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California suffers under a historic drought – there is a severe lack of rain. There has been very little rainfall for the past four years. California is famous for its huge sequoia trees. They are among the largest and oldest living things on Earth. But scientists say the trees are having difficulty because of the lack of water. Now the National Park Service is studying how the drought has affected the sequoias and what can be done to help them survive. The Sierra Nevada mountain range is the only place on earth where sequoias live. Sequoias can grow to more than 90 meters tall. The bottom of the tree can be up to 15 meters wide. Some trees are more than 3,000 years old. The Sierra Nevada range once had plenty of water because of mountain streams. But less water is available now because of the drought. Each sequoia needs more than 3,000 liters of water a day. The trees now are getting much less. Some of them are showing signs of thirst, says Anthony Ambrose, a tree biologist with the University of California, Berkeley. He says they are seeing unusually high numbers of leaves dying, which they have not seen before in the park. Researchers are measuring air temperature and humidity levels. They also are studying sequoia seedlings, information from individual trees. One solution would be to cut down less important tree species. Scientists say that over thousands of years, sequoias have survived many disasters. And they say the sequoias will probably survive this drought too.
