DOI: 10.5061/dryad.brv15dv92
title: Energetic constraints imposed on trophic interaction strengths enhance resilience in empirical and model food webs

description: 1. Food web stability and resilience are at the heart of understanding the
 structure and functioning of ecosystems. Previous studies show that models
 of empirical food webs are substantially more stable than random ones, due
 to a few strong interactions embedded in a majority of weak interactions.
 Analyses of trophic interaction loops show that in empirical food webs the
 patterns in the interaction strengths prevent the occurrence of
 destabilizing heavy loops and thereby enhances resilience. Yet, it is
 still unexplored which biological mechanisms cause these patterns that
 enhance food web resilience. 2. We quantified food web resilience using
 the real part of the maximum eigenvalue of the Jacobian matrix of the food
 web from a seagrass bed in the Yellow River Delta (YRD) wetland, that
 could be parameterized by the empirical data of the food web. 3. We found
 that the empirically based Jacobian matrix of the YRD food web indicated a
 much higher resilience than random matrices with the same element values
 but arranged in random ways. Investigating the trophic interaction loops
 revealed that the high resilience was due to a negative correlation
 between the negative and positive interaction strengths (per capita
 top-down and bottom-up effects, respectively) within positive feedback
 loops with three species. The negative correlation showed that when the
 negative interaction strengths were strong the positive was weak, and vice
 versa. 4. Our invented reformulation of loop weight in terms of biomasses
 and specific production rates showed that energetic properties of the
 trophic groups in the loop and mass-balance constraints, e.g. the food
 uptake has to balance all losses, created the negative correlation between
 the interaction strengths. This result could be generalized using a
 dynamic intraguild predation model, which delivered the same pattern for a
 wide range of model parameters. 5. Our results shed light on how energetic
 constraints at the trophic group and food web level create a pattern in
 interaction strengths within trophic interaction loops that enhances food
 web resilience.
description: This dataset represents the fluxes, the negative and positive
 interaction strengths, resilience, and trophic interaction loops of the
 food web in the Yellow River Delta wetland, China. Data were processed as
 described in the associated manuscript.
description: Files: 1_Interaction strengths, biomass
 ratios, and fluxes in the food web of Yellow River Delta wetland:
 Representing the biomass ratio between the preator and the prey, the
 negative interaction strength of the predator on the prey, the positive
 interaction strength of the prey on the predator, the flux from the prey
 to the predator for each trophic link in the food web.
 2_Resilience of all random food webs based on the four
 randomizations: Representing the food web resilience quantified by the
 real part of the maximum eigenvalue of all random food webs based on the
 four randomizations described in the associated manuscript. 
 3_Maximum loop weights of all random food webs based on the four
 randomizations: Representing the maximum loop weight of all random food
 webs based on the four randomizations described in the associated
 manuscript.  4_Trophic interaction loops of the food
 web in Yellow River Delta wetland: Representing the results of trophic
 interaction analysis of the food web in the Yellow River Delta wetland.
 Please note that the loop length means the number of species in the loop.
 Here we analysed all loops with length from 3 to 8.
 5_Output of the intraguild predation modelling: Representing the
 results of trophic interaction analysis based on the intraguild predation
 model.