1 23 AMBIO A Journal of the Human Environment ISSN 0044-7447 AMBIO DOI 10.1007/s13280-014-0545-4 Consequence of altered nitrogen cycles in the coupled human and ecological system under changing climate: The need for long- term and site-based research Hideaki Shibata, Cristina Branquinho, William H. McDowell, Myron J. Mitchell, Don T. Monteith, Jianwu Tang, Lauri Arvola, et al.