Problem 2
Some authors have argued that biological invasions are nothing new and have occurred throughout evolutionary time. Imagine that you are an alien scientist visiting a new continent with no prior information about which species are native and which are exotic. How would you decide which species are "pests" and would your job be easier if someone gave you a list of which species are exotics and which are natives? Larson (2007) discusses this question.
Problem 4
While most evaluations of the benefits of ecosystem services give a positive value, Clinch (1999) estimated the value of water supply provisioning in an Irish temperate forest at minus \(\$ 20\) per hectare. Review the general issue of evaluating the dollar benefits of ecosystem services and discuss how some potential services might in fact have a negative value.
Problem 5
The concept of ecosystem health has been criticized as a concept that applies well to individuals but poorly to a whole ecosystem. Discuss the application of the idea of health to populations, communities, and ecosystems. Rapport et al. (1998) discuss this question.
Problem 7
Nitrogen is often a critical nutrient limiting crop growth, and yet it occurs in abundance in the atmosphere. Discuss the nitrogen requirements of modern agriculture and the possible ways in which nitrogen requirements of crops can be provided in a sustainable manner. Crews (2005) discusses this problem.
Problem 8
Are there ecosystem services that cannot be evaluated in dollars? Is it necessary to place a monetary value on environmental concerns in order to obtain political action? Pearce et al. (2007) discuss this issue with respect to biodiversity.
