Variability in the contribution of different life stages to population growth as a key factor in the invasion success of Pinus strobus.

Zuzana Münzbergová,Věra Hadincová,Jana Kindlmannová,Jan Wild

doi:10.1371/journal.pone.0056953

Abstract

BackgroundDespite the increasing number of studies attempting to model population growth in various organisms, we still know relatively little about the population dynamics of long-lived species that reproduce only in the later stages of their life cycle, such as trees. Predictions of the dynamics of these species are, however, urgently needed for planning management actions when species are either endangered or invasive. In long-lived species, a single management intervention may have consequences for several decades, and detailed knowledge of long-term performance can therefore elucidate possible outcomes during the management planning phase.Methodology and Principal FindingsWe studied the population dynamics of an invasive tree species, Pinus strobus, in three habitat types represented by their position along the elevation gradient occupied by the species. In agreement with previous studies on the population dynamics of long-lived perennials, our results show that the survival of the largest trees exhibits the highest elasticity in all of the studied habitats. In contrast, life table response experiments (LTRE) analysis showed that different stages contribute the most to population growth rates in different habitats, with generative reproduction being more important in lower slopes and valley bottoms and survival being more important on rock tops and upper slopes.ConclusionsThe results indicate that P. strobus exhibits different growth strategies in different habitats that result in similar population growth rates. We propose that this plasticity in growth strategies is a key factor in the invasion success of the white pine. In all of the investigated habitats, the population growth rates are above 1, indicating that the population of the species is still increasing and has the ability to spread and occupy a wide range of habitats.

Highlights

Invasive species are known to have strong effects on native species, communities, and ecosystems, e.g., [1], [2], [3], often having strong economic impacts, e.g., [4], [5]
The results indicate that P. strobus exhibits different growth strategies in different habitats that result in similar population growth rates
The aim of this study is to extend our knowledge of the population dynamics of invasive conifers and describe the spatial and temporal variation in the population dynamics of an invasive tree species, Pinus strobus, in a sandstone area in the Czech Republic, Europe

Summary

Introduction

Invasive species are known to have strong effects on native species, communities, and ecosystems, e.g., [1], [2], [3], often having strong economic impacts, e.g., [4], [5]. Effective control of invasive species requires understanding the mechanisms allowing their populations to grow and spread Such an understanding can be attained by developing models that combine information on local population dynamics with information on the distribution of suitable habitats for the species and its long distance dispersal [7], [6]. There has been an increasing number of studies attempting to model population growth (e.g., [3], [11], [12], [13] and references therein) and to quantify the extent of variation in population dynamics using matrix models, e.g., [14], [15], [16], [17], [18]. In long-lived species, a single management intervention may have consequences for several decades, and detailed knowledge of long-term performance can elucidate possible outcomes during the management planning phase

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