A dataset of spatial distribution of bioclimatic variables in China at 1km resolution

Bioclimatic variables are often used to investigate the relationships between species and vegetation distribution and climate in global change research, as well as to further simulate the geographical distribution patterns of both species and vegetation, and their functional characteristics. Regional bioclimate data sets, however, have been less reported. Based on an already interpolated dataset of 1km resolution climate variables in China at every 30-year averaged from 1951 to 1980 and from 1981 to 2010, respectively, nine kinds of bioclimatic variables were calculated in the present study, including the mean temperature of the coldest month, mean temperature of the warmest month, absolute maximum temperature, absolute minimum temperature, annual growing degree days above 0°C and 5°C, growing season precipitation, annual drought index and annual moisture index. Results show that every bioclimate variable demonstrates a decreasing trend from the southeast to the northwest of China and to the Tibetan Plateau except mean temperature of the warmest month and absolute maximum temperature, and varies greatly in different vegetation regions. An overall upward trend of bioclimatic change existed between 1951-1980 and 1981-2010, but such increase was small. This dataset provides reasonable environmentally mechanistic explanations for research on the relationships between species and vegetation and climate, and offers a convenient and diverse way for researchers to use bioclimatic variables to simulate species distribution pattern and vegetation structure and functions.Nine 1km spatial resolution bioclimatic variables datasets from 1951-1980 and 1981-2010 were deposited in two folders ( Appendix I and II ), 1951-1980 and 1981-2010, respectively, with the following naming rules : China-S-X-1km.Z. S Represents the years (1951-1980/1981-2010）. X represents the bioclimatic variables, Z represents the format of the data, respectively, two-dimensional uniform grid format (.grd ), ASCII character set encoding text file format (.asc ) and tag image file format (.tif ). In this way, this dataset has three sets of formats that can be used for different research objectives. In addition, the image file format for each variable (.jpg ) is provided for ease of access.

生物气候变量（bioclimatic variables）广泛应用于全球变化研究领域，用于探究物种、植被分布与气候之间的内在关联，同时可进一步模拟物种与植被的地理分布格局及其功能特征。但目前针对区域尺度生物气候数据集的相关研究报道仍较为匮乏。
本研究基于两套已完成插值的中国区域1km分辨率气候变量数据集，分别以1951-1980年、1981-2010年两个时段的30年平均值为基础，计算得到九类生物气候变量，包括最冷月平均气温、最热月平均气温、绝对最高气温、绝对最低气温、0℃与5℃以上年生长积温、生长季降水量、年干旱指数及年湿润指数。
研究结果表明，除最热月平均气温与绝对最高气温外，其余生物气候变量均呈现从中国东南沿海向西北内陆及青藏高原逐渐降低的空间分布格局，且在不同植被区域间存在显著差异。1951-1980年至1981-2010年间，区域生物气候整体呈现缓慢上升的变化趋势，但增幅相对较小。
本数据集可为物种、植被与气候之间关联的相关研究提供合理的环境机制解释，同时为研究者利用生物气候变量模拟物种分布格局、植被结构与功能提供了便捷多样的应用路径。
两套分别对应1951-1980年、1981-2010年的1km空间分辨率生物气候变量数据集已分别归档至两个文件夹（附录I与附录II），命名规则为：China-S-X-1km.Z。其中S代表年份区间（1951-1980/1981-2010），X代表生物气候变量类型，Z代表数据格式，具体包含二维均匀网格格式（.grd）、ASCII字符集编码文本文件格式（.asc）以及标签图像文件格式（.tif）。本数据集共提供三类数据格式，可适配不同的研究目标。此外，为便于快速查阅，还为每个变量提供了图像预览文件（.jpg）。