Question

Tree's for privacy   Hi Marc, I have some trees that divide my fence and my neighbor's fence. Recently, my neighbor spoke to my husband  in regard to the trees and asked if it was possible that we get rid of the trees since their roots are damgaging his concrete. Although I never liked those trees because of maintence issues, I did like how it kept our privacy from our neighbor and from a busy street that our house faces(I posted a picture). We are in the process of having them removed but would like to know what can I do to replace those trees for privacy? IS there any type of tree that is good for privacy without having big roots, or do you have any other suggestions? I live in southern california and I  would truly appreciate your advice.

Answer
Those look like Privet (Ligustrum) that were planted as a hedge long ago, but now have overgrown the space. And, yes, they have invasive & shallow roots.  Off the top of my head, here are three for Southern California plants that I remember growing up with (I'm from the Melrose/Fairfax area):

Orange Jessamine -Murraya paniculata
A lush green, thick foliage plant with masses of white flowers in Spring, and sporadic flowering throughout the year in Southern California.   Bonus is a beautiful jasmine scent.

Cape Plumbago - Plumbago capensis
Fast growing, tall, but used as a hedge so can be easily shaped.  One of the fastest growing hedges,  it has the drawback of requiring lots of pruning to keep neat.  Some prefer to let it grow a bit, and prune only once or twice a year.   It is quite a lush looking hedge.    It is however very tough and water thrifty once established.   Plumbago makes a good screen plant, but also has a tendency to grow fairly wide and bushy, which is just what you might want, but may cause added maintenance.    

Bush Christmas Hedge/Water Gum/Water Cherry/Wilypilly ?Syzygium var.
Part of the Myrtle family, with 100+ varieties, so it/they should be pretty easy to find in the nursery. It can be a bit slow growing to create a tall hedge, but for lower hedges is excellent.  The foliage is a rich red/green color.   Best to grow in full sun but will take some shade.  Will grow well in most soils. Bonus is that the fruit is non-toxic, and actually tasty, if you have little ones

There are others, but what you're looking for is a thick hedge, rather than a small tree.  Here are two sources, to discover others that might fit this space:

http://www.bhg.com/gardening/gardening-by-region/southern-california/  
(See top left ?selection guide by zone & type)

www.fs.fed.us/psw/programs/uesd/uep/products/2/cufr_48.pdf   
(see Small Trees, page 65)

All the best, Elsa. ~Marc