Leaf trait co-ordination in relation to construction cost, carbon gain and resource-use efficiency in exotic invasive and native woody vine species

Background and Aims: Success of invasive plant species is thought to be linked with their higher leaf carbon fixation strategy, enabling them to capture and utilize resources better than native species, and thus pre-empt and maintain space. However, these traits are not well-defined for invasive woody vines. Methods: In a glass house setting, experiments were conducted to examine how leaf carbon gain strategies differ between non-indigenous invasive and native woody vines of south-eastern Australia, by investigating their biomass gain, leaf structural, nutrient and physiological traits under changing light and moisture regimes. Key Results: Leaf construction cost (CC), calorific value and carbon : nitrogen (C : N) ratio were lower in the invasive group, while ash content, N, maximum photosynthesis, light-use efficiency, photosynthetic energyuse efficiency (PEUE) and specific leaf area (SLA) were higher in this group relative to the native group. Trait plasticity, relative growth rate (RGR), photosynthetic nitrogen-use efficiency and water-use efficiency did not differ significantly between the groups. However, across light resource, regression analyses indicated that at a common (same) leaf CC and PEUE, a higher biomass RGR resulted for the invasive group; also at a common SLA, a lower CC but higher N resulted for the invasive group. Overall, trait co-ordination (using pair-wise correlation analyses) was better in the invasive group. Ordination using 16 leaf traits indicated that the major axis of invasive-native dichotomy is primarily driven by SLA and CC (including its components and/or derivative of PEUE) and was significantly linked with RGR. Conclusions: These results demonstrated that while not all measures of leaf resource traits may differ between the two groups, the higher level of trait correlation and higher revenue returned (RGR) per unit of major resource need (CC) and use (PEUE) in the invasive group is in line with their rapid spread where introduced.

Anise Myrtle (Syzygium anisatum) Oils

Syzygium anisatum (formerly Backhousia anisata and Anetholea anisata) is an Australian rainforest tree with leaves that produce an essential oil (EO) that has the characteristic aroma of aniseed. It is referred to as aniseed myrtle or anise myrtle in the trade and the fresh and dried leaves of this plant are used as a herb in culinary applications. The EO is extracted by steam distillation of the leaves and the major aromatic volatile compound is anethole. The EO has broad spectrum antimicrobial activity but is more effective against bacteria than fungi. Indigenous Australians have used anise myrtle for its medicinal values and in recent times it has been used as a flavoring agent by the food and beverage industry. This chapter covers the use of anise myrtle EO in food and agricultural applications, botanical aspects, and chemical composition.

Lemon Myrtle (Backhousia citriodora) Oils

Lemon myrtle has been traditionally used by indigenous Australians for cooking and healing. More recently, lemon myrtle leaves are used as a dry or fresh herb in food applications and the essential oil (EO) used as a flavoring agent in food and beverages. The leaf of the lemon myrtle (Backhousia citriodora) is steam distilled to produce the EO. Lemon myrtle EO is known for its characteristic lemon flavor and the major chemical component contributing to the aroma is citral. The EO has broad spectrum antimicrobial activity and is very effective against fungi and has increased the potential of using the EO in food preservation and treatment of postharvest diseases in fruits. This chapter covers the use of lemon myrtle EO in food and agriculture applications, general usage, botanical aspects, and chemical composition.

Tasmanian Pepper Leaf (Tasmannia lanceolata) Oils

Tasmannia lanceolata, commonly known as Tasmanian pepper leaf or mountain pepper, is an Australian native plant that produces an essential oil with a characteristic pungent flavor attributed to the sesquiterpene polygodial. The dried and fresh leaves are used in culinary applications. The essential oil is produced by a solvent extraction process, and the resultant concrete is a rich source of the principal pungent molecule polygodial and other volatiles. The Tasmanian pepper leaf extract has broad-spectrum antimicrobial activity and is very effective against fungi, especially yeasts. This demonstrates its potential to be used in the food industry as a natural preservative. Indigenous Australians have used Tasmanian pepper leaves for therapeutic purposes; in recent times, it is been used as a flavoring agent and enhancer of pungency in food products. This chapter covers the use of Tasmanian pepper leaf essential oil in food applications, its botanical aspects, and its chemical composition.