PS 62-78 - Demography of an invasive species (Kalanchoe delagoensis) in Northern Mexico

Thursday, August 11, 2011
Exhibit Hall 3, Austin Convention Center
Sylvia Patricia Ruiz-González1, Jordan Goluvob2 and María del Carmen Mandujano Sánchez1, (1)Ecología de la Biodiversidad, Instituto de Ecología, UNAM, Mexico city, Mexico, (2)El hombre y su ambiente, UAM-X, Mexicoo city, Mexico

Invasive species are a major threat to biodiversity because they are able to expand and displace native species driving them to local extinction. The impact is so great that they are considered one of the motors of global change. Demographic studies of invasive species can help us identify the phases of life cycle that present a higher contribution to its population growth rate and thus propose plans for control or eradication. Kalanchoe delagoensis is a succulent plant native to Madagascar, it was brought to the American continent as a garden plant, but it quickly expanded and became invasive due to its ability to spread clonaly through plantlets and its resistance to drought. In this study we describe the demography of a population in Tamaulipas, México. In 2010, eight 30 x 30 cm plots were set within a K. delagoensis population. In each plot, all individual plants were measured (height and tall), and reproductive structures were counted (vegetative and sexual) during two years. 


We found that that population rarely presents sexual reproduction, only five of the 529 individuals measured presented flowers and none had seeds. We divided the population into five categories based on plant size and number of plantlets produced by their leaves. In 2011 one plot was completely destroyed (unknown causes) and another was partially destroyed because grass grew on it. Based on information gathered on preserved plots, matrix population models indicate a growth rate (l) of 1.8 which projects a fast growing population. Elasticity analysis show that growth and reproduction are the demographic processes that have the highest contribution to l, so efforts to eradicate this species should focus on individuals with the higher production of plantlets.

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