Weak indirect effects inherent to nitrogen biogeochemical cycling within anthropogenic ecosystems: A network environ analysis

Yong Min, Xiaogang Jin, Jie Chang, Changhui Peng, Baojing Gu, Ying Ge and Yang Zhong

Ecological Modelling, 2011, vol. 222, issue 17, 3277-3284

Abstract: Indirect effects are assumed to be the major causes of the complexity and stability of ecological networks. The complexity of urban–rural complexes (URCs) could also be attributed to the indirect effects associated with human activities. No studies, however, have quantified the strength of indirect effects in relation to urban biogeochemistry. A network environ analysis (NEA) was used for this study to investigate and compare indirect effects in relation to the nitrogen (N) cycling networks of 22 natural ecosystems and five URCs. Results show that indirect effects were proven to be weak for URC N cycling networks (accounting for only ∼2% of the overall effects measured in natural ecosystems). The weak indirect effects found provide a counterexample for the hypothesis that indirect effects are in fact the dominant components of biogeochemical networks. It also implies that human activity in itself does not always raise the complexity of ecological processes as previously suggested. Weak indirect effects also lead to perturbation fragility for URC N cycles (where the decay rate is greater in comparison to natural ecosystems by a factor of 13). In order to improve the robustness and efficiency of URC biogeochemical cycling, a knockout analysis was carried out. By comparing results after removing single interactions between natural ecosystems and URCs it was found that the loss of indirect effects require cooperative strategies to optimize N cycling networks within URCs.

Keywords: Cascading effects; Complexity; Fragility; Urban; Ecological network (search for similar items in EconPapers)
Date: 2011
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Citations: View citations in EconPapers (4)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:ecomod:v:222:y:2011:i:17:p:3277-3284

DOI: 10.1016/j.ecolmodel.2011.06.013

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