| National Forests and Water Guidelines require the establishment of riparian
buffers to help protect the freshwater environment from disturbance by silvicultural
operations on the adjacent land. The main functions of the riparian buffer are considered
to be sediment removal and erosion control, protection of water quality, moderation of
shade and water temperature, maintenance of habitat structural diversity and ecological
integrity, and improvement of landscape quality. This review paper assesses how these
functions are affected by the design and management of the riparian forest zone, with a
focus on the width of the buffer, the structure of the vegetation and species choice. It
is not possible to specify a definitive riparian buffer width that will protect the
freshwater environment from every potential threat. Forestry agencies usually recommend
widths between 10 and 30 m. Buffer widths towards the lower end of this scale tend to
protect the physical and chemical characteristics of a stream, while the maintenance of
ecological integrity requires widths at the upper end. In terms of structure and species,
the benefits are greatest where the riparian buffer replicates native riparian woodland
with an open canopy of mixed species of varied age class. The optimum level of shade is
difficult to quantify but limited work suggests that a good balance is achieved where
around 50% of the stream surface is open to sunlight and the remainder covered by
dappled shade. Within the management of riparian woodland there is a need to consider a
stream’s sensitivity and intrinsic value. Some sites will benefit from active
intervention such as thinning, coppicing or pollarding, while others will be favoured by
a hands-off approach. Long-term continuity of management is important to ensure that the
potential benefits to the freshwater environment are realised.
Keywords: riparian woodland, riparian buffer, woodland management, freshwater environment,
water quality |