LTREB Renewal at Hubbard Brook: Hydrologic-nutrient cycle interaction in small, undisturbed and human-manipulated ecosystems

在新罕布什尔州怀特山脉的哈伯德布鲁克实验森林中收集的降水、溪流水量和化学成分的记录是目前世界上最长的连续生物地球化学记录。因此，它们代表了与当前环境问题相关的信息宝库，例如酸雨、氮沉积、森林生长和大气二氧化碳水平上升。这个十年项目的前五年主要关注干扰和环境变化的影响，包括酸雨的持续减少和哈伯德布鲁克河谷内气候的变化。许多令人惊讶的发现已经出现，包括早期气候变化对水流温度的影响消失，镜湖冰盖覆盖时间缩短，酸雨对土壤化学变化的影响现在正在影响森林生长。从降水和水流化学的长期趋势的综合和外推来看，一个主要的惊喜是，整个哈伯德溪谷的地表水正在无情地稀释，在不久的将来，地表水很可能接近去矿化（极度稀释）的水。这表明，未来的基线条件可能比工业革命前想象的更稀薄，显然是因为酸雨耗尽了土壤养分，以及联邦空气污染法规对降水化学的影响。这对近期北方阔叶林及其相关水生生态系统的结构、功能和管理具有重要意义。预期在这一长期项目的最后五年里，对过去五年所追求的许多问题的重要答案将会得到或更加明确。对于努力解决重大环境问题的研究人员和决策者来说，这种精心记录和综合的长期数据对于提供准确和定量的视角来了解我们的大气、森林和水生生态系统中的化学变化以及推进生态学的理论基础至关重要。此外，许多学生参与了这项研究，并且数据可以免费提供给其他用途。

The records of precipitation and stream water amount and chemistry collected at the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire are now the longest continuous biogeochemical records of this type in the world. As such, they represent a treasure trove of information relevant to current environmental problems, such as acid rain, nitrogen deposition, forest growth, and rising levels of atmospheric carbon dioxide. The first five years of this decadal project focused primarily on the effect of disturbance and environmental change, including the continued decline in acid rain and the changing climate within the Hubbard Brook Valley. A number of surprises have emerged, including the disappearance of an early climate change effect on stream water temperature, decreased ice cover duration on Mirror Lake, and the impacts of acid rain on soil chemical changes that are now affecting forest growth. A major surprise seen from a synthesis and extrapolation of long-term trends in precipitation and stream water chemistry was that a relentless dilution of surface waters is occurring throughout the Hubbard Brook Valley and that surface waters are likely to approximate demineralized (extremely dilute) water in the near future. This suggests that future baseline conditions may be more dilute than thought for the time before the industrial revolution, apparently because of the depletion of soil nutrients by acid rain and the impacts of federal air pollution regulations on precipitation chemistry. This has important implications for the structure, function and management of northern hardwood forests and their associated aquatic ecosystems in the near future. It is expected that important answers to many of the questions pursued during the past five years will be obtained or made clearer during the final five years of this long-term project.For researchers and decision makers grappling with solutions to major environmental issues, such carefully documented and synthesized, long-term data are essential for providing an accurate and quantitative perspective on chemical changes in our atmosphere and in our forest and aquatic ecosystems, as well as to advance the theoretical underpinnings of ecology. In addition, numerous students are engaged in this research and the data are made freely available for other uses.