用混合模型的回归线绘制图

I have a data frame of 60 trees. i need to find one slope for the EWMZ according to DOY. I used the mixed model and found a negative slope but when making plots it gives me a positive regression line. I dont know if the way that i used to make plot with ggplot is correct or not.I have a data frame of 60 trees. i need to find