Benjamin Deloso, University of Guam Cycad Biologist measures the size of the male cone of Cycas micronesica plants 15 years old at the Montgomery Botanical Center Miami. Because Guam's trees are severely damaged by invasive insects, the University of Guam is investigating pollination biology of this Florida tree. Credit: Montgomery Botanical CenterThe 15-year-old reciprocal transplant study of Guam's native Cycas micronesica tree by the Plant Physiology Laboratory of the University of Guam’s Western Pacific Tropical Research Center revealed that cycads are able to adapt to local soil conditions and this is crucial in their survival rate. Results showed that 70% to 100% of the cycads transplanted under local conditions survived, compared with less than 10% for those transplanted under foreign conditions. The journal Diversity published the article that describes the study.Conservation requires transplantationTo determine the degree of local adaptation, biologists frequently use reciprocal transplant experiments. Conservationists need to have the information they provide in order to make informed management decisions about endangered species.As part of their conservation strategy, natural resource managers may need to transplant threatened species populations. These transplants are often necessary when habitat destruction is unavoidable, as in the case of Guam's ongoing military buildup. The transplantation must be sustainable and regenerative.Benjamin Deloso (UOG Cycad Biologist) stated that since little is known about the local adaptation of threatened tree species, it is important to use translocation sites near the affected habitats. "Most tree species are able to adapt to local conditions. Trees that are planted in conditions other than those of which they are adapted will eventually become unhealthy and die."These methods are not sufficient to ensure the use of a local recipient location. It is necessary to conduct reciprocal transplant experiments in different habitats. This was the Guam Cycad study.Study process and the resultsGuam's island is similar to other islands in that some soils are derived by volcanic activity, while others are derived form historical oceanic reef activity that was tectonically elevated. Guam's northern soils tend to be alkaline and porous. Guam's south soils, however, are more acidic and less porous.The sibling plantings were done in two locations, one in the North and the other in the South of Guamto both locations. The plants were kept in check for 15 years. Each year, the maximum length, stem height, diameter, leaf number and leaf number were measured. Both locations showed that the local genotypes far outperformed foreign genotypes in terms survival and growth. The Southern site had 100% survival, while the Northern site was 70%. The survival rate of foreign genotypes declined by four years and fell to less than 10% by 2015.Deloso stated that "the chemical and hydrological characteristics of these soil types are highly contrasted, and this study to reveal localized adaption of the cycad populations to the different soils is not surprising." "But, as with all predictions in science, the answer is not known until the study has been funded, designed, implemented, and published.Application to ongoing activitiesThe results of the study can be easily applied to Guam's current conservation efforts. The military buildup has destroyed thousands of endangered Cycad trees from forests. Tree rescue projects that cost a lot of money are funded as part of construction budgets.According to the UOG study, the best habitat for the cycad is one that has forest conditions similar to the habitat that was destroyed. One of the most successful transplant projects to date was done at a heavily disturbed site. Invasive trees have caused soil conditions that are different from the construction site. This indicates that the conservation project's long-term success is unlikely.To accurately measure success, long-term monitoring is necessaryIt is necessary to assess and monitor the success of transplantation over a longer period of time, according to the study. The paper claims that if this project had been completed in the usual one to three year period for most public-funded projects, it would have shown no local adaptation. Local adaptation was not evident at the two Cycas micronesica gardens sites until about four to five years after they were established.Deloso stated that Cycad plants are slow-growing and most growth studies require patience from funders.The researchers recommend that natural resource managers consult cycad experts to help them anticipate future conservation needs. They were the ones who first started collecting cycad seed 11 years before the species was officially listed as endangered. Endangered Species Act was adopted in 2015.Learn more The Cycad branching behavior improves conservationFurther information: Thomas E. Marler's Reciprocal Garden Study Reveals acute Spatial-Edaphic adaptation for Cycas micronesica. Diversity (2021). Thomas E. Marler: Reciprocal Gardens Study Reveals An Acute Spatial–Edaphic Response for Cycas micronesica (2021). DOI: 10.3390/d13060237
