BROADACRE GARDEN

Honey bee

Solitary bee

On Tuplipa turkestanika, naturalised in grass, in the spring.

Putting numbers to observations on flowers and bees enables us to rank flowers for bee forage.

On the flowers of Japanese greens grown for salad over the winter

Ecology improves on Natural History by putting numbers to things. Sometimes we have to use arbitrary scales. Here numbers are used but they are replacements for descriptive terms such as “rare”, “common”, “abundant” etc. They are not true numbers and you cannot perform statistical analysis on them. Nevertheless they allow comparisons to be made with a greater clarity than verbal descriptions.

A flower that is moderately attractive to bees over many weeks may be more useful than a flower which is very attractive for just a few days. Each week I recorded the attractiveness of a wide variety of flowers to bees and I multiplied the average of my observations by the number of weeks a given flower was visited. This I call the flower index. E.g. if, over 6 weeks, I observe values of 1, 3, 3, 2, 3, 2 then the average is 2.33 and the flower index is 6 x 2.33 = 14

I use an arbitrary 1-3 scale. If there were very few bees on a flower it is a “1”, lots of bees are a “3”, anything in between is a “2”. It is very subjective. Another observer might make different judgements. Even so, for one observer it allows a number to be put on the relative merits of different flowers. Even independent observers will be likely to place the attractiveness of the flowers in the roughly same relative order. continued