| Front page | | Contents | | Back | | Printing instructions |

Buffer zones for biodiversity of plants and arthropods: is there a compromise on width?

Table 3.17. Parameter estimates for the modelled Species-Area relationships (the Spar model is presented above). a (as estimated by the y-intercept - see also Fig. 3.29) indicates the plot-scale diversity in the hedge bottom (measured as species richness). ß is a measure of the change in species richness across spatial scales (distance from field edge in m – see also Fig. 3.29).

Test taxa Distance Para-meter Estimate Standard error of estimate (S.E.)
      Buffer
0		 Buffer
4		 Buffer
6		 Buffer 12 Buffer 24 Buffer
0		 Buffer
4		 Buffer
6		 Buffer 12 Buffer 24
Wild plants 0-18 b α 28.90 aa 31.97 a 30.56 a 30.53 a 27.07 a 5.20 5.22 5.19 5.13 5.04
(incl. dist. 0)   β 0.333 a 0.323 a 0.337 a 0.375 a 0.424 a 0.144 0.131 0.136 0.133 0.146
    σ² 42.1                  
                         
Wild plants 2-18 α 41.20 a 48.79 b 46.72 c 46.25 c 44.26 d 0.34 0.34 0.34 0.34 0.34
(excl. dist. 0)   β 0.0920 a 0.0102 b 0.0273 b 0.0889 a 0.0813 a 0.0083 0.0073 0.0076 0.0074 0.0078
    σ² 0.1395                  
                         
Heteroptera 0-18 α 17.50 a 22.65 b 22.51 bc 21.84 c 25.42 d 0.23 0.23 0.23 0.23 0.23
    β 0.0628 ab 0.0532 a 0.0686 ab 0.0884 b 0.0846 b 0.0114 0.0088 0.0088 0.0090 0.0077
    σ² 0.0693                  
                         
Herbivorous 0-18 α 6.77 a 7.72 b 9.62 c 7.23 ab 7.03 ab 0.30 0.30 0.30 0.29 0.29
coleopterans   β 0.118 a 0.177 a 0.173 a 0.298 b 0.285 b 0.038 0.032 0.026 0.032 0.033
    σ² 0.125                  
                         
Carabidae 0-18 α 16.85 a 18.71 ab 19.05 ab 20.71 b 19.92 ab 1.05 1.06 1.07 1.08 1.06
    β 0.338 a 0.305 a 0.266 a 0.255 a 0.319 a 0.050 0.046 0.046 0.043 0.043
    σ² 1.724                  
                    6.77    
Lepidoptera 2-18c α 5.610 a 6.211 b 6.792 c 6.929 c 7.005 c 0.109 0.111 6.77 0.109 0.111
    β 0.169 a 0.033 b 0.070 b 0.147 a 0.054 bc 0.019 0.019 0.017 0.016 0.016
    σ² 0.0151                  

a Estimates followed by the same letter are not significantly different (P>0.05).

b For more information on modeling and statistical analyses see section 2.6.3.2.

c Distance 0 is included in distance 2 for Lepidoptera.

| Front page | | Contents | | Back | | Printing instructions |



Version 1.0 November 2009, © Danish Environmental Protection Agency