Substantial K in rainforest through fall.

[Stone]

If the only source of nutrients was from rainfall or through fall then the ratios would be a valid rate. But since all the things I mentioned add nutrients to the through fall it actually does change the ratios

.

You should re-read this Lance. Its the FINAL composition of the TF I'm talking about regardless where it comes from.

 

[gonewild]

Not the same as it takes up!!

No not the same as what it takes up. But what there is is what the epyphites need.

 

[Stone]

Had nothing to to do with wild vs cultivated plants.

He essentially repeated the Cornell work (with a hybrid phal) and fixed fert concentration/application rate to look at the effect of different substrates on nutrient uptake and growth.

Same thing

 

[Stone]

No not the same as what it takes up. But what there is is what the epyphites need.

Yep

 

[gonewild]

.

You should re-read this Lance. Its the FINAL composition of the TF I'm talking about regardless where it comes from.

I know what you are talking about. You need to not rely solely on published data and look at the reality of the forest structure.

The final composition of the through fall is like a snapshot moment in time. It is like taking a photograph and thinking you have recorded an entire event when in reality you have only recorded perhaps 1/200 of a second.

Rain falls through the canopy to the ground for a small fraction of time. When it does it simply dilutes all the nutrients that are held within the mosses, bark and foliage of the trees. After the rain is over and the through fall is over the nutrients once again concentrate around the epyphites roots from all the other sources I mentioned. Moist moss, bark, lichens, organic matter, ect. all excrete nutrients on in and around them. And they are on in and around epyphites and provide nutrients in much different ratios and values than what shows in the highly diluted through fall data.

 

[Rick]

http://sourcedb.xtbg.cas.cn/zw/lw/201402/P020140217559696116343.pdf

Here downloadable.

Decomposition of epiphytic moss/lichens/ferns/tree leaves for arboreal soil.

Not everything comes from the rain in the trees.

 

[Stone]

http://sourcedb.xtbg.cas.cn/zw/lw/201402/P020140217559696116343.pdf

Here downloadable.

Decomposition of epiphytic moss/lichens/ferns/tree leaves for arboreal soil.

Not everything comes from the rain in the trees.

* This study was done in the very same mountains as my example therfore all the throughfall and stemflow data for that is relevant for this as well.

* The throughfall and stemflow figures obviously take into account the decomposition of the epiphytic biomass and its contribution to the final analysis.

* The epiphytic biomass obtains its nutrients from the very same rain and stemflow as that recorded at the bottom of the trees.

* Therefore this study does not change anything.

 

[Trithor]

Wow now I understand why I had such disturbed sleep last night! You guys have been very busy with your 'tennis match' Any chance of a summary for us interested parties who have short attention spans (mine is a bit like that of a gnat)
I think quite obviously the epiphytes are exposed to another source of nutrients other than that which is in rainfall/throughfall. I think the crux of the matter is - what ratio are the macros at that the plants are exposed to, or does it not matter within a fairly rough range? We already know and accept (I think) that plants are capable of accepting different elements/compounds at different rates. (are these different rates due to ionic exchange, or is there an active pathway involved (energy driven and independent of ion exchange)?). An active pathway would enable plants to move nutrients independently of each other and independent of a concentration ratio, provided the exposure is continuous/extended (the opposite of the photograph 1/200th of a second analogy, - every photojournalist is cringing at the exposure of that fact, they plainly should only earn a miniscule fraction of what they are paid!)

 

[Stone]

I know what you are talking about. You need to not rely solely on published data and look at the reality of the forest structure.

Where do we get the reality of the forest structure other than from published data?

The final composition of the through fall is like a snapshot moment in time. It is like taking a photograph and thinking you have recorded an entire event when in reality you have only recorded perhaps 1/200 of a second.

This study was colated over a year I think or was it two?

After the rain is over and the through fall is over the nutrients once again concentrate around the epyphites roots from all the other sources I mentioned.

Please show me data for these ''other sources'' really! I want to see them so we can form a complete picture. Believe it or not it's the truth that interests me.

Moist moss, bark, lichens, organic matter, ect. all excrete nutrients on in and around them. And they are on in and around epyphites and provide nutrients in much different ratios and values than what shows in the highly diluted through fall data.

Your talking about the epiphytic biomass here as well as any decomposing bark and whatever dust may blow onto the branches, insects, nitrogen fixing blue green algae, other bacteria. Yes I understand the disolved nutrients will concentrate as water evaporates but how does that change their ratios?
The plants can only take up what is disolved in water.
It may very well be that nutrient uptake is increased dramatically as water evaporates until it becomes too dry for osmosis to take place. But that really is not the point here.

