I am analyzing a data set where the response variable is the total non-native plant cover within a plot. There are non-native grasses and non-native herbaceous plants with overlapping canopies, so the response variable comes from adding together two percentages (percent cover in each layer within the plot). Therefore, the variable is bounded between 0 and 200. I also have both random and fixed effects.
Can I run a linear mixed model with this response variable, or would that be invalid? Would a GLMM make more sense, and if so what type of distribution would fit?