Networks of small habitat patches can preserve urban biodiversity

November 13, 2008

Sets of small and seemingly insignificant habitat patches that are within reach for mobile species may under certain circumstances, as a group, provide an acceptable alternative to larger and contiguous habitats. This finding can make preservation of important ecological functions possible even in urban and other heavily exploited areas.

The study by Dr. Erik Andersson and Dr. Örjan Bodin at the Department of Systems Ecology, and Stockholm Resilience Centre, both at Stockholm University, is unique in the sense that they empirically test and verify an often used modelling approach where habitat fragments are seen as individual nodes in larger networks of interconnected habitat patches.

According to the study, published yesterday in Ecography, sets of small habitat patches can host species that require much larger habitat patches for their daily needs than what each patch itself can provide. Many species are actually capable of moving back and forth between neighbouring patches, given that they are not perceived as being too far apart. Thus, many species are able to make use of the total of the habitat fragments in the network instead of relying on the individual habitat patches for their persistence.

"By defining the habitat patches as parts of a larger network, spatially explicit analyses of how the sum of the patches contributes to species dynamics on the level of landscapes are possible" said Dr. Andersson.

In human dominated areas, such as cities or intensively cultivated landscapes, it is often impossible to set aside large contiguous areas of natural vegetation. Instead, when multiple users compete for a limited area of land, only smaller pockets of natural vegetation (or just green areas) can realistically be preserved.

"Land managers need comprehensive and reliable tools that could help them to direct their conservation efforts to habitat patches where they get as much biodiversity as possible given a limited budget. Our study empirically shows that the network modeling approach is a good candidate for developing such a tool" said Dr. Bodin.

The study combines empirical field studies of birds with theoretical and statistical modelling. A range of bird species were surveyed in various green areas of different size and type in the urban area of Stockholm, Sweden. Geographical Information System (GIS) techniques were deployed to model the urban landscape as a network of individual habitat fragments. The field data were then used to test and verify the assumptions behind the network model.

Modelling a landscape as a network provides for many new analytical possibilities. However, the network modelling approach as such has, until now, rarely been tested empirically.

"Our study gives strength to the network perspective of landscapes, and thus supports further development of new and exiting network-based analyses that could help managers to preserve valuable ecological functions even in very fragmented landscapes" said Dr. Andersson.

The study also showed that it is important to differentiate between different types of green areas when constructing a habitat network since many species have quite different habitat preferences. In addition, the effect of movement barriers and the existence of stepping stones should be included in the analysis, a fact which is particularly relevant in urban areas.

Source: Wiley

Explore further: New study showed spawning frequency regulates species population networks on coral reefs

Related Stories

Minding the gap: City bats won't fly through bright spaces

June 4, 2015

Researchers at the University of Birmingham have discovered that bats living in a city are less likely to move from tree to tree in brightly lit areas, according to research published online today (5th June 2015) in the journal ...

Butterflies rely on connections amid changing climate

October 16, 2014

Butterflies in Canadian mountain meadows rebounded after a severe population crash. Why? It's all about connections, found a study by the University of California, Davis, in collaboration with Western University in Ontario, ...

Dwindling waterways challenge desert fish in warming world

September 3, 2014

(Phys.org) —One of Arizona's largest watersheds – home to many native species of fish already threatened by extinction – is providing a grim snapshot of what could happen to watersheds and fish in arid areas around ...

Recommended for you

Long-sought chiral anomaly detected in crystalline material

September 3, 2015

A study by Princeton researchers presents evidence for a long-sought phenomenon—first theorized in the 1960s and predicted to be found in crystals in 1983—called the "chiral anomaly" in a metallic compound of sodium and ...

Making nanowires from protein and DNA

September 3, 2015

The ability to custom design biological materials such as protein and DNA opens up technological possibilities that were unimaginable just a few decades ago. For example, synthetic structures made of DNA could one day be ...

Ice sheets may be more resilient than thought

September 3, 2015

Sea level rise poses one of the biggest threats to human systems in a globally warming world, potentially causing trillions of dollars' worth of damages to flooded cities around the world. As surface temperatures rise, ice ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.