My experiment was carried out in a grassland ecosystem. The plant biomass was harvested in the middle of August, and I'm wondering if I can use this plant biomass to estimate the availability of plant carbon input to microbes as it was usually measured by litter-bag experiments.
Dear Sen Yang,
mineral composition of senescent leaves differ highly from that of growing leaves. In my opinion the best way to obtain freshly fallen litter that has proper composition is to use litter traps that catch freshly fallen leaves.
You will find more info in these books:
http://www.springer.com/us/book/9783642388200
http://store.elsevier.com/Litter-Decomposition-a-Guide-to-Carbon-and-Nutrient-Turnover/isbn-9780123736178/
Kind regards,
Michał Filipiak
http://www.springer.com/us/book/9783642388200
http://store.elsevier.com/Litter-Decomposition-a-Guide-to-Carbon-and-Nutrient-Turnover/isbn-9780123736178/
It really depends on your research question. If you want to evaluate evaluate C available to microbes, you must be aware that at least in the temperate zone, litterfall occurs in the autumn and minimal litterfall from deciduous trees occurs during the summer (unless there is drought stress). Therefore, if you want to determine C availability to microbes during the actual event of litterfall, you need to collect leaves in a littertrap during autumnal litterfall and then use this material for your study. The best approach is to use the litterbag decomposition method (as described in some of the books recommended by Michael Filipiak.
Dear Sen Yang,
I agree with Michael and Maren, working on harvested biomass is not the right method due to changes in chemical composition during senescence (think about difference between green wheat hay and wheat straw).
However you are working on grassland, not on deciduous forest, so you must adapt the method. Grass litter derive from senescent material (leaf blade and tillers) which are poorer in N and soluble sugars than harvested live biomass. Senescence process increase probably during drought or cold season, and is minimal in spring.
If you find many forbs, the aerial parts die probably in autumn before being incorporated to litter.
In both cases, you should probably pick manually senescent material just before it incorporate the litter, in order to run analyses and litterbag decomposition method.
This is important point, I'm sorry for ignoring the fact that you work in a grassland ecosystem. You should correct your study design considering Maurice's answer.
Don't hesitate to send me a paper when its published!
Best!
MF
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