If you are looking for Ecological journals specifically, reference I think would be Ecology http://esapubs.org/esapubs/EcolTypes.htm. You could also look at Biology Letters for short notes http://rsbl.royalsocietypublishing.org/site/misc/about.xhtml.
Depending on the scope and length of your paper you might also consider Ecology Letters http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1461-0248/homepage/ProductInformation.html, or go really broad with Science or Nature.
Acta Oecologia, Web Ecology and Ecological Research seems to accept short communications.
Other journals have forum/hypothesis/perspectives sections for more conceptual short papers, e.g. Ecography, Ecology & Evolution, Evolutionary Ecology, Functional Ecology, Journal of Animal Ecology, Journal of Ecology and Oikos