It occurs to me that nursery-grown plants (in the absence of herbivores) do not develop (inducible) defenses, and that when planted out, may suffer greater herbivore damage, at least initially. Does anyone have examples of this, or suggestions of it, from the literature?
It makes sense that phenotypic plasticity of defenses (as an adaptive trait, but not Darwinian framework) would be affected, and also absorption of allelopathic substances would be lower, hence lower defenses in a safer environment
https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.12726/full
Hello Truman; Here is a paper that might be in the right ballpark.
https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=8623&context=etd
FIRE - HERBIVORY INTERACTIONS IN AN EAST AFRICAN SAVANNA: EFFECTS ON ACACIA DREPANOLOBIUM TREES
Regards, Jim des Lauriers
Does this paper help?
https://journals.ashs.org/horttech/view/journals/horttech/28/5/article-p596.xml
Baisden et al. 2019.
Do Cultivars of Native Plants Support Insect Herbivores?
Or this: Article Sourcing native plants to support ecosystem function in diff...
It is known that animal causing injury to the plant elicit a cascade of chemical reactions leading to different mechanisms of defence. The best known example are the giraffes feeding on acacias in the African savanna. Moreover you just need an insect to cause such defence reactions. In the saliva of insects the presence of molecules such as Volicitine or Caeliferin A , for example, triggers such defence reaction by the plants. More recently it has been shown that the mechanism of defence involves also a depolarisation of cell membranes that triggers the formation of stress hormones such as jasmonate (in experiments it has been shown that in the plant defence mechanisms involve some electrical phenomenons). By the way stress hormone emitted by the plant can also trigger a defence reaction by neighbouring plants (communication between plants!)
Thank you all for interesting suggestions, but I am less interested in a) cultivars or b) induced defense generally. But rather the idea the individual (and in fact entire communities) that develop in the absence of herbivores are then at risk when herbivores are re-introduced to them (or vise versa).
Truman; My impression of inducible defenses is that they develop quickly...a day or two. Judging from what happens in my vegetable garden at home, that might be too slow...you might be onto something. Various herbivores can wipe out a new garden of plants started in the nursery. An easy experiment - if you have insect herbivores in mind - is to clip a leaf on the experimental group of nursery stock and leave intact the controls. Set them out and assess the difference in mortality.
If that yields a difference then the prophilactic is to simply terrorize the nursery stock a few days before setting them out. That is a little experiment that I might actually try... Jim des Lauriers
These are very interesting questions and so important to restoration ecology. You might also want to ask about plant-herbivore co-evolution and local adaptation given that most nursery stock can have low diversity and the plants are moved thousands of km from their native range. See the studies by Richard Karban (Richard Karban ), Jenn Forbey (Jennifer Sorensen Forbey ) and others.
David's observation that rehabilitation projects typically use seeds or nursery stock from distant or unknown provenance is to the point. This can be analogized to long-distance, "sweepstakes" dispersal of propagules. The odds of success are not good.
I once did a small rehab project in Southern Calif chaparral (Cajon Pass) in which the intent was to obliterate an old road. Ripping, reseeding and replanting nursery stock was compared to simply isolating sections of the road from traffic were compared. The nursery stock and seeds were provided from a FS nursery in Ventura. The stock was described as "local".
The mortality rate for the planted stock was 100% and there was no evidence that the seeds established any plants during the next spring. The untreated sections were spontaneously obliterated within 5 years. One conclusion was that "local" really means LOCAL.
Whether all of this applies to what Truman is thinking about is another matter. What do you think, Truman? Cheers, Jim Des Lauriers
Sometimes restortion failure may be due to inappropriate plant provenance, but rarely do we know for sure. Restoration plantings fail for many reasons.
Truman; Since this problem with distant source material seems to be generally recognized, can you say something about why it persists? Jim Des Lauriers
Dear Truman,
See all the literature on insects (weevils...) affecting reforestation (i.e.seedlings from forest nurseries) as compared with natural regeneration .
Best,
Guy
Hi Truman,
An interesting and important question. From work that we have done using several different exclosure experiments, we found some evidence that suggests that plants growing without mammal herbivores tend to have higher chemical defences (we assume because of reduced offtake and higher availability of resources to invest in chemical defences without herbivory) and much stronger evidence showing that plants had much reduced structural defences without herbivory (branching/caginess/spines). So yes I would suggest that "naive" nursery grown plants would definitely suffer more damage from mammal herbivores at least.
Ben,
Thanks! I have seen your neat paper on this (from Mpala!).
Truman
Another aspect you might want to consider is that inbreeding in plants can increase herbivory susceptibility (e.g. Kariyat et al 2013, American Journal of Botany, 100(6), 1014-1021). As nurseries generally provide benign conditions, inbred offspring survive which would die under more harsh natural conditions (e.g. Ismail et al. 2014, Conservation Genetics, 15(3), 533-545). This might be another reason why nursery grown seedlings appear more susceptible to herbivory. Just an idea I have been thinking about.
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