UrbanEcology.ca

Val wrote a new article on backyard habitat and biodiversity that was published in Pacific Horticulture Magazine here. The article includes a link to a Web Extra on ecological memory. Building on the original article on the importance of backyard habitat to urban biodiversity ( Rudd, H., Vala, J. and V.H. Schaefer 2002), in the journal Restoration Ecology, it elaborates on the possible impacts of unseen thresholds, synergisms, layered landscapes, novel ecosystems and connectivity embedded in backyard habitat and points out the major importance of gardening in supporting these processes.

I developed an Urban Habitat Quality Index to help identify a threshold between functional resilient communities and those that have not yet achieved the biodiversity and inter- and intra-species relationships to be functional. The index was developed while I was on a sabbatical in Oxford, UK, and was in part inspired by an article on ecological memory by Sun et al. for which I was a co-author. It involves 15 parameters, each rated on a Likert scale of 0-5. I presented the work at a conference of the Society for Ecological Restoration, Western Chapter, in 2018 and in the article here on the academia.edu website I am describing the research and results on which that presentation was based.

https://www.academia.edu/75459888/A_Qualitative_Assessment_of_Urban_Ecosystem_Resilience_Using_a_Habitat_Quality_Index

Moments in Nature: A Journal is the title of the living document version of Beyond the Pail – a 270 page book with its own ISBN. I continued to add more stories to the original book. To distinguish it from the completed Beyond the Pail I gave the new evolving expanded version the new name of Moments in Nature: A Journal, that I provide s a free pdf upon request made to schaefer@uvic.ca

When returning to sites that we restored it was clear that in some of them the plants had survived but they were not forming communities. We were essentially landscaping with native plants rather than restoring natural areas. This raised the question of was a planting a functioning system and when was it just ornamental. On reflection it was clear that a functional community had an identity and could maintain itself in the face of disturbance. In other words, it was resilient. I explored a number of approaches to identify this threshold which I am presenting here.

Ecological Memory

Sun et al. (2014) looked at ecological memory in community development and discovered that in a terrestrial forest ecosystem, in order to move from disturbance to a grassland, the first stage of succession, 46.5% of ecological memory needed to be in place.

Impervious Surface

Bauer and Loeffelholtz (2004) concluded that an impervious surface area of more than 60% in an urban watershed did not support a community and the stream was merely drainage. There had to be at least 40% permeable surface to maintain some kind of water quality.

Symbiosis

A functioning community implies that there are healthy symbiotic relationships between species to maintain some balance. Schaefer and Bocking (2014) looked at soil microarthropods as grazers of mycorrhizae, the assumption being that the mycorrhizae would not be established in an ornamental landscape. They discovered a threshold where there were significantly more of these grazing microarthropods, especially mites, in natural areas compared to urban and transitional sites.

Urban Habitat Quality Index

In order to more comprehensively assess habitat along an urban-natural area gradient to identify a resilience threshold I developed an Urban Habitat Quality Index where I identified 15 parameters that were each qualitatively rated on a Likert Scale for 0-5 (Schaefer 2018). The study was done in Oxford and the results are shown in the table below. Aston’s Eyot was the most disturbed, most urban site and the other sites represented a gradient with Wytham Woods being the most natural. Expressed as a percentage, there appeared to be a threshold of 40% between the most urban, ornamental sites and the transitional and natural sites.

A minimum requirement of 40% ecosystem function for ecological resilience was similarly found by Cantarello et al. (2017) in a temperate forest landscape.

Conclusion

The above examples would seem to indicate that there is a threshold between an urban habitat that is merely ornamental compared to one that is functional. That threshold is at about 40% functionality and this represents the point at which a community has become resilient.

References

Bauer, M.E. and B. Loeffelholz. 2004. Estimation, mapping and change analysis of impervious surface area by Landsat remote sensing. In: ASPRS Annual Conference. Proceedings:23–28 May 2004, Denver, CO

Cantarello, E.; Newton, A.C.; Martin, P.A.; Evans, P.M.; Gosal, A.; and M..S. Lucash, 2017. Quantifying resilience of multiple ecosystem services and biodiversity in a temperate forest landscape. Ecol. Evol. 7:9661–9675.

Schaefer, V.H. 2018. A qualitative assessment of urban ecosystem resilience using a habitat quality index. Society for Ecological Restoration Conference: Restoration for Resilience. Burnaby, BC. Proceedings. p. 16-17

Schaefer, V.  and M. Bocking. 2015.  Detecting the Threshold between Ornamental Landscapes and Functional Ecological Communities: Soil Microarthropods as Indicator Species. Urban Ecosystems 18:1071-1080.

Sun, Z., Ren, H., Schaefer, V., Lu, H., Wang, J., Li, L. and N. Liu. 2014. Using ecological memory as an indicator to monitor the ecological restoration of four forest plantations in subtropical China. Environmental Monitoring and Assessment 8229-8247.

The University of Victoria campus is a unique and important natural area. The campus is in four watersheds that extend in all directions through Victoria, Oak Bay and Saanich. It has several large forests, Garry Oak meadows, the remnants of an old orchard, a ravine, stormwater management installations that include several rain gardens, and hundreds of native large veteran native and ornamental trees from around the world. The natural areas are used for research, teaching and promoting environmental stewardship. This report presents a summary of the various initiatives to restore habitat on campus, the studies that have been done in support of management plans, the various people and groups involved in restoring habitat and what has been accomplished. The document is available here below in 5 parts to download.

U Vic Campus Restoration Guide_Part1

U Vic Campus Restoration Guide_Part2

U Vic Campus Restoration Guide_Part3

U Vic Campus Restoration Guide_Part4

U Vic Campus Restoration Guide_Part5

Full document (approx. 22MB)

Having spent a sabbatical earlier this year with trips to Oxford and San Francisco, Val shares his images and impressions about the urban forest and novel ecosystems he observed in these two landscapes along the theme of layered landscapes. The presentation is available here in two parts – Part 1 and Part 2.