Effects of Nitrogen Addition on Leaf Decomposition of Single-Species and Litter Mixture in Pinus tabulaeformis Forests

Abstract

Abstract:The litter decomposition process is closely correlated with nutrient cycling and the maintenance of soil fertility in the forest ecosystem. In particular, the intense environmental concern about atmospheric nitrogen (N) deposition requires a better understanding of its influence on the litter decomposition process. This study examines the responses of single-species litter and litter mixture decomposition processes to N addition in Chinese pine (Pinus tabulaeformis Carr.) ecosystems. Chinese pine litter, Mongolian oak (Quercus mongolica Fisch. ex Ledeb.) litter, and a pine-oak mixture were selected from a plantation and a natural forest of Chinese pine. Four N addition treatments, i.e., control (N0: 0 kg N ha´1¨year´1), low-N (N1: 50 kg N ha´1¨year´1), medium-N (N2: 100 kg N ha´1¨year´1), and high-N (N3: 150 kg N ha´1¨year´1), were applied starting May 2010. In the plantation, N addition significantly stimulated the decomposition of the Chinese pine litter. In the natural forest, N addition had variable effects on the decomposition of single-species litter and the litter mixture. A stimulatory effect of the high-N treatment on the Chinese pine litter decomposition could be attributed to a decrease in the substrate C:N ratio. However, an opposite effect was found for the Mongolian oak litter decomposition. The stimulating effect of N addition on the Chinese pine litter may offset the suppressive effect on the Mongolian oak litter, resulting in a neutral effect on the litter mixture. These results suggest that the different responses in decomposition of single-species litter and the litter mixture to N addition are mainly attributed to litter chemical composition. Further investigations are required to characterize the effect of long-term high-level N addition on the litter decomposition as N deposition is likely to increase rapidly in the region where this study was conducted.

Decomposition and Carbon and Nitrogen Releases of Twig and Leaf Litter Were Inhibited by Increased Level of Nitrogen Deposition in a Subtropical Evergreen Broad-Leaved Forest in Southwest China

“…Our findings stated that the initial C/N ratio in leaf and twig litters was 32 and 65, respectively. Therefore, lower initial N content and higher C/N ratio, as well as higher lignin and cellulose residues in twig litter, could be one of the main reasons for their slower decomposition rate than the leaf litter [17]. In addition, Our outcomes demonstrated that the initial P content and the ratios of litter C/P and N/P might be critical factors that affect rates of decomposition.…”

“…Tie et al [3] discovered that a lower C/N ratio and litter pH in the soil was associated with the N additions, which inhibited the degradation of litter and nutrient availability in a subtropical forest. However, Wang et al [17] found no significant difference in litter composition, possibly because of the fact that the stimulatory impact of N addition on the Chinese pine litter may counteract the inhibitory action on the Mongolian oak litter in a temperate forest. The above-mentioned studies primarily discussed the effect of N additions on the decomposition of leaf litter.…”

Decomposition and nutrient release from the mixed leaf litter of three agroforestry species in the Sudanian zone of West Africa

“…In these two mixtures, non-additive effects and synergistic interactions have been reported. These findings suggest that N-rich leaf litter (A. africana) may transfer nutrients to N-poor litter (V. paradoxa), which increases the decomposition rate [8,14,30,39]. This evidence is supported by a study in northern Canada [40] that found the decomposition rate was increased only in a mixture containing N-rich speckled alder leaves, and was conversely inhibited by mixing yellow birch leaves with red maple leaves.…”

Soil microbes-mediated enzymes promoted the secondary succession in post-mining plantations on the Loess Plateau, China

“…Since the 1990s, P. tabulaeformis has been widely used in vegetation recovery of soil dumps in the mines in Chinaʼs Loess Plateau, and is known for its excellent coldand barren-resistant capability (Qi et al, 2020). After 30 years of growth, a small part of the P. tabulaeformis plantations is succeeded by more diversified native ecosystems (Wang et al, 2016). However, a greater proportion of the P. tabulaeformis plantations also undergo vegetation degeneration, as typified by the small, aged trees and even extensive death (Zhao et al, 2017).…”