Fast-growing forest plantations have been expanding in Brazil in the last 50 years, which reach productivities by over 40 m³ ha⁻¹ year⁻¹ in reduced rotation between 5 and 15 years. In the 1990s, environmental warnings about these plantations guided research projects seeking to understand their effects on water and propose forest management actions to minimize them. The assessment of forest management effects on water resources is conducted by long-term experiments in paired catchments. In this paper we present results of some studies conducted at the hydrological monitoring centre of Itatinga Experimental Forest Station, of the University of São Paulo, where hydrological monitoring began in 1987, and currently include three catchments (83–98 ha) under different forest management regimes: short-rotation Eucalyptus plantation, long-term forest plantation mosaic and native forest restoration. Results show that at similar conditions observed at study area including deep soils and good natural water regulation, hydrological effects vary according to the forest management regime adopted, increasing water consumption and making the flow regime vulnerable to intra- and inter-annual seasonality. Regarding water quality, weekly sampling results showed suspended sediments and nitrate concentrations below water quality thresholds criteria by silvicultural operations, and the effects were transient but higher concentrations of nutrients were observed in intensive management regime. In the study area, reducing the management intensity of forest plantation by increasing the rotation time, adopting forest age mosaic and avoiding the coppice technique are alternative choices that reduced water use and increased flow regulation. Different adopted forest management schemes directly affected water use, showing that in water-deficit tropical regions, management regime of fast-growing forest plantations controls water availability.

中文翻译：

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快速生长森林的管理替代方案如何影响巴西东南部的水量和水质？配对集水区实验的见解

在过去的 50 年中，巴西的快速生长的人工林不断扩大，其生产力达到了 40 m ³  ha ^-1 年^-1在 5 到 15 年之间减少轮换。在 1990 年代，关于这些人工林的环境警告指导了研究项目，试图了解它们对水的影响，并提出森林管理行动以尽量减少它们。森林管理对水资源的影响评估是通过成对流域的长期试验进行的。在本文中，我们介绍了在圣保罗大学 Itatinga 实验森林站的水文监测中心进行的一些研究的结果，该中心于 1987 年开始进行水文监测，目前包括不同森林管理下的三个集水区（83-98 公顷）制度：短轮换桉树人工林、长期森林人工林镶嵌和原生森林恢复。结果表明，在研究区观察到的相似条件下，包括深层土壤和良好的自然水分调节，水文效应因采用的森林管理制度而异，增加了用水量，使流量制度容易受到年内和年际季节性的影响。在水质方面，每周采样结果显示悬浮沉积物和硝酸盐浓度低于造林作业的水质阈值标准，影响是短暂的，但在集约化管理制度下观察到更高浓度的营养物质。在研究区，通过增加轮作时间来降低人工林的经营强度，采用林龄马赛克和避免使用矮林技术是减少用水和增加流量调节的替代选择。不同的森林管理方案直接影响用水量，表明在缺水的热带地区，速生林的管理制度控制着水资源的可用性。