Abstract Detail

Conservation Biology

Cronk, Quentin [1].

Extinction dynamics of island plants with particular reference to St Helena: modelling the past and predicting the future.

Only 3.5% of the land area of St Helena still remains as suitable habitat for the endemic plants, due to threats such as introduced invasive plants, pests and mammalian herbivores. Numerous endemic plant species have become extinct, and extinction can be divided into three broad phases: (1) The pre-historical phase between 1502 and 1771, i.e. after the discovery of the island by humans but before scientific recording; (2) the historical phase, from the visit of Banks and Solander during Cook's first voyage in 1771 to the present, and (3) the future. During the historical phase we know that there have been 8 plant extinctions, an extinction rate of 581 E/MSY. In addition there are likely to have been "dark extinctions": unknown historical extinctions, i.e. the extinction of species before they are discovered and named. Using extinction modelling we can estimate that there were c. 10 dark extinctions during the pre-historical phase, and c. 1 dark extinction in the historical phase. Forward modelling of extinction from simple plant demographic parameters suggests that over the next two hundred years extinction will continue (at a rate of c. 625 E/MSY). Despite recent advances in many areas of extinction science, particularly around the concept of "extinction debt", we still lack a general theory of extinction. I will discuss what such a theory will need to include and what it will need to do.

1 - Department Of Botany, Room #3200 - 6270 University Boulevard, Vancouver, BC, V6T 1Z4, Canada

Keywords:
conservation
Extinction
invasive plants
island biology
dark extinction.

Presentation Type: Oral Paper
Session: CB01, Conservation Biology 1
Location: /
Date: Wednesday, July 21st, 2021
Time: 10:00 AM(EDT)
Number: CB01001
Abstract ID:137
Candidate for Awards:None