Lecture: Urban forest: Narrator: Listen to part of a lecture in a urban planning class. Professor: So far this semester we focus on major issues urban planing has to deal with, like transportation and providing affordable housing. But there are other less obvious factors that need to be considered and these can have a significant economic impact on the city and affect the quality of life. As you remembered, we began discussing one of these factors last class – the urban forest. Remember an urban forest refers to all the trees in the city individual trees in relevant yard, trees lining city streets, or trees in parks. And we started talking about the idea of signing a monetary value to trees. This tend to influence how many in or what kind of trees we planted. As I mentioned last class the missions are to put a price tag on a tree, but many stakeholders like city officials, business owners, or private citizens, they wanna see a dollar figure before decisions are made about planting new trees or maintaining trees. OK, so continuing with approaches used to determine the trees worth, can someone describe the one way we discussed last class, John? John: We talked about the sales comparison approach which involves looking at what house sales for and trying to determine what different value they worth. So with trees, if two houses are exactly alike except one house has a few trees in the back yard and the other doesn't, we can determine the trees value based on any difference in the sale prices of the houses. So if the house without trees sales for one hundred thousand dollars and the on with trees sales for one hundred five thousand dollars, then the trees are worth five thousand dollars. And everything else is the same. Professor: Exactly. The last part is very important, everything else is the same. The chances of finding two homes that are exactly the same, same location, same size, same amenity, seems like a big effort, are pretty slim. So to figure out what the trees, for instance, they worth, the placers, the people who determine the value of the house estimate the values after adjusting for the absent or present different amenities. So the houses and the trees can be compared. This adjustment depends on the skill of the placer and it may vary depending on who is doing the placing. OK, so that's the sales comparison approach. Today I want to look at two other approaches: the benefit based approach and the cost based approach. So the benefit based approach. Kay, what you think is involved? Kay: Um, well that's so many meanings, I guess determine how trees improve things, like providing shades which save energy because then people use less air-conditioning to cool their home. Professor: Good. Kay just gave us a example of one benefit trees can provide and one we can convert it into dollar figure. And now there are several other benefits this approach can take into account. For example, trees can also protect the pavement of the street from the Sun, protect it from deteriorate. So street with trees don't need to be repaired as often as street without trees and this save city's money. John: Can this approach really be acted? I mean trees take a long time to grow. So if we check and put a value on a tree that not fully grown like if we determine how much shade provide to save energy? The figure would be different if we checked it again a few years later. Professor: You are right. If we plant a tree we may cannot see all the benefit it can provide for several years. So calculations for this are made based on expected tree grows. So that's another element of planting we need to consider. OK, what else goes into the benefits approach? Well, it also consider the amount of storm water run off reduced by trees. Tree absorb rain water and this is specially use for very heavy rains because it can reduce flooding. Cities can spend millions of dollars a year managing storm water, so trees help reducing this cost. Yes, Kay? Kay: Is it really possible to count for all the benefit of trees? I mean with a monetary value? What about like social benefits? I read some where that trees can actually make people happier with increase worker productivity and even make community relationship stronger I mean between neighbors. Professor: Good point. Societal benefits like the one you just mentioned, well, those are harder to calculate. You can't just put a monetary value on them and we'll talk more about that later. But first let's move on to the cost based approach.