【苔藓植物中碳、氮含量与同位素特征】Verónica Delgado^1* Alicia Ederra¹ Jesús Miguel Santamaría². Nitrogen and carbon contents andδ¹⁵N andδ¹³C signatures in six bryophyte species: assessment of long-term deposition changes (1980–2010) in Spanish beech forests. Global Change BiologyVolume 19Issue 7 pages 2221–2228 July 2013

Abstract

In this study we used recent (2010) and herbarium material (1980) of six bryophyte species to assess long-term atmospheric deposition in natural forested areas in northern Spain. For this purpose tissue nitrogen and carbon content as well as δ¹³C and δ¹⁵N signatures of samples of Hypnum cupressiforme Polytrichastrum formosum Leucobryum juniperoideum Rhytidiadelphus loreus Homalothecium lutescens and Diplophyllum albicans were analysed and comparisons made between years and species. In addition the usefulness of each of the six species was evaluated. The range of values observed was similar to that in other studies carried out in rural areas. Significantly lower values were found in 2010 for N (H. cupressiforme) δ¹⁵N (R. loreus and D. albicans) C (R. loreus) and δ¹³C (all except L. juniperoideum). Our natural areas are thus now less influenced by atmospheric pollutants than they were most probably due to changes in some traditional local activities. Differences were observed between species for all the four parameters studied so different species must not be analysed together. Finally R. loreus and H. lutescens seem to be good bioindicators sensitive even with a few samples although further studies are needed to corroborate their usefulness.

【根系分泌物刺激与亚高山针叶林土壤氮转换】Huajun Yin¹² Yufei Li¹² Juan Xiao¹² Zhenfeng Xu³ Xinyin Cheng¹² Qing Liu^12*. Enhanced root exudation stimulates soil nitrogen transformations in a subalpine coniferous forest under experimental warming. Global Change Biology.Volume 19Issue 7 pages 2158–2167 July 2013

Abstract

Despite the perceived importance of exudation to forest ecosystem function few studies have attempted to examine the effects of elevated temperature and nutrition availability on the rates of root exudation and associated microbial processes. In this study we performed an experiment in which in situ exudates were collected from Picea asperata seedlings that were transplanted in disturbed soils exposed to two levels of temperature (ambient temperature and infrared heater warming) and two nitrogen levels (unfertilized and 25 g N m⁻² a