The New Zealand Plant Conservation Network

Can the Macrocarpa be dangerous to other plants? For example, a plant put near a Macrocarpia that gets a lot of ' droppings' from the tree, could that be harmful to that plant? I am in NSW.

I have a feeling I've seen that some conifers do produce chemicals that suppress the growth of potential competitors but I can't find the info again. But C. macrocarpa leaves do have chemicals which are toxic to cattle.

Cupressus in general seem to make good nurse trees for NZ native understorey shrubs. They can have a very dense canopy when young preventing growth of understorey plants by shading and they are almost as efficient as pines and eucalypts at intercepting soil moisture.
Mike's point about poisoning refers to the abortive potential of the volatile oils that cause spontaneous abortion during the third trimester in mammals, most commonly reported with cattle and C. macrocarpa.

Thank you both very much for your replies to my query. Both were helpful, Vera