Zhiqun Huang

Correlation between phytotoxicity on annual ryegrass (Lolium rigidum) and production dynamics of allelochemicals within root exudates of an allelopathic wheat

An improved allelopathic correlation between phytotoxicity measured in root growth bioassay upon annual ryegrass (Lolium rigidum Gaud.) and the concentrations of a selection of dynamically produced allelochemicals quantified in the root exudates of cv. Khapli wheat (Triticum turgidum ssp. durum (Desf.) Husn.) monitored during the first 15 days of wheat seedling growth in a sterile, agar–water medium, has been established. Changes over the 15-day growth period in the quantities of five exuded benzoxazinones and seven phenolic acids were measured simultaneously using GC/MS/MS. Substantiating pure compound dose–response measurements were conducted over a range of concentrations for the putative allelochemicals within the wheat exudates. One synergism-based proposal using the monitored compounds to explain the observed low-exudate-concentration phytotoxicity was explored, but was found to be experimentally inadequate.

Allelopathy of phenolics from decomposing stump-roots in replant Chinese fir woodland

The change of total phenolic content in decomposing Chinese fir stump-roots of different ages in replant woodland and its effects was investigated. The total phenolic contents in stump-roots decreased with increasing stump-root age. The order of total phenolic content in different parts of stump-roots was, root > stump heartwood > stump sapwood. Phenolics released from Chinese fir stump-roots reduced the growth of fir seedlings. The growth of Chinese fir seedlings was negatively correlated with total phenolic content in stump-roots that had been added to the soil. Extracts of Chinese fir stump-roots inhibited fir seed germination. The results, based on paper chromatography and HPLC, revealed that eight phenolic compounds were present in the Chinese fir stump-roots.

Chemical composition of decomposing stumps in successive rotation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations

Decomposition of stumps in successive rotation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations was studied using a chronosequence approach. The results showed that decomposition rate constant of Chinese fir stump was 0.02695 as calculated from Olson’s model. The N content of stump increased during the first two-year decomposition. When the dead stump C/N ratio was 463.2 ± 27.3, the stumps started to release N. The pattern of P release was similar to that for N. However, K content of stumps showed a consistent declining trend over time during the whole decomposition.13C nuclear magnetic resonance spectroscopy with cross polarization and magic-angle spinning (13C CPMAS-NMR) was used to analyse organic carbon (C) components in decomposing stumps. The13C CPMAS-NMR spectra of stumps displayed that stump was dominated by cellulose and hemicellulose. The spectra also showed the accumulation of intensity in alkyl C, aromatic C, and carboxyl C spectral regions, which was expected as the labile cellulose and hemicellulose components inO-alkyl C spectral region were selectively decomposed first.

Preface to the special issue for the 8th International Symposium on Forest Soils: Linking Soil Processes to Forest Productivity and Water Protection under Global Change

The 8th International Symposium on Forest Soils: Linking Soil Processes to Forest Productivity and Water Protection under Global Change was held during 24–28 October 2015 on the campus of Fujian Normal University in Fuzhou, China. The Symposium was organized for two principal reasons: first, to celebrate the 2015 International Year of Soils; and second, to address a crucial gap in the forest soils and forest management literature in a concerted effort. There is a pressing need for a Bstate-of-the-art^ publication on the nature and research needs of integrating soil information and expertise into the management of Chinese forest resources. Especially in South China, most forests are located in the mountains and hills. Soils of the region are perceived to be fragile and easily damaged. Relatively few studies have been published in the international literature on forests and forest soils of southern China. Thus, our intention was to emphasize regionally available datasets, to incorporate the pertinent information from the world literature, and to place the issues facing forest scientists in southern China in an international context. The 8th International Symposium on Forest Soils continues the series of International Symposia sponsored by the International Union of Soil Science (IUSS) (previously International Society of Soil Science or ISSS) and other related agencies. The 3rd Symposium of this series was held in Balikpapan, Indonesia, 29 October–3 November 1995, with the 4th held in Vila Real, Portugal, 18–22 September 2000. The 5th, 6th, and 7th symposia were held in Bordeaux, France, 15–18 September 2004; in Noosa, Queensland, Australia, 19–23 August 2007; and in Shenyang, China, 17–20 September 2013, respectively. Next, the Forest Soils Working Group of IUSS will co-sponsor the joint North American Forest Soils Conference/the 9th International Symposium on Forest Soils, 10–16 June 2018, in Quebec City, Quebec, Canada. The Quebec symposium will be co-sponsored by the Soil Science Society of America (SSSA), the Canadian Society of Soil Science (CSSS), and the International Union of Forest Research Organizations (IUFRO). In addition, the Forest Soils Working Group, currently convened by Professor Zhihong Xu of Griffith University, Nathan, Brisbane, Australia, and Professor Chris Johnson of Syracuse University, USA, has also hosted both oral and poster sessions on forest soils during each IUSS (ISSS) World Congress of Soil Science since 2002. This special issue (SI) of Journal of Soils and Sediments includes 16 papers selected from more than 50 submissions from the 8th Symposium. The papers in this SI discuss important fundamental and applied issues in forest soil science and forest ecology and provide a worthwhile contribution to the advancement of forest soil science. There has been increasing attention being paid to the benefits provided by soil organic matter for forest ecosystem functioning and health. Two of the papers in this SI deal * Zhiqun Huang zhiqunhuang@hotmail.com