Hydrological impacts of converting native forests and grasslands to pine plantations, South Island, New Zealand
Hydrological impacts of converting native forests and grasslands to pine plantations, South Island, New Zealand
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DOI：
10.1016/s0168-1923(96)02376-3
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发表时间：
1997-03-01
影响因子：
6.2
通讯作者：
Jackson, R
中科院分区：
文献类型：
--
作者：
Fahey, B;Jackson, R
自20世纪70年代中期以来，在新西兰研究了用商业软木取代原始森林和草地所引起的水量、洪水水文和低流量的变化。本文讨论了其中两项研究的长期结果。第一部分研究了南岛西北部常绿混交林向松林的转变。经过2年的校准期后，留下一个集水区作为对照（DC2），另外两个集水区于1981年采收，一个用滑车采收（DC1），另一个用拖车采收（DC4），此后不久种植在松树上。在收获后的前4年，DC1和DC2 Nas之间的平均年产水量差异为352毫米（69%），DC4和DC2之间的平均年产水量差异为463毫米（90%），与校准期相比，分别增加了312毫米（61%）和344毫米（68%）。在收获区种植使两个集水区的水量在8年内恢复到收获前的水平，并在DC4估计在5年内减少340毫米的径流。平均洪峰在收获后增加，特别是在滑木集水区的中小型暴雨（75-100%）。风暴对收获的反应类似，但要温和得多。收获后低流量也增加了。树的生长带来了风暴，高峰流，急流流。低流量在10年内恢复到原始山毛榉林的水平。第二项研究利用从新西兰南部东部高地的两个集水区收集的数据，研究了将草丛转变为松树种植园的影响。经过3年的校准期（1980-1982），一个集水区种植了超过67%面积的松树，另一个集水区则保留在草丛中。到1989年，种植集水区的年水量差为130毫米，1991年至1994年平均为260毫米（占对照区总径流量的27%）。低流量的差异（以年最小7天平均值表示）也表现出类似的趋势，这表明在干旱期，灌丛草地造林可以减少0.18 mm d（-1）。冠层蒸发增加造成的截留损失增加被认为是产水量减少的主要原因。经过10-12年的树木生长，平均洪水峰值下降了55%至65%，流通量下降了约50%。
Changes in water yield, flood hydrology, and low flows caused by replacing indigenous forests and grasslands with commercial softwoods have been investigated in New Zealand since the mid-1970s. The long-term results of two of these studies ale discussed here.The first deals with the conversion of mixed evergreen forest to pine plantation in the northwestern South Island. After a 2-year calibration period one catchment was left as the control (DC2) and the other two catchments were harvested in 1981, one by skidder (DC1) and the other by hauler (DC4), and planted in pines shortly thereafter. For the first 4 years after harvesting the average annual difference in water yields between DC1 and DC2 Nas 352 mm (69%), and between DC4 and DC2 it was 463 mm (90%), which equates to an annual increase of 312 mm (61%) and 344 mm (68%), respectively, when compared with the calibration period. Planting the harvested areas caused the water yield from both catchments to return to pre-harvesting levels within 8 years, and an estimated reduction in runoff of 340 mm within 5 years at DC4. Mean flood peaks increased after harvesting, especially for small and medium storms on the skidder-logged catchment (75-100%). The response of the storm quickflows to harvesting was similar but much more subdued. Low flows also increased after harvesting. Tree growth brought storm peak flows, quickflows. and low flows back to the levels of those in the original beech forest within 10 years.The second study examines the impact of converting tussock grasslands to pine plantations using data collected from two catchments in the eastern uplands of southern New Zealand. After a 3-year calibration period (1980-1982) one catchment was planted in pines over 67% of its area and the other was left in tussock. By 1989 the difference in annual water yield from the planted catchment was 130 mm, and between 1991 and 1994 it averaged 260 mm (27% of total runoff from the control). Differences in low flows (represented by the minimum annual 7-day mean) showed a similar trend, and suggest that in dry periods, afforestation of tussock grasslands can reduce water yields by 0.18 mm day(-1). Higher interception losses from increased canopy evaporation is believed to be the main reason for the reduction in water yield. After 10-12 years of tree growth mean flood peaks had fallen between 55 and 65%, and quickflows had decreased by about 50%.