accounted for 50% of the benefits. An ecosystems/natural capital approach should increase the chances of NFM projects getting off the ground as it creates additional motivation.
How effective will NFM be over time at reducing flooding, particularly as we experience to a greater extent the effects of climate change? Evidence from the UK on the potential reductions in peak flows was applied to UKCP09 climate change projections. It was concluded that as time progresses NFM measures are less likely to mitigate the effects of climate change (Kay et al., 2019). This is another reason to factor in wider ecosystem services into decision making.
Based on the evidence to date, woodlands as an NFM tool and NFM more broadly seem to be affective on a small scale, but evidence to support them as a large-scale catchment tool or as a long-term tool is lacking. The results from Pontbren and Pickering show tangible benefits, but there needs to be a realistic understanding of the limitations of the evidence. If we wait for perfect and conclusive data sets, it will be very hard to get NFM off the ground. The evidence base has to be built as projects are implemented. Given the time it takes for trees to grow and for projects to unfurl at a catchment scale, the picture is going be built up slowly. NFM projects need to be monitored and reviewed over the long term. Ideally the professionals instigating the projects should be in a position to commit to the long term and to building the evidence base.
Social, economic and cultural barriers to implementing NFM The Defra pilot at Pickering highlights some barriers to using woodlands to alleviate flooding (Nisbet et al., 2011). While initial calculations suggested a net gain when offsetting the costs of the measures and loss of agricultural use against the benefits, these calculations did not factor in agricultural subsidies. It was concluded that funding policies would mean that benefits were unlikely to outweigh the costs for private landowners, especially on floodplains which are more agriculturally productive. Other identified barriers were landscape designation and the value people attach to cultural landscapes, i.e. public concerns about reforestation of open moorland, wetlands and sites of archaeological importance.
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