Tree spacing in semi-arid areas

I write this with a heavy heart because it may indicate that I have doing everything wrong. My research is indicating that thick forests in semi arid areas actually suck up more water than they store in groundwater. Instead it seems that a patchwork of trees widely spaced is what is best in terms of biodiversity, biomass production, and water retention.

First, I'll start with this study on forests in Burkina Faso https://www.cifor.org/knowledge/publication/5996/. This is the Sahel region of North Africa at the edge of the Sahara. The biome would be sub-tropical grassland under a monsoon cycle of dry and wet times of year. They found that the best water infiltration and soil moisture was achieved at 10-20% tree coverage with space left between tree canopies. They did find that the patchwork of trees outpeformed treeless grassland and desert.

Second, Utah State University as well as Colorado State officially recommend 50 feet spacing between mature pinyon and juniper trees https://www.youtube.com/watch?v=p39djKA0zNU&t=1644s. As they described it, this spacing allows for maximum biomass and biodiversity.

Third, the Dehesa silviculture system of Southern Spain uses grazing of pigs and sheep between widely spaced oaks. I'm not sure of the exact spacing, but you can tell from this picture that their is significant space.

Finally, my own observations of the pinyon juniper forest. When the forest is thick and the canopies are touching, the trunks are thin, the branches are spindly, and there is low nut production. There is also little to no grass, bushes or herbs in the understory, just dry pine needles, bare ground and rocks. Now sunlight is abundant here in southern Colorado so sunlight is not the limiting factor in explaining the lack of undergrowth, so it is probably lack of water. When the trees are by themselves they have abundant grass growing under them as well as berry bushes. Unfortunately most of my property is thickly wooded pinyon. If I used a chainsaw 10 hours a day it would take months to reach 50 ft spacing and create a massive fire hazard of dry lumber. One of my goals when I moved in was to restore stream flow to a nearby river. If the Burkina Faso study is correct, then my thickly wooded property is sucking and holding water in the trees, and not releasing water to aquifers or stream flow.

Conclusion. In the permaculture world we have a vision of a thick forest out of Bambi. This is appropriate to the tropics and humid temperate regions, but not so for the semi arid regions which covers a huge part of the world. Instead we should be shooting for a savannah checkerboard of widely spaced trees with significant areas of grass between. Under each of these tree islands we can still have vines and berry bushes surrounding the tree.

If we are to be responsible land stewards we should seek to implement systems of food forests that regenerate ground water. At this current point in the western US, pinyon-juniper forests have quintupled in the last 100 years due to fire exclusion, use of coal and gas as opposed to firewood, removal of the buffalo and overgrazing of grassland. While, I celebrate and love these forests which are reclaiming land from the deserts, the truth is that these forests are far too dense and create the conditions for destructive wild fires. They are also detrimental for large grazing animals as they preclude grass growth. So, I say we in the West, learn to love the chain saw and space our new plantings responsibly... or tell me I'm wrong and should spam more trees into the ground (I would be good with that). Thanks for reading the long post. Potato.  

Do you have run off during wet times?  If not there  is almost nothing you can do.  But if there is, soil building(likely needing clearing), swales and hugelkulture till there is no run off.  Guessing that would mean clearing areas where water concentrates first.  If you can clear enough adding deep root stuff during the wet season to try and increase soil moisture year by year.  Cleared wood goes into biochar, hugelkulture and possibly some sort of chipper to become mulch.

I definitely think you're on the right track with this. I'm not as familiar with the Four Corners/Colorado Plateau ecosystem although I did hang out there a bit back in the day, but it's basically a colder variant of the Madrean Highlands of SE AZ without as much of a summer monsoon component. The really productive savannah landscapes in the borderlands are more oak dominant but do have a lot of pinyon/juniper in the mix. Nearly all of it was badly overgrazed in the last century and ended up being much more of a woodland or scrub environment, with mesquite invading huge portions. Then there was fire suppression, which curbed one of the factors that would have brought it back into balance.

Now there are several areas that are being managed more holistically, like the Empire-Cienega ranch, and using regenerative grazing along with returning fire to the mix. Mature oaks and junipers resprout after fire and pines over a certain size are pretty impervious to cool, fast-moving grassland burns. The difference is striking, both visually and in terms of how much more abundance there is on the land. Stream flows have rebounded, springs have reappeared, wildlife increased, you name it, all the positive indicators are there.

Fire and grazing will save you a lot of time and chainsaw work, if you have access to them. Then again, all that excess timber would make some nice biochar and that would do great things for your soil and the landscape in general.

I'm pretty sure the Quivira Coalition is active in your area and they would be a good place to start.

Skyler,  
I'm not familiar with the Pinyon trees.  Any knowledge I have would be of the Eastern Red Cedar infestations in western Oklahoma.  The state wildlife department along with NRCS has been pretty active with cost share programs to control and get rid of them.   When I lived there I had a forestry mulcher that I ran as a subcontractor for a man who did a lot of that work.  I used it on my own place during slow times.  However the most cost effective is to cut them off with loppers or an axe when they are small enough.  If you cut the trunk off below the bottom branch they will die.  If you go out with an axe and spend half a day or better yet a whole weekend it is amazing what a difference you can make.  You need to get the little ones out of the way to get under the big ones anyway.

