How is that proof that the Sahara used to be a lot wetter?这又怎么能证明撒哈拉沙漠曾经是湿润的呢?
Without a tree to soak up moisture from the ground, the soil remains wetter than in the surrounding forest.如果没有树木吸收地面中的水分,土壤一直会比周边的树林更加湿润。