liaotungensisis modulated by site quality and stand density in the Loess Plateau, China

“…Hence, in the later growth stage, the growth rate of oak in the pure stands is much higher than in the mixed stands, and the mortality rate in the mixed stands was also higher than pure stands (Table 2) On the other hand, the yield of large DBH class pines in mixed stands was higher than it in pure stands, which probably because the mixing with oak improved the soil water and nutrient condition. By accelerating the decomposition rate of litter, improve litter quality and forest floor conditions, mixed stands have better soil water and nutrient conditions (Perez-Suarez et al 2009;Laganiere et al 2010;Cheng et al 2014;He et al 2019), pine tends to associate more with fungi in the presence of oak (Suz et al 2017) and these fungi facilitate tree water and nutrient uptake in exchange for photosynthetic carbon (Cornelissen et al 1999). Also, mixing could improve the absorption of nitrogen by pines under low site quality, and leading the increase of pine yields (Zhang et al 2018).…”