🚀 go-pugleaf

Hello,

I apologize also that I am not responding with good advice on leaf area
meters.  I just want to encourage you at this early stage in your plans to
you consider your methods very carefully.  Meg Lowman and others have made
the excellent point that leaf area removed can be a deceiving way to
estimate herbivory.  There are at least several problems with it: 1) what
of the leaves that are entirely destroyed by herbivores?  Very often, these
will not be counted at all, and if they are, how does one know what the
leaf would the area might have been?  2) Many herbivores (at least
arthropods) do most of their leaf feeding when the leaf is tender and
nitrogen- and water-rich---still expanding.  In this case, a small chewing
bout can have dramatic consequences on leaf size and shape that are not
representative of the actual quantity of tissue removed.  Thus, herbivory
estimates using leaf area "damaged" may either underestimate or
overestimate actual herbivory in a system.  Lowman suggests the best way to
estimate herbivory may be to monitor leaves as they grow, that way one can
know when they turn up missing.

good luck

Dan

At 02:50 AM 2/10/98 -1000, you wrote:
>Kristina A. Ernest wrote:
>>
>> I will be purchasing a portable leaf area meter to do field measurements
>> of % leaf area damaged by herbivores.  I have some information on ADC
>> (from Dynamax) and CID meters, but could consider others as well.  Can
>> anyone recommend which meter is best?
>> Thanks,
>> Kris Ernest
>>
>Kristina:
>I am not comfortable with your reference to a leaf area as being
>"damaged" by herbivores. Perhaps an alien herbivorous species can be
>said to cause such damage. However, any native herbivores are part of
>the larger ecosystem and have co-evolved with the leaves they eat. And
>over long spans of time, the "eating" of leaves of thousands of species
>out there has resulted in an enormous evolution of herbivores as well as
>the dependent carnivores in most ecosystems. So, really there should be
>a more accurate terminology here.
>
>I am also reminded of a parallel example:  thus, in the wider scheme of
>things, a native pollinator (foraging for and eating nectar or pollen)
>cannot be said to cause damage the flower (although often there is
>physical damage) since we have here an evolved symbiotic relationship.
>As well, herbivory in aquatic ecosystems has an enormous food chain
>effect on the small and large dependent fauna.  -Hope you find the best
>meter.
>
>Ted Mosquin
>--
>
---------------------------------
Daniel S. Gruner
Department of Zoology/U Hawaii
2538 the Mall - Edmondson Hall
Honolulu, HI 96822
Phon (808)956-8678 Fax (808)956-9812
email:  dgruner@hawaii.edu