 um is by Pei Ling Wang at the University of Victoria um and it will still stay on the terrestrial domain and like look at quantifying land use impacts. Thank you for having me here. My name is Pei Ling Wang. I'm very excited to share with you part of our very big project. I work with Professor Johannes Fedema at University of Victoria. So we want to quantify human-induced soil degradation. So we know human activities depend a lot on soil and we also constantly change soils all the time and that affects soil water holding capacity and infiltration rate and as a result it will affect water energy and biogeochemical cycles. We know this from a lot of small scale studies however in most of the earth system models despite the land use and land cover changes in the history the soil properties in those models often stay constant and that will affect model projections and impact assessments. So that's why we would like to fill in this missing piece to put the soil degradation model. So the first question we ask is what type of soils do we like? So to make the question even easier we group different types of soil into four groups based on the hydrological potential. So group A is more sandy and so group D is more clay and then we want to see what type of soil is the best. So we introduce we look at the major land uses and land cover and we rank those land use and land cover in by its importance to human beings. So the most important land use is crop land then it's pasture land grazing secondary vegetation and the primary vegetation. Then the next step we overlaid globally those land use land cover with the distribution of different type of soils then we count how much portion of each land use located in each type of soil group and if the soil get more important land uses then we consider it's a more important soil. So the result with five soil group B the loamy soil is the most important one followed by clay soil sandy clay loam and sandy soil is the least preferred soil for human use. So once we get that if we get a data map in a single grid we know the portions of this much of land use then covered in this grid and we know there are this much of different type of soil in this grid then we can link land use with soil based on the most important land uses located on the best soil and the least important land use on poor soils. So we can do this for globally. So this is an example we allocate land use land covers in 850 on four different groups of soils. So as you can see soil B is the best soil so you can see most of the agriculture and pasture located in the best soil while soil A is poor soil so in 850 most of the soil A is remain untouched. So using the same methodology we can do this for land use for the time history from 850 to 2015 based on the land use and land cover history. So we allocate land use then covered to four types of soil and you can see time goals soil B has a lot of increases in important land use of crop land and pasture and soil A although is poor soil under the population growth soil A we start to see more than more human land uses. So if you are interested to know more of the detail we just published this in global biogeochemical cycles. So the next question we want to ask is how soil properties are changed by land use then covers. Here we focus on soil organic carbon texture and bulk density because those properties affect soil hydrological properties. So to answer this question I read more than 1,000 papers and try to collect observations of soil samples under primary vegetation and disturbed condition and because I only want observations from comparing to soil that's never be disturbed and most of the studies they look at so compared to soil on the secondary vegetation which is being disturbed in the past. So I end up have 140 papers with 700 pair observations and in addition to the soil data from the literature we also include a global data set of MPP and moisture index. So these figures we plot soil organic carbon change along with death under four different land use land covers then we calculated the average at each soil layer so we have we defined seven layers here and for each layer we have an average to represent the different land use impact and we can see how the impact change along with death. Then with that we also include environmental factors such as MPP then we do a forward modeling to see how land use MPP and the soil texture can affect soil organic carbon change. So this is the model we come up to predict soil organic carbon change based on human land use MPP and the clay content of the soil. So this model can nicely explain how the soil organic carbon change varies on the different land use and in on the different environment. And then with this model you can see the soil organic carbon change decreases with increasing clay content and the changes also a negative change in soil organic carbon decreases with increasing MPP. So with the similar methodology we also use that to to build models to predict how sensual clay and soil bulk density change under various human land use and land covers. So with that now we have a couple of models that can be used to predict soil property change on the different land use land cover and on in different environmental conditions. So the application of the results first is we can use that to conduct impact assessment of land use land land use on the different environments. And then we want to incorporate land use land cover history to model human induced soil degradation over time. Then finally we want to apply the soil states we got from the human soil degradation model into the earth system models to estimate the impact of soil degradation on climate. So that is my presentation. Thank you.