Crop pollination outputs query
I am using the crop pollination model to examine changes in pollination services from additions native vegetation in a cropping district of South Australia.
I don't have any trouble getting the model to run (in fact it is great!) but I am getting some strange results that I am struggling to interpret.
I have been getting much lower pollinator abundance values (p_abund in the farm_results shapefile) than I was expecting. More importantly, I am getting much lower changes/increases in abundance with additional re-vegetation/nesting habitat.
- For example, in one scenario, adding 80 hectares of quality pollinator habitat (nesting index ~0.8) adjacent to the paddock I am getting changes increases in p_abund from 0.023381 to 0.0355506.
- Similarly, in a scenario with a relatively high overall habitat suitability for pollinators, adding 80 hectares of quality pollinator habitat (nesting index ~0.8) adjacent to the paddock I am getting changes increases in p_abund from 0.024365 to 0.036005.
I realise that there are a number of factors affecting this value but I would have though with all other things being equal that 80 ha of quality nesting and foraging vegetation adjacent to the paddock should show more of an increase. After I realised this I have tried to force the p_abund to increase but adding larger and larger amounts of nesting habitat to the land use raster but it is very difficult to 'move' this value significantly. Has anyone else noticed this or had these problems?
These problems led me to investigate the outputs in a little more detail and I was wondering if anyone could explain what the 'farm_pollinators.tif' is? This raster has much higher values and but more importantly, the changes in values with additional nesting habitat are more what I was expecting. For example, adding 80 ha of nesting habitat increases the values in the farm_pollinators_tif from an average of about 0.17 to 0.25. Can this be interpreted as an increase in pollinator abundance on the farm? I assume not, given the outputs but what is it and how is it different from the p_abund in the farm_result shapefile?
Unfortunately I can find very little information on what this raster layer is. I have had a look at the code but struggling to work it out.
Any suggestions would be greatly appreciated.
Thanks in advance.