ISLSCP II Potential Natural Vegetation Cover

This data set was developed to describe the state of the global land cover in terms of 15 major vegetation types, plus water, before alteration by humans. It forms a complement to the historical croplands data set developed by Ramankutty and Foley (1999). By overlaying the two, one can determine the extent to which natural vegetation has been cleared for cultivation. This data set can be used directly within spatially-explicit climate and biogeochemical models. There are four total files in this data set. Two files contain the land cover types representing potential natural vegetation before human alteration, and two other files contain those points in the original data set submitted by the Principal Investigator that have been modified in order to match the land/water mask of the ISLSCP Initiative II.

The geographic distribution of contemporary land cover types can be derived from remotely-sensed data. However, humans now dominate much of the world and there is little evidence of the pre-human-settlement natural vegetation or Potential Natural Vegetation (PNV). PNV, as defined here, does not necessarily represent the world's natural pre-human-disturbance vegetation. Rather, our definition of PNV represents the world's vegetation cover that would most likely exist now in equilibrium with present-day climate and natural disturbance, in the absence of human activities.

本数据集旨在以15种主要植被类型及水域为维度，描述人类活动干预之前全球土地覆盖的现状。该数据集与Ramankutty和Foley（1999年）开发的历 史农业用地数据集相辅相成。通过叠加这两个数据集，可以确定自然植被在农业生产中被清除的范围。该数据集可直接应用于空间显式的气候和生物地球化学模型。该数据集共包含四个文件。其中两个文件包含代表人类干预前潜在自然植被的土地覆盖类型，另外两个文件则包含原始数据集中由主要研究者提交并被修改以匹配ISLSCP II计划土地/水域掩膜的那些点。当代土地覆盖类型的地理分布可以通过遥感数据获得。然而，由于人类活动在全球范围内占据主导地位，关于人类定居前自然植被或潜在自然植被（PNV）的证据寥寥无几。在此定义中，PNV并不一定代表人类干扰前世界的自然植被。相反，本定义的PNV代表在当前气候和自然干扰下，在没有人类活动干预的情况下，世界植被覆盖最有可能达到的均衡状态。