Ecosystem engineering and food web stability

Abstract

Ecosystem engineering, which involves organism-triggered physical modification of the environment, is a widespread phenomenon. Despite this, the role of engineering in ecological communities remains poorly understood. This study employs a food web model to uncover the key roles of ecosystem engineering in maintaining food webs. While engineers facilitating population growth and suppressing consumers' foraging activity can help maintain complex communities with diverse species, engineering effects that suppress population growth and facilitate consumers' foraging activity can largely destabilize community dynamics. Furthermore, in the middle levels of engineering-related species within a community, an increase in species richness can increase community stability, contrary to classical ecological prediction. The study findings suggest that ecosystem engineering can explain biodiversity persistence in nature, but it depends on the proportion of engineering-related species and how engineering affects organisms.

Fig. 1

Effects of engineering on community stability. Change in engineering effect on stability with varying (a) proportion of receiver species p_R and (b) proportion of different types of engineering effects (decreasing growth rates q_r and foraging rates q_a). In (a), q_r = 0.2 and q_a = 0.8. In (b), p_R = 0.3. A random food web is assumed. N = 60 and C = 0.1.

Fig. 2

Effects of engineering on a complexity–stability relationship. Colors represent the levels of species richness. (a) p_R = 0.1. (b) p_R = 0.2. (c) p_R = 0.5. A random food web is assumed. The parameters are q_r = 0.2, q_a = 0.8, and C = 0.1.

Fig. 3

Effects of engineering dominance on a complexity–stability relationship. Kendall’ Tau was calculated between (N = 20, 40, 60, 80, 100) and each persistence value, depending on combinations of parameters (p_E and p_R), serving as an index of the relationship between complexity and stability. Data for N = 10, exhibiting higher stability, were excluded due to the potential masking effect of a “concave upward pattern” on the positive correlation, despite a strong positive complexity-stability relationship. Contours depict Kendall’s Tau values ranging from − 1 to 1, where negative values indicate a negative complexity-stability relationship, positive values indicate a positive complexity-stability relationship, and a dashed line represents no correlation (0). The left and right green lines denote different engineering dominance values (p_Ep_R), 0.03 and 0.16, respectively.