Food Forests and Light Levels

I've kind of wondering about a big obstacel with forest gardens. I've heard the density of trees in a food forest from being like woodland, to a well - spaced Orchard. However, I've also seen Food Forest with patches in it that look almost like "meadows" for plants that need full sunlight. But, before I can really ask my question I have to set a pretext. I (personally) consider a food forest to be a well - spaced orchard with plants planted within it following the 7 - layer system. So, I think that a food forest recieves partial light, but some plants like tomatoes want full sun. I've heard solutions such as adding patches like meadows in it, as well as growing full - light plants along trails where there's sun, and even planting full sun plants near ponds. One thing that I am wondering is if you surrounded your full sun pants with Zebra stripes, black to attract to the vicinity, and white to bounce it back at the plant. So, any suggestions as how to increase light levels? Really anything at all would help.

Howdy Benjamin, My goal for my 10 acre food forest is to try to do what mother nature is doing. On my 10 acres I have deep dark wet forest and dry sunbeaten sagebrush desert, and everything in between. I am cutting some trees to create roads and pathways, which also creates edges where there were none before. These edges will also have future hugels and berms. I will probably leave much of the dark wet places intact and find food plants that will live there. The thinnings will also help to create hugels in the dryer places.
So I guess my answer would be to selectively thin, create edges and hugels.

Some say most productive system is not actually forest, but savanna. In a dense forest photosynthesis is mostly happening in a relatively thin layer of canopy, in the savanna, light is coming in from all directions.

My situation is a suburban forest garden, so the design is to surround the property with trees that serve as a productive privacy hedge, but the center of the property is open with well-lit garden beds, herbs, shrubs, etc.

On a larger scale, I would row crop. Trees in rows interplanted with 7 layers and plant annual crops or graze livestock between the rows. And don't forget mushrooms in the shady spots!

I am very curious about this topic too. I have read many of the approaches people are trying and am intrigued by the depth of ideas. I am a Forester and it is interesting that the academics in the field of forestry and the academics/practitioners in the field of permaculture are having the same issue of proper terminology for the wide array of speices diversity, spacing and disturbance regimes, found in both managed and un-managed "forests" and food "forests". In Missouri the ecologists have no fewer than 7 terms for what most folks, including myself, would look at and call a "forest", they are determined based on tree densities and the presence of various indicator shrubs and forbes that give a glimpse of site quality.

Since un-managed "forests" have widely varying canopy densities depending on geographic location, rainfall, elevation, soil type, overstory species composition, and the main driver of non-anthropogenic disturbance (the natural cause of succession), it makes sense that food "forests" would have an equally diverse composition. In a "forest" the two most "productive" life stages(in temperate, even-aged forests and plantations), from a biomass production stand point, are often considered the "establishment phase" (think the mad flush of vegetation post clear-cut), and the time where the stand is fully stocked with very large "mature" trees just prior to what folks might call the "old growth phase". The least productive time is considered the "stem exclusion" phase where trees are closed canopy but small and competing so heavily for light, water, and nutrients, that there is essentially no mid or under story layer at all. There are of course many better ways to judge productivity and I understand that such a myopic view will be off putting to some. That said, I am very interested in trying to mimic natural forest succession patterns but inserting food crops into the mix.

I am intrigued with two specific approaches to food forests. The savanna approach, keeping a low density of mainly shrubs(like hazelnuts) and small trees (like apples) present in fields and pastures in numbers that do not greatly diminish the productivity of sun loving grasses and brambles. I like this approach for some riparian areas I am trying to reforest from pastures, it seems like it would make sense in many temperate food forests that are being started from scratch. I am also planting many long lived nut trees, hickories, pecans, walnuts, and chestnuts in single tree gaps in closed canopy forests on my land that I fully intend to care for until they reach canopy dominance. I like the closed canopy "nut-tery" approach in existing forests since it allows for an increase in food crops without doing much to change the overall function of an established ecosystem, it also will allow for under story crops like mushrooms and ginseng I hope. In the transition zone "edge" of my pastures and forests I am attempting to insert a very diverse shrub mix including persimmon, hazelnut, elderberry, wild plum, and many named varieties of fruits. I am also trying to do some forested strips in existing pasture, I talked about that in another post though.

