Raising Soil Grade - Protecting Existing Trees

[Farm Newbie]

Hello. I'm looking for advice regarding raising the soil grade around some existing trees to ensure they are protected.

I have recently purchased some land in Laos that has been used for rice production. We are currently raising the soil grade by approximately 1 meter in preparation for future house construction.

As it is extremely hot, I would really like to keep the existing trees for their shade and beauty, but I know nothing about ensuring the tree safety as the grade is raised around them. I have asked that the soil not be placed closer than the general overhang of the larger trees in order to try some of the techniques I have seen online regarding building a small retaining wall and filling the area close to the trees with stones for drainage and topped with soil to avoid soil compaction.

I'm not currently in Laos which complicates things, and I have to deal with a language barrier as well. The workers say they have raised the grade right up to the tree for previous clients without problem, but I think that will lead to a long slow death. They also say if they leave the tree well open now, it will just fill with water and kill the tree that way. Also, I'm not sure when I will be back to try to finish some type of drainage/ventilation system around each tree.

I'm attaching some pictures with an aerial map view with numbers on the largest and most important trees. You can see some before shots when the land is wet as the rice is planted, and some recent shots after the land is being raised. The soil will eventually be raised completely around each of the trees.

Any advice would be appreciated. I don't know the type of trees, or even if they are worth saving. I can ask for better pictures if that would help.

Thanks in advance.

 

[Farm Newbie]

Here are some more before pictures from different angles.

 

[Farm Newbie]

Here are some more during the soil grade raise. The soil will eventually surround the entire perimeter of the trees.

 

[Farm Newbie]

Here are some pictures with advice on filling the tree wells. Not sure if this is a good idea or not. Any advice appreciated.

Thanks.

 

[frans]

That's a tough question because these trees are acclimated to the flooding. Honestly I think your plan may work but why fill soil over the rocks? Just leave it open.

 

[Raj]

Welcome to the House!

 

[DMc]

Very nice presentation and request. Unfortunately, it looks to me to be a little too late for the trees. Adding that much soil is always going to be a crap shoot for trees even in well-drained locations. Most older established trees will not do well long term even with underground aeration structure. Death does not come quickly for back-filled trees and that is why construction people don't see the problem.

I'm guessing that the location will see significant rain fall during the rainy season. All those vent tubes will quickly fill with water defeating their purpose. The trunk wells will also, and be at increased risk from pathogens and decay. I just don't see enough slope for anything else to happen.

In that kind of temperate zone trees should grow fast. Instead of spending so much energy trying to save these trees, I would give strong thought on reastabishment of new ones that fit well with the property's future intended use.

 

[SeanKroll]

I agree with DMc.

Put effort into the right trees in the right location. These can live for some years. If not right next to the homesite, endangering anything, they can be left to their own, and serve as habitat-snags over time.



You will have to understand they are bringing in disturbed, mixed up 'dirt' so to speak, not well-established, developed over time, living, breathing, layered soil.

 

[Farm Newbie]

That's a tough question because these trees are acclimated to the flooding. Honestly I think your plan may work but why fill soil over the rocks? Just leave it open.

These plans were just what I found searching Google for grade level changes. I was thinking too many rocks over the root structure might be as much of a problem as soil compaction. I may just go with the rocks though, and not have them fully level with the surrounding area.

Thanks for your input!

Welcome to the House!

Thank you very much! It looks like I'm getting some good feedback here.

Very nice presentation and request. Unfortunately, it looks to me to be a little too late for the trees. Adding that much soil is always going to be a crap shoot for trees even in well-drained locations. Most older established trees will not do well long term even with underground aeration structure. Death does not come quickly for back-filled trees and that is why construction people don't see the problem.

I'm guessing that the location will see significant rain fall during the rainy season. All those vent tubes will quickly fill with water defeating their purpose. The trunk wells will also, and be at increased risk from pathogens and decay. I just don't see enough slope for anything else to happen.

In that kind of temperate zone trees should grow fast. Instead of spending so much energy trying to save these trees, I would give strong thought on reastabishment of new ones that fit well with the property's future intended use.

Thanks for the great advice. I plan on planting many new trees, but was hoping to save these as well as they provide much needed shade.

I'm thinking that anything too elaborate will just be a waste of time, and your comments seem to confirm that. I may just try to ensure some type of drain system to avoid having the tree well flood, and then just enjoy them as long as I can. I'm not back there for a few months, so hopefully they will be ok as rainy season isn't until June/July there.

Thanks again.

I agree with DMc.

Put effort into the right trees in the right location. These can live for some years. If not right next to the homesite, endangering anything, they can be left to their own, and serve as habitat-snags over time.



You will have to understand they are bringing in disturbed, mixed up 'dirt' so to speak, not well-established, developed over time, living, breathing, layered soil.

Yes, thanks for your input. As mentioned in some earlier replies, I will be planting many more trees, but hope to have these stick around as long as possible during the construction phase. It can get REALLY hot out there!

Fingers crossed.....thanks again!

 

[Bermy]

Look at all that heavy machinery too, your new 'soil' is getting pretty well compacted. I see it pushed up right to the tree trunks too, there is bound to be some mechanical damage to the trunks.
I concur that it doesn't look good right now, start planning ahead for replanting.

As has been said that 'soil' is just dirt at the moment, you need to think about getting some animal manure and green waste and start getting some good stuff ready help the whole system.

All that having been said, it is amazing what abuse trees can tolerate in the tropics!

 

[Farm Newbie]

Look at all that heavy machinery too, your new 'soil' is getting pretty well compacted. I see it pushed up right to the tree trunks too, there is bound to be some mechanical damage to the trunks.
I concur that it doesn't look good right now, start planning ahead for replanting.

As has been said that 'soil' is just dirt at the moment, you need to think about getting some animal manure and green waste and start getting some good stuff ready help the whole system.

All that having been said, it is amazing what abuse trees can tolerate in the tropics!

Yeah, I tried to make it very clear that I didn't want heavy machinery getting too close to the trees.... using pictures of big trucks with X's over them etc., but even that got lost in the translation.

The soil has now been moved away from the trunks, and gravel has been added in the tree wells to help with drainage, and then a top layer of soil.

I have no idea how they will hold up, but hopefully I can get back there before the rainy season to get a better system to keep the tree wells from filling with water.

There will definitely not be a shortage of manure and green waste for planting new trees though, so that's the long term plan.

Thanks very much for the feedback!

 

[treelooker]

In 2011 I saw a tee in Singapore with ~1m fill all around, except for a narrow tree well, and pavement above that. In 2017 I saw it again and it looked fine. Good luck!