The Invasive Woody Weed Ligustrum robustum subsp. walkeri Threatens Native Forests on La Réunion

Authors: Lavergne C.¹; Rameau J-C.²; Figier J.³

Source: Biological Invasions, Volume 1, Number 4, 1999 , pp. 377-392(16)

Publisher: Springer

Abstract:

One of the last primitive island ecosystems in the Indian Ocean has been invaded since 1969 by the Sri Lankan privet, Ligustrum robustum. L. robustum is still spreading in the forests of La Réunion Island, where only 30% of the original vegetation remains, but where 98% of the primary native vegetation of the Mascarene Islands still exists. On Mauritius, where L. robustum was introduced about 1895, it now forms dense, impenetrable thickets, and its presence has been correlated with the inability of native vegetation to re-establish. We assessed the potential impacts of L. robustum invasion on the native ecosystems of La Réunion and identified the factors of invasibility. We determined the degree of invasion in 12 plots of 156 m^2 and followed native flora and privet recruitment for 3 years in 12 seedling plots of 39 m^2. The data show that monocultural L. robustum stands now exist in human-disturbed primary forest patches (3.3 individuals/m^2 and 80% of total individuals) and high seedling densities (0.3–0.6/m^2) occur in the least disturbed patches. L. robustum's rapid growth, high shade tolerance and seed production, bird-assisted seed dispersal and high seedling recruitment contribute to its invasiveness in intact forests. The conservation of the original ecosystems of La Réunion depends on the setting up of a long-term and immediate global control strategy.

Keywords: endangered native ecosystems; invasive alien plant; La Réunion; Ligustrum robustum subsp. walkeri; Mascarene Islands; Mauritius; Sri Lankan privet

Language: English

Document Type: Regular paper

Affiliations: 1: Laboratoire de Recherches en Sciences Forestières (Ecosystèmes Forestiers), Ecole Nationale du Génie Rural des Eaux et Forêts, Centre de Nancy, 14 rue Girardet F-54042 Nancy Cedex, France; Laboratoire de Biologie Végétale, Faculté des Sciences et Technologies, Université de La Réunion, 15 Avenue René Cassin, BP7151, F-97715 Saint-Denis Messag Cedex 9, Ile de La Réunion, France (email: lavergne@univ-reunion.fr; fax: +262-938119) 2: Laboratoire de Recherches en Sciences Forestières (Ecosystèmes Forestiers), Ecole Nationale du Génie Rural des Eaux et Forêts, Centre de Nancy, 14 rue Girardet F-54042 Nancy Cedex, France 3: Laboratoire de Biologie Végétale, Faculté des Sciences et Technologies, Université de La Réunion, 15 Avenue René Cassin, BP7151, F-97715 Saint-Denis Messag Cedex 9, Ile de La Réunion, France

Publication date: 1999-01-01

• In this: publication
• By this: publisher
• In this Subject: Agriculture (General) ,  Anatomy & Physiology ,  Biology ,  Hydraulic & Environmental Engineering
• By this author: Lavergne C. ;  Rameau J-C. ;  Figier J.

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