Grass just dies down in summer here so it does not compete with trees for water in the dry season.
Maybe it is a good idea to reduce vegetation at the feet of trees when they are newly planted but to much reduction of the ground cover is not ecological, no ground plants means less organic matter to form soils and less plants to fix carbon . In olive grooves and citrus grooves here, there is such a reduction of grund cover as must do for the soils where these trees are grown and the trees themselves are so prunned as to give very little shade to the earth or leaves to contribute organic matter or a dry leaf mulch that would protect the soil from the suns rays. I think havign total bare soil under olives is new, i think they used t graze animals under the trees before, though they overgrazed and left hhing pretty bare. They certainly fed prunned branches to the sheep it is mentioned as
feed o¡in my book on spanish races of sheep. .
Sepp Holzer sells
apple trees with all the plants he can pull up with their roots at their feet. I suppose comfrey some deep rooted plants who know fox gloves gentians, the plants of all those seeds he puts on his
land. The
tractor carrying the tree carries a has a tree with a good thichk patch of vegetation on the soil pulled up with the roots
The trees i plant live though there is grass at their feet as long as i manage to keep them watered the first summer.
I wonder which is more important the grass covering the ground and stopping surface evaporation if ther is a
shower of rain or the water the grass might drink from the soil.
Dry grass would shade the soil reducing th eloss of moisture in summer. you can shade new trees to, i do with branches and shade cloth.
Also vegetation does absorb the wet of rains through their leaves, reducing the loss of water from evaporation. The tree takes it up before it can evaporate off. There was a study done of this with juniper trees.
Other evidence that leaves take up wateris the fact that foliar feeds only get absorbed when the leaves are wet when they are sprayed on or after rains or with dew on the leaf, in ht edays after the spraying, so there is quiet a bit of evidence to prove that wetness gets absorbed by leaves where there is vegetation instead of getting lost through evaporation and grass seems to get so tremendously wet with dew that i wonder if it is not specially good at condensing the humidity in the air, making dew for itself. Any wetness absorbed will be distributed through the plant, that means to the roots that lose water to hot soils, look up hydraulic redistribution trees. So plants will contribute to the humidity in the soil.
Plant roots greatly better the earth, as they die back in it and regrow they leave a lot of organic material in the ground and all plants except the cabbage family have mycorrhyzal fungi that leaves glomalin in the ground that makes soils stick together into crumbs breaking up the heavyness of clays and sticking sands together a bit, so helping with drainage and the amount of air held in soils, air is important to plant roots, also th ebettered soil lets plant roots penetrate the soil better, as well as making the soil easier to work . Google glomalin to read about this.
The clearing of undergrowth in woods means the empoverishment of soils in woods as it reduces the growth that provides organic material, as does the clearing of bushes in woods to reduce fire risk and and the extraction of
wood when the trees are cut. If trees lay were they fall their wood would contribute to form soils.
Oaks here in spain are dying of a variety of illnesses collectively called seca, dry, which would point to their defenses having been reduced and hunger is a good reason for a reduction in defenses. Herbicides used without the knowledge of authorities is another.
I think the reduction in health maybe a result of some change in farming, the clearing of undergrowth to reduce competition with the trees from other plants wich maybe was not done so much before. Clearing the undergrowth would mean a great reduction in the amount of organic matter avaliable for soils, so soils with less capacity to absorb and rtetain water and also a reduction of nitrogen in the soil, from the break down of organic matter in the soil.
Spanish evergreen oaks die if they have too much water or nitrogen, they live on poor soils but maybe there is a too poor even for them.
Another idea for helping the oaks that exists nowdays that might be new, that may prejudice them more than it helps them, is the plouging of the ground at their feet in order to break up any crust that might have formed on the soil and so improve the absorption of rain. If there was undergrowth it would break up the soil as it grew up through the soil and died down again. More important this breaking up of the crust would mean distruction of the superficial roots of the oaks, those roots of trees that run horizontal and paralel to the ground just below the soil, and Heidi Guildmeister says that though it is not what we imagine the more superficial roots are impoartant in a dry coutry, they take up the rain of summer showers, and of dew, breaking them would weaken the trees. agri
rose macaskie.