Ground cover under trees is competition for moisture as far as a tree is concerned.

Not sure why you think leaves under a tree is a fire hazard, but then perhaps you have people smoking around there. But if mulch would make you feel better you can buy some of that instead.

i just use generic roundup on weeds under trees ...

oak leaves tend to not mat.. so i doubt they would kill weeds ... unless VERY deep.. and they never move ...

i dont understand the title about groundcover.. which is plant material ... and your talk about using leaves as a mulch ... can you clarify what you want discussed

ken

Mulch would be covered in leaves every fall. A definite fire hazard, I ran in to that problem years ago on my wooded acreage, which joins my yard.

My neighbor burns his trash and it sparked a leaf fire. It did a lot of damage, but it was isolated from my house, because I keep the leaves cleared around the house.

If groundcover couldn't grow under trees, there wouldn't be very many plants used as groundcover. Fortunately, the list of shade tolerant plants suitable for such a use is extensive.

We tend to lump plants into categories based on notions that we find convenient. Vinca, pachysandra, and that truly devastating bane of the unimaginative, hosta, would all qualify, but so would rhododendron, hellebores, and microbiota.

As mentioned, the hardest part of establishing a planting under large, established trees is competition for water.

Some time ago, I did some research into fire resistant landscaping that is becoming codified into certain parts of the country where major wildfires have made major news. Long story short, such landscaping is radically different than what most are accustomed to, and would render obsolete the cherished memories of my grandparent's small farm house tucked away under a few burr oak trees.

I like Ajuga under my trees. If you have dry soil I would think the shallow rooted Ajuga would die before the tree. It shades the soil too, so kinda helps keep moisture there too. Just my 2 cents. Vinca major and minor will run over all but the bigger shrubs. Mine swallowed up one of the bigger hostas "sum and substance" so unless I get a ton of roundup, that bed is tree and vinca. My wet area oaks have creeping jenny. There is variegated goutweed under Sycamore. Something under the Beech ( forget what it is) with green crinkly thick evergreen leaves. I like that I don't have to groom the area near the trunks and no trimmers and mowers need to go up to the trunks.