Strategies for conservation of germplasm in endemic redwoods in the face of climate change: a review

Abstract

This study reviews the various conservation strategies applied to the four redwood species, namely coast redwood (Sequoia sempervirens), Sierra redwood or giant sequoia (Sequoiadendron giganteum), dawn redwood (Metasequoia glyptostroboides) and South American redwood or alerce (Fitzroya cupressoides), which are endemic in the USA, China and South America, respectively. All four redwood genera belong to the family Cupressaceae; they are monospecific, share a number of common phenotypic traits, including red wood, and are threatened in their native ranges due to human activity and a changing climate. Therefore, the management objective should be to conserve representative populations of the native species with as much genetic diversity as possible for their future survival. Those representative populations exhibiting relatively high levels of genetic diversity should be selected for germplasm preservation and monitored during the conservation phase by using molecular markers. In situ and ex situ strategies for the preservation of germplasm of the redwoods are discussed in this study. A holistic in situ gene conservation strategy calls for the regeneration of a large number of diverse redwood genotypes that exhibit adequate levels of neutral and adaptive genetic variability, by generative and vegetative methods for their preservation and maintenance in their endemic locations. At the same time, it would be desirable to conserve the redwoods in new ex situ reserves, away from their endemic locations with similar as well as different environmental conditions for testing their growth and survival capacities. In addition, other ex situ strategies involving biotechnological approaches for preservation of seeds, tissues, pollen and DNA in genebanks should also be fully exploited in the face of global climate change.

Genetic structure of coast redwood (Sequoia sempervirens [D. Don] Endl.) populations in and outside of the natural distribution range based on nuclear and chloroplast microsatellite markers

“…The combination of low sexual reproduction and local adaptation could cause insufficient ability to meet the challenges of climate change and will increase the pressure on coast redwood [ 9 ]. California has become drier in the last 2000 years [ 16 ], and the very important fog has been declining in its frequency during the last century [ 39 , 103 ].…”

“…is one of the four redwood species in the Cupressaceae family [8]. All four are characterized by a particular red coloured wood, an endemic narrow natural distribution range, and are listed as threatened or endangered by the International Union for Conservation of Nature (IUCN) [8,9]. Coast redwood stands out from the other three redwood species due to its valuable wood, high growth rate and natural vegetative reproduction [10][11][12].…”

Fate of forest tree biotechnology facing climate change

“…3 B) in a hormone-free medium, and ex vitro in a peat-perlite potting mixture, and later the young plants were grown in the greenhouse (Fig. 3 C) (Ahuja, 1996(Ahuja, , 2011a. More than 1000 plants were produced from the three trees by tissue culture, and several hundred clones were tested under field conditions for testing their overwintering capacity.…”

“…However, under field conditions at Trenthorst, only those clones survived that were sheltered by a tree canopy towards the edge of the field. Therefore, sheltering of Sequoia clones derived from frost-tolerant trees were necessary during several years of their early growth period for their later survival in harsh winters in temperate climate zones (Ahuja, 1996(Ahuja, , 2011a(Ahuja, , 2017.…”