# Pollination half-saturating constant and scalar

**URL:** <https://community.naturalcapitalalliance.org/t/pollination-half-saturating-constant-and-scalar/5543>\
**Category:** Science, Research & Data\
**Tags:** pollination\
**Created:** [October 27, 2024, 4:06pm UTC](https://community.naturalcapitalalliance.org/t/pollination-half-saturating-constant-and-scalar/5543 "2024-10-27T16:06:39Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![sibylles](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@sibylles](https://community.naturalcapitalalliance.org/u/sibylles)\
**Post date:** [October 27, 2024, 4:06pm UTC](https://community.naturalcapitalalliance.org/t/pollination-half-saturating-constant-and-scalar/5543/1 "2024-10-27T16:06:40Z")

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Dear community

The model that translates pollination services to agricltural production is described here using an example:  
_Ricketts and Lonsdorf (2013) Mapping the maring: comparing marginal values of tropical forest remnants for pollination services. Ecological Applications 23: 113-1123._  
[Ricketts\_2013-Mapping the margin.pdf](https://community.naturalcapitalalliance.org/uploads/short-url/iK2V6D2WcuVjj9B4JXfZGKvDSRb.pdf) (5.7 MB)

Question: I am wondering how the half-saturating constant and the scalar was calculated? In the method description I just found “was set to”.

_We use field results from Ricketts et al. (2004) to_  
_estimate yield parameters. The maximum yield of coffee_  
_is approximately 21.5 fanegas per hectare (1 fanega ¼_  
_200 liters of berries). Ricketts et al. (2004) observed that_  
_yield declined 18% between areas with abundant bee_  
_visits and areas with fewest bee visits, so we set mc to_  
_0.18. To fit the saturating function to the maximum_  
_abundance observed in the field (i.e., 108 total visiting_  
_bees) we set jc to 30 and multiplied the saturating_  
_function by a scalar equal to 1.27._

In a previous section it was mentioned that the half-saturating constant is 0.153 (yielding a predicted abundance of 54, however this seems to be another half-saturating constant than the one above with 30) and the shape of the saturating function is 3.298, respectively. How are these two values translated to the value of 30 and 1.27?

_we used Monte Carlo parameterization to determine the_  
_values of half-saturation constant j and c that_  
_maximized the fit (0.153 and 3.298, respectively; Fig._  
_2A)._

Many thanks  
Sibylle

@elonsdorf  
@lons0011