I. IntroductionIII. ResultsIV. ConclusionsV. Works CitedI. IntroductionFor this experiment I wanted to examine the effects that changes in groundcover have on various climatic factors. I wanted to look at changes in vegetation as well as changes from naturallandscapes to urban landscapes. For centuries we have been altering our environment by changing the groundcover. Originally we did this by simply cutting down trees to make more farmland, but more recently we have been building cities and putting in impervious cover. This isall bound to have an effect on the climate of our region, and perhaps globally. I expect that changes in the type and amount of vegetation should have an effect on evaporation and precipitation, as well as surface runoff. These changes should also have an impact on the heat fluxes and the temperatures of the ground and canopy. Many experiments have been done to look at similar effects. Foley, et al., looked at the Global effects of land use in 2005. Foley, et al. asked “are land-use activities degrading the global environment in ways that may ultimately undermine ecosystem services, human welfare, and the long-term sustainability of human societies?” What they found is that may be undermining our land in the long-term on regional and global scales by our current land-use practices (Foley, et al., 2005) Also in 2005, Lepers, et al., worked on putting together an assortment of information on rapid land-cover change from 1981-2000 (Lepers, et al., 2005). Costa, et al., examined how the discharge of the Tocantins river is affected by large-scale changesin land cover (2003). They found that while they did not see significant changes in precipitation, they did see an increase in the annual mean discharge (Costa et al., 2003). For this experiment I used the Community Land Model developed by the National Center for Atmospheric Research. This model is part of the Community Climate System Model. The CLM version used in this study has a primary land cover and up to five plant functional type (PFT) patches (Bonan et al., 2002). The primary land cover can be composed of glacier, lake, wet-land, urban, or vegetated. The vegetated can then be split in up to 5 different PFTs. In the version used for this study there are sixteen PFTs available. This study only uses ten types: not vegetated, needleleaf evergreen temperate tree, broadleaf evergreen temperate tree, broadleaf deciduous temperate tree, broadleaf evergreen shrub, broadleaf deciduous temperate shrub, c3 non-arctic grass, c4 grass, corn, and wheat. II. MethodsFor this study, I ran a series of thirteen tests. These tests separate easily into two groups. In the first group I have 9 tests where I altered the plant functional types (PFTs) to see how different PFTs affect different climatic factors. The remaining four tests make up the second group. For this I chose one PFT and changed the percentage of coverage, assuming that the uncovered portion was not vegetated. For these tests, I left most of the defaults as is, however I changed the latitude and longitude to be near central Texas at 30N, 100W. I was not successful ingetting the model to work for changes in the primary land cover, so I wasn’t able to do any experiments looking at urban changes in the environment. Therefore, this experiment looks only at what effects changes in vegetation have. Table 1 provides a detailed summary of the conditions used in my thirteen tests. Looking at the PFTs of the first nine, we see that they can be divided into 4 sub-categories: trees, shrubs, grass, and crops (as denoted in column 8, above). To be able to easily see the variations of different types of vegetation, I took an average of the values computed for each of the PFTs in each category, and that gave me the general value for that category.Case NumberPFT1 % of PFT1PFT2 % of PFT2PFT3 % of PFT3Sub-cat1 Needleleaf evergreen temperate tree80 c3 non-arctic grass2 Not vegetated18 Tree2 Broadleaf evergreen temperate tree80 c3 non-arctic grass2 Not vegetated18 Tree3 Broadleaf deciduous temperate tree80 c3 non-arctic grass2 Not vegetated18 Tree4 Broadleaf evergreen shrub80 c3 non-arctic grass2 Not vegetated18 Shrub5 Broadleaf deciduous temperate shrub80 c3 non-arctic grass2 Not vegetated18 Shrub6 c3 non-arctic grass98 c4 grass 2 N/A 0 Grass7 c4 grass 98 c3 non-arctic grass2 N/A 0 Grass8 Corn 60 c3 non-arctic grass2 Not vegetated18 Crop9 Wheat 60 c3 non-arctic grass2 Not vegetated18 Crop10 Broadleaf deciduous temperate shrub10 c3 non-arctic grass2 Not vegetated88 N/A11 Broadleaf deciduous temperate shrub40 c3 non-arctic grass2 Not vegetated58 N/A12 Broadleaf deciduous temperate shrub70 c3 non-arctic grass2 Not vegetated28 N/A13 Broadleaf deciduous temperate shrub96 c3 non-arctic grass2 Not vegetated2 N/ATable 1. Summary of tests run.III. Resultsa. Changes in plant functional typeFirst, we will look at the effects of groundcover changes on precipitation and runoff. Looking at figures 1 and 2 we see that there is no variation in the rainfall, but there is a little variation in the runoff amount. Overall, however, there are not drastic differences in the precipitation and runoff between the different types of vegetation. This is not what I expected. According to Costa, et al., changes in vegetation alters the balance between rainfall, evaporation, and runoff because it changes the hydrological cycle of the drainage basin (Costa, et al., 2003). So, what I expected was that even if there was no change in the precipitation, that we would see apattern in the change of runoff, however, upon careful examination, there is no pattern apparent to me.Figure 1. Rainfall amount/day. Figure 2. Runoff amount/day. Next let’s look at the changes in heat fluxes. Figure 3 shows the ground heat flux, there doesn’t seem to be a large difference between the different types of vegetation. Looking at figure 4, the latent heat flux, there seems to be some difference between the vegetation types. The most obvious difference is that the grass overall has less latent heat flux than the crops. We see the opposite when looking at the sensible heat flux, figure 5; the crop has the least sensible heat flux, then grass, then shrubs. Upon closer examination, shrubs and trees have similar values for sensible heat flux. This makes sense to me because shrubs seem like little trees.Figure 3. Ground heat flux (W/m2)Figure 4. Latent heat flux (W/m2).Figure 5. Sensible heat flux (W/m2).Finally, lets look at