I'm afraid you'll have to excuse my ignorance, I'm totally new to researching this.
We're in Central Portugal and have a couple of acres of land situated a few hundred metres down the road from our house and gardens. At the moment it's pretty much bare except for a bit of gorse and some cork oak seedlings that are springing up here and there, plus a small amount of brambles beginning to come. When we bought it a couple of years ago it was a recently felled and cleared pine forest, it had had to be removed due to being rife with a pine tree insect that rips through pine forests in Portugal. The soil is poor after decades of monoculture pine cropping. It has only a small supply of water and is on a south west facing slope with roadway and top and a small olive grove and stream at the bottom. The site is long and relatively thin and is surrounded by badly maintained eucalyptus which makes for a fire risk on all sides. We have pretty heavy rainfall roughly November to April (about 100cm of rain) and are almost completely dry and hot May through to October. We get mild frosts but no snow or ice.
We are thinking to use the land to provide firewood and polewood, and possibly some nut crop.
Black Locust sounds like a great species to have there for these purposes, and I'm wondering about the viability of interspersing sweet chestnut, walnut, or olive (or a combination) throughout - possibly growing some vines underneath. As for ground covers I really don't know. The situation isn't really suitable for livestock of any kind to be kept there.
In looking around the net for information I'm struggling to find good information for a total beginner like myself regarding how we go about starting, and I wonder if you kind people might be able to give me some good and practical suggestions of how to proceed? Could we combine some or all of these species? What kind of planting distances? Any ideas for ground covers and how to go about establishing them (and the trees)? Any ideas for reducing our fire risk somewhat? Should we put swales at intervals down the hillside as we go?
If it's bare I would dig swales first while you can... that will definitely help with water. You might wanna check out the work of Geoff Lawton for details on that, he's sort of the swale king.
Walnut is alleopathic, but that's the only tree out of the bunch that you would need to worry about. There are plenty of plants that are resistant to juglone (the toxin walnuts secrete) and if you haven't read Gaia's Garden by Toby Hemenway, now would be a good time. He talks a bit about that. There's also a table with a lot of productive plants that are resistant to juglone in Edible Forest Gardens vol 2 by Dave Jacke and Eric Toensmeier.
As for planting distances, that depends on how much shade you want. All you really have to do is keep in mind the mature canopy size of the trees when you plant them. Generally you want to keep it a bit open. It helps to draw a map to plan that out.
I'm not very familiar with your climate so I can't make any recommendations for ground cover, but I do suggest looking at the native groundcovers around you and using those.
Anyway, you should be able to put livestock through there once the system is established. Good luck!
"To oppose something is to maintain it" -- Ursula LeGuin
I don't see any reason that you couldn't grow all of those. The walnuts might take some planning, as they exude a toxin from their roots that kills other plants, though there are plenty ones that aren't affected.
Probably your soil is acid from mono-cropping pine on it, but if you can get ahold of a test kit and test the individual spots you want to plant trees in, it would be best because sometimes small differences can make a big difference in which trees will thrive or fail in a spot. I doubt the soil is poor from the pines, actually, but possibly from the management of them. In natural pine forests they often grow in poor soil and enrich it with their 'litter' over the years.
I agree that swales of some sort would be useful to you in holding moisture for your trees to grow with. When they are mature, they should help draw moisture to the spot from passing weather, and will also recycle the moisture quite efficiently. Open spacing is also a very good idea, especially for your canopy layer of trees. I don't know if you've ever walked through natural forests or not, but they are rather different than orchards or tree farms. Mature forests have open spacing and glens/small meadows here and there. Second growth/immature forests have trees packed very close together, trees that are spindly and obviously not as healthy as the younger trees in a mature forest. Too close together, and too much competition. Eventually, many of the trees in second growth forests die off or are cut out for the health of the forest. Forests are a communal organism, and work much better with larger variety. The nature of your acreage might limit you in some ways, but it can also give you more creative opportunities.
Also, a healthy forest, without a lot of dead wood and dry underbrush is MUCH more fireproof than a forest with crowded trees and too much mast (dead plant matter on the ground). Nature controls fire risks by having small forest fires that clear the mast, which burns quickly, and leaves the bigger plants basically untouched. Some trees are more resistant than others to begin with, too, so you might look into that aspect. (I assume that the eucalyptus aren't yours?)
As for groundcovers, I would look around in your area and observe what does well.
Once you get your trees up to a reasonable height and your vines fairly mature, I don't see why you couldn't start introducing smaller livestock, such as chickens or quail. Long, thin areas tend to be less suited for larger livestock, which might also eat your vines. Some things will move in on their own over time, of course. You certainly DON'T want to introduce livestock that will damage your relatively fragile emerging ecosystem. Goats and sheep, and other large livestock can be detrimental, stripping young plants and keeping the ground too clear, causing erosion and moisture loss. It depends, of course, on how rich the forest is and how deep, how much wildlife/stock animals it can support.
I wish I could give you better advice, but my climate is rather different than yours. Where I grew up sounds a bit closer, but neither is quite the same, and that can make a huge difference in what you choose to grow and which livestock you can imput without harm into your emerging ecosystem.
That's fantastic help guys thanks alot, that's exactly the information and reassurance I was looking for!
