Structural parameters and functional patterns of simulated earthworm burrow systems

Summary Earthworm burrow systems have been simulated by modelling, from field observations, five main characteristics of burrow units: density (number of burrows per unit volume), mean length, angular orientation, middle coordinates and diameter. The functional properties of the burrow systems have been analysed using structural parameters, i. e. number of full perforations, mean available burrow surface and minimal burrow spacing, and by estimating the shortest pathway through the burrow system. The simulations are used to study the effects of each of the main characteristics on structural parameters and the shortest pathway. This work reveals that the specific role of density is to lead to a threshold by determining an optimal horizontal distance, and that the mean length governs the vertical critical dimension of the system. These simulations may be applied to explain the nature of field burrow systems.