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北半球近地大气O3浓度在最近几十年里持续升高,对陆地生态系统产生深远的影响。本文选取5年生银杏(Ginkgo biloba)为研究对象,利用开顶式气室(OTCs)开展了3个不同浓度的O3(自然对照浓度约40 nmol·mol-1、处理浓度80和120 nmol·mol-1)熏蒸试验,持续熏蒸2个生长季(2012—2013年)后,于2013年11年月初收集其凋落叶,测定并分析不同处理下银杏凋落叶化学成分的变化。结果表明:与对照相比,高浓度O3处理组银杏凋落叶的N、K含量均显著升高,总酚含量以及C/N、木质素/N降低;而C、P、木质素含量以及C/P并未呈现出显著差异。可溶性糖、缩合单宁含量在两高浓度O3处理下变化趋势并不一致:与对照相比,可溶性糖含量仅在120 nmol·mol-1处理下表现出显著差异,降低38%;缩合单宁含量在80 nmol·mol-1处理下显著升高(343%),而在120 nmol·mol-1处理下无显著变化。木本植物凋落物的化学组成在O3熏蒸下会发生一定变化,这种变化可能会对树木凋落物在O3污染地区的分解及区域气候变化下森林生态系统的物质循环,特别是碳循环产生重要影响。
O3 concentrations in the near-Earth atmosphere in the northern hemisphere have continued to rise in recent decades, with far-reaching implications for terrestrial ecosystems. In this study, Ginkgo biloba (5-year-old) was selected as the research object and O3s were used to investigate the effects of different concentrations of O3 (natural control concentration about 40 nmol · mol-1, treatment concentrations 80 and 120 nmol · mol -1) fumigation test. After two fumigation days (2012-2013), the litter was collected at the beginning of November 2013, and the changes of the chemical composition of the litter under different treatments were determined and analyzed. The results showed that compared with the control, the content of N and K in the litter of ginkgo leaves increased significantly, the content of total phenols and C / N and lignin / N decreased in high concentration O3 treatment group, while the content of C, P, lignin and C / P did not show a significant difference. The content of soluble sugar and condensed tannin did not change with the increase of the concentration of O3. Compared with the control, the content of soluble sugar and soluble tannin showed a significant difference at the concentration of 120 nmol · mol-1, a decrease of 38%. The content of condensed tannin It was significantly increased at 80 nmol · mol-1 (343%) and no significant change at 120 nmol · mol-1. The chemical composition of woody litter will change under O3 fumigation, and this change may be important for the decomposition of tree litter in O3-contaminated areas and the material circulation of forest ecosystems under regional climate change, especially the carbon cycle influences.