A comparison of decomposition dynamics among green tree leaves, partially decomposed tree leaf litter and their mixture in a warm temperate forest ecosystem

Abstract

Decomposition dynamics were compared among green tree leaves, partially decomposed tree leaf litter (i.e., decayed tree leaf litter on forest floor) and a mixture of the two in a warm temperate forest ecosystem in central China to test the influence of litter chemical quality on the degree of decomposition. The study was conducted in situ at two contrasting forest sites, an oak forest dominated by Quercus aliena var. acuteserrata Maxim., and a mixed pine and oak forest dominated by Pinus armandii Franch. and Q. aliena var. acuteserrata. We found marked differences in the rate of decomposition among litter types at both forest sites; the litter decomposition constant, k, was about 39 % greater at the oak forest site and more than 70 % greater at the pine-oak forest site, for green leaves than for partially decomposed leaf litter. The decomposition dynamics and temporal changes in litter chemistry of the three litter types also greatly differed between the two forest sites. At both forest sites, the higher rate of decomposition for the green leaves was associated with a higher nitrogen (N) content and lower carbon to N ratio (C/N) and acid-unhydrolyzable residue to N ratio (AUR/N). We did not find any nonadditive effects when mixing green leaves and partially decomposed leaf litter. Our findings support the contention that litter chemical quality is one of the most important determinants of litter decomposition in forest ecosystems at the local or regional scale, but the effect of litter chemical quality on decomposition differs between the contrasting forest types and may vary with the stage of decomposition.

Can mixed pine forests conserve understory richness by improving the establishment of understory species typical of native oak forests?

“…Indeed, in the same experimental device, we found a significant positive correlation between the percentage of basal area of P. pinaster and the C/N ratio of the fresh leaf litter (see López-Marcos et al 2018). This finding suggests that the C/N ratio of the fresh leaf litter of dominant tree species, as a proxy of the leaf litter decomposition rate (Wang et al 2016), could be one of the drivers of understory composition; the higher the C/N ratio is, the more recalcitrant the leaf litter, i.e., in monospecific stands of P. pinaster (Herrero et al 2016), and in turn the lower C input into the soil as humic substances. Additionally, the tree species of the canopy can exert their effect on the understory by their influence on other soil properties such as water content.…”

Effects of Hydrological Regime on Foliar Decomposition and Nutrient Release in the Riparian Zone of the Three Gorges Reservoir, China

“…Generally, leaves with a small number of structural macromolecules (lignin and cellulose) and higher nitrogen (N) and phosphorus (P) content are conducive to the colonization of microorganisms, and their decomposition rate is usually higher (Kalburtji et al, 1999;Das et al, 2008;Zhang et al, 2014;Alvim et al, 2015). Some studies have also found that the decomposition rate of soft green leaves with a large surface area is higher than that of hard coniferous litters (Fonte and Schowalter, 2004;Li et al, 2009;Wang et al, 2016). The release dynamics of N and P in the foliage was also the key link of nutrient flow in soil-water (Zhang et al, 2016).…”

Changes in soil organic carbon contents and fractionations of forests along a climatic gradient in China

“…1). Although it is generally believed that the physio-chemical protection, not the initial chemical composition, may be the dominant factor controlling SOC decomposition (Lützow et al 2007;Schmidt et al 2011), litter quality can affect SOC stabilization by affecting the microbial processes in the initial decomposition stage (Prescott et al 2000;Pisani et al 2013;Castellano et al 2015;Wang et al 2015Wang et al , 2016Zhang and Zhou 2018). Vegetation community structure may also affect SOC pool size by altering both micro-environment and soil characteristics (You et al 2014).…”