Assessment of Biodiversity Metacommunity Resilience via Neutral Models

Climate extremes and rapid urbanization are stressors that both shape and threat
ecosystems. For this purpose models that predict reliably the whole ecosystem
dynamics and species persistence time across multiple scales and species are in need.
Here we reproduce biodiversity patterns of the Amazon’s MAP (Madre de Dios - Acre- Pando) tropical rainforest affected by the construction of the transoceanic highway and climate change with a neutral metacommunity model at different scales and resolutions. The influence of environmental variability in species loss and richness increases with scale and decreases with tree clumpiness heterogeneity. At the ecosystem scale drought sensitivity is 37% higher than at the plot scale where the difference in scales is of seven orders of magnitude. Conversely, the anthropic disturbance played by the road is much larger at the plot scale, and undetectable at the ecosystem scale because dispersal is not affected. We predict a loss of 10, 3, and 1 % of species richness per 104 m2 in a drought scenario of 65 % variation in the average annual precipitation for forest plots with low, medium, and heterogeneously high clumpiness. This loss is 54, 21, and 11 % in the scenario where a road is cutting the forest plots in half. Hence, heterogenous clumpiness of trees enhances species richness and resilience of forest plots to natural and human stressors. A non trivial pattern is found between the species cluster size and the persistence time. Bimodal distributions of clumpiness results in highly stable species richness and persistence time distributions. The species persistence time follows a power law function whose exponent increases with the magnitude of disturbance. This power law is preserved together with the distribution of tree cover despite changes in the shape of the species richness distribution.
We propose the product of the persistence time, its probability of occurrence and the average species cluster size as a measure of metacommunity risk of ecosystems as a function of its resilience. A spatial resilience index as ratio of metacommity risks in the disturbed and undisturbed case is calculated to identify the most resilient communities.

Authors: 
Matteo Convertino and James Valverde
Room: 
2
Date: 
Tuesday, September 25, 2018 - 12:00 to 12:15

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