I have a rather large pecan tree in my back yard that not only blocks the tv dish in spring-fall but is hollowing out at the bottem. next month i am planning on having the tree taken down. the wood i will cut up and split to burn in the fire place come this winter. now the tree trimmers will chomp the rest up into wood chips. i have gotten wood chips from tree trimmers before and used it as mulch, but in this case i am not so sure if i should. i know walnut trees seem to excreet somthing in the ground around them making most plant life growing there die. almost the same for ceder. i am wondering if pecon wood would harm my soil or my plants. any thoughts. this tree is massive. about 3 foot across at the bottem and 80-100 foot tall. i am sure i will get all the wood i need for the next winter from this one tree. any thoughts on the mulch?

Pecan shells and hulls are high in tannic acid which is bad for plants. As for the bark, I can't say but it would probably be safer to not use it. You don't want to find out later that it is then it will be too late.

If you do a quick search for pecan mulch (mostly from hulls) you'll find many places selling it and singing its praises, as well as some articles.

Here is a thread asking a similar question at GW from a few years ago: http://forums.gardenweb.com/forums/load/okgard/msg1111244212346.html

A tree of that size has been growing in your yard and dropping leaves and twigs for decades. Have you noticed anything harmful from that? If not, use the chips for mulch. Although related, pecans are said to produce only a slight amount of juglone when compared to black walnuts.

no i havent noticed anything off around the tree. as a matter of fact i have used the dry leaves in the compost and thats some good stuff. and yes i am thinking this tree has to be close to 100 years old or in that ball bark. but these pecans and black walnuts are like weeds around here. every body has them and the squirrals bury loads of them every where. every year more pop up here and there. i did a quick search and found people talking about how great it was too. i was just not so sure as i know the black walnut trees nothing grows around them but moss (not even grass).

Around here, we mulch our trees with shells from clams and oysters. The figs like the extra calcium. I have shells in with all of my potted trees.

I don't think it will hurt to use the mulch.  Although distantly related to walnuts, pecans are actually a type of hickory.  Just keep in mind that the mulch will be a little acidic so you might want to sprinkle some lime in with it to conteract the acidity.