Climate Change, Genetic Diversity, and Conservation of Paleoendemic Redwoods

Abstract

Global climate has always been changing in the past and will continue to change in the future. However, according to current predictions, the climate has been changing more rapidly and has impacted species distributions, requiring strategies to conserve genetic resources in forest trees. Conservation of genetic resources of four endemic redwoods, Sequoia sempervirens, Sequoiadendron giganteum, Metasequoia glyptostroboides, and Fitzroya cupressoides, from the family Cupressaceae are discussed in this paper. All four genera are monospecific, share a number of common phenotypic traits, including red wood, and are threatened in their natural habitats. Although fossil history of the redwoods can be traced back to more than 100 million years ago in the Cretaceous Period, these redwoods were widespread during the Tertiary period (7–65 million years ago) in the northern and southern hemisphere. Following the geological upheavals and climate changes, the redwoods have become living fossils or paleoendemics, and are now restricted in their native narrow ranges in USA, China, and South America. Therefore, it is necessary to conserve the genetic resources in these paleoendemic redwoods and, at the same time, maintain an appropriate level of genetic diversity in the redwood species and populations for their future survival. In situ and ex situ strategies for the conservation of genetic resources of redwoods are discussed in this paper. Although these redwoods are protected in the national parks, reserves, and in privately owned forests in their habitats, it would be desirable to conserve them in new ex situ reserves, and by other ex situ strategies involving biotechnological approaches to preserve seed, tissues, and DNA in gene banks for future exploitations in the face of climate change.