Hydrology and related changes after harvesting native forest catchments and establishing pinus radiata plantations. Part 2. The native forest water balance and changes in streamflow after harvesting

Abstract

Six small, steep, south-west facing catchments (1.63-4.62 ha) have been monitored in Westland, New Zealand since 1974. Two catchments were retained in native mixed evergreen forest and the rest were subjected to various harvesting and land preparation techniques before being planted with Pinus radiata between 1977 and 1980.The 1 1-year water balance for the native forest catchments was: rain = streamflow + interception loss + transpiration + seepage (2370mm = 1290mm + 620 mm + 360 mm + 100 mm). In the year after treatment streamflow generally increased by 200-250 mm, except for one treatment (clearfelling, herbicide application, no riparian reserve) where the increase was 550mm. The catchments were planted with Pinus radiata, but rapid colonization by bracken (Pteridium esculentum) and Himalayan honeysuckle (Leycesteria formosa) led to a rapid decline in streamflow, which returned to pre-treatment levels after an average of about five years. Streamflow yields then continued to decline for another two to three years before stabilizing at a level about 250mmyr-' lower than pre-treatment levels. At this time the catchments had a dense bracken/honeysuckle understorey beneath 5 m tall pine trees.

Summer flows in experimental catchments with different forest covers, Chile

“…These differences seem low as Rowe and Pearce (1994) and Bari et al (1996) report that, in the year that follows the final harvest, increases in total runoff of 10-20% of the fallen rain can take place. Los Ulmos2 can be considered as having a 'after the final harvest' condition while that of Los Ulmos1 is 'with forest', and for the period 2000/2001, the 21.1 mm of difference among total runoff corresponds to only 4.8% of the rainfall.…”

Forest cover influence on regional flood frequency assessment in Mediterranean catchments

“…Experimental studies show that forest cover reduces the annual catchment discharge as result of increased rainfall interception, increased transpiration and lower soil moisture regime during interstorm periods and higher permeability of forest soil (e.g. Bosch and Hewlett, 1982;Cornish, 1993;Rowe and Pearce, 1994;Stednick, 1996;Fahey and Jackson, 1997;Bruijnzeel, 2004). On the other hand, it is more difficult to assess the impact of forests on floods catchment response response to rainfalls with low frequency, due to lack of experimental data for quantifying the effect of forests on the catchment response to rainfalls with low frequency (Nelson and Chomitz, 2007).…”

Paired catchments observations on the water yield of mature eucalypt and immature radiata pine plantations in Victoria, Australia

“…Comparison with New Zealand and South African data Rowe and Pearce (1994) presented results generated by harvesting native forest catchments and establishing radiata pine plantations in New Zealand. The catchments were small (1.6-4.6 ha) and in a high-rainfall (2000-2500 mm).…”