***Disclaimer***
I am only in year 2 of these projects so take my thoughts with a grain of salt. I lack the experience to speak with any useful authority on these subjects.

Please share your views on the subject. I am very keen to hear the holes in my logic and the ideas of those more versed.

luck to all

J

Benjamin,

There are some interesting studies that have been done in uneven-aged managed forests that show many shade tolerant species respond better to difuse light than direct light. This means reducing the number of trees in a stand by say 30 percent, and allowing more light from the sides, makes many under story plants grow more than poking a big hole in the tree canopy and letting in 100% light to the forest floor.

Since you question was about pure sun loving plants like tomatoes I know this is not really helpful, but I am curious if you could do some tree pruning to allow more light into areas you would like to plant sunloving annuals. It might require sacrificing some over story productivity to increase diversity and possible system wide productivity. Also, many trees, like honey locust and peaches have naturally thinner canopies than say maples or apples, perhaps a specific planting of those thin crowned trees in areas of potential annual crop sewing could help?

These are thoughts from the general rectal region, take them as you will.

J

I think that putting in meadows would be a smart way to increase light, and would also give you some cool chill out places. But many plants that "need" full sun do not actually need full sun if they are in a good soil full of nutrients. I don't know about tomatoes exactly but it might be something to start trying.

Another thing to consider is that many plants that 'need' full sun do not need a full days worth of full sun. Many plants can photosynthesize adequately with 3 to 4 hours of full sun so having a hole or alley for light to come through particularly in the afternoon when sunlight is most intense can get good results. My mom grows tomatoes in little pots on here back porch and she is surrounded by woods with massive ceders blocking out much of the afternoon sun. Her plants get dappled light through most of the day and perhaps an hour and a half of good direct light. Does she get hundreds of pounds of massive fruits? No. but she gets enough to make them worth growing. Hope that helps.

According to my reading and limited observations; it seems flora and fauna thrive in the transitional evirornment. So having heavily wooded transition to savanna to pond to etc, sounds like a good idea.

One forest transition system that I have been giving a lot of thought to and hope to experiment with in my small forest (~9 acres high sierra conifers - ponderosa pine, douglas fir, white fir and incense cedar mostly) is the large edge area that would be created when a massive old tree came down. You basically get a massive ready-made hugelbed, many times the tree will be rotten in the middle, it's canopy will have massive amounts of varied biomass that has accumulated over the past few hundred years, and all that will have probably wiped out a swath a couple hundred feet long with a width anywhere from 10'-80'+ if it wipes out a few other trees as it goes down. You're not going to get all day sun in there, but you'll get a lot more filtered light and probably a few hours of direct sun. Not to mention if the tree happened to fall in an ideal direction to create a mid-hill swale that also happened to fall along an optimum light path - a one in a million chance occurrence but one we can try to identify and recreate.

Those seem like pretty good conditions for most of the fruit trees that will handle the climate here. Depending on the size clearing/hugelbed I get I figure I can fit up to a couple dozen overstory fruit trees with their associated guilds/understory plantings.

Couple that with a recreated high mountain meadow or two which you can plant your true sun loving plants in a hugelbed along the northern border. I've noticed a lot of the natural meadows here are where a shallow pond or lake would have been which has filled in over time. Often there will be a natural hugelbed where the outflow of the lake captured logs and debris that fell into the lake.

So I guess you can boil it all down to what other people are saying also - maximize transition areas and edge areas.

I like Martin Crawford's term - forest garden lie between orchard system and natural woodland and form some of the lowest-energy-input systems for producing useful product.
Clear and simple.

It totally depends where you are, what climate.
It's a big difference between tropical and temperate forest garden.

