Vegetation dynamics in water-limited ecosystems

Drylands are home to approximately 35% of the world’s population and cover about 40% of Earth’s land surface, often in developing countries where the economy and human well-being strongly depend on ecosystem services. Therefore, understanding dryland dynamics and, more specifically, predicting and mitigating their response to ongoing climate change is a critical ecological and socio-economic issue. Around the globe, dryland vegetation often forms regular spatial patterns such as rings, spots, and stripes. Many theoretical studies proposing different pattern-forming mechanisms suggest that pattern shapes indicate proximity to desertification transitions, as plants tend to self-organize into specific spatial configurations to optimize the use of what little water is available and ensure survival. However, none of these studies has established a direct connection between pattern-forming mechanisms and ecosystem-level consequences when drylands approach desertification transitions. For the last few years, we have developed a bottom-up approach, combining mathematical modeling, greenhouse experiments, and field and satellite data analysis to describe vegetation dynamics in drylands. We have worked at all relevant scales, from individual plants to the whole ecosystem. At the plant individual level, our work has revealed the mechanisms that drive belowground plant competition and how these lead to different spatial distributions of root biomass and plant-level patterns of root biomass allocation.This work resolved a long-standing debate about the key drivers of below-ground plant interactions, and you can learn more about these results in this outreach movie. At the ecosystem level, we tested model predictions on the consequences of vegetation patterning using satellite images from Sudan and remotely sensed time series of vegetation biomass and precipitation intensity.

Selected references:

Martinez-Garcia, R., et al. (2023). Integrating theory and experiments to link local mechanisms and ecosystem-level consequences of vegetation patterns in drylands. Chaos, Solitons & Fractals, 166, 112881.
Cabal C., Maciel G.A., Martinez-Garcia R., (2023) The evolutionary stability of plant antagonistic facilitation across environmental gradients and its ecological consequences: soil resource engineering as a case study. bioRxiv 2023.02.05.527181.
Veldhuis, M. P., Martinez‐Garcia, R., Deblauwe, V., & Dakos, V. (2022). Remotely‐sensed slowing down in spatially patterned dryland ecosystems. Ecography, 2022(10), e06139.
Cabal, C., Martínez-García, R., de Castro Aguilar, A., Valladares, F., & Pacala, S. W. (2020). The exploitative segregation of plant roots. Science, 370(6521), 1197-1199.