Mature Apple tree - steep grade - understory planting

Hi forest gardeneers,

I live in the Italian Alps and have terrain that is south-southeast facing with a relatively steep grade: 30° = 55-60% (so roughly: for every 2ft horizontal the terrain rises a little over 1 ft vertically).

When I bought the place there were some established fruit trees such as apples, peaches, plums. All of them of shorter growth or pruned. The tallest ist about 12ft. Chestnuts grow in the forest around me.

Over the last few years I have built terrasses with rocks (some rock walls are 5 feet tall due to the steepness of the terrain). This was done to improve water retention, accumulate better and deeper soil for most of the slope otherwise has not much more than a foot of soil on sheer rock. These terrasses are also in keeping with the traditional type of mountain agriculture in the area which is a plus.

Learning more about forest gardening, I would like to shift to cultivate more perennials and seeing the incredible root system of the tough grass that grows on my mountain, I would like to make life easier for my trees, get rid of the grass, add some benefitial plants. Mulching can be done in principle but the only practical way to do this really is by terracing (otherwise heavy rains would just wash away the mulch downhill. With a radius of 6ft from stem to drip line, this would mean that the lower, southfacing, terrace wall would have to be about 3ft high to flatten the terrain. Where's the problem?  It's not the wall. I enjoy making them - including the huffing, puffing and sweat as I collect suitable large rocks from the surrounding mountains side (there is no other gym up here). But my worry is, that this the root system of the apple tree would then be burried under 3ft of soil. Considering apple tree roots are naturally shallow, would I be doing more harm then good? Does anyone have experience with earth works around established trees? Any recommendations?

Thanks,
Johannes  

Other details about the location - not pertinent to the question, but usually requested here:
@4000ft elevation
solid hardiness zone 7 (though all but two winters checking the data over the last 11 years stay well within zone . It shows in the garden, as for example I have a 25 year old laurus nobilis  (bay laurel) that is usually given a usda rating of 8-11. It sits against a wall so benefits from a micro climate and I need to prune the top regularly to keep it under 15ft (otherwise it would throw shade on my solar panel on the terrace above). But it's younger cousin (10 years) is doing just fine free standing unprotected.

Sounds like a lovely place where you live.  I like rock walls, too.

I would like to recommend wood chips around your trees.  The wood chips will hold in moisture.

I have also found the rocks will help maintain moisture too.  So, making a rock circle around the trees will help hold the wood chips in place.

What do you think of this idea?

Hi Anne,

thanks for the reply! Yes, it is a nice place: .

Wood chips are hard to come by up here. I'm trying to find out if anyone in the area has a wood chipper that I could borrow. Otherwise I would have to invest into a solid machine and that would be rather costly. The garden shredders I have seen seem a little weak.
So far I use mainly maple and other "good" leaves to mulch. They accumulate on a small path up the mountain that I maintain. I could put a foot of that material under the trees as well to stunt the growth of the grass around them.

I guess my fear is that if I terraced the area under the tree to make it somewhat level with the stem that the roots that were formerly near the surface would then be burried and maybe find it more difficult. Or would they be fine and maybe develop upwards into the earth and mulch permed by the stone wall?

Johannes said "Mulching can be done in principle but the only practical way to do this really is by terracing (otherwise heavy rains would just wash away the mulch downhill

... So far I use mainly maple and other "good" leaves to mulch.

Johannes, how is your adventure working out?

I bet you have lots of leaf mold if you look in the right places. Leaf mold is made by nature when the leaves fall to the ground and just sit there year after year.

Look for trees that are bunched together where it stays mostly shady. The reason we look for shady trees is that grass does not grow there so it is easier to get the leaf mold.

Get a shovel, a rake, and a bag to put the leaf mold in.  Then move or bush away the fallen leaves. under where the leaves were will be rich compost-looking 'soil". that is leaf mold.

Do you compost or make compost tea? Compost tea would be could for your trees.

What if you made a box to go around the trees sort of like making a raised bed? would that hold in the mulch?  Or use the rock circle I mentioned?