You can't establish a forest garden here in central Europe in a way Geoff does it in the sub-tropics.
No way.
Succsession and the end result is totally different.
First of all, we don't have so much woody legume pioners, secondly we don't need them.
Our most beneficial pioners and biomass comes in the herbaceous layer.

Spacing?
For sure 10m+ inbetween big trees for us.
Sun energy in tropics can be 8 times stronger than here, so we can't really make a "forest" garden.
What we consider forest here is a closed canopy tree ecosystem where nothing really grows under it, just some herbaceous plants in spring, and some shade lowing shrubs here and there and seedling of young trees of course.
We don't really want this because our climate is just amazingly rich in berries (shrub layer) so the density of trees needs to be optimized for enough light to come to the lowest layer.

I love to look at the edge of the forest, that's where true classroom is for us.
Just some tweaks and we can create a beautiful forest garden.

I had the good fortune to tour Martin Crawford's forest garden yesterday. One technique he uses that is relevant to this discussion is that his emergent layer is mostly n-fixing trees (Italian alders) which are then limbed up to the the extent of a telescopic lopper (about 20'?) allowing a lot of light to come into the lower layers. This means that the tallest trees in the system are support species which fits well because of course he doesnt need to climb up to get their products, and also through this limbing system they have a minimized impact on the light levels at canopy level ( mostly 15-25' in his case I would guess).

As i can see in nature, chestnut is quite shade tolerant as a seedling.
I just seen a nice example of pioneer forest on acid soil (birch, aspen, chestnut, fern, blueberries, moss, oak, heather).
Close spacing of everyone, beautiful chestnuts in there.
In young forest setting trees are much closer togheter and then they are thinned by thmesleves our by human.
In mature close canopy chestnut/beech forest trees are spaced out somwhere 4-6 meters apart with wild blueberries as groundcover.

Robin Hones wrote:I had the good fortune to tour Martin Crawford's forest garden yesterday. One technique he uses that is relevant to this discussion is that his emergent layer is mostly n-fixing trees (Italian alders) which are then limbed up to the the extent of a telescopic lopper (about 20'?) allowing a lot of light to come into the lower layers. This means that the tallest trees in the system are support species which fits well because of course he doesnt need to climb up to get their products, and also through this limbing system they have a minimized impact on the light levels at canopy level ( mostly 15-25' in his case I would guess).

Lucky one!!!
Can you tell us more about posiotion of alder.
Mostly on north sides or everywhere?

The Italian Alders are dotted about the system. At least two sides of his 2 acre site are protected by pre-existing conifers. I will post photos when I get them downloaded off the camera.

Robin Hones wrote:The Italian Alders are dotted about the system. At least two sides of his 2 acre site are protected by pre-existing conifers. I will post photos when I get them downloaded off the camera.

Here are 2 photos which show the limbed Italian Alders

And #2

This grove of alder occupies space where I will eventually build a house and have an orchard. For now I'm managing for maximum biomass that feeds hugel beds. All will be removed in a few years.

That seems like a smart idea.

Here is something interesting... The Maya had food forests in which grew everything except corn, squash, and beans. So they obviously grew one of the most light loving plants I know of.. tomatoes. These food forests were known as pet - kot, because of the loose wall of stones around them. These stones I believe were used to increase light levels. For one thing they were not mortared, just stacked on top of each other, in a circle. As well they were only 2 - 3 feet tall. Not tall enough to keep anything out of the garden. And, if it were to mark land why not make the wall smaller? Or even Mortared. Circles are great for reflecting light back on things. Furthermore, the most common stone in the Yucatan Peninsula used by the Maya is Limestone. Limestone is not only white, but it also sometimes contains shiny crystals. The perfect stone for reflecting light back on to the under story, and in the perfect arrangement to receive light and reflect it back at the "under story." Plus the Mayas didn't worship any crops or consider pet - kot sacred, like they thought corn was. So, to me the only logical explanation for the wall of loose stones surrounding their forest gardens was to increase light levels within their food forests, or pet - kot. (pet - kot actually means, wall of loose stones, and they referred to their food forests as "pet - kot".)

