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+--- Thread: Ohia trees are dying rapidly, Why? (/showthread.php?tid=12550)
RE: Ohia trees are dying rapidly, Why? - Carey - 09-09-2014
The Wednesday talk by Friday should be very informative!
In the list of articles I posted earlier (pg 2 top) in this thread, Friday was one of the authors:
"OK, I didn't post links before... but the dieback problems with ohia are VERY WELL RESEARCHED & DOCUMENTED, Peter Vitousek is probably one of the early gurus of ohia dieback research & has given talks in Hilo & around the island since we have been here, along with other researchers... In order to give some a little research, here are some of the research papers I have looked at, some dated back a few decades (Before GMO ... would that be BGMO years???)
http://scholarspace.manoa.hawaii.edu/handle/10125/922
http://www.annualreviews.org/doi/abs/10.1146/annurev.es.17.110186.001253?journalCode=ecolsys.1
http://www.scopenvironment.org/downloadpubs/scope55/scope55-ch10.pdf
http://agroforestry.net/tti/Metrosideros-ohia.pdf
http://www.hear.org/books/hte1985/pdfs/hte1985muellerdombois.pdf
ADDED: some of these papers are also pre the east rift eruption, geothermal, most of the pesticides in current use....and the fact that the very early reports of these dieoffs predate any pesticide use & some of the areas that are currently effected would not even be areas of pesticide concern..... not the lower stuff most of the Puna people are noting but the mauka dieoffs... & large ohia dieoffs that have been noted for a century...points to a cyclic problem that is probably older than many of the more recent introductions..."
Enjoy!
RE: Ohia trees are dying rapidly, Why? - Justin - 09-09-2014
I unfortunately cannot make the meeting tonight, but I'd be greatly interested in a report from anyone who can attend.
RE: Ohia trees are dying rapidly, Why? - Carey - 09-09-2014
Justin, unless you have crossed the date line, the meeting IS tomorrow, Wed. Sept 10...
"Update on Ohia Die-off
Extension Forester J. B. Friday will present an update on recent developments in studying the die-off of Ohia in Leilani and lower Puna.
Wednesday, September 10, 2014
7 – 8:30 pm Leilani Community Center Meeting Room"
RE: Ohia trees are dying rapidly, Why? - Midnight Rambler - 09-09-2014
Part of the "yes, but" with ohia and albizia is that yes, ohia do indeed do just fine with more nitrogen. The problem is that it also does pretty well with low nitrogen, while other invasive plants that are nitrogen-limited can outcompete it when growing under albizia. Also, ohia requires a lot of sun in growing up, and albizia creates dense shade while koa doesn't. Ohia is very good at surviving as a small seedling or sapling for years until a treefall opens up a light gap, but albizia itself is so fast-growing that it's often able to fill in gaps from fallen albizia trees.
Also, the ohia rust fungus doesn't kill large ohia trees, or even affect them very much (thankfully). But it can severely weaken or even kill small seedlings, which happened to one I was growing, so it may be a long-term problem. There are many different strains of this fungus, which all attack plants in the same family as ohia but vary in how badly they affect different plant species. The one we have here killed nearly all the rose apple (which you can see big dead stands of in Hamakua), along with the Oahu nioi, a native relative of mountain apple that's barely surviving as small plants instead of the big trees that used to be around.
We can only hope that one doesn't get here that has the same effect on ohia, because our politicians and bureaucrats have shown little interest in stopping imports of cut eucalyptus branches for flower arrangements, which is how the fungus got here. OTOH, if one arrived that was deadly to strawberry guava, that would be the ultimate biocontrol for it!
RE: Ohia trees are dying rapidly, Why? - Justin - 09-13-2014
Did anyone manage to attend this talk? (I know, it is a much lower priority than two months ago). But I'm still very intrigued to hear what information was provided. Mahalo.
RE: Ohia trees are dying rapidly, Why? - wakan - 09-13-2014
Since this problem has been documented for quite a while, it would seem that the die off may be a cyclical phenomena. In any event, I have been saddened to watch many Ohia (including some old growth trees on my own land in good soil) die back over the years.
As many people have pointed out, they are very sensitive to root disturbance and dozing anywhere within five feet of them is almost sure to kill them. I also lost a number of big trees to Stink Maile. The Stink Maile just grows straight up into the canopy and and overwhelms them with its own foliage. I started a routine of going tree to tree several times a year to cut down the vines and it stopped the die off.
The most catastrophic threat to Ohia in Puna is, no doubt, Papaya farming. I witnessed with great sadness the destruction of thousands of acres of old growth Ohia forests in the Kamaili Road area in the early 90's. I've scavenged quite a few downed Ohia's from the Papaya field berms where they were unceremoniously bulldozed into piles to compost.
