Ecology: Rewilding

• Ecosystems are patchworks of different microhabitats created by habitats in different states of succession/transition due to disruptive influences (i.e., grazing, fire, weather extremes, etc.)
• Disruptive influences must be allowed to continue (i.e., fire), but must not dominate
• Factors controlling and regulating disruptive influences and environmental conditions

  • Keystone species (i.e., top-down processes)
  • Foundation species (i.e., bottom-up processes)
  • Ecosystem engineers
• Trophic levels


  • Low trophic levels regulate productivity and land use
  • High trophic levels regulate consumption & behaviour
• Types of species interactions

  • Mutualism (+/+)
  • Competition (-/-)
  • Predation / herbivory / parasitism (+/-)
  • Commensalism (+/0)
• Species interactions drive evolution, adaptation & niche utilisation
• Fundamental and realised niche may differ depending on competition, predation risk, or the presence of mutualistic relationships
• Human activity has had a global impact on these interactions
• Rewilding


  The reorganisation of biota and ecosystem processes to set an identified social-ecological system on a preferred trajectory leading to the self-sustaining provision of ecosystem services with minimal ongoing management
• Traditional conservation is often static. Many of our rare species are specialised to transitional habitats that naturally only occur after disturbance (e.g., fire), and only last a short amount of time
• Rewilding aims to re-establish natural ecological processes and ecosystem functions, using natural management strategies, and reintroducing native species (keystone, foundation, & ecosystem engineers)
• Our ecosystems are no longer functioning. Traditional conservation often works to preserve a particular set of conditions, often in small areas with heavy management to prevent succession (metapopulations disconnected)
• Without predators, Ireland & Britain have a herbivore problem. Deer populations are high, increasing pressure on plants. Without predators, deer spend more time feeding and breeding, rather than being vigilant or moving
• Traditional conservation


  • Works to preserve a particular set of conditions
  • Often small areas with heavy management to prevent succession
  • Metapopulations disconnected
• Multiple herbivores


  • Provide redundancy and create unique niches
  • Having multiple species creates more diverse environments
  • Multiple complementary cycles & competition keep ecosystems stable
• Wolves are returning across western Europe
• Wolves


  • Are a keystone species
  • Have top-down effects to regulate populations of other species
• Beavers are once again managing floodplains in Britain
• Beavers


  • Are an ecosystem engineer
  • Create and manage habitat for many other species
• Trophic cascade


  A series of interconnected changes to an ecosystem that directly and indirectly result from the introduced/re-established action of a keystone species
• Wolves reintroduced in Yellowstone in 1995 had an immediate effect on elk numbers
• Wolves arrived in Isle Royale National Park in 1948 and had an immediate stabilising effect on moose numbers
• Wolves


  • Are a keystone species with direct and indirect effect which propagate throughout the ecological network
  • Effect both the biotic community and the abiotic environment
• Wolves create a 'landscape of fear' that changes elk behaviour, moving them more frequently and stopping them overgrazing any one area
• Sea otters are vital for healthy kelp forests in North America
• Without sea otters, sea urchins take over
• Recovery of sea otters along the Pacific coast of North America has restored kelp forests by controlling herbivorous sea urchins and reduced coastal erosion by controlling burrowing crabs
• Stopping management will not necessarily return the system to its original state as invasive species or lost connections/behaviours will reform in new configuration
• Rewilding does not mean no management, we need to understand the natural ecosystem and misplaced rewilding can threaten important native habitats
• Benefits of rewilding


  • Tourism
  • Natural flood protection
  • Natural water purification
  • Natural pest control
  • Natural pollinator reservoir
  • Carbon sequestration
  • Natural soil preservation/enrichment
  • Recreation / healthy living
  • Resilience to climate change