Code
F03
Sector
Forest
The complete description of the NWRM
Summary

Planting trees in reservoir catchments can have both negative and positive effects. . Afforestation of previously bare or heavily eroded areas can control soil erosion, thereby extending the life of the reservoir and improving water quality. Water quality can also be improved if precipitation is able to infiltrate into forest soils before flowing to the reservoir. These potential improvements in water quality need to be balanced against the possibility that less precipitation will be available for reservoir recharge due to the potentially greater interception and evapotranspiration associated with forests. Studies have indicated decrease of water yield after afforestation of the catchment and with the increase of forest age. Forests in reservoir catchments should typically not be managed for timber production, but maintained in as close to a natural state as possible as the fertilization and ground disturbance associated with intensive forest management can have negative impacts on reservoir water quality. Increased acidification and eutrophication after afforestation with conifer species have also been reported. Use of long-lived native deciduous tree species for afforestation instead of fast growing conifers or eucalypts is likely to bring enhanced biodiversity benefits while minimizing water loss.

Illustration(s)
Possible benefits with level
Benefits Level
BP1 - Store runoff
High
BP2 - Slow runoff
High
BP5 - Increase evapotranspiration
High
BP6 - Increase infiltration and/or groundwater recharge
High
BP7 - Increase soil water retention
High
BP8 - Reduce pollutant sources
High
BP9 - Intercept pollution pathways
High
BP10 - Reduce erosion and/or sediment delivery
High
BP11 - Improve soils
Medium
BP12 - Create aquatic habitat
Low
BP13 - Create riparian habitat
Medium
BP14 - Create terrestrial habitats
High
BP15 - Enhance precipitation
Low
BP16 - Reduce peak temperature
Medium
BP17 - Absorb and/or retain CO2
High
ES1 - Water storage
Medium
ES2 - Fish stocks and recruiting
Low
ES3 - Natural biomass production
High
ES4 - Biodiversity preservation
High
ES5 - Climate change adaptation and mitigation
High
ES6 - Groundwater/aquifer recharge
High
ES7 - Flood risk reduction
Medium
ES8 - Erosion/sediment control
High
ES9 - Filtration of pollutants
High
ES10 - Recreational opportunities
High
ES11 - Aesthetic/cultural value
High
PO1 - Improving status of biology quality elements
Low
PO2 - Improving status of physico-chemical quality elements
Low
PO3 - Improving status of hydromorphology quality elements
Medium
PO4 - Improving chemical status and priority substances
Low
PO5 - Improving quantitative status
Medium
PO6 - Improving chemical status
Medium
PO7 - Prevent surface water status deterioration
Low
PO8 - Prevent groundwater status deterioration
Medium
PO9 - Take adequate and co-ordinated measures to reduce flood risks
High
PO10 - Protection of important habitats
Medium
PO11 - Better protection for ecosystems and more use of Green Infrastructure
High
PO13 - Better management of fish stocks
Low
PO14 - Prevention of biodiversity loss
High

Case studies per NWRM