Skip to content

Green Opinions

Wolves and a Window of Opportunity for Ecosystems

by Paul Robinson 06 Feb 2013
Wolves and a Window of Opportunity for Ecosystems

Stop Violence Against Women; Credit: © Shutterstock

When the wolf was killed off in many countries, the farmers thought that was good for their self-contained environment. When we lose such top predators from the food web, there are some obvious responses and ten there are the less obvious.

Obviously degradation of the system is normal, but a total understanding of all the changes involved is lacking. While the fish, bass can be re-introduced to some lakes without ecological turmoil, what often happens in many cases is that predator removal causes a proliferation of the dominant plant. That in itself could be the pollution or be the cause of a plague of plant-eaters (consumers).

Over ten years in Yellowstone, browsing animal effects and stream alteration by beavers were studied. Three willow species' height, growth and their accumulation of biomass were measured while stream depths at dammed and undammed stretches were recorded. Kristin N. Marshall, N. Thompson Hobbs, and David J. Cooper from the US Natural resource and Ecology Lab. and Colorado State University were all involved in discovering how the hydrology limited the recovery of the old ecosystem containing the wolves.

To exclude grazers, a 2.4m fence was erected around two lots while two others were left unfenced. Artificial dams were constructed on half of the plots to raise the water level, raising the water table by an average of 33cm.

After a decade of no ungulates eating them the willows could not reach the height threshold that indicated recovery to "ancient" levels. If the water table was raised, however, the willows were 50% taller and accumulated 90% more biomass. This indicates that many stream conditions were affected, including the supply of nutrients and water.

So 100 years ago, the loss of wolves here caused the production of an "alternative" ecosystem. Wolves have not yet restored the "ancient" ecosystem, while beavers have not yet recolonised either. The danger is that the alternative ecosystem is resistant to predator restoration. It now remains to be seen if beavers can be recruited into the area and other species start recreating their previous hierarchies.

The key to success with these predator re-introductions seems to be in establishing the ancient co-evolutionary relationships. Animals and plants evolved together to succeed in a particular way. Without support, the old system crumbles away and new relationships have to develop. Now we can start wondering what support is needed for tigers re-establishing in Asia or even your local peregrines, locating in quarries where they haven't been seen before. This paper was published today by the Proceedings of the Royal Society B: Biological Sciences.


Trending Eco-Friendly Clothing

Love My Planet Women's Relaxed Fit Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Love My Planet Women's Relaxed Fit Hoodie
Love My Planet women's eco-friendly relaxed fit hoodieSize Guide Centimeters 8 10 12 14 16 18 Bust 84 88 92 97 103 108 Waist 66 70 75 80 85 91 Hips 91 95 99 104 109 116 Bust: Measure around the fullest part of...
£38.00
£38.00
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Penguins Hate Push-Ups men's eco-friendly pullover HoodieSize Guide Centimeters XS S M L XL XXL Height 171 175 179 183 189 195 Chest 86 93 99 104 116 129 Waist 71 76 81 89 99 112 Chest: Measure all round your chest just below...
£38.00
£38.00
Close
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Earth
Quick Add
Close
Notify me
Notify me
Notify me