Relative tree growth and mortality responses to the 2012 midwestern US drought in the central hardwood ecoregion

This dataset contains relative drought-driven tree growth and mortality responses derived from the USDA FS Forest Inventory and Analysis dataset (Gray et al., 2012) in the North American central hardwood ecoregion (a region representing the four US states of Indiana, Illinois, Kentucky, and Brandt et al., 2014). Data represents a period of 2000 – 2018 and characterizes relative responses to the severe 2012 midwestern drought (Mallya et al., 2013) between co-located trees with a diameter at breast height greater than 12.7 cm. Analyses were limited to regions of the study area that experienced  â€˜Severe’ or ‘Extreme’ drought conditions from March to October of 2012, as defined by the US drought monitor program (Svoboda et al., 2002). Co-located trees were defined as those growing within the same discrete 875 km2 hexagonal boundary following a tessellation approach by which Forest Inventory and Analysis plots were aggregated across 560 uniform hexagons imposed over the study area. Rela..., Relative growth and relative growth sensitivity To calculate relative growth (gr_ij) we first quantified species-specific growth in each hexagon as a relative growth rate across three successive inventories from 2000 – 2018. The relative growth rate equation (RGR_i) was expressed as (Brzostek et al., 2014): RGR_i  = [(BA_i,1 â€’ BA_i,0)/BA_i,0] Ã— 100          (Equation 1)    where BA_i,0 is the species-specific tree basal area at the initial inventory and BA_i,1 is the species-specific tree basal area at the next inventory. Next, the impact of drought on RGR_i was characterized as a rate change parameter, ΔRGR_i (% growth/year), whereby RGR_i after 2012 was subtracted by the RGR_i of the conspecific individuals occupying the same hexagon prior to drought disturbance. Specifically, ΔRGR_i was quantified as: ΔRGR_i =  RGR_i,post_drought  ‒ RGR_i,pre_drought     (Equation 2) where RGR_i,post_drought is spec..., # **Relative tree growth and mortality responses to the 2012 midwestern US drought in the central hardwood ecoregion.** Dataset DOI: [10.5061/dryad.280gb5n2b](10.5061/dryad.280gb5n2b) #### **Description of the data and file structure** The files here include: (1) the georeferenced coordinate centers of each tessellated hexagon imposed across the study area (i.e., HexagonCoordinates.csv), (2) relative growth responses during drought (*gr_ij*) between individual species within each hexagon (i.e., gr_ij.csv), (3) Relative growth sensitivity values, which reflect a synthesized species-level characterization of the percentile difference of the number of co-located species which experienced relatively larger or smaller drought-driven growth declines (i.e., RelativeGrowthSensitivity.csv), (4) relative mortality responses during drought (*mr_ij*) between individual species within each hexagon (i.e., mr_ij.csv), (5) Relative mortality sensitivity values, which reflect a synthesized species-le...,本数据集基于美国农业部林务局（USDA FS）森林资源清查与分析数据集（Gray等，2012），获取了北美中部硬木生态区（涵盖美国印第安纳州、伊利诺伊州、肯塔基州及原文疑似标注错误的区域，Brandt等，2014）内由干旱驱动的树木相对生长与死亡响应数据。数据集覆盖2000年至2018年时段，针对胸径（diameter at breast height）大于12.7 cm的同域树木（co-located trees），刻画了其对2012年美国中西部严重干旱（Mallya等，2013）的相对响应特征。本分析仅纳入研究区内2012年3月至10月期间达到美国干旱监测项目（Svoboda等，2002）定义的“重度”或“极端”干旱等级的区域。同域树木被定义为生长在同一离散的875 km²六边形边界内的个体，本研究采用镶嵌划分（tessellation）方法，将研究区内的森林资源清查样地聚合为560个均匀六边形网格。 ## 树木相对生长与生长敏感性 为计算相对生长量（gr_ij），我们首先以2000年至2018年的三次连续清查数据为基础，量化每个六边形网格内物种特异性的相对生长速率。相对生长速率（RGR_i）的计算公式如（Brzostek等，2014）所示： $RGR_i = [(BA_{i,1} - BA_{i,0})/BA_{i,0}] imes 100 (公式1)$ 其中$BA_{i,0}$为初始清查时的物种特异性树木胸高断面积（basal area），$BA_{i,1}$为下一次清查时的物种特异性树木胸高断面积。随后，将干旱对$RGR_i$的影响以生长速率变化参数$Delta RGR_i$（单位：%生长/年）进行表征，即取2012年干旱扰动后同六边形网格内同种个体的$RGR_i$，减去干旱扰动前同种个体的$RGR_i$。具体而言，$Delta RGR_i$的计算公式为： $Delta RGR_i = RGR_{i, ext{post-drought}} - RGR_{i, ext{pre-drought}} (公式2)$ 其中$RGR_{i, ext{post-drought}}$为[原文此处截断，暂保留原文标注]…… # **北美中部硬木生态区2012年美国中西部干旱下的树木相对生长与死亡响应** 数据集DOI：10.5061/dryad.280gb5n2b #### **数据与文件结构说明** 本数据集包含以下文件：(1) 研究区内所有镶嵌六边形网格的地理坐标中心点文件（即HexagonCoordinates.csv）；(2) 各六边形网格内不同物种在干旱期间的相对生长响应文件（即gr_ij.csv）；(3) 相对生长敏感性值文件，该指标综合表征了同域物种中出现干旱驱动生长下降幅度相对更大或更小的物种数量的百分位差异（即RelativeGrowthSensitivity.csv）；(4) 各六边形网格内不同物种在干旱期间的相对死亡响应文件（即mr_ij.csv）；(5) 相对死亡敏感性值文件，该指标综合反映了物种层面的[原文此处截断，暂保留原文标注]……