Aim  To examine the different uses and perceptions of introduced Australian acacias (wattles; Acacia subgenus Phyllodineae) by rural households and communities. Location  Eighteen landscape‐scale case studies around the world, in Vietnam, India, Réunion, Madagascar, South Africa, Congo, Niger, Ethiopia, Israel, France, Portugal, Brazil, Chile, Dominican Republic and Hawai‘i. Methods  Qualitative comparison of case studies, based on questionnaire sent to network of acacia researchers. Information based on individual knowledge of local experts, published and unpublished sources. Results  We propose a conceptual model to explain current uses and perceptions of introduced acacias. It highlights historically and geographically contingent processes, including economic development, environmental discourses, political context, and local or regional needs. Four main groupings of case studies were united by similar patterns: (1) poor communities benefiting from targeted agroforestry projects; (2) places where residents, generally poor, take advantage of a valuable resource already present in their landscape via plantation and/or invasion; (3) regions of small and mid‐scale tree farmers participating in the forestry industry; and (4) a number of high‐income communities dealing with the legacies of former or niche use of introduced acacia in a context of increased concern over biodiversity and ecosystem services. Main conclusions  Economic conditions play a key role shaping acacia use. Poorer communities rely strongly on acacias (often in, or escaped from, formal plantations) for household needs and, sometimes, for income. Middle‐income regions more typically host private farm investments in acacia woodlots for commercialization. Efforts at control of invasive acacias must take care to not adversely impact poor dependent communities.

Aim Many Australian Acacia species have been planted around the world, some are highly valued, some are invasive, and some are both highly valued and invasive. We review global efforts to minimize the risk and limit the impact of invasions in this widely used plant group.Location Global.Methods Using information from literature sources, knowledge and experience of the authors, and the responses from a questionnaire sent to experts around the world, we reviewed: (1) a generalized life cycle of Australian acacias and how to control each life stage, (2) different management approaches and (3) what is required to help limit or prevent invasions.Results Relatively few Australian acacias have been introduced in large numbers, but all species with a long and extensive history of planting have become invasive somewhere. Australian acacias, as a group, have a high risk of becoming invasive and causing significant impacts as determined by existing assessment schemes. Moreover, in most situations, long-lived seed banks mean it is very difficult to control established infestations. Control has focused almost exclusively on widespread invaders, and eradication has rarely been attempted. Classical biological control is being used in South Africa with increasing success.Main conclusions A greater emphasis on pro-active rather than reactive management is required given the difficulties managing established invasions of Australian acacias. Adverse effects of proposed new introductions can be minimized by conducting detailed risk assessments in advance, planning for on-going monitoring and management, and ensuring resources are in place for long-term mitigation. Benign alternatives (e.g. sterile hybrids) could be developed to replace existing utilized taxa. Eradication should be set as a management goal more often to reduce the invasion debt. Introducing classical biological control agents that have a successful track-record in South Africa to other regions and identifying new agents (notably vegetative feeders) can help mitigate existing widespread invasions. Trans-boundary sharing of information will assist efforts to limit future invasions, in particular, management strategies need to be better evaluated, monitored, published and publicised so that global best-practice procedures can be developed.

Many studies have shown that plant or bird invasions can be facilitated by native species, but few have demonstrated the possibility of a positive interaction between introduced species. We analysed the relationships between four invasive alien fleshy-fruited plants, Clidemia hirta, Rubus alceifolius, Lantana camara, Schinus terebinthifolius, and an invasive alien bird, the red-whiskered bulbul Pycnonotus jocosus introduced to Reunion Island (Indian Ocean). We compared the distribution of food items in the bulbul diet according to seasons and to abundance classes of this bird. Pycnonotus jocosus is mostly frugivorous and frequently eats the main alien plants (more than 80% frequency of food items). Sites with alien species, such as Clidemia hirta, providing fruits throughout the year supported more birds than sites providing fruits, such as Schinus terebinthifolius, seasonally. The birds facilitated seed germination by removing the pulp of fruit: the final per cent germination (FG) of cleaned seeds was higher than those within the fruit for three of the four plant species and in some cases passage through birds significantly increased FG (Schinus terebinthifolius) or Coefficient of Velocity (CV) (Lantana camara).

We present a study of the genetic diversity and structure of a tropical tree in an insular system. Santalum austrocaledonicum is endemic to the archipelago of New Caledonia and is exploited for oil extraction from heartwood. A total of 431 individuals over 17 populations were analysed for eight polymorphic microsatellite loci. The number of alleles per locus ranged from 3 to 33 and the observed heterozygosity per population ranged from 0.01 in Maré to 0.74 in Ile des Pins. The genetic diversity was lowest in the most recent islands, the Loyautés, and highest in the oldest island, Grande Terre, as well as the nearby small Ile des Pins. Significant departures from panmixia were observed for some loci-population combinations (per population F IS = 0 -0.03 on Grande-Terre and Ile des Pins, and 0 -0.67 on Loyautés). A strong genetic differentiation among all islands was observed ( F ST = 0.22), and the amount of differentiation increased with geographic distance in Iles Loyauté and in Grande Terre. At both population and island levels, island age and isolation seem to be the main factors influencing the amount of genetic diversity. In particular, populations from recent islands had large average F IS that could not be entirely explained by null alleles or a Wahlund effect. This result suggests that, at least in some populations, selfing occurred extensively. Conclusively, our results indicate a strong influence of insularity on the genetic diversity and structure of Santalum austrocaledonicum .