Autochthonous or allochthonous resources determine the characteristic population dynamics of ecosystem engineers and their impacts

作者：Nishijima Shota^*; Takimoto Gaku; Miyashita Tadashi

来源：Theoretical Ecology, 2016, 9(2): 117-127.

DOI：10.1007/s12080-015-0274-8

• Allee effect
• Limit cycle
• Positive feedback
• Resource subsidy
• Runaway growth
• Timescale

Ecosystem engineering, or the modification of physical environments by organisms, can influence trophic interactions and thus food web dynamics. Although existing theory exclusively considers engineers using autochthonous resources, many empirical studies show that they often depend on allochthonous resources. By developing a simple mathematical model involving an ecosystem engineer that modifies the physical environment through its activities, its resource, and physical environment modified by the engineer, we compare the effects of autochthonous and allochthonous resources on the dynamics and stability of community with ecosystem engineers. To represent a variety of real situations, we consider engineers that alter either resource productivity, engineer feeding rate on the resource, or engineer mortality, and incorporate time-lagged responses of the physical environment. Our model shows that the effects of ecosystem engineering on community dynamics depend greatly on resource types. When the engineer consumes autochthonous resources, the community can exhibit oscillatory dynamics if the engineered environment affects engineer's feeding rate or mortality. These cyclic behaviors are, however, stabilized by a slowly responding physical environment. When allochthonous resources are supplied as donor-controlled, on the other hand, the engineer population is unlikely to oscillate but instead can undergo unbounded growth if the engineered environment affects resource productivity or engineer mortality. This finding suggests that ecosystem engineers utilizing allochthonous resources may be more likely to reach high abundance and cause strong impacts on ecosystems. Our results highlight that community-based, compounding effects of trophic and physical biotic interactions of ecosystem engineers depend crucially on whether the engineers utilize autochthonous or allochthonous resources.

• 出版日期2016-6