 

[Rick]

or is there an active pathway involved (energy driven and independent of ion exchange)?). An active pathway would enable plants to move nutrients independently of each other and independent of a concentration ratio,

Yes totally

Back when we first started this topic (May 2011) we posted a link to a paper on K uptake in bromeliads ("And then there were Three"). Using rubidium tracers the authors determined that the uptake of K includes an energy driven uptake pathway (independent of simple ion exchange).

There have not been active pathways determined for Ca Mg, with the results observed in that typical Poole and Seeley figures I posted a few posts back.

Ca deficiency in cultivated plants (not just ornamental epiphytes) has been linked to K overdose for decades in the Agri business with full understanding of that antagonistic mechanism.

 

[Rick]

* This study was done in the very same mountains as my example therfore all the throughfall and stemflow data for that is relevant for this as well.

* The throughfall and stemflow figures obviously take into account the decomposition of the epiphytic biomass and its contribution to the final analysis.

* The epiphytic biomass obtains its nutrients from the very same rain and stemflow as that recorded at the bottom of the trees.

* Therefore this study does not change anything.

Except if you notice in Table 2 the initial nutrient ratios of most of the epiphytic lichens, mosses, ferns and higher plants do not have the same ratios you hammer on for throughfall concentrations.

The moss in particular has more than 2X the Ca than K. Most of the other things are at 1:1. Out of 7 species only 2 have high K verging on the ratios in the throughfall. Also reading the text (not just the figures/tables, but Figure 2 is cool too), it sounds like the biomass of bryophytes is predominant providing a massive slow release Ca sink that's not going to loose high concentrations to the throughfall waste.

The throughfall water is the waste water with the lost leachates (not the input results). If you want to know what the plants are eating you have to determine what's in the leaves (not what washes out of them).

Do you measure the uptake in higher organisms only by measuring how much they poop or exhale? Do you know how much K a human has ingested by only measuring the concentration they pee, or that's washed off of your body in the shower?

 

[TyroneGenade]

I'm going to change the subject a little... but wasn't there a K-light vs normal K experiment in the works? Any results thus far? These debates are getting a bit old and I'm eager for some experimental data.

 

[cnycharles]

* the referee has called for a time-out

If plants can draw in things actively, then a ratio of passing water isn't necessarily a primary indicator of what they need. You may say that it might be a starting point, but if a plant actively draws up potassium, then it must seemingly need to scrounge for it. This would seem to indicate that there doesn't need to be very much available sitting around, it will gather more from around.
Another point noticed from reading these exchanges that's not mentioned in the discussions is that many orchids only grow on certain trees. Why is that? If food was only in rainwater then any tree might be good. Mychorrizae connected to roots on a damp tree can supply food from elsewhere than the flowing water. Some roots of phals go long distances and submerge in crotchets or pockets of trees where there is more moisture and food, which is diluted when it rains. Forests and trees are not homogeneous entities, so if studies include through fall from a wide area it may not be showing the specific compounds falling off of certain trees that have orchids on them. Also higher and lower elevations will have different flora, as well as those growing over different geology


Sent from my iPhone using Tapatalk

 

[Rick]

* the referee has called for a time-out

If plants can draw in things actively, then a ratio of passing water isn't necessarily a primary indicator of what they need. You may say that it might be a starting point, but if a plant actively draws up potassium, then it must seemingly need to scrounge for it. This would seem to indicate that there doesn't need to be very much available sitting around, it will gather more from around.

Exactly
Low K was not based on any ratios in mind, just the means of reducing K concentration in feed to the point where antagonism with Ca is overwhelmed (which looks to be somewhere below 10ppm K). You could probably feed just about anything and get the same result as K lite as long as the overall K concentration applied was in single digit ppm with no limit on Ca in the root zone. Look at what JMPC does.

The plant has a set K demand for metabolic operation, but has adaptive mechanisms to grab and store K from very dilute sources, even for luxury storage in times of plenty. However, adaptation is conservative. High K is not a reality in the jungle on a regular basis, so plants don't have kidneys to dump excess (toxic levels) of K.

 

[Rick]

* the referee has called for a time-out


Another point noticed from reading these exchanges that's not mentioned in the discussions is that many orchids only grow on certain trees.

The Zotz work and a few others indicated that it's not that clear cut over which trees are special or not. Some of their work suggested that it might be a secondary issue based on the preferences of certain colonial ant species. The Panamanian results were fairly inconclusive on orchid preference for certain tree species to the point where I wouldn't use the level of exclusivity you suggest Charles. But other authors may have found cleaner results.

While rooting around for the paper on lichen and moss degradation I did come across a paper on a tree species in Australia that had higher leachability characteristics of its bark (or water retention capabilities), that did seem to increase the numbers of epiphytic species that colonized it.

