Ecology & Conservation - Restoration

What is restoration

  • Ecological restoration is the process of assisting the recovery of an ecosystem that has been degraded, damaged, or destroyed.
  • According to the Society for Ecological Restoration Science and Policy Working Group (2002), it involves halting and reversing degradation to improve ecosystem services and recover biodiversity.
  • FAO, IUCN CEM & SER (2021) define it as the process of halting and reversing degradation, resulting in improved ecosystem services and recovered biodiversity.

Why is it needed?

  • Ecological restoration aims to recreate, initiate, or accelerate the recovery of a disturbed ecosystem.
  • Ideally, restoration returns normal ecosystem function to an area and provides social or economic value to humans.
  • This includes:
    • Ecosystem services
    • Mitigating impacts to ecosystems elsewhere
    • Habitat for threatened or endangered species
    • Aesthetic concerns and moral reasons
    • Legal requirements (e.g., Clean Water Act)
    • Improved human livelihoods
    • Empowerment of local people
    • Improved ecosystem productivity

What to restore?

  • Significant habitat loss has occurred in the USA:
    • 53% of wetlands lost
    • 50-70% loss of brackish intertidal mudflats, shores, and coastal plains
    • 70% loss of riparian forests
    • 90% loss of old-growth forests
    • 99.5% loss of old-growth forests (eastern U.S.)
    • 90% loss of short and tall-grass prairie ecosystems
    • 90% of shrub-steppe ecosystems degraded by livestock grazing (Noss et al., 1995)

Restoring structure, function and composition

  • Structure: Systematic physical organization of the abiotic and biotic components of an ecosystem.

  • Function: Exchanges of material, energy, and nutrients within an ecosystem, including ecosystem services.

  • System dynamics

  • Evolutionary processes

  • Energetics

  • Riparian succession

  • Surface water storage processes

  • Surface-subsurface exchange processes

  • Hydrodynamic character

  • Hydrological condition

  • Sediment Processes/ Character

  • Sedimentation processes

  • Substrate and structural processes

  • Quality and quantity of sediments

  • Biological communities and processes

  • Necessary habitats for all life cycles

  • Trophic structures and pathways

  • Water and soil quality processes

  • Chemical processes and nutrient cycles

  • Landscape pathways and processes

Composition matters too

  • Not all grasslands are equivalent (Zaloumis & Bond 2016, Phil Trans R Soc)
  • What is the aim or goal of restoration?
  • What state or condition is desired?

Defining reference conditions

  • 'Natural' pre-disturbance condition with assumed properties/ processes.
  • What represents the reference state?
    • Nearby reference site
    • Pre-disturbance surveys
    • Historical information
  • The range of historical or natural variability in ecological structures and processes that reflect evolutionary history, disturbance regimes, and abiotic and biotic conditions (Covington et al. 1997).
  • Harder when deciding what time in past should be the reference state:
    • before human disturbance?
    • before agric or industrial intensification?
  • Historical targets are not always appropriate under current/projected climate or biotic conditions.
  • May choose to maintain desirable human-derived states

Defining reference conditions: Ponderosa pine

  • Written records:
    • Lt. Edward Beale, 1857 (northern Arizona): “A vast forest of gigantic pines, intersected frequently with open glades, sprinkled all over with mountains, meadows, and wide savannas, and covered with the richest grasses, was traversed by our party for many days.”
    • C. DuBois, 1903 (San Juan Mountains): “Throughout the [“bull” or ponderosa pine] type there is good cattle range, consisting of blue-stem grass beneath the trees and bunch grass in the parks. The underbrush is very heavy, chiefly oak brush, choke-cherry, scarlett thorn, and wild rose. Reproduction of bull pine is poor.”
  • Photographs from around 1911 show the landscape conditions.
  • Contemporary data includes:
    • Fire scars & tree rings
    • Species composition & structure
    • Soil seed bank
    • Biotic and abiotic soil characteristics
    • Traditional Ecological knowledge

Defining reference conditions: Ponderosa pine

  • Fire is a key disturbance that regulates ponderosa pine forests.
  • Low intensity fires occur at 2-20 year interval.
  • It results in:
    • Large diameter trees interspersed with grassy meadows
    • Diverse, productive herbaceous understory

Shifting baselines

  • A shifting baseline is a type of change to how a system is measured, usually against previous reference points (baselines), which themselves may represent significant changes from an even earlier state of the system.

Approaches for restoration

  • Natural succession
  • Engineering interventions
  • Disturbance regime: Fire, flooding
  • Planting native vegetation (e.g., tree planting)
  • Removing invasive species
  • Reintroducing animal species incl ecosystem engineers

Restoration in practice

  • Ecosystem engineers can reintroduce functions and help change structure and composition (Hilderbrand et al. 2005. Ecology and Society).
  • Southern Cairngorms: > 50% of wetland area destroyed during the 20th century (Law et al. 2017, Science of the Total Environment).
  • Beavers facilitated restoration (Law et al. 2017, Science of the Total Environment).

Re-wilding

  • Rewilding is large-scale conservation aimed at restoring and protecting natural processes and core wilderness areas, providing connectivity between such areas, and protecting or reintroducing apex predators and keystone species.
  • Farmland, especially in remote areas, is being abandoned due to a combination of socio-economic, political, and environmental factors (Navarro & Pereira 2012, Ecosystems).
  • Land abandonment facilitates rewilding in Europe (Chapron et al. 2014, Science).
  • Opportunities for re-wilding of large carnivores

Re-wilding & conservation in the UK

  • How much of the UK is undisturbed/ non-human modified landscape?
  • What is our template if we move outside the cultural landscapes that we have inherited?
  • What are we trying to conserve?
  • We cannot go back with re-wilding
  • “Natural” past is not tenable as a model
    • Conditions uncertain
    • Climate and soils have changed
    • Species gained and lost
    • Human influence being pushed back in time
  • Develop towards future natural regime?
  • Withdraw obvious driving human influences
  • Give up targets
  • Focus on allowing ‘natural’ processes
  • Can we go forward?

Re-wilding in the UK

  • Regulation: Welfare legislation, reintroduction difficult, disease issues
  • Public: Lose treasured landscapes
  • Loss public access to land
  • Concern over danger to stock & humans (predators esp)
  • Alladale Estate, Scottish Highlands 23 000 acres

Summary

  • Restoration is ultimately unpredictable and dynamic – just like natural systems!
  • “Ecosystems are not only more complex than we think, ecosystems are more complex than we can think.” - Frank Egler
  • Human degradation of habitats - lots of habitat needs restoring
  • Restoration is more than just planting trees
  • Defining goals and reference state can be tricky
  • Re-wilding is a form of restoration with potential in many areas in Europe