I roamed through a few giant sequoia groves over the last week and did find a few mature giant sequoia that aren’t weathering the four-year drought well. Some of these afflicted giant sequoia simply were shedding leaves and their crowns appeared thinner and less green than normal. Others, had lost nearly all of their leaves and appeared to be dying. These trees were mid-sized giant sequoia that are probably centuries old, but not millennia old. So why are the middle-aged giant sequoia showing the worst signs of drought stress?
Scientists don’t know why yet, but a few hypotheses have emerged. The one I find most interesting is that perhaps these giant sequoia grew to their current size without experiencing a drought of this magnitude before. Since in the past the water was plentiful, the trees may not have grown roots very deep into the soil. Now, water in the upper layers of soil is drying out and these “spoiled” trees don’t have access to deeper water that some of their larger giant sequoia neighbors have. Any other ideas? Have you seen any large giant sequoia in the groves show signs of decline?