Is an invasive species a notorious invader or carbon sequencer?

Abstract

Non-native species invading habitats often cause ecosystem damage and biodiversity losses. Elevating temperature and CO₂ concentrations promote the invasiveness that is highly associated with the nitrogen fixation rates and traits that foster the adaptation of the non-native species, resulting in invasive plants as a cosmopolitan problem. Nevertheless, recent studies revealed a high carbon sequestration capacity of invasive plants in land and coastal habitats, arousing a question if invasive plants always a notorious invader. Badlands are characterized with poor soil development and nutrition, which restrict the growth of plants and soil microbes. Interestingly, leguminous plant with symbiotic nitrogen-fixation bacteria help them explore habitats with low nutrition. Leucaena with high seed yields and deep roots acts as a pioneer in badland ecosystems, usually forming a dominant vegetation with bamboos. Roots exudates likely attract microbes beneficial to the plant growth. Even so, microbial metabolism and respiration tend to increase the CO₂ emission from the soils. Nevertheless, biologists discovered that carbon precipitated by roots is more effective in forming mineral-associated soil organic carbon than leaf and root litter inputs. Soil microbial biomass ultimately transforms into necromass with specific properties, constituting an important source of soil organic matter, which compensates largely the CO₂ from microbial metabolism. Furthermore, deep roots of Leucaena likely interact with soil microbes through various biogeochemical processes, promoting soil formation, altering rocks and soil minerals, and providing carbon to deeper layers. From the viewpoint of carbon sequestration, invasive Leucaena can make more significant contribution to the badland ecosystem than native species.