Practical Exam Help required!

[Jenjey]

Hi there everyone, I stumbled across this site whilst conducting a bit of research for my biology practical (which is the biggest pain in the world!)

Basically....my planning exercise is:

"After a fire, slow growing heather is able to recolonise bare heathland quicker than other species of plants. It is thought that this is due to the ash formed by the burning of heather producing a natural soluble inhibitor. This dissolves in soil water and inhibits the germination of seeds of other plant species.

Design an experiment that would prove if the ash of burnt heather contains a natural inhibitor of germination."

My plan is to have 5 seed trays and add different concentrations of the burn heather ash to each one to the the effect. My control will be growing seeds in just distilled water and noting this germination rate.


One of the questions asks me to give a quantitative prediction for the investigation and to briefly state any biological principles that would support my prediction.

Can anyone give me any help into this? I know very little about heather! (calluna vulgaris) and I just don't know how to tackle this.


All help is greatly appreciated, thanks,
Jen.

[b_d_41501]

Here's some general info on Heather. Heather is naturalized in North America from Newfoundland west to Michigan and south through Nova Scotia and the New England states to the mountains of West Virginia. It is widespread throughout Europe also.

Some common plant associates of heather in Europe include Scotch pine
(Pinus sylvestris), Norway spruce (Picea abies), birch (Betula spp.),
heath (Erica spp.), dwarf bilberry (Vaccinium myrtillus), mountain
cranberry (Vaccinium vitis-idaea), bearberry (Arctostaphylos uva-ursi),
crowberry (Empetrum nigrum), willow (Salix spp.), red raspberry (Rubus
idaeus), sheathed cottonsedge (Eriophorum vaginatum), bracken fern
(Pteridium aquilinum), sedges (Carex spp.), hairgrass (Deschampsia
flexuosa), moor-grass (Molinia spp.), reindeer lichens (Cladonia spp.),
Sphagnum spp., fire moss (Ceratodon purpureus), Polytrichum spp.,
mountain fern moss (Hylocomium splendens), and feathermoss (Pleurozium
schreberi). I didn't know if this would be helpful, but I threw it in anyway.

Some importance to livestock and wildlife include several things as well. Heather leaves and shoots are the most important yearlong food of rock ptarmigan and grouse in Scotland and Denmark. Heather may comprise 80 to 100 percent of the diet of grouse, and also constitutes a large portion of the diet of domestic sheep [10]. Red deer and mountain hare also browse heather. You may write up of how the droppings of these animals in particular may affect germination.

In response to your particular experiment Heather releases allelopathic substances that may inhibit invasion and growth of some trees in heather-dominated heaths and moors in particular.

If I were to start a quantitative prediction based upon the differing concentrations of the ash solution I would have to say that the growth of the plants would be limited by 25% in a solution of 25% Ash : 75% Water. This is just your prediction so it can be altered as your data presents more results.

Hope I was of help.

[ERS]

If you are going to go ahead with your water idea as a control group, consider having two controls for this experiment. The second control being one that is planted in the same soil as your other five trays but without your ash mix added. This should be able to confirm beyond reasonable doubt that the ash is or isn't an inhibitor of germination.

Hope this helps.

ERS
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Rhetoric only gets your so far...