 

[Rick]

I'm going to change the subject a little... but wasn't there a K-light vs normal K experiment in the works? Any results thus far? These debates are getting a bit old and I'm eager for some experimental data.

That small test I'm doing with lowii seedlings is still going.

The normal K are still alive (and don't look that bad from the leaf stdpt), but there's not much in the way of roots. Half the time I walk by they fall out of their pots.

The low K in comparison are starting to pull ahead at a better rate. They are well rooted. I can pick them up pot and all by the leaves.

Although lowii can be epiphytic, I don't know if they would still qualify for answering Stones point about Asian epiphytes like Phalaes and Dendrobium.

Maybe I need to take the surviving lowii and strap them to plaques?

 

[eteson]

We do have another experiment running in-vitro with some Plbs and tiny plants. We made 2 media, the first one with K-lite ratios and the other with MSU PW ratios. We are using epiphihes, a paphio and a phrag. In a few weeks we could have some results.

 

[Rick]

These debates are getting a bit old

I agree. I have no idea why I get hooked into them either.

I just went out into the GH ,and that stupid side by side test is wasting space that I need for some new compots coming in. I can't even water/feed without rearranging the hanging plants above to keep from contaminating that test!:sob:

Since mortality is so low now, I have dozens of seedlings still in compot that I have no space for and end up giving away before they get individually potted.

The other 99% of my collection is doing better than ever, and that's all I wanted with the program to start with. I'm turning into a neglectful orchid dad while yammering away on ST

 

[TyroneGenade]

Can you take some photos and maybe weigh each plant. Maybe there is a detectable difference in biomass? Also measures on leaf length and breadth would be useful...

If you need homes for those seedlings I can help you out. oke:

These threads are very good reading. Lots of drama... and always some interesting wild-plant studies.

 

[gonewild]

Where do we get the reality of the forest structure other than from published data?

Get it from looking at the forest. look at where in the forest orchids grow and look at where they might get nutrients. of course not many people can go into the forest and look at wild orchids.... but I can. You can choose to listen when I talk about what I observe or you can dismiss me as a layperson.

When I stand at the base of a big forest tree that has orchids growing on the trunk mid way up to the canopy and it is pouring down monsoon type rain and I decide to collect a "stem flow" water sample and there is no water flowing down the trunk it makes me think. When it rains in the forest the canopy acts like an umbrella and sheds falling rain water away from the trunk.
Through fall water is exactly that.. water falling through without adding much in the way of nutrients for epiphytes. This observation is in a primary type forest like those used for the studies you presented.

But as I mentioned before most orchid species come from more open forest of even tree-less locations. The zones in the Andes that have the most orchids really don't have a forest canopy to nutrify falling rain. The orchids grow on the ground on in small shrubs or small trees. No falling nutrified rainwater. Instead the plants grow in living moss with lichens associated. Rain wets the moss and the moss environment releases nutrients. Since we can't find any university students that have researched and published this you choose to dismiss the concept. That's OK with me, it doesn't hurt my feelings.

This study was colated over a year I think or was it two?

It still only measures the nutrient content that is diluted by a rainfall that occurs in only a fraction of the years total duration.

Please show me data for these ''other sources'' really! I want to see them so we can form a complete picture. Believe it or not it's the truth that interests me.

Truth is not always in published form. If you only believe something if it is printed then you only know what other people already know.
The real issue is that we will never know the truth because there are an infinite number of combinations of evolved species we have to consider.
The nutrient process and ratios are probably different for every species of orchid.

I don't have the sources with me now, they are in California. Google about Lichens and chemicals they contain/produce. A lot of new research and discoveries are being made in Australia. Lichens have not been well studied as far as plant nutrition but people are starting to look at it.

Your talking about the epiphytic biomass here as well as any decomposing bark and whatever dust may blow onto the branches, insects, nitrogen fixing blue green algae, other bacteria. Yes I understand the disolved nutrients will concentrate as water evaporates but how does that change their ratios?

Not all nutrients are dissolved and leach freely. Some are (may be) bound ionically to the moss, lichen, bark, dirt that the orchid roots grown in/on.

In the through fall you only see those that are loose.

The plants can only take up what is disolved in water.

Perhaps or perhaps not. Disolved in water can also be during non rain events and the water may be in the form of condensation that does not flow.
Rain likely does not leach nutrients from lichens and the lichens may secrete the nutrients when moist but not when flooded.
The "best" time for plants (and lichen) to grow is when there is light available. Light is low during rainfall and so plants grow between rains. Lichens do the same and so probably secrete nutrients when it is not raining and as the nutrients are secreted they are consumed by epiphytes. When the rain comes again the process slows and the "doors" close. So not all the nutrients are leached into through fall.