Impacts of invasive Australian acacias: implications for management and restoration
Date
2011
Journal Title
Journal ISSN
Volume Title
Publisher
Blackwell Publishing Ltd
Abstract
Aim The biophysical impacts of invasive Australian acacias and their effects on
ecosystem services are explored and used to develop a framework for improved restoration practices.
Location South Africa, Portugal and Chile.
Methods A conceptual model of ecosystem responses to the increasing severity
(density and duration) of invasions was developed from the literature and our
knowledge of how these impacts affect options for restoration. Case studies are
used to identify similarities and differences between three regions severely affected by invasions of Australian acacias: Acacia dealbata in Chile, Acacia longifolia in Portugal and Acacia saligna in South Africa.
Results Australian acacias have a wide range of impacts on ecosystems that increase with time and disturbance, transform ecosystems and alter and reduce ecosystem service delivery. A shared trait is the accumulation of massive seed banks, which enables them to become dominant after disturbances. Ecosystem
trajectories and recovery potential suggest that there are important thresholds in
ecosystem state and resilience. When these are crossed, options for restoration are
radically altered; in many cases, autogenic (self-driven and self-sustaining) recovery to a pre-invasion condition is inhibited, necessitating active intervention to restore composition and function.
Main conclusions The conceptual model demonstrates the degree, nature and reversibility of ecosystem degradation and identifies key actions needed to restore
ecosystems to desired states. Control and restoration operations, particularly active restoration, require substantial short- to medium-term investments, which can reduce losses of biodiversity and ecosystem services, and the costs to society in the long term. Increasing restoration effectiveness will require further research
into linkages between impacts and restoration. This research should involve
scientists, practitioners and managers engaged in invasive plant control and
restoration programmes, together with society as both the investors in, and
beneficiaries of, more effective restoration.
Description
Keywords
Acacia, biodiversity loss, biological invasions, degradation ecology, ecosystem functions, ecosystem services, impact mechanisms, invasive species, seed banks, soil nutrients
Citation
Le Maitre, D.C.; Gaertner, M.; Marchante, E.; Ens, E.-J.; Holmes, P.M.; Pauchard, A.; O'Farrell, P.J.; Rogers, A.M.; Blanchard, R.; Blignaut, J. and Richardson, D.M. (2011) Impacts of invasive Australian acacias: implications for management and restoration. Diversity and Distributions, 17, 1015-1029