Once the design is together and the the swales in place how would you suggest us establishing the trees/ground covers? At the moment I'm thinking of spot mulching around the trees, broadcast sowing ground cover plants and then giving a rough weeding occasionally to take out anything thats overtaking the ground covers and that may cause any problems - is that a practical method or is there a better way?
Yes that sounds fine to me... I would recommend starting with a lot more nitrogen fixers than you'll end up with. Many people put an Nfixing bush in the same hole as their canopy trees and use that as a nurse while they grow... nut trees can take a long time to grow.
"To oppose something is to maintain it" -- Ursula LeGuin
Well, it depends. Say you have a fast growing Nfixing shrub like a bush clover or indigobush, you can plant that in the same hole as the nut tree and chop and drop it for mulch and it will probably die long before the nut tree matures. By the time the smaller shrub dies the nut tree can have its roots in the zones of the larger Nfixing trees or shrubs, say a black locust which you can coppice for fence posts. Every time you cut off a branch of a tree a corresponding amount of roots die off... that means all the nitrogen fixing nodes on the roots of the Nfixer die and release some sugar to their neighbors.
"To oppose something is to maintain it" -- Ursula LeGuin
Spot mulching sounds good.
Recommend that if you broadcast sow, that you rake the seed in unless you have no birds at all in the area. Birds adore seed that sits on top of the soil, especially if it isn't "watered in". Raked in seed rarely has bird problems, in my experience. Planting just before a short rainy stretch would be a good idea. Alternately, you can lay tarp or boards over the area until the seed has germinated, to keep it moist and give it a chance against birds. The downside of that being that some seeds need light to germinate, and tarps and boards are rather labor-intensive to move.
As for trees, besides nutrients/ph/light requirements, they also have water-amount preferences. Most plants do. After digging the swales, you may find water collects in certain spots more than others. Planting moisture-lovers in the wetter spots, and plants that hate wet feet in the drier spots (such as grapes) will save you some frustration.
You could even purposely design your swales to create such spots if you have good observation skills and good mathematical/geometry skills (or really good visualization or drawing skills), but that would be beyond me without months of observation and trial and error. You could certainly attempt it, but it would likely be easier to just observe the wet/dry spots that result from making normal swales and work with that.
You might try putting the pertinent info for each species onto a sheet of paper, index card, or spreadsheet, to help you decide what to plant where. Don't be dismayed if you sketch out your plan for planting and go through 20 sketches and then end up coming back after planting and updating it to what you really did. The land never translates perfectly to paper, and the more you work with it, the more you will learn its quirks and be able to find lasting solutions. You may find that you have spots where everything grows luxuriantly, and spots where no tree will grow, or spots that only one variety of tree will grow (but unfortunately don't come with labels.) Research-books and online, asking local gardeners/growers, trial and error, and a 'forest journal' of what works and doesn't are probably your best tools for such puzzling spots.
I don't know much about perennial nitrogen fixers (except the european sweetpea, which is a beautiful riot of color and biomass, but has deep roots that make plants of a year or more very hard to remove), but many annual n-fixers like peas and beans and sorrel (the cousin of clover, not the perennial garden sorrel) will happily self-seed every year.
Humans mimic nature's method of fireproofing by using controlled burns, but these can prove dangerous if there is a lot of dead/flammable plant material on the ground and/or the wind shifts suddenly, but most particularly if it is very dry. If it's rained recently, the danger drops correspondingly. I know that my grandfather used to do controlled burns of the grass that was around his burnbarrel every year, and sometimes several times a year, and he never let that grass get long. It acted as a firebreak area, so that if a spark escaped, it would land where there was nothing to burn and couldn't creep down the hill into the forest or over the path into the orchard.
I'm in more than a slight rethink on species choices today after discovering that Portuguese law classifies Black Locust and Acacia Dealbata as invasive.... I think its against the law to plant them but waiting on finding out for sure
Controlling through burning isn't really an option here, you can rake and pile stuff from the floor and burn in a bonfire but only for certain months of the year. Wildfire is a big problem here, when it goes it really goes, on a windy day the fire can travel really really quickly. Ash and burning particles blown through the air start more and more fires significant distances from the original point, thus travelling over motorways, firebreaks and anything else that you would hope would contain it. There was a fire this year already that ripped through central Portugal, travelling 20km from its starting point and taking out large chunks of woodland over the couple of days that it was burning. A lot of the problem is that the woods here are commercially farmed eucalyptus and pine, bare ground beneath save for dry shed eucalyptus bark and pine cones/needles (perfect fire starting material!). I'm guessing that a damper site with green ground covers would be much better protected, and the cork oak that has self-seeded survives fire when it comes through. Its definitely a factor at play in species consideration and placement though!
yep its official, its illegal to plant black locust and acacia dealbata in portugal (and a big list of other acacia's too)
So now I'm looking for other species that are:
Coppicable for firewood/polewood (preferably with long lasting poles)
Nitrogen fixing and suitable for chop and drop
Drought tolerant/frost tolerant
Preferably easy (and fast) to grow from seed/cuttings
any suggestions? just had the rug pulled out from under my feet today
Your climate may be on the edge in terms of being a bit hot and seasonally dry, but if you mulched the trees well after the rainy season, European silver birch might be one choice. I have gotten, in rich soils in the northeastern US, specimens that are nine plus meters tall in year eight, from seed. It is the equal of some oak species in terms of firewood, and coppices well. We have hot and sometimes dry summers, and average about the same 100 cm annual precipitation.
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