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Abstract Detail



Conservation Biology

Lawson, Dawn [1], Vanderplank, Sula [2], Falcone, Erin [3], Jacobsen, Jeff [4], Ezcurra, Exequiel [5].

Assessing vegetation recovery after the removal of non-native herbivores on Isla Clarión.

Clarión Island is a remote island, 700 km (436 mi) from the Mexican mainland (and 314 km (195 mi) from the nearest island, Socorro). The island is almost 20 square kilometers in area (8 mi2), and reaches a maximum elevation of 335 m (1,100 ft) at Monte Gallegos. It was first discovered in 1542; rabbits and sheep were introduced in 1979, and pigs in 1991. The flora of Clarión Island today includes more than 50 species with 4 single-island endemic taxa. In 1999 the vegetation of Clarión Island was systematically surveyed using 0.10 acre circle plots, along transects of regular interval across the entire island, for a total of 48 vegetation plots. The rabbits remain on Clarión island, but Island Conservation Group and the Mexican Government worked together to successfully eradicate the sheep and pigs in 2002. In February of 2017, 56% (27/48) of the plots were re-surveyed using the same methodologies. While there appear to be significant increases in cover over the past 18 years, the non-native buffel grass (Cenchrus ciliare) accounts for a large portion of the increase and the non-native puncture vine (Tribulus cistoides) was the most abundant species in the plots resampled. However, the most abundant natives, Brickellia peninsularis and Waltheria indica, were dominant in many of the plots sampled. Despite high beta diversity, the landscape is dominated by habitat patches of low diversity. A vegetation map of the island was created from the 2017 data and additional observation points. A new vegetation map for Clarión Island is here presented, and it is hoped that the vegetation can again be re-surveyed when the non-native rabbits are also removed. These results highlight the detrimental impact of non-native herbivores on island ecosystems, and the recovery that ensues when they are removed. Non-native plant taxa continue to threaten the biodiversity of Clarión Island, particularly buffel grass (Cenchrus ciliare), and puncture vine (Tribulus cistoides).


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1 - San Diego State University, Biology Department, 5500 Campanile Dr, San Diego, CA, 92182, USA
2 - Botanical Research Institute of Texas, 1700 University Drive, Fort Worth, TX, 76107, United States
3 - Marine Ecology and Telemetry Research, 2420 Nellita Rd NW , Seabeck, WA, USA
4 - Humboldt State University, Biological Sciences, CA, USA
5 - University of California, Riverside, Institute for Mexico and the United States, Riverside, CA, USA

Keywords:
none specified

Presentation Type: Oral Paper
Number: 39004
Abstract ID:491
Candidate for Awards:None


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