> Dear all,
> I'm looking for the following papers,
a) Sheppard PR and Thompson 2000. Effect of extraction pre-treatment on radial 
variation of nitrogen concentration in tree rings. J. Environm.Qual. 29:2037-
2042
b)Poulson SR, CP Chamberlain and J. Friedland 1995. Nitrogen isotope variation 
of tree rings as potential indicator of environmenatl change. Chem.Geol 
125:307-315
c)Mitchell AK,Hinckley TM.1993. Effect of foliar nitrogen concentration on 
photosynthesis and water use efficiency in Douglass-fir. Tree Physiol 
12:403.410

> > I hope you can help me,Thanks in advance.
> Please, reply to me directly and not to the list.
> 
> Best wishes,
> Giovanna Battipaglia 
****************************************************************
> Giovanna Battipaglia,PhD
Environmental Science Department
Second University of Naples
Via Vivaldi, 43 81100 Caserta
Tel: +39 0823 274648
fax: +39 0823 274605
e-mail:[log in to unmask]
> 
> 
>