EEMB/ES 171 Chapin et al. 1986. The American Naturalist Name: Jasmine Jefferies Discussion questions 1. What is the difference between nutrient supply and limitation?Nutrient limitation is the limitation of the efficiency of a particular plant caused by a lackof supply of essential nutrients available in the soil (in other words greater productivitydepends on greater abundance of nutrients). Nutrient limitation can be seen when growthincreases due to an added limiting nutrient. On the other hand, nutrient supply is the levelof nutrients that are available to plants. 2. How can you experimentally test a plant community’s nutrient limitation?Since plant communities normally grow in infertile areas, they don’t always respond toadded nutrients meaning we have to use a different method other than adding nutrients tothe community. In order to experimentally test plant communities, we can fertilize thecommunity and see how it affects the growth of total production within the community.Having an index of soil fertility is an easy way to predict the composition of acommunity. Typically species that are in nutrient poor ecosystems grow less in responseto an added nutrient compared to species that come from more fertile areas. Communityproduction on infertile areas will have a decreased response to fertilization. The 2 mostdistinct measures of nutrient limitation is nutrient supply level, and increasing primaryproduction when a lot of limiting nutrients are added. 3. Why might low nutrient supply not equal nutrient limitation for a plant community? Low nutrient supply may not equal nutrient limitation for a plant community becauseplant communities in infertile areas are not always the most responsive to nutrientaddition. Also, communities vary in the extent to which added nutrients are available tocertain plants. It is hard to exactly determine the available nutrients a plant has. Normally,community nutrient limitation is determined by nutrient supply, but this concept can becomplicated due to the various physiological traits of species adapted to different fertilitylevels.EEMB/ES 171 Chapin et al. 1986. The American Naturalist Name: Jasmine Jefferies Discussion questions4. Explain Fig. 3Figure 3 is split up into 2 parts. The top graph displays the production of 3 species along a nutrient gradient when released from nutrient limitation. Figure 3 describes how nutrient limitation depends on 2 things: species composition and the degree to which nutrients can meet the max growth rate. The bottom graph shows the predicted nutrient limitation from the above graph and the most probable pattern of nutrient limitation givenchanges in species composition. Given the graph, it looks like nutrient limitation is highest when fertility levels are at an intermediate