Hi everyone,
I was wondering, when both data types are available, which is best (for which research objective?) to compute community weighted means? Density, biomass or cover seem to be used as if they were exchangeable even though they relate to different aspects of the vegetation, and are not necessarily correlated in my case. Density could be biaised towards species with high seed output, biomass could be biaised towards tall species, whereas cover could be biaised towards a creeping growth form.
What data type do you recommend to compute community weighted means in relation to which research objective?
The only publication which has investigated this question - to the best of my knowledge - is :
Q. Guo, P.W. Rundel, Measuring dominance and diversity in ecological communities: choosing the right variables, Journal of Vegetation Science, 8 (1997) 405-408.
-> which recommends biomass, with few explanations
FYI: I work on weed community response to agricultural practices. Therefore, both biomass and density are very common measures. One obvious problem with density in such cases is when associating average trait values to late germination flushes (i.e. seedlings of summer weeds in winter cereals).
Any documents which could partially answer this question are welcome.
Thank you very much for your interest.
Sincerely,
GA2
I think you've answered your question. But biodiversity seems more interesting :)
Hello Guillaume; Weed abatement in an agricultural setting must balance crop yield against the cost of weed abatement. I imagine that that is an important aspect of the research plan. The curves that describe declining yield and the one for abatement costs will intersect at a point that represents some optimum. Which of your variables most reliably does that? That is the one to focus on. Best regards, Jim Des Lauriers
Andrew Paul McKenzie Pegman what do you mean biodiversity is more interesting? Whether one focuses on functional identity or diversity purely depends on research objectives... I wouldn't say one is more interesting than the other, they are often complementary.
James Des Lauriers indeed weed biomass is often a better predictor of crop yield losses than density (partitularly in the case of multispecific weed communities).
Igor Eloi that is also my personal belief but I am more interested in how to back that up with arguments and in what are the potential drawbacks....
Yes, I know, I've studied both. But plants and animals are definitely more interesting than biomass lol. But like I said, you seem to have answered your own question :)
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