[Keystone species] When will we learn?

[El_Machinae]

Today?

Mistletoe as a keystone resource: an experimental test

Various entities have been designated keystone resources, but few tests have been attempted and we are unaware of any experimental manipulations of purported keystone resources. Mistletoes (Loranthaceae) provide structural and nutritional resources within canopies, and their pervasive influence on diversity led to their designation as keystone resources. We quantified the effect of mistletoe on diversity with a woodland-scale experiment, comparing bird diversities before and after all mistletoe plants were removed from 17 treatment sites, with those of 11 control sites and 12 sites in which mistletoe was naturally absent. Three years after mistletoe removal, treatment woodlands lost, on average, 20.9 per cent of their total species richness, 26.5 per cent of woodland-dependent bird species and 34.8 per cent of their woodland-dependent residents, compared with moderate increases in control sites and no significant changes in mistletoe-free sites. Treatment sites lost greater proportions of birds recorded nesting in mistletoe, but changes in species recorded feeding on mistletoe did not differ from control sites. Having confirmed the status of mistletoe as a keystone resource, we suggest that nutrient enrichment via litter-fall is the main mechanism promoting species richness, driving small-scale heterogeneity in productivity and food availability for woodland animals. This explanation applies to other parasitic plants with high turnover of enriched leaves, and the community-scale influence of these plants is most apparent in low productivity systems.

Science!

 

[peter grimes]

Wow - although, I can't say that I'm completely surprised.

I wonder, though, whether or not just about every member of an ecosystem could be considered a 'keystone'. But a quick scan of the paper didn't show me how they are defining the term keystone, exactly. I remember reading (a long long time ago) The Web of Life by Fritjof Capra. I was completely fascinated by the profundity of the interactions between disparate niches in an ecosystem - I think the metaphor he used (perhaps cribbed from Darwin?) was pulling on a strand in one spot will cause the web of life to unravel in ways that aren't always superficially obvious.

Except mosquitos. Those little jerks bring nothing to the table and are clear evidence that if there are gods they hate us.

 

[GoodGame]

El Mach, this is interesting find.
But how tightly did they control for other variables, that their conclusion is eloquent?

I'll definitely give this one a read.

 

[peter grimes]

El Mach, this is interesting find.
But how tightly did they control for other variables, that their conclusion is eloquent?

I'll definitely give this one a read.

They acknowledged that there was not a careful audit of the potential confounding conditions related to prior habitat disruption before they started the trial.

In other words, if the population of a certain bird had been in decline forcseveral years prior to the removal of mistletoe, they would still mistakenly count that population loss as bring due to the removal of mistletoe.

There may be others that I missed - I only skimmed it a few hours ago.

 

[GoodGame]

Another question I have (not being an ecologist-type), is a species a keystone for its inputs (like mistletoe here is hypothesized) is it a keystone for being a "canary in a coal mine" (e.g. a sampling sensor)?

I'm wondering, because I just recently learned that the walrus is considered a keystone species in the arctic.
I suspect that this isn't intended in the same way as mistletoe.

 

[El_Machinae]

They're quite different. I think of 'umbrella species' as the canary. They need a lot of inputs working in cohesion in order to be prosperous, so if their behaviour significantly changes, then you know something is going on.

 

[Algeroth]

Another question I have (not being an ecologist-type), is a species a keystone for its inputs (like mistletoe here is hypothesized) is it a keystone for being a "canary in a coal mine" (e.g. a sampling sensor)?

I'm wondering, because I just recently learned that the walrus is considered a keystone species in the arctic.
I suspect that this isn't intended in the same way as mistletoe.

"Canary" species are refered to as indicator species. They can or can not be also keystone species.

Today?

Mistletoe as a keystone resource: an experimental test



Science!

Haven't you (or someone else here) linked it here some time ago? I swear that I've read this pare before, but i doubt that I have time to read it when I was finishing my thesis.

Anyway, i dont think that you should implicate somthing important from this paper. I'm not convinced that they have controlled sufficently for other factors. And I really miss some information about the type of forest where they conducted this experiment. If it was in climax forests (as I suppose) than it should come as no suprise that reduction in nearly any species would have consequencess across all the local ecosystem because climax temperate forests are realativelly poor in species richness. And if it wasn't climax forest, they havn't accounted for any ecological dynamics where the number of species is generally reduced as they move toward climax.

 

[Algeroth]

They're quite different. I think of 'umbrella species' as the canary. They need a lot of inputs working in cohesion in order to be prosperous, so if their behaviour significantly changes, then you know something is going on.

I don't want to sound pedantic, but umbrella species are used for species that when protected, ensure protecion of many other species due to protection of habitat of umbrella species that is used by many other organisms, etc. They are similiar concepts, overlapping in some cases, but they are not the same.

 

[El_Machinae]

No, not pedantic. I was incorrect, and I didn't know it. Thanks.