On 03/28/2012 06:09 PM, Jari Oksanen wrote:
> On 28/03/2012, at 18:59 PM, cristabel.duran wrote:
>
>> On 03/28/2012 05:36 PM, Jari Oksanen wrote:
>> thank you for your help. I want to know the rarefied richness of single plots.
>> and I  just now rarefied my data within each factor level with rarefy(), and I got what I was looking for.
>>
>> I was wondering that the rarefy richness really is much lower than the original:
>> original:
>>
>>
>>
>>   P1  P5  P9 P11 P17 P23 P30 P33 P36 P38 P41 P50 P54 P56 P59 P62
>>    9  14   2   8  10  11   6   7   6  16  13  10  11  12  10  12
>>
>>
>>
>>
>> rarefied:
>>
>>
>>
>>        P1       P5       P9      P11      P17      P23      P30      P33      P36
>> 3.313725 2.827956 2.000000 3.293040 2.946823 3.592810 2.263004 3.087552 3.195238
>>       P38      P41      P50      P54      P56      P59      P62
>> 3.659412 3.547713 2.555684 3.376906 3.202633 3.227595 3.428148
>>
>>
>>
>>
>> My data is from regeneration of tropical forest, with few species with high abundance and lots of species with few abundance.
>>
>> I do doubt of the results, but as I never worked with rarefaction I do not know how interpret such a disparity between non-rarefied and rarefied richness.
> Well, the function has been tested and used before...
>
> Study these questions with your data: How many trees did you have originally in each plot? How many trees do you have in your rarefied plots? How many species can you have with that number of trees?
>
> Cheers, Jari Oksanen
Sorry, I typed too fast my answer. I wanted to say: I do NOT doubt of 
the results....
Thanks for your help,

Cheers, Cristabel.

-- 
Dr. Cristabel Durán Rangel.
Institute of Silviculture. Faculty of Forest and
Environmental Sciences. University of Freiburg.
Germany
Telf: +49 (761) 203 8603 (ofc)
https://portal.uni-freiburg.de/waldbau

"Man lernt die Physiognomie einer Landschaft desto besser
kennen, je genauer man die einzelnen Züge auffaßt, sie
untereinander vergleicht und so auf dem Wege der Analysis
den Quellen der Genüsse nachgeht, die uns das große
Naturgemälde bietet."
                 Alexander von Humboldt, 1799


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