Sunday, 6 July 2014

More than life or death, part II: plant reintroduction monitoring

After writing about the problems associated with relying on basic demographic parameters for evaluating animal reintroduction projects, in this post I'll be looking more closely at how plant translocations can be more accurately monitored and evaluated by using a more nuanced set of indicators than just survival alone.  Although this post was prompted by a recent commentary by Ed Guerrant on the conclusions of three recent reviews of plant reintroductions (one being mine, another by Ed and a third by Sandrine Godefroid and co-authors, all citations below), I wanted to look again at an older publication by Bruce Pavlik from 1996. Ed's commentary quite rightly encourages people undertaking plant conservation translocations to use several measures as indicators of success, namely abundance, extent, persistence and resilience proposed by Pavlik in the Center for Plant Conservation volume Restoring Diversity. As with many messages from this book, I am disheartened that there has not been wider uptake of the recommendations especially considering that it is now 18 years since publication.

Pavlik's description of the four indicators of success are useful because he adds valuable extra detail to the main indicators conveying the complexity of measuring the success of a plant translocation.  He described abundance as incorporating establishment, vegetative growth, fecundity and population size.  I am sure that I am not alone in relying the the last measure rather too heavily in the past. The measure of extent constitutes number and distribution of populations but also importantly, includes dispersal.  Resilience results from genetic diversity, resistance to perturbation and dormancy - an avoidance technique particularly useful for plants in strongly fluctuating environments. And finally, persistence is characterized as self-sustainability where the effective (reproducing) population is a realtively large proportion of the overall population size, the ability to utilise more than one microhabitat, and the extent of community 'membership' i.e., are pollinating insects present, has the species become assimilated into a diverse community, and are seed dispersal vectors operating properly?

As Pavlik states, "success cannot come without risk", so indicators of success must be nuanced enough that we can work out where the risk is felt most keenly.  As someone who has based large reviews of reintroductions on coarse measures of presence or absence, I have found that survival only tells a very small part of the story and without a selection of indicators across the four headings described by Pavlik, causes for failure cannot be discerned and adaptive management cannot be undertaken.

Godefroid S, Piazza C, Rossi G, Buord S, Stevens AD, Aguraiuja R, Cowell C, Weekley CW, Vogg G, Iriondo JM, Johnson I, Dixon B, Gordon D, Magnanon S, Valentin B, Bjureke K, Koopman R, Vicens M, Virevaire M, Vanderborght T. 2011. How successful are plant species reintroductions? Biol. Conserv. 144(2): 672-682.

  • Guerrant, E.O., Jr. 2012. Characterizing two decades of rare plant reintroductions. In Plant reintroduction in a changing climate: promises and perils. Edited by J. Maschinski and K.E. Haskins. Island Press, Washington, D.C. pp. 9–29.
Guerrant, E. O. (2013). The value and propriety of reintroduction as a conservation tool for rare plants. Botany, 91 (5): v–x.

  • Pavlik, B.M. 1996. Defining and measuring success. In Restoring diversity: Strategies for the reintroduction of endangered species. Edited by D.A. Falk, C.I. Millar, and M. Olwell. Island Press, Washington, D.C. pp. 127–156.

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