What are the impacts of wind energy generation activities on riparian vegetation?
Maintaining a buffer zone of riparian vegetation along the banks of streams and rivers reduces the impact of earthworks associated with wind farm development. Care should be taken to avoid damaging existing riparian vegetation and stream banks as these complex habitats are not easy to reconstruct and it may take decades before the habitat recovers, even with replanting. Vegetated riparian buffers can help to reduce inputs of contaminants from surface runoff where wind farms are being constructed. Riparian vegetation maintains the stability of the stream bank, provides shade and habitat for mahinga kai, and reduces sediments that become exposed and wash into waterways during the construction phase. Stormwater runoff from roads and tracks also needs to be directed away from direct entry to streams.
Potential impacts of reducing or removing riparian vegetation on water quality and mahinga kai
- Increased bank erosion - the loss of roots decreases the stability of the bank, increasing its vulnerability at times of flooding.
- Increased water temperature - loss of shading from trees or overhanging streamside vegetation means waterways become more exposed and are more liable to fluctuate in temperature, (Our native fish fauna generally cannot tolerate temperatures over 25ºC and trout need temperatures to be less than 19ºC for growth.)
- Decreased dissolved oxygen through increased aquatic plant growth - plants and weeds growing within the waterway are more likely to thrive in unshaded waterways, potentially clogging and stemming flow, which can decrease oxygen levels in the waterways.
- Modified channel form - erosion through loss of vegetation can lead to scouring and breakdown of stream and river banks, eventually changing the form of the channel.
- Loss of species habitat - many mahinga kai species need the protection and habitat provided by riparian vegetation growing around streams and rivers. (Trees provide wood and roots to the stream that are habitat for fish and kōura, and loss of cover can result in loss of breeding and feeding habitat.)
- Decreased water clarity - erosion and increased sediment from bank erosion may contribute to decreased water clarity and reduced visibility for fish to find food.
- Increased nutrients in streams - riparian vegetation filters contaminants and sediment from the land. (Loss of riparian vegetation may also be associated with changes in land use (e.g., farming, forestry) that increase the amount of contaminants that are present in surface water runoff.)