Influence of riparian buffer width on air temperature at Whangapoua Forest, Coromandel Peninsula, New Zealand

Air temperatures were measured mid-way within a 5- and a 30-m wide riparian forest buffer and in an adjacent open clear-felled riparian area over an 11-month period. Median reductions in maximum daily air temperatures were 3.2 °C in the 5-m wide and 3.4 °C in the 30-m wide riparian forests as compared to maximum daily air temperatures in an adjacent treeless riparian area. Both forested sites had slightly warmer minimum daily air temperatures than those in the open site (median differences of 0.5 °C for the 5-m and 0.7 °C for the 30-m wide riparian forests). The 30-m buffer was slightly cooler than the 5-m buffer during the day (median difference in maximum daily air temperature of 0.3 °C) and slightly warmer during the night (median difference in minimum daily air temperature of 0.4 °C). Buffer performance in reducing the daily maximum temperature was most effective as the air temperature increased at the open site, whereas performance in reducing the minimum temperature increased as the air temperature declined. These results suggest forested riparian buffers as narrow as 5-m wide can substantially moderate air temperatures as compared to a treeless environment.