Effectiveness of water-saving technologies during early stages of restoration of endemic Opuntia cacti in the Galápagos Islands, Ecuador

Patricia Isabela Tapia; Luka Negoita; James P Gibbs; Patricia Jaramillo

doi:10.7717/peerj.8156

Effectiveness of water-saving technologies during early stages of restoration of endemic Opuntia cacti in the Galápagos Islands, Ecuador

PeerJ. 2019 Dec 3:7:e8156. doi: 10.7717/peerj.8156. eCollection 2019.

Authors

Patricia Isabela Tapia^#^{1

2}, Luka Negoita^#², James P Gibbs³, Patricia Jaramillo^{2

4}

Affiliations

¹ School of Natural and Environmental Sciences, Newcastle University, Newcastle Upon Tyne, Tyne and Wear, United Kingdom.
² Charles Darwin Research Station, Charles Darwin Foundation, Santa Cruz, Galápagos, Ecuador.
³ Department of Environmental and Forest Biology, State University of New York, Syracuse, NY, United States of America.
⁴ Facultad de Ciencias, Universidad de Málaga, Málaga, Spain.

^# Contributed equally.

Abstract

Restoration of keystone species is a primary strategy used to combat biodiversity loss and recover ecological services. This is particularly true for oceanic islands, which despite their small land mass, host a large fraction of the planet's imperiled species. The endemic Opuntia spp. cacti are one example and a major focus for restoration in the Galápagos archipelago, Ecuador. These cacti are keystone species that support much of the unique vertebrate animal community in arid zones, yet human activities have substantially reduced Opuntia populations. Extreme aridity poses an obstacle for quickly restoring Opuntia populations though water-saving technologies may provide a solution. The aim of this study was to evaluate current restoration efforts and the utility of two water-saving technologies as tools for the early stages of restoring Opuntia populations in the Galápagos archipelago. We planted 1,425 seedlings between 2013 and 2018, of which 66% had survived by the end of 2018. Compared with no-technology controls, seedlings planted with Groasis Waterboxx^® water-saving technology (polypropylene trays with water reservoir and protective refuge for germinants) had a greater rate of survival in their first two-years of growth on one island (Plaza Sur) and greater growth rate on four islands whereas the "Cocoon" water-saving technology (similar technology but made of biodegradable fiber) did not affect growth and actually reduced seedling survival. Survival and growth rate were also influenced by vegetation zone, elevation, and precipitation in ways largely contingent on island. Overall, our findings suggest that water-saving technologies are not always universally applicable but can substantially increase the survival and growth rate of seedlings in certain conditions, providing in some circumstances a useful tool for improving restoration outcomes for rare plants of arid ecosystems.

Keywords: Adaptive management; Conservation; Galápagos Islands, Ecuador; Groasis waterboxx; Islands; Keystone species; Opuntia echios; Opuntia megasperma; Restoration; Water-saving technology.

Grants and funding

Funding was provided by the COmON Foundation, The Leona M and Harry B. Helmsley Charitable Trust, and the BESS Forest Club. There was no additional external funding received for this study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.