Abstract

We have closely followed your study (Zhao and Running 2010), on Net Primary Productivity (NPP). Our empirical records (in fieldwork) match with the data derivate of your paper, so we are very pleased that you and your team have updated the NPP data. However, we have found a weakness that we do not know how to solve since we are inexpert in geomatics or programming of the information that you handle (for example, using the developed algorithm). The problem is that the plant-growing season in our forests (temperate forests of the southern hemisphere, in Patagonia in Argentina and Chile) begins in August-September during a certain year and ends in May of the following year. This occurs differently in the temperate forests of the northern hemisphere where growing seasons start (generally) in May-April and end in October-November of the same year. Therefore, the annual NPP data for the northern hemisphere is ready to use, but the NPP data for our forests in the southern hemisphere takes the NPP values for one semester of one year and the beginning of another. We would like to know how we can solve this since we only use monthly gross primary production (GPP). Is it possible to get information from the NPP monthly?