Model experiment helped to determine the mechanisms by which invasive plants successfully fixed in the new territories: this is a speed dial aboveground biomass, returning it to the soil and microbial mineralisation, and the ability of nitrogen fixation and an increase in microbial biomass in the rhizosphere. According to a study published in the journal Science, thanks to these features woody invasive nitrogen-fixing bacteria (in particular — silver wattle) have a great potential for land reclamation and combating climate change.
It is known that invasion of plant species transformerait ecosystems on the planet, and therefore have an impact on the carbon cycle, and therefore can be useful (or, conversely, dangerous) in the context of climate change. Thus, scientists have linked the biogeochemical role with the accelerated recruitment of biomass and its return to the soil.
However, the research of the quantitative characteristics of these processes was very small, and such aspects as the change in microbiome in the rhizosphere, the impact on nitrogen fixation and the mineralization of organic matter, biotic interactions with herbivores was almost neglected by scientists. Meanwhile, it is important to understand the biogeochemical cycles that involve invasive species, to understand how to deal with them, or how and where to use them for good.
Scientists led by Lauren Waller (Waller Lauren) from the University of Lincoln investigated the material flows and cycles of elements which change under the influence of invasive species in ecosystems in New Zealand. To do this, they conducted a simulation experiment, creating 160 controlled ecosystem that grows in different proportions 19 of 20 invasive and native species — among them was as woody and herbaceous, and among the invasive was and nitrogen-fixing bacteria, a rare new Zealand flora.
Each community was realized as mezokosm (artificially controlled ecosystem) in a container with a volume of 125 liters. Previously plants of each species were collected in natural environment together with the surrounding their roots to the native soil and were grown in two-gallon containers for 9-10 months to ensure the safety of species-specific soil biota that accompanies each plant. The pots were added to the populations of herbivorous invertebrates, bacteria, fungi, oomycetes and nematodes to model important ecological Guild. All mesocosm was sealed in a metal grid with small cells to hold the pilot in invertebrates and to prevent the penetration of others.
In each model system the following parameters were measured: aboveground and underground biomass of plants, biomass of soil bacteria, mycorrhizal fungi and grazing animals, soil respiration, the amount of organic matter in the soil and the rate of mineralization of organic residues. Plants have also recorded square leaf plates, root length and the rate of growth of aboveground and underground biomass.