Where I've occasionally had a problem with wood chip mulch is fresh and in the vegetable garden on young vegetables. The actual research I've seen is that you can rarely harm a tree with alleopathic mulch and I use tons of mulch from unidentified trees in my fruit tree nursery and in scores of home orchards every season. What was said about such compounds leaching out quickly is correct- but it can take about 6 months of rainy weather as I recall. Fresh mulch may leach some of these compounds but not enough to noticeably affect young trees in my experience.

If you have lots of shade.... synthetic

No personal experience, but it appears there are strong germination inhibitors in the mesocarp (flesh of the fruit) and care must be taken to clean the seed - "Typically, the seeds are soaked in water at room tem-perature for 48 to 72 hours (Schulte and others 1992). Treated seeds germinate in 20 to 25 days with a germination rate of 50 to 80 percent " "The seeds are sown in seedbeds or directly in containers with two seeds per container. It is recommended to use a light and permeable substrate, maybe because inhibitors need to be washed out before the seeds can germinate. Germination starts after about two weeks and is normally terminated after four weeks"

There are a few people who just love Peruvian Pepper trees. I could never understand why they think pepper trees are so nice. I guess they have draping branches and fern-like leaflets, but the trunk shape and texture are not especially pretty, they seem to lurch over as if the tree was never meant to grow that tall (and they're not). I suspect the reason why so many people in hot climates like (or THINK they like) pepper trees is because the trees are so well adapted to arid climates, so these pepper trees look more lush and green the other trees around them. I have mixed feelings about these Peruvian pepper trees, in fact I do not really know how to feel about them. There's something almost captivating about their draping branches, has a Spanish Mission feel to them. But at the same time they are kind of ugly. They are also kind of invasive, all those leaves and dry berries can get messy, and just to top it off, some people have an allergic reaction to contact with the leaves. The bark is really rough, it's not the type of tree I would want to climb in.