Hi Claudia,
I think you'll find the following article most useful:
Dormann, C. F., J. M. McPherson, M. B. Araujo, R. Bivand, J. Bolliger,
G. Carl, R. G. Davies, A. Hirzel, W. Jetz, W. Daniel Kissling, I. Kuhn,
R. Ohlemuller, P. R. Peres-Neto, B. Reineking, B. Schroder, F. M.
Schurr, et R.
Claudia,
Here is a more specific paper with hierarchical Bayesian model:
Stephen L. Rathbun and Songlin Fei
A spatial zero-inflated poisson regression model for oak regeneration
Environmental and Ecological Statistics, 2006, 13: 409-426
