Soil changes mediated by invasive Australian acacias

Abstract

Invasive Australian acacias can have a great impact on abiotic soil properties and on the structure of soil microbial communities, altering processes and services in the invaded ecosystems. In general, invasive acacias cause a significant increase of litter, carbon and nitrogen contents, alter biogeochemical cycles and reduce water availability in the invaded ecosystems. Invasive acacias also modify the functional and genetic diversity of soil bacterial and fungal communities. Interestingly, there is also a co-invasion of exotic N-fixing bacteria associated with the invasion of some Australian acacias. These exotic microsymbionts can associate with native legumes, therefore disrupting the native legume-rhizobia symbiosis. All these changes in the abiotic and biotic soil properties due to the invasion by Australian acacias can be detrimental for native plant species, decreasing their growth or impairing their performance. In addition, these changes can boost invasion because they have a positive effect on the germination, growth and competitive ability of the exotic acacias. These positive plant-soil feedbacks are maintained over time and can jeopardize the natural recovery of the invaded ecosystems.