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Predation risk shaped by habitat and landscape complexity in urban environments


Frey, David; Vega, Kevin; Zellweger, Florian; Ghazoul, Jaboury; Hansen, Dennis; Moretti, Marco (2018). Predation risk shaped by habitat and landscape complexity in urban environments. Journal of Applied Ecology, 55(5):2343-2353.

Abstract

1. Habitat loss and modification are hallmarks of anthropogenic ecosystems, but the consequences for ecosystem functioning and service provisioning often remain unclear. Understanding these links in cities is complicated by strong but fine‐scale differences in habitat structure among green space patches, and a high variance in habitat amount across urban landscapes.
2. We used airborne laser scanning data to disentangle the effects of 3D woody habitat heterogeneity of urban home gardens, and woody habitat amount at four landscape spatial scales (50, 100, 250, and 500 m), on the predation risk of artificial sentinel prey by birds and arthropods.
3. In both predator groups, and at all the investigated spatial scales, cross‐scale interactive effects between garden habitat heterogeneity and habitat amount in the urban landscape were the main drivers of predation. Risk of predation by birds was highest in heterogeneous garden habitats, but only in densely built urban landscapes where habitat amount was low to intermediate (10%–20%) at large spatial scales (250–500 m). It dropped independently of garden habitat heterogeneity when habitat amount became too low (<10%) at small (50–100 m) spatial scales. In contrast, risk of predation by arthropods mostly peaked in homogeneous garden habitats when habitat amount was intermediate (20%) at large spatial scales.
4. Our findings show that the ability of urban green space patches, such as gardens, to sustain ecosystem functions in cities mainly depends on cross‐scale interactive effects with larger scale habitat amount. In birds, predation activity can increase when high patch‐scale habitat heterogeneity contrasts with reduced larger scale habitat amount, suggesting concentration effects. Yet, thresholds exist under which ecosystem functioning drops independently of habitat structure.
5. Synthesis and applications. The potential of small‐scale interventions to enhance habitat heterogeneity (e.g., by planting native trees with understorey shrubs) for restoring ecosystem functions, such as bird predation, in urban areas is dependent on wider landscape habitat structure. Urban planning should therefore adopt a multiscale approach to sustain and restore ecosystem functions and services; a simple but still not broadly recognized finding. Airborne laser scanning is a useful tool to infer habitat structure across a hierarchy of scales in spatially heterogeneous anthropogenic ecosystems.

Abstract

1. Habitat loss and modification are hallmarks of anthropogenic ecosystems, but the consequences for ecosystem functioning and service provisioning often remain unclear. Understanding these links in cities is complicated by strong but fine‐scale differences in habitat structure among green space patches, and a high variance in habitat amount across urban landscapes.
2. We used airborne laser scanning data to disentangle the effects of 3D woody habitat heterogeneity of urban home gardens, and woody habitat amount at four landscape spatial scales (50, 100, 250, and 500 m), on the predation risk of artificial sentinel prey by birds and arthropods.
3. In both predator groups, and at all the investigated spatial scales, cross‐scale interactive effects between garden habitat heterogeneity and habitat amount in the urban landscape were the main drivers of predation. Risk of predation by birds was highest in heterogeneous garden habitats, but only in densely built urban landscapes where habitat amount was low to intermediate (10%–20%) at large spatial scales (250–500 m). It dropped independently of garden habitat heterogeneity when habitat amount became too low (<10%) at small (50–100 m) spatial scales. In contrast, risk of predation by arthropods mostly peaked in homogeneous garden habitats when habitat amount was intermediate (20%) at large spatial scales.
4. Our findings show that the ability of urban green space patches, such as gardens, to sustain ecosystem functions in cities mainly depends on cross‐scale interactive effects with larger scale habitat amount. In birds, predation activity can increase when high patch‐scale habitat heterogeneity contrasts with reduced larger scale habitat amount, suggesting concentration effects. Yet, thresholds exist under which ecosystem functioning drops independently of habitat structure.
5. Synthesis and applications. The potential of small‐scale interventions to enhance habitat heterogeneity (e.g., by planting native trees with understorey shrubs) for restoring ecosystem functions, such as bird predation, in urban areas is dependent on wider landscape habitat structure. Urban planning should therefore adopt a multiscale approach to sustain and restore ecosystem functions and services; a simple but still not broadly recognized finding. Airborne laser scanning is a useful tool to infer habitat structure across a hierarchy of scales in spatially heterogeneous anthropogenic ecosystems.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Uncontrolled Keywords:Ecology
Language:English
Date:1 June 2018
Deposited On:19 Aug 2018 12:59
Last Modified:19 Aug 2018 16:16
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0021-8901
Additional Information:This is the peer reviewed version of the following article: Frey D, Vega K, Zellweger F, Ghazoul J, Hansen D, Moretti M. Predation risk shaped by habitat and landscape complexity in urban environments. J Appl Ecol. 2018;55:2343–2353. which has been published in final form at https://doi.org/10.1111/1365-2664.13189. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving (https://authorservices.wiley.com/author-resources/Journal-Authors/licensing-open-access/open-access/self-archiving.html).
OA Status:Closed
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1111/1365-2664.13189
Project Information:
  • : FunderSNSF
  • : Grant IDCRSII1_154416
  • : Project TitleStrategies for Better Gardens: integrated analysis of soil quality, biodiversity and social value of urban gardens
  • : FunderSNSF
  • : Grant IDP2EZP3_172198
  • : Project TitleHow does forest microclimate affect biodiversity dynamics?

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