A new dissertation looks at environmental change in the Lake Ventina area. Sediment cores provide pollen and isotopic evidence, which combined with historical and archaeological records show heavy anthropogenic impact from the beginning of the study onward. Comparing modern pollen samples with those found in sediment cores, the author also argues that these pollen samples underrepresent the human impact on the landscape throughout the period under consideration. Sediment core pollen also suggests a very different landscape than the present one. Read more about it here.