Potential Effects of Climate Change on the Geographic Distribution of the Endangered Plant Species Manihot walkerae

Gisel Garza,Crystian Sadiel Venegas Barrera,Jon Dale,Teresa Patricia Feria Arroyo,Armida Rivera,José Guadalupe Martinez-Ávalos

doi:10.3390/f11060689

Abstract

Walker’s Manihot, Manihot walkerae, is an endangered plant that is endemic to the Tamaulipan thornscrub ecoregion of extreme southern Texas and northeastern Mexico. M. walkerae populations are highly fragmented and are found on both protected public lands and private property. Habitat loss and competition by invasive species are the most detrimental threats for M. walkerae; however, the effect of climate change on M. walkerae’s geographic distribution remains unexplored and could result in further range restrictions. Our objectives are to evaluate the potential effects of climate change on the distribution of M. walkerae and assess the usefulness of natural protected areas in future conservation. We predict current and future geographic distribution for M. walkerae (years 2050 and 2070) using three different general circulation models (CM3, CMIP5, and HADGEM) and two climate change scenarios (RCP 4.5 and 8.5). A total of nineteen spatially rarefied occurrences for M. walkerae and ten non-highly correlated bioclimatic variables were inputted to the maximum entropy algorithm (MaxEnt) to produce twenty replicates per scenario. The area under the curve (AUC) value for the consensus model was higher than 0.90 and the partial ROC value was higher than 1.80, indicating a high predictive ability. The potential reduction in geographic distribution for M. walkerae by the effect of climate change was variable throughout the models, but collectively they predict a restriction in distribution. The most severe reductions were 9% for the year 2050 with the CM3 model at an 8.5 RCP, and 14% for the year 2070 with the CMIP5 model at the 4.5 RCP. The future geographic distribution of M. walkerae was overlapped with protected lands in the U.S. and Mexico in order to identify areas that could be suitable for future conservation efforts. In the U.S. there are several protected areas that are potentially suitable for M. walkerae, whereas in Mexico no protected areas exist within M. walkerae suitable habitat.

Highlights

Anthropogenic activities have had a significant influence on the geographic distribution, rate of extinction, and endangerment of many of the world’s plant species [1]
Occurrence data were obtained from three different sources: (1) Historical populations identified according to Source Features (SF; observations) shapefiles and Element Occurrences (EO) provided by the Texas Natural Diversity Database (TXNDD) (TXNDD 2016)
(2) Non-digital data in the form of reports, handwritten notes, pictures and maps obtained from the Texas Parks and Wildlife Department (TPWD). (3) Shapefiles provided by expert botanists that contain precise latitude and longitude data for parcels within the Lower Rio Grande Valley National Wildlife Refuge

Summary

Introduction

Anthropogenic activities have had a significant influence on the geographic distribution, rate of extinction, and endangerment of many of the world’s plant species [1]. These activities have led to the fragmentation and destruction of plant habitats, as well as the introduction of invasive competitors and Forests 2020, 11, 689; doi:10.3390/f11060689 www.mdpi.com/journal/forests. Invasive plant species that find higher temperatures favorable are expanding in range and out-competing native species [9], while many endemic plants are projected to lose their suitable habitat and are facing extinction. For endemic plants that are already faced with habitat fragmentation and competition by invasive species, climate change could act as a catalyst for extinction [6,9,11,12,13]

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Conclusion