Even though they are evergreen, redwood and pine trees are known for shedding large quantities of brown needles during late summer and early fall, a natural process that often catches people by surprise. This needle drop is part of the trees’ annual cycle and serves to conserve water and support new growth. To cope with drought stress, these trees allow their oldest needles to die off, thus reducing the overall demand for water. Additionally, this annual shed helps rid the trees of less-efficient foliage: Needles typically last for…