Empirical and virtual investigation of the population dynamics of an alien plant under the constraints of local carrying capacity: Heracleum mantegazzianum in the Czech Republic

Authored by N Nehrbass, E Winkler, J Pergl, I Perglova, P Pysek

Date Published: 2006

DOI: 10.1016/j.ppees.2005.11.001

Sponsors: European Union Academy of Sciences of the Czech Republic

Platforms: No platforms listed

Model Documentation: Other Narrative Flow charts Mathematical description

Model Code URLs: Model code not found

Abstract

During the last decades, invasive alien species have become a global concern because of their ecological and economic impact. Heracleum mantegazzianum (Apiaceae), is a tall monocarpic perennial native to Caucasus and invasive in Europe since the 1950s. Within an interdisciplinary EU project aimed at assessing, suitable management strategy, we analysed the demography and ecology of this species in Its invasive range. The monitoring of population dynamics in the Czech Republic led to the result that in the observed sites the species showed decreasing populations. To find an explanation for this unexpected result, two types of models were parameterized, based on the empirical data: (1) a stage-based transition matrix model, which projected a continuous negative development, and (2) a spatially explicit individual-based model (IBM), including individual variation. This second model was able to create a population with steady individual numbers. Analyses of the simulation showed that in more than 54\% of the simulated years (n 5000) the growth rate was smaller than one. Still.. population increase in the remaining years was sufficient to sustain a population. Nevertheless long-term observations document an invasive behaviour of the observed populations. Hence, we could assume temporal changes in the course of an invasion and thus wanted to evaluate the probability of sampling negative growth in dependence of time since first invasion. By using a method from `Virtual Ecology', we approached the question: first we create an invasive population, based on the empirical data of H. mantegazzianum and second empirical sampling techniques were mimicked using the Virtual Ecologist approach. The results demonstrate how the probability of sampling negative growth increases with time since first invasion. Hence, we assume that the studied populations have already reached a maximum of their local invasive potential and thus stagnate in their size. (c) 2005 Rubel Foundation, ETH Zurich. Published by Elsevier GmbH. All rights reserved.

Tags

Management Conservation ecology patterns Biology Central-europe Invasions Life-history parameters