Jay Hayes wrote:Since un-managed "forests" have widely varying canopy densities depending on geographic location, rainfall, elevation, soil type, overstory species composition, and the main driver of non-anthropogenic disturbance (the natural cause of succession), it makes sense that food "forests" would have an equally diverse composition. In a "forest" the two most "productive" life stages(in temperate, even-aged forests and plantations), from a biomass production stand point, are often considered the "establishment phase" (think the mad flush of vegetation post clear-cut), and the time where the stand is fully stocked with very large "mature" trees just prior to what folks might call the "old growth phase". The least productive time is considered the "stem exclusion" phase where trees are closed canopy but small and competing so heavily for light, water, and nutrients, that there is essentially no mid or under story layer at all. There are of course many better ways to judge productivity and I understand that such a myopic view will be off putting to some. That said, I am very interested in trying to mimic natural forest succession patterns but inserting food crops into the mix.

Jay - you should have definitely gotten a couple of apples for your thoughtful response! In my (limited) experience you are right on the money with the above.

I live in an urban, hot desert (Phoenix) - Our "forest" trees are adapted to our temperature extremes and low humidity and precipitation. Because Phoenix is in a sub-tropical area (like most deserts in the world) we can get away with planting citrus, some tropical and some temperate fruit and nut trees in addition to our natives. According to Geoff Lawton, emergent species for us are saguaro cactus and palms, understory is a variety of native legumes like mesquite and paolo brea/palo verde/acacias and then under that can go deciduous fruit trees, vines and bushes. Many of these greatly enjoy the partially shaded micro-climates formed by the overstory and perform better with it than without in THIS climate because they stay cooler and moister, longer. Citrus thrive in heat and sun so they go along the edges of my property to combat solar heat gain into the thermal mass of walls (saving me on electricity bills). I keep them trimmed to picking height which is also a perfect size to use as "solar baffles" for low rising or setting sun. Citrus can also suffer from frost damage so having them in warmer microclimates helps with that as well.

Regarding native support species - the ratio of support species to food species varies by climate with humid temperate climate being able to max out fruit production 50/50 or 40/60) and those of us in hot drylands needing the most support species (75/25). Not all support species need to be kept at mature size. Their purpose is to stabilize soils, form fungal nets, fix nitrogen and provide biomass that is constantly being returned to the soil, enriching the site over time. Some support species can be kept as a pollard hedge or coppiced for crafts or stick fuel. Apparently a coppiced tree is the oldest tree in the world. Coppice trees were used for the rims of wheels, spokes, chair and table legs, wattle materials and on and on.

Robert Kooyman is an Australian botanist who has some interesting thoughts on designing productive, multiuse forests.

William,

I think your project will be a much more labor intensive undertaking than mine. Being in the Northern Hardwoods you have a whole suite of under,mid, and over story light competitors that I don't have to worry about. I think you are correct that the only real way to insert a new species into your mix would be with the aggressive and regular use of a billhook for the first 5-10 year to make certain it keeps on top of the competitors. It is really an unfair fight for the new tree since most of your canopy trees are quite shade tolerant and will accumulate for many years in the under story developing roots and bidding their time to race for a canopy hole.

My land is located in the Central Hardwoods that are Oak and Hickory dominated. I don't have a maple or birch on my entire farm. My forests are very open underneath and have very few native shrubs in comparison to yours, mine are particularly devoid because they were open grazed until I took over the land 2 years ago. Filling single tree canopy gaps can be done with much less urgency and work than you will have.

I don't have any pictures, but I did just place and order with F.W. Shumacher for a big ole' pile of walnut, chestnut, and apple seeds, an order for 50 hazelnuts from Arbor day, and 450 native fruit trees from the state nursery...They will probably all die, but I'll give an update in the spring when I start planting if anyone is interested.

J