I would probably agree with those who have suggested that there is a fungus (or other parasite) that is killing off all the Keikis. The old growth Ohia on my land are being crowded out by introduced trees, including Strawberry Guava, and the keikis of that species which are obviously so prolific in the understory that the Ohia Keikis are virtually non-existent. However, there is a dense grove of old growth Ohia in the Nanawale Forest Reserve adjacent to my land that is still fairly free of the Strawberry Guava; and there are still almost no Keikis. The adult tress are all healthy though. The trees are very large and dense creating a dark forest floor without a lot of other intruders, but still few Keikis.
The last stand of the Ohia's may be the more recent lava flows, where they can apparently take root (when there is enough rainfall) after about 40 years. Not many of the introduced species can do that (Casurinas, to some extent).
RE: Ohia trees are dying rapidly, Why? - carley - 09-13-2014
Hi,
I am new to punatalk, just been reading...but have a suggestion for the dying ohia trees.
a while back(do not know how many years) a bug was introduced to kill the rose aples trees.
This bug is killing the ohia as well as our grape leaves. It is a small bug black that comes just before it gets dark to our lanai, and the ohia forest we live in. Not sure why it attacks some trees and not others.
Why isn't the university talking about this i wonder?
RE: Ohia trees are dying rapidly, Why? - peteadams - 09-14-2014
We hand cleared nearly two acres for garden display beds for the nursery. Regular guava, strawberry guava, paperbark and tibouchina, along with heavy stands of California grass, densely covered the property. Within a year we started seeing ohia seedlings popping up from the cleared ground. We were lucky to have a large mother tree and several smaller ones on the windward side of the property (the area had been mostly logged off many years ago and subsequently used for agricultural purposes). Now several years later many of the seedlings are 3 to 4 feet tall and a few larger and they are still coming up. I would suppose that any land that once hosted ohia and has not been bulldozed or cultivated heavily could restart from the seed bank. Lacking volunteer seedlings, ohia seed is fairly easy to germinate. This is a good time to look for and collect the seed pods (ask! if it's not your property), best if from a nearby area as there is some selection for rainfall and elevation. Ohias produce plentiful amounts of seed.
RE: Ohia trees are dying rapidly, Why? - Midnight Rambler - 09-14-2014
quote:There is no bug (assuming you mean an actual insect) killing rose apple. The rose apple trees were all killed by the rust fungus, Puccinia psidii variously called ohia rust or guava rust. It was introduced to Hawaii accidentally on cut eucalyptus twigs (the kind that are included in floral arrangements).
Originally posted by carley
Hi,
I am new to punatalk, just been reading...but have a suggestion for the dying ohia trees.
a while back(do not know how many years) a bug was introduced to kill the rose aples trees.
This bug is killing the ohia as well as our grape leaves. It is a small bug black that comes just before it gets dark to our lanai, and the ohia forest we live in. Not sure why it attacks some trees and not others.
Why isn't the university talking about this i wonder?
It only attacks plants in the myrtle family, which includes ohia, mountain apple, Java plum, guava, eucalyptus, and rose apple, but not grapes. Different strains have varying degrees of virulence towards different plant species; the one we have here kills rose apple and our native nioi, and damages and occasionally kills ohia seedlings; it can sometimes infect but not severely damage mature ohia, and has little effect on others.
The small black bugs that periodically fly around in swarms at dusk are usually reproductive ants (mostly males). They drove me nuts because they would usually be out right at the time I was biking home.
RE: Ohia trees are dying rapidly, Why? - Midnight Rambler - 09-14-2014
quote:Ohia is very much a sun-loving plant. The seedlings may be unable to survive in a dense forest, or if they do they may look quite different - the ones you see in the higher elevation forest are often only about 1/4" diameter at the base, less than two feet long, and vine-like, waiting for a treefall to open up some sunlight above them. The different varieties found at high and low elevations may have different survival abilities in deep shade. Unfortunately, strawberry guava is able to grow in dense shade just fine, which is why it's such a terrible pest.
Originally posted by wakan
I would probably agree with those who have suggested that there is a fungus (or other parasite) that is killing off all the Keikis. The old growth Ohia on my land are being crowded out by introduced trees, including Strawberry Guava, and the keikis of that species which are obviously so prolific in the understory that the Ohia Keikis are virtually non-existent. However, there is a dense grove of old growth Ohia in the Nanawale Forest Reserve adjacent to my land that is still fairly free of the Strawberry Guava; and there are still almost no Keikis. The adult tress are all healthy though. The trees are very large and dense creating a dark forest floor without a lot of other intruders, but still few Keikis.