Nature types - degradation and restoration

Question 1

Forest degradation causes

Answer 1

Deforestation (destruction of forests)
• Agriculture, settlements, other human use
• Degraded land (rangeland), less-productive land often used for grazing
• Why is deforestation a problem?
○ Loss of production (biomass, fibre, timber, other forest product
○ Loss of protective functions (soil protection, erosion, avalanches)
○ Loss of habitats
○ Loss of regulating functions (climate)
○ Loss of cultural services

Question 2

Forest restoration goals

Answer 2

Ecological goals 
Processes
	• Regeneration
	• Closed nutrient cycle
	• Dead wood for decay
Structures
	• Natural species/robust species 
	• Habitat diversity
	• Predator-herbivore balance
Geophysical conditions 
	• Natural hydrology
	• Size and connectivity
Self-sustainable
	• Robust, resistant and resilient 
	• Potential for adaption to climate change 

Political goals - Parliamentary decision (in Denmark)
Biodiversity forest
• Forests should set aside for biodiversity. 10000 ha as non-intervention forests and 3300 ha managed specifically for biodiversity
• Support to private forest owners for management of forest diversity
• Conversion can be up to 10 years for deciduous forest and up to 50 years for conifers including a transformation

Question 3

Forest restoration tools

Answer 3

Afforestation (planting trees where they weren't before, e.g. on abandoned farmland)
Reforestation (replanting trees)
	• E.g. beech planting in Germany
Rewetting
	• Filling up ditches 
Grazing 
Scything 

Close to nature forestry
• Native species
• Adopted introduced species to a minor extend
• No clear cut - group-wise natural regeneration
• Forest development types
• Mainly target diameter cuttings, self-thinning as much as possible
• No fertilizer, no pesticides

Question 4

Mires, wetlands, bogs, fens (def)

Answer 4

• Mires are peatlands where peat (100% OM) is currently being formed >20 cm peat.
• Wetlands may be mires but also saturated mineral soil land.
• Bogs are mires raised above the surrounding landscape and solely fed by precipitation. Always acidic (pH<4)
• Fens are mires placed in depressions, also fed by ground- and surface waters. Often neutral or slightly alkaline (spring water lime).

Question 5

Mire degradation causes

Answer 5

Peat extraction
• Responsible for about 10% of worlds mire losses
• Energy
• Soil melioration
• Horticulture
• Mineralization may continue after extraction
• Disturbed mires are a CO2 source
• Growing mires are a CO2 sink
• Mires are often a CH4 source
Indirect change in hydrological regimes
• Indirect change in the hydrogeology, e.g. following ground-water abstraction
• Cause oxidation, mainly of fens
• May lead to acidification
• NO3-leaching may also lead to acidification
Landscape drainage to reclaim forest of arable land
• Many examples of bogs (Lille Vildmose) for agricultural production (e.g. potatoes)
• Fens and bogs for forest production
Atmospheric N deposition
• Deposition often reach 15-20 kg N ha-1 y-1
• Cause eutrophication (mainly a problem for spagnum ssp)
• Critical load, often < 5 kg N ha-1 y-1

Question 6

Mire restoration tools

Answer 6

Re-wetting
• Closing ditches
• Terminating ground-water abstraction
Re-vegetation
• Assisted migration / haying, seeding.
• When severely damaged, rehabilitation might be the only option.

Question 7

Lake degradation causes

Answer 7

Eutrophication
	○ Nutrients from agriculture
	○ Sewage sludge
Pollution
	○ From industry 
Acidification
	○ Air pollution , NH3 and H2SO4
Sediment load
Physical modification 
	○ Drainage

Question 8

Lake restoration tools

Answer 8

1. Reduction of external N and P load
   a) Point and non-point sources
   b) Dilution of lake water by diverting more streams toward the lake
2. In-lake measures
   a) Biomanipulation
   b) Measures against P-rich sediments
   a. Dredging
   b. Oxidation
   c. Flocking
   c) Liming against acidification
3. Rewetting reclaimed land

Question 9

Heathland degradation causes

Answer 9

Plantation forestry
Agriculture
Lack of disturbance (cutting, grazing, burning)

Question 10

Heathland restoration tools

Answer 10

Restoration tools
	· Cropping
	· Top soil removal
	· Artificial acidification
	· Cutting of trees
Conservation tools 
	· Grazing
	· Fire
	· Mowing
	· Do nothing (Nørholm)???

Question 11

Restoration in heathlands are difficult because of:

Answer 11

○ Nutrients (agriculture, air pollution)

○ Tree seed sources

Question 12

Rivers are very dynamic features because of:

Answer 12

1. Inherent conditions
   a) Slope
   b) Bedrock
   c) Complexity
2. External factors
   a) Climate precipitation
   b) Land use / landscape type in catchment
   c) Flow regulation
   d) Urbanization
   Determines
   • Sorption processes
   • Sediment redistribution

Question 13

River degradation causes

Answer 13

1. In-stream human impacts
   a. Dredging
   b. Collection of stones
   c. Eutrophication
2. Changes to the run
   a. Mills
   b. Hydropower
   c. Infrastructure
   d. Navigation and timber floating
   e. Flood protection
   f. Culverting (rørlægning)
3. Changes in the catchment
   a. Reclamation and intensive agriculture
   b. Deforestation and afforestation
   c. Land use changes

Question 14

River restoration tools

Answer 14

Includes a continuum from headwaters, through streams to rivers.
Differences in scale causes different restoration approaches.