I didn't help much with "understory planting" suggestions.  You could try different plants to see what might work.  We tried pinto beans one year.

Johannes Schwarz wrote:Hi Anne,

thanks for the reply! Yes, it is a nice place:

.

Wood chips are hard to come by up here. I'm trying to find out if anyone in the area has a wood chipper that I could borrow. Otherwise I would have to invest into a solid machine and that would be rather costly. The garden shredders I have seen seem a little weak.
So far I use mainly maple and other "good" leaves to mulch. They accumulate on a small path up the mountain that I maintain. I could put a foot of that material under the trees as well to stunt the growth of the grass around them.

I guess my fear is that if I terraced the area under the tree to make it somewhat level with the stem that the roots that were formerly near the surface would then be burried and maybe find it more difficult. Or would they be fine and maybe develop upwards into the earth and mulch permed by the stone wall?

Oh my Johannes, that is quite a stunning spot! The views must be incredible.
However your terrain does indeed look very steep! And I can imagine little to no vehicles can reach the house, right? So I see your conundrum with the wood chips.
We are not situated as remotely as you are by far, but we do share the difficulty of brining in wood chips due to difficult access.
Rock mulching, or lithic mulching, which is basically just using rocks as a protective top layer to prevent erosion of topsoil due to wind, rain, sun and gravity, has been working interestingly for me.
I first heard of the practice when learning about agriculture practices on EasterIsland. Here's an article that talks about it a bit.
Rocks are overabundant where we are situated, and they create incredible microclimates for our less cold hardy crops and extending the growing season for them. I can imagine this could be interesting for you as well, as you probably don't have any trouble finding rocks at your place.

Hi Johannes

I may have been listening to too many John Kempf  (Advancing Eco Agriculture) podcasts on regenerative agriculture, but is it possible that the native grass with its deep rooting system and the shallow rooted apple tree are actually sharing nutrients? (This may by now only be hypothetical for you. I only just came across your post. Hope you will post about any results.)

I live in a sub-alpine environment in New Zealand, though nowhere as extreme as yours, so always interested in posts about growing under challenging conditions.  What I have found over the years is that almost all the inputs I need are already present in my environment. My driveway passes through a stretch of non-deciduous native "beech" forest and leaf litter tends to accumulate, breaking down very quickly as it is accumulating at a steady rate, making the driveway somewhat hazardous in very wet weather. In winter this year I dumped barrow loads of this leaf litter under two self-seeded young fruit trees growing in a guild with (self-seeded) gooseberries on what is essentially glacial moraine with almost no topsoil. (The trees only grew there because I had previously experimented with keyhole gardening at this site and there must have been plum and peach stones in the compost "keyhole." The gooseberry seed was generously donated by a wild bird who admired my efforts.)  I also ferment weeds in an old plastic dust bin, primarily nettle which I am a great fan of, along with chopped up banana and avocado skins, and once or twice a season I have been applying this with a watering can after sifting out any remaining debris. The effects have been electric for plum and gooseberry. Both are heavily fruiting at present. (The young peach is reserving its options. Maybe next year.) Plums and peaches do not typically do well in this environment. Apple trees are a bit more resilient.

I noted your comments about wood chippers. I have a very light electric one which will only process very thin apple prunings and such but comes into its own with wild blackberry vines which I have a profusion of. (Nature always provides.) A mix of dead and green vines make great "ramial wood chip" mulch. Strawberries and other small plants love it.

cathie

Some plants that I would suggest include sweet fennel, anything in the mint family (spearmint, wintergreen, lemon balm etc), some clumps of native wildflowers for your local native pollinators. It would also behoove you to make sure there’s something blooming on the property the year round so that the pollinator friends have sustenance for the entire year. Other things would include fruit/nut bearing shrubs, (aronia, goumi, hazelnut, mullberry etc) a ground cover layer (perennial clover is a favorite in my zone 6b as well as strawberries, chickweed, purslaine, plants from plantago the genera, dandelion etc.) I hope my incoherent rambling and name dropping helped. Lol