The effects of riparian forest management on the freshwater environment: a literature review of best management practice

Abstract

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 streams 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.

Environmental Services Provided from Riparian Forests in the Nordic Countries

“…Various technical details on buffer width, designs and nutrient sink effectiveness can be found in (Luke et al 2007;Mayer et al 2007;Broadmeadow and Nisbet 2004;Polyakov et al 2005). In general, vegetated buffer widths of at least 20-30 m are recommended to obtain benefits for water, biodiversity and GHG exchange.…”

“…The design and efficiency of riparian buffers for control of nutrient transport to surface water are relatively well studied outside the Nordic countries (Broadmeadow and Nisbet 2004) especially in agricultural landscapes (Mayer et al 2007;Sabater et al 2003;Polyakov et al 2005). However, other functions of buffer zones are rarely discussed.…”

The influence of riparian vegetation shading on water temperature during low flow conditions in a medium sized river

“…Stream water temperature is an important and limiting parameter for a number of organisms such as fish or aquatic invertebrates (Broadmeadow and Nisbet, 2004;Matulla et al, 2007;Rahel and Olden, 2008;Logez and Pont, 2013;Pletterbauer et al, 2014). It results from the multiple processes, which influence the gains and losses of thermal energy in streambeds, depending on the amount of stream discharge, topography and atmospheric conditions along the river course (Caissie, 2006).…”

Willow (Salix spp.) and aspen (Populus tremula) regrowth after felling by the Eurasian beaver (Castor fiber): implications for riparian woodland conservation in Scotland

“…Detailed accounts of the effects of beavers on the landscape and associated fauna and flora can be found in several published reviews (Nolet, 1997;Collen and Gibson, 2001;Kitchener, 2001). A more general concern is over the potential conflict between beaver felling activity and the desire to restore broadleaf riparian communities (Broadmeadow and Nisbet, 2002;Forestry Commission, 2003), especially willow species (Salix spp.) and aspen (Populus tremula L.).…”