Research Article

Quantifying Effects of Spatial Heterogeneity of Farmlands on Bird Species Richness by Means of Similarity Index Pairwise

Table 7

Results of Poisson regression for the best model relating the bird species richness to environmental parameters of farmlands in Central Italy. The table shows the most significant variables selected after a stepwise backward procedure using AIC criterion. A comparison of models with all possible variables, classified in the four different categories of spatial heterogeneity, showed that the significant parameters are the same for all the evaluated levels.

Environmental parameterEstimateSEZ valueP-values

Farmlands ( )
Powerlines0.028050.012422.2570.0240*
Shrubs1.239660.506812.4460.0144*
Uncultivated0.946630.537771.7600.0784
Hedgerows1.516440.335854.515 ***
Intercept2.216320.0901824.576 ***

Significance codes: ***P < 0.001, **P < 0.01, *P < 0.05, P < 0.1.