So you gentlemen seem to all be saying make biochar. Is there a way to make biochar so that one person could run the operation on weekends and be mobile enough to be moved? I am thinking a 55 gallon drum with a retort. I could move to the wood piles, burn all weekend, and dump when it fills up with charcoal. Is there a better way?

Bryan, the rocky mountain juniper is the equivalent and genetic cousin of the red cedar. I know that Selah Ranch said they restored their streams by removing large numbers of the cedar. I don't want to eradicate them, but just space them out. They make amazing hedge trees and they are the main food source of the bear. Anyways you are correct, in one day I could do alot of good with loppers going after the young trees.

Skyler, if the soil isn't too hard or rocky I would recommend digging a pit close to your fuel. You can make it as big as you need to accommodate the size of stuff that is going in (unlike a barrel). Slope the sides to form a cone, stack kindling in it and light the top. Add progressively larger branches, a few at a time, to keep the flames going but not so much that you cool the fire and create smoke. Keep going until the pit is full, then pile the excavated dirt over the coals to exclude air. Leave it for a week or more to cool down.

When you uncover the pit, this is the time to inoculate with microbial goodness. Compost tea, urine, and manure slurry are all good ways to get the party started. All that remains is to scoop it out and spread or bury on the land.

I plant denser with the plan of only keeping a fraction of the trees long term. Those that struggle, die, or were planted for soil building will be used, even if only as mulch.

I plant denser with the plan of only keeping a fraction of the trees long term. Those that struggle, die, or were planted for soil building will be used, even if only as mulch. I will let tree health be the primary factor. One benefit I foresee of doing this, planting 10x what I expect to have at maturity and only leaving the healthiest trees to thrive, is how their offspring will have space to continue breeding towards something resembling a land race. Oops, somehow posted the first part twice.

First, I am sorry to hear of your hard work, Skyler, and hopefully the redirection and recovery won't take too much time and effort.  Thank you for sharing from your research and especially for the valuable guides!

Phil:

"Skyler, if the soil isn't too hard or rocky I would recommend digging a pit close to your fuel. "

(My assumption is that Skyler already understands these thing, but for the benefit of others reading this post...):
I would highly advise against digging pits and burning the wood for two main reasons:
1) Colorado is extremely dry and windy. A forest fire (or under-ground-fire) would have grave consequences.
2) The majority of the soil in that  is very, very alkaline, and adding wood ash would increase the alkalinity and may prevent plants from growing in/around that pit for decades into the future.

Skyler, If you want to add biochar, you may consider doing the 55-gal retort burning (carefully) and inoculate the biochar with only acidic or neutral mediums. Not sure if everything could be done on a weekend or not. You could also consider selling the wood - I would buy some from you!

Colorado climate at your elevation can take 10+ years to recover, at the very least. Be gentle and cut wisely, perhaps slowly and watch the impact or check with other SLV locals that have worked with permaculture on their properties.   Good luck to you!

Re: biochar -- If you have access to water to put out the fire, the easiest fastest way to make a whole lot of biochar is just in a pile on flat ground. Start a small fire, when the coals start to turn white put on another layer of wood, repeat until you're either out of wood or the pile of coals gets too big to work safely around. Hose it out good while raking it back and forth, but don't breath the steam because it contains carbon monoxide. Usually for me by the time it's too big / too hot I've got a pile that's like 10-12 feet in diameter and 2 feet high in the middle. The next day after it has cooled off, I drive back and forth over it with the truck to crush it into fine particles. As others have pointed out, to reduce the alkalizing effect of the charcoal, you're gonna wanna mix it with compost and let it sit for a few months or a year before you disperse it on the land.

With the tree spacing you've mentioned two concerns, soil moisture and fire danger. If you can adopt a management practice where you grow as much vegetation as you can during the wet times, and then trim it back, graze it off, or do controlled burns before the fire season, you might be able to both increase the water holding capacity of the soil while also reducing the fire risk. Growing trees and other perennials is probably the best way to get organic matter down deep in the soil, which increases the soil water holding capacity. Then cutting/grazing/burning the above ground vegetation causes roots to die below ground, which then decomposes into water holding organic material. If you can cycle the vegetation on an annual schedule you'll probably have pretty good results on both fronts, and increasing the soil water holding capacity a little bit every year eventually you'll begin to have an effect on the aquifer recharge.

If it's gonna take 10 hours a day for months on end to get thinned out to a more reasonable tree spacing, you might post on craigslist or facebook marketplace for some u-cut firewood. Flag the trees you want cut or drop them yourself and then let the firewood getters saw them up and haul them off. You never know, you might find a great sawyer who's good at felling trees and might pay you a little bit so that he can turn it around and sell firewood for $300 a cord or whatever.