Statistical modeling of seedling mortality

Seedling mortality in tree populations limits population growth rates and controls the diversity of forests. To learn about seedling mortality, ecologists use repeated censuses of forest quadrats to determine the number of tree seedlings that have survived from the previous census and to find new ones. Typically, newly found seedlings are marked with flags. But flagging is labor intensive and limits the spatial and temporal coverage of such studies. The alternative of not flagging has the advantage of ease but suffers from two main disadvantages. It complicates the analysis and loses information. The contributions of this article are (i) to introduce a method for using unflagged census data to learn about seedling mortality and (ii) to quantify the information loss so ecologists can make informed decisions about whether to flag. Based on presented results, we believe that not flagging is often the preferred alternative. The labor saved by not flagging can be used to better advantage in extending the coverage of the study.