Effect of elevated atmospheric CO2 concentration on growth and leaf litter decomposition of Quercus acutissima and Fraxinus rhynchophylla.

Sangsub Cha,Hee-Myung Chae,Sang-Hoon Lee,Jae-Kuk Shim,John J Kelly

doi:10.1371/journal.pone.0171197

Abstract

The atmospheric carbon dioxide (CO2) level is expected to increase substantially, which may change the global climate and carbon dynamics in ecosystems. We examined the effects of an elevated atmospheric CO2 level on the growth of Quercus acutissima and Fraxinus rhynchophylla seedlings. We investigated changes in the chemical composition of leaf litter, as well as litter decomposition. Q. acutissima and F. rhynchophylla did not show differences in dry weight between ambient CO2 and enriched CO2 treatments, but they exhibited different patterns of carbon allocation, namely, lower shoot/root ratio (S/R) and decreased specific leaf area (SLA) under CO2-enriched conditions. The elevated CO2 concentration significantly reduced the nitrogen concentration in leaf litter while increasing lignin concentrations and carbon/nitrogen (C/N) and lignin/N ratios. The microbial biomass associated with decomposing Q. acutissima leaf litter was suppressed in CO2 enrichment chambers, while that of F. rhynchophylla was not. The leaf litter of Q. acutissima from the CO2-enriched chambers, in contrast with F. rhynchophylla, contained much lower nutrient concentrations than that of the litter in the ambient air chambers. Consequently, poorer litter quality suppressed decomposition.

Highlights

In terrestrial ecosystems, carbon dioxide (CO2) is absorbed or emitted through primary production and respiration processes [1,2,3]
Ten Q. acutissima seedlings and six F. rhynchophylla seedlings were transplanted in each pot, which resulted in a total of 40 and 24 seedlings, respectively, for each treatment
The shoot/root ratio (S/R) ratio of Q. acutissima was significantly lower in elevated CO2 chamber

Summary

Introduction

Carbon dioxide (CO2) is absorbed or emitted through primary production and respiration processes [1,2,3]. Temperate forests cover only 8% of the land area globally, but they account for approximately 40% of the total terrestrial C storage. These forests are important for sequestering C from atmospheric CO2 [6,7,8]. The rising CO2 concentration may induce global warming [9, 11,12,13], and it has had direct impacts on the structure and function of ecosystems, including effects on tree physiology and growth [4, 14,15,16].

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