Effects of simulated climate change on soil characteristics under Carpobrotus edulis invasion in a coastal backdune

Abstract

Background and aims Along coastal habitats worldwide, Carpobrotus edulis is a highly invasive and detrimental species, that acts as an ecosystem engineer by modifying many soil properties for its own benefit. However, the combined effects of C. edulis and climate change on soil characteristics remain largely unknown.

Methods To address this knowledge gap, we set up a factorial field experiment with five treatments and eight replicates per treatment: natural vegetation as an uninvaded control under current climate conditions, C. edulis under current climate conditions, and C. edulis subjected to increased temperature (+ 2 ºC), decreased rainfall (- 33%), and both factors combined (+ 2 ºC and - 33% rainfall). The soil 0–5 and 5–10 cm layers were sampled after 14 months and analysed for 21 properties.

Results Although the effect of depth on soil characteristics was greater in most cases, the treatments significantly affected soil pHKCl, electrical conductivity, organic δ13C, NH4+-N, NO3−-N and available Al, Ca, Cu, Fe, Mg, Mn, P, and Zn. The discriminant analyses clearly differentiated the invaded from the uninvaded soils, reinforcing the view of C. edulis as an ecosystem engineer and highlighting the significant role of the species in shaping ecosystem dynamics. Besides, the analyses indicated that decreased precipitation had a greater impact on invaded soils than increased temperature, and suggested a synergistic effect of both climatic treatments.

Conclusion These findings underline the complex interactions between invasive species and climate change, highlighting the need for specific management strategies to mitigate C. edulis impacts on soil health and ecosystem integrity.