Computer Lab – Part III:



Computer Lab – Part III:

Simulating the effects of climate change in a temperate forest ecosystem

We will use the software Forest Simulator (SimForest) to model the effects of climate change on a temperate forest community, and explore these effects under different environmental conditions.

1. Download and install SimForest from

2. Open the program and click on the properties tab. You will see various environmental variables, which can be adjusted to your preference. Climate variables may be adjusted by clicking the + and – buttons below each plot.

[pic]

3. Click on the ‘overhead’ tab, and in the panel to the right, click on the ‘nursery’ tab. SimForest incorporates life history data for a wide range of tree species into its models. Click on each tree species you wish to represent in your plot, and click in the plot to the left to “plant” them in your model forest. Your trees will start out as seedlings by default; if you wish to adjust the age and diameter of any individuals, click on them in the plot and enter the information. Thus you can start out with a model climax forest by adjusting diameters and ages accordingly.

[pic]

4. Make sure ‘recruit on’ is checked under the ‘manager’ tab in the panel to the right (this means your forest will naturally reseed itself). Now click on the ‘seed pool’ tab in the same panel, and de-select any species you do not wish to include in your plot by clicking on them (names will turn grey when de-selected).

5. Click on the ‘Summary’ tab in the main panel. This will allow you to see data for your forest plot in spreadsheet form.

[pic]

6. While running your simulation you will want to be under either the ‘orthogonal’ or ‘overhead’ tab, depending on your visualization preference. At the top of the window you will see a toolbar that you can use to run the simulation. The box at the far right of the toolbar sets the number of years per permutation. You can adjust this to your preference, or leave as is (two years).

|Run Pallet | |

|The Run Pallet has the following buttons: | |

|step back; rewind; stop; run; run at 1/2 speed; run at 1/4 speed; step. | |

| |[pic] |

|Rewind plays backward, through the simulation you just ran. But if you | |

|run forward from there it runs the simulation starting with the state you | |

|see on the screen, and does not replay the old run that you just ran | |

|backwards (so rewind has limited usefulness). | |

| | |

|The Step button advances the simulation a certain number of years, | |

|according to what you type in the box to the right of the button. | |

Once your have familiarized yourself a little bit with the program, address the questions below by adjusting the parameters of your simulation. Before you begin, you may wish to consider the following: What time frame are you interested in? What starting conditions... e.g. a climax forest? A young forest? A plot of seedlings? Make note of the starting conditions you choose.

Also, bear in mind that different runs of a simulation under the same parameters may generate different results due to stochastic factors. To get the best data, you may want to run the program several times under each set of parameters, and save the data for each run so that you can calculate the mean & variance.

When running your simulations, you will want to save your starting conditions so that you can conduct your multiple runs under the same parameters. You will need to save your climate and forest data separately. To save your forest data, click the ‘save snapshot’ button to the upper right. To save your climate data, click the ‘save site data’ button. When you wish to retrieve your data, click ‘load snapshot’ or ‘load site data’ and select the appropriate file.

To save the data generated from each simulation, click on the summary tab (to view your data) and once again click on the ‘save snapshot’ button to the upper right. You will have many of these files, so be sure to give them a file name that you can make sense of! To work with your data in Excel, save the ‘.dat’ file as a ‘.txt’ file, and you should be able to open them successfully in Excel. Bear in mind that you may need to assemble a master data sheet from the separate files in order to interpret your data.

Questions to consider:

1. Recent climate simulations predict that average global temperatures will increase between ~2( C and ~6( C by the end of the century (TNC). How is tree diversity affected by an increase in temperatures of 2( C? How is diversity affected by a temperature increase of 6( C? Note that you can alter your starting temperature conditions with the + and – buttons by ‘degree days,’ and you can change the monthly temperature fluctuations by clicking on each point and moving it with your mouse.

- Hint: remember how to calculate your Shannon diversity index!

Graph your results in Excel. Think about how best to represent your data given the question of interest!

2. NOAA climate research predicts a 10% drop in precipitation for our area by the end of the century (see climate map at ), accompanied by 5( C increase in average temperature. Based on your simulations in SimForest, how does a temperature increase and monthly precipitation decrease of this magnitude effect forest composition in your plot? Illustrate your results graphically in Excel. Think critically about how you might best represent forest composition given the data you have available. Although there is no one right answer, some strategies may be more effective than others.

3. SimForest incorporates quite a range of variables, and it’s possible to play around with these in interesting ways to explore how they may be differentially affected by climate change. Frame at least two of your own questions/hypotheses you might wish to test about the effects of climate change on the growth of your forest. Be creative! Before you start, you might wish to step back for a minute and think about the data that you are given or can calculate (e.g. volume by species, diversity, % composition, growth rate by species, tree age distribution, etc.); at the same time, think about all the parameters you can vary (soil parameters, temp, rainfall, seedbank species composition, starting species, starting size of individuals of different species). You may also wish to consider actual climate predictions such as those illustrated at (temperature; see clickable climate map on right side of page) and (precipitation). As you look at these maps, consider the geographic area that you are interested in, and bear in mind that most of the trees in SimForest are eastern species rather than our native Sonoran Desert taxa. You could also think about the life history of the tree species you plan to deal with, and how that might affect your results. Use SimForest to explore at least one question of your own formation, but you may also choose among the following example questions if you wish.

a. Do the effects of increased temperatures on forest diversity or composition vary with soil characteristics?

b. How does the dominance (i.e. percent composition) of tree species change with temperature?

c. Climate simulations conducted by the Nature Conservancy predict that between 1990 and 2080, average annual temperatures will increase by 5( C in southern AZ. How does a temperature increase of this magnitude affect forest age structure over a 100-year period?

Questions for discussion:

1. What are the limitations of this type of simulation?

2. Do these types of programs have a role in conservation efforts? Why or why not, and if yes, in what ways?

3. How might you expand on this SimForest program to make it more useful/applicable?

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download