Pitch pine (pinus rigida) White Spruce (Picea glauca).

If you plant only one species, everything could get wiped out by one beetle.

What are the soil conditions? Are you near the coast?

Tomp, I'd urge you to do three things: First, look around you. What native conifers-if any-exist in the region? Second, I'd talk to experts. There are people in your area that could talk your ears right off on the topic of "original" or native vegetation. Use their expertise! And third, if your state had an original land survey done, and I'm reasonably certain it did, those surveyors probably took extensive notes of what was growing around them as they moved across the state. These notes can then be used to create a map, displaying the original plant communities as they existed at the time of European settlement. My state has just such a map, and it is an incredible tool. I use it often for my area to support or refute, as the case may be, others' claims as to what plant community existed in my area in the mid 1800s. Really great stuff!

+oM

Depends what you mean by "urban". They don't do well in the city itself, but do reasonably well in large suburban lots. They are very pretty and very disease resistant, in my experience. A reasonable choice for a nature preserve. I'd like to know more about the site.

Agreed. I think that assertion about white pine went wide of the mark. Whether urban or rural, soil conditions are the primary factor. Right here in this town, there are some very nice big ones....in older sections of the city, developed before scalping off all the A horizon become the norm. Then too, some folks do try to plant them into their newish yards of clay subsoil with a thin coating of topsoil....you know-placed to get the grass growing...and they suffer miserably. Soil is the main determinant, not human population density, or whatever would hinge on the urban/rural designation.

+oM

Well, in the city itself people don't usually have room for a white pine and are more likely to eventually chop it down. In northern cities the pine is more likely to be close to the road, where it will get road salt. It will also get more pollution from cars...I've heard white pine is vulnerable to this, though I can't say I've noticed. Also probably more root compaction and soil trampling. Now that I write this, I see a lot of this hinges on lot size. I sort of agree with carlclaws statement they don't do well in urban areas, but the original poster was talking about a "nature preserve" so I'm not sure that applies. I'd really love to know more about the site. A quarter acre park in a city, an abandoned farm, and an abandoned gravel pit by the sea would call for different suggestions.

Out of curiosity, what conifers *WOULD* be good in an urban area?

Sorry Ed, I think that question is just too broad. What sort of urban area? What part of the country. Lot size? Owner's sense of aesthetics? I could go on and on but the point is, there's not a few answers to that question, there are many, many answers, too many to waste bandwidth here. Conifers forum is right next door. People there will talk your head clean off about this or that conifer!

+oM

Callitris oblonga and Callitris callitris glaucophylla do OK in the Melbourne region and in southern NSW. You can get them via mail order from here: http://www.gregsindigenouslandscapes.com.au

Try contacting an urban forester (many cities have them) or US Fish and Wildlife. The latter agency is active in enriching habitat by adding native plants.