Bisley rainfall and throughfall, and chemistry of rainfall and throughfall

This data set contain summaries and analyses mean of collected weekly measurements expressed as mm per day, and calculation of fluxes, rates and means calculated after water chemistry analyses are conducted. Rainfall and throughfall are collected weekly at the Bisley LEF site. These data sets begin March 1988 and ends December 2003. Rain and throughfall samples are the total catch for the week, and are exposed to field conditions for that time. No event sampling is conducted on a routine basis. Rainfall Collected in Bisley (RCB) are bulk or always-open collectors that receive dry deposition by sedimentation. All samples are measured for pH and conductivity, and then filtered (pre-combusted Whatman GF/F glass fiber filter) prior to further analysis. From 1983-1994 samples were cooled and returned to the San Juan chemistry laboratory for analysis. During those years, samples for NH4 and NO3 analyses were refrigerated continuously until analysis. Sub samples for NH4 analysis were also preserved with 1 molar HCl. From 1994 on, samples for NH4 and NO3 were frozen until analysis, were not acidified, and all analyses were conducted at the University of New Hampshire. Nutrient fluxes in rainfall and throughfall were measured weekly in a mature subtropical wet forest in NE Puerto Rico over a 15-year period that included the effects of five hurricanes and several prolonged droughts. Annual inputs of K, Ca, Mg, Cl, Na, and SO4-S are similar to those reported from other marine-influenced tropical forests. Rainfall input of nitrogen is comparatively low and reflects the relative isolation of the air shed. Mean annual rainfall and throughfall were 3482 and 2131 mm yr-1 respectively. On average, rainfall, throughfall, rainfall pH, and rainfall flux NH4-N and NO3-N had small but significant decreases throughout the study period. More nutrients fluxes had seasonal differences in rainfall (6 out of 12) than throughfall (4 out of 12). All volume weighted enrichment ratios calculated for the 15-year period were greater than one. However, median weekly enrichment ratios were less than 1 for sea salts and dissolved organic carbon and between 1 and 2 for Mg, Ca, SiO2 and SO4-S. In contrast, median weekly enrichment ratios were greater than 10 for NH4-N, PO4-P, and K and reflect biological enrichment within the canopy. Droughts reduced enrichment ratios of cations and sea-salts, but increased enrichment ratios for NH4-N, PO4-P and K. In the weeks following hurricanes relative throughfall tends to be higher and enrichment ratios tend to be lower. These long-term observations indicate that physical and biological processes associated with water passing through the canopy act to buffer internal nutrient cycles from inter-annual, and seasonal variations in rainfall inputs. Support for this work was provided by grants BSR-8811902, DEB-9411973, DEB-9705814 , DEB-0080538, DEB-0218039 , DEB-0620910 , DEB-1239764, DEB-1546686, and DEB-1831952 from the National Science Foundation to the University of Puerto Rico as part of the Luquillo Long-Term Ecological Research Program. Additional support provided by the University of Puerto Rico and the International Institute of Tropical Forestry, USDA Forest Service.

本数据集包含以每日毫米为单位的每周采集测量值的汇总与均值分析，以及完成水化学分析后计算得到的通量、速率与均值。降雨与穿透水在比斯利长期生态研究场（Bisley LEF Site）每周采集，数据集的时间跨度为1988年3月至2003年12月。

降雨与穿透水样品为当周的总截留量，在采样周期内暴露于野外环境，且未开展常规的事件驱动采样。比斯利采集的降雨（Rainfall Collected in Bisley, RCB）采用敞口式积尘采样器，通过沉降作用收集干沉降物。所有样品均测定pH值与电导率，随后在进行后续分析前，使用经预灼烧的Whatman GF/F玻璃纤维滤膜进行过滤。

1983年至1994年期间，样品经冷藏后送往圣胡安化学实验室开展分析。此阶段用于铵态氮（NH4）与硝态氮（NO3）检测的样品全程冷藏至分析前；用于铵态氮分析的子样品还采用1mol/L盐酸（HCl）进行保存。1994年起，铵态氮与硝态氮样品采用冷冻保存直至分析，且无需酸化，所有分析工作均在新罕布什尔大学完成。

本数据集针对波多黎各东北部一处成熟亚热带湿润森林中的降雨与穿透水养分通量开展了为期15年的每周监测，监测期间涵盖5次飓风与多次长期干旱事件的影响。钾（K）、钙（Ca）、镁（Mg）、氯（Cl）、钠（Na）以及硫态硫酸盐（SO4-S）的年输入量与其他受海洋影响的热带森林的已有报道结果相近。降雨携带的氮输入量相对较低，这反映了该区域气域相对孤立的特征。研究区的年均降雨量与年均穿透水量分别为3482 mm·yr⁻¹与2131 mm·yr⁻¹。

在整个研究周期内，降雨量、穿透水量、降雨pH值以及降雨中的铵态氮（NH4-N）与硝态氮（NO3-N）通量均呈现小幅但显著的下降趋势。降雨中的养分通量存在季节差异的种类占比（12种中有6种）高于穿透水（12种中有4种）。整个15年周期内计算得到的所有体积加权富集比均大于1。不过，海盐与溶解性有机碳的周度富集比中位数小于1，镁、钙、二氧化硅（SiO₂）以及硫态硫酸盐的周度富集比中位数介于1至2之间。与之相反，铵态氮、磷态磷酸盐（PO4-P）以及钾的周度富集比中位数大于10，这反映了林冠层内的生物富集作用。

干旱事件会降低阳离子与海盐的富集比，但会提升铵态氮、磷态磷酸盐以及钾的富集比。飓风过后的数周内，相对穿透水量往往偏高，而富集比则偏低。上述长期观测结果表明，与林冠层水流相关的物理与生物过程，能够缓冲内部养分循环免受降雨输入的年际与季节波动影响。

本研究的资助来自美国国家科学基金会（National Science Foundation）拨付给波多黎各大学的多项拨款，具体编号为BSR-8811902、DEB-9411973、DEB-9705814、DEB-0080538、DEB-0218039、DEB-0620910、DEB-1239764、DEB-1546686以及DEB-1831952，属于卢基略长期生态研究项目（Luquillo Long-Term Ecological Research Program）的一部分。额外资助来自波多黎各大学与美国农业部林务局（USDA Forest Service）。