I have computed GLMM using glmer in R. My response variable is species richness and my explanatory variable is grazing treatment (with three categories: cattle, sheep and ungrazed). In the model I have included site as a fixed variable and also a new object with the same number of variations as I have to attempt to account for underdispersal (`obs`):

    model2<-glmer(VegRichness~Grazing+(1|Site)+(1|obs),family="poisson",data=veg.rich)

My output is below and the questions I have about it are:

How do I interpret the fixed effects section?
Cattle grazing seems to be missing in the oputput, is this because it is somehow incorporated into the intercept?


    > summary(model2)
    
    Generalized linear mixed model fit by maximum likelihood (Laplace
      Approximation) [glmerMod]
     
    Family: poisson  ( log ) 
    
    Formula: VegRichness ~ Grazing + (1 | Site) + (1 | obs)
       Data: veg.rich
    
    
         AIC      BIC   logLik deviance df.resid 
        178.8    185.2    -84.4    168.8       22 
    
    Scaled residuals: 
        
    Min..........           1Q............           Median....       3Q.........        Max
     
    -1.4936...      -0.5698.....       -0.1928...      0.4923...   1.3646 
    
    Random effects:
    
     Groups  ... Name......        Variance..... Std.Dev.
    
     obs.........      (Intercept).. 0.00000....  0.0000 
     
     Site.........     (Intercept).. 0.03596....  0.1896
      
    Number of obs: 27, groups:  obs, 27; Site, 3
    
    Fixed effects:
                    .......Estimate.... Std. Error..... z value... Pr(>|z|)    
    (Intercept)............      3.55358.......    0.12309.......  28.869.....  < 2e-16 ***                                                                 
    GrazingSheep......     0.01242......    0.07876........   0.158.......  0.87467    
    GrazingUngrazed -0.27526.....    0.08503........  -3.237......  0.00121 ** 
    
    ---
    Signif. codes:  0 x***x 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
    
    Correlation of Fixed Effects:
                (Intr)....GrzngS
    
    GrazingShe......................... -0.322       
    GrzngUngrzd...................... -0.298...  0.466