Supplement 1. Plot descriptions and calculation of canopy N from foliar N data.

File List
FolNdata.txt

Description
The file FolNdata.txt contains the full data set used in the source paper. This data set is inclusive of all independent variables, foliar N data, and species composition measurements collected at each of 75 plot locations in the Adirondack Park. The combination of the foliar N data and the relative species abundance data are used to make the canopy N measurement at each plot. The user should note the following.

(1) Documented forest disturbance events are coded as:

1, selective logging prior to 1916

2, clearcut logging prior to 1916

3, clearcut logging and fire prior to 1916

4, moderate (25–50%) canopy loss in a 1950 blowdown event

5, severe (50–100%) canopy loss in a 1950 blowdown event

6, moderate (30–60%) canopy loss in a 1995 blowdown event

7, moderate or intenseley damaged (10-64% canopy loss) in a 1998 ice storm event

(2) A look-up table for description of the bedrock types is available at www.nysm.nysed.gov/data/bedrock.txt

(3) Species abbreviations follow the convention of USDA species code (http://plants.usda.gov) and generally are the first two letters of the genus and first two letters of the species.

(4) Canopy N values for two plots with "no data" for Soam represent the weighted average from all other species in the plot. Soam (Mountain-ash) leaf samples collected in these two plots were lost during sample processing.

文件列表
FolNdata.txt

数据集说明
文件FolNdata.txt包含了源论文所使用的完整数据集。该数据集涵盖了阿迪朗达克公园（Adirondack Park）内75个样地采集的全部自变量、叶片氮（foliar N）数据以及物种组成测量数据。通过结合叶片氮数据与物种相对丰度数据，可计算得到每个样地的冠层氮（canopy N）含量。请注意以下事项：

(1) 已记录的森林干扰事件编码规则如下：

1：1916年前的选择性采伐
2：1916年前的皆伐作业
3：1916年前皆伐后遭遇火灾
4：1950年暴风事件中冠层损失中度（25%–50%）
5：1950年暴风事件中冠层损失重度（50%–100%）
6：1995年暴风事件中冠层损失中度（30%–60%）
7：1998年冰暴事件中中度至重度受损（冠层损失10%–64%）

(2) 基岩类型（bedrock types）说明查询表可通过网址www.nysm.nysed.gov/data/bedrock.txt获取。

(3) 物种缩写遵循美国农业部（USDA）物种编码规范（详见http://plants.usda.gov），通常采用属名前两个字母与种名前两个字母的组合形式。

(4) 针对Soam（Mountain-ash，花楸）数据缺失的两个样地，其冠层氮值采用该样地内其余所有物种的加权平均值计算得到。这两个样地中采集的Soam（花楸）叶片样品在样品处理过程中遗失。