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Interaction strengths in balanced carbon cycles and the absence of a relation between ecosystem complexity and stability.

Neutel AM, Thorne MA - Ecol. Lett. (2014)

Bottom Line: We analyse the role of recycling, predation and competition and find that ecosystem stability can be estimated by the strengths of the shortest positive and negative predator-prey feedbacks in the network.Our results show how functional relationships dominate over average-network topology.They make clear that the classic complexity-instability paradox is essentially an artificial interaction-strength result.

View Article: PubMed Central - PubMed

Affiliation: British Antarctic Survey, High Cross, Madingley Rd, Cambridge, CB3 0ET, UK.

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Feedbacks and stability. Empirical parameterisations of the interaction strengths of the Antarctic dry and wet tundra systems and 21 soil food webs (for legend see Fig. 3, with plus signs for the 21 soil webs) are compared with symmetric (yellow symbols) and asymmetric (green symbols) parameterisations. (a) 3-Link and 2-link predator-prey feedbacks  and system vulnerability λd (N = 71, R2 = 0.97, P < 10−15). λd is correlated with (b) complexity  in the symmetric webs (N = 23, R2 = 0.94, P < 10−13), (c) the level of omnivory  (N = 23, R2 = 0.84, P < 10−9) in the asymmetric webs, and (d) maximum ratio of 3-link and 2-link feedback in omnivorous structures (N = 25, R2 = 0.79, P < 10−08) in the empirical webs. (e) Weights (Neutel et al. 2002) of 2- and 3-link feedback loops in the Antarctic dry tundra for the different parameterisations. The spectra are representative of the other food webs and the symmetric and asymmetric spectra contain the 2- and 3-link feedbacks of 100 samplings of those parameterisations.
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fig04: Feedbacks and stability. Empirical parameterisations of the interaction strengths of the Antarctic dry and wet tundra systems and 21 soil food webs (for legend see Fig. 3, with plus signs for the 21 soil webs) are compared with symmetric (yellow symbols) and asymmetric (green symbols) parameterisations. (a) 3-Link and 2-link predator-prey feedbacks and system vulnerability λd (N = 71, R2 = 0.97, P < 10−15). λd is correlated with (b) complexity in the symmetric webs (N = 23, R2 = 0.94, P < 10−13), (c) the level of omnivory (N = 23, R2 = 0.84, P < 10−9) in the asymmetric webs, and (d) maximum ratio of 3-link and 2-link feedback in omnivorous structures (N = 25, R2 = 0.79, P < 10−08) in the empirical webs. (e) Weights (Neutel et al. 2002) of 2- and 3-link feedback loops in the Antarctic dry tundra for the different parameterisations. The spectra are representative of the other food webs and the symmetric and asymmetric spectra contain the 2- and 3-link feedbacks of 100 samplings of those parameterisations.

Mentions: The absence of an effect of detritus feedbacks on system stability allowed us to make a direct comparison between the empirically-based parameterisations and synthetic (symmetric and asymmetric) parameterisations underlying the canonical ideas on the destabilising effects of diversity or link density (Gardner & Asby 1970; May 1972) and omnivory (Pimm & Lawton 1978). The ratio roughly predicted system stability irrespective of the type of parameterisation (Fig. 4a).


Interaction strengths in balanced carbon cycles and the absence of a relation between ecosystem complexity and stability.

Neutel AM, Thorne MA - Ecol. Lett. (2014)

Feedbacks and stability. Empirical parameterisations of the interaction strengths of the Antarctic dry and wet tundra systems and 21 soil food webs (for legend see Fig. 3, with plus signs for the 21 soil webs) are compared with symmetric (yellow symbols) and asymmetric (green symbols) parameterisations. (a) 3-Link and 2-link predator-prey feedbacks  and system vulnerability λd (N = 71, R2 = 0.97, P < 10−15). λd is correlated with (b) complexity  in the symmetric webs (N = 23, R2 = 0.94, P < 10−13), (c) the level of omnivory  (N = 23, R2 = 0.84, P < 10−9) in the asymmetric webs, and (d) maximum ratio of 3-link and 2-link feedback in omnivorous structures (N = 25, R2 = 0.79, P < 10−08) in the empirical webs. (e) Weights (Neutel et al. 2002) of 2- and 3-link feedback loops in the Antarctic dry tundra for the different parameterisations. The spectra are representative of the other food webs and the symmetric and asymmetric spectra contain the 2- and 3-link feedbacks of 100 samplings of those parameterisations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4285907&req=5

fig04: Feedbacks and stability. Empirical parameterisations of the interaction strengths of the Antarctic dry and wet tundra systems and 21 soil food webs (for legend see Fig. 3, with plus signs for the 21 soil webs) are compared with symmetric (yellow symbols) and asymmetric (green symbols) parameterisations. (a) 3-Link and 2-link predator-prey feedbacks and system vulnerability λd (N = 71, R2 = 0.97, P < 10−15). λd is correlated with (b) complexity in the symmetric webs (N = 23, R2 = 0.94, P < 10−13), (c) the level of omnivory (N = 23, R2 = 0.84, P < 10−9) in the asymmetric webs, and (d) maximum ratio of 3-link and 2-link feedback in omnivorous structures (N = 25, R2 = 0.79, P < 10−08) in the empirical webs. (e) Weights (Neutel et al. 2002) of 2- and 3-link feedback loops in the Antarctic dry tundra for the different parameterisations. The spectra are representative of the other food webs and the symmetric and asymmetric spectra contain the 2- and 3-link feedbacks of 100 samplings of those parameterisations.
Mentions: The absence of an effect of detritus feedbacks on system stability allowed us to make a direct comparison between the empirically-based parameterisations and synthetic (symmetric and asymmetric) parameterisations underlying the canonical ideas on the destabilising effects of diversity or link density (Gardner & Asby 1970; May 1972) and omnivory (Pimm & Lawton 1978). The ratio roughly predicted system stability irrespective of the type of parameterisation (Fig. 4a).

Bottom Line: We analyse the role of recycling, predation and competition and find that ecosystem stability can be estimated by the strengths of the shortest positive and negative predator-prey feedbacks in the network.Our results show how functional relationships dominate over average-network topology.They make clear that the classic complexity-instability paradox is essentially an artificial interaction-strength result.

View Article: PubMed Central - PubMed

Affiliation: British Antarctic Survey, High Cross, Madingley Rd, Cambridge, CB3 0ET, UK.

Show MeSH
Related in: MedlinePlus