- Environment and natural resources
Google
Data-Driven Research Collaboration Group: Lunch Seminar
Professor Lauri Mehtätalo, Natural Resources Institute Finland (Luke), Joensuu, will give a talk on the title The benefit of subject-matter theory in model building: the case of tree stem volume.
Chair: Annamari Laurén
Models for the volumes of tree stems are one of the most basic models needed in practical forestry and are needed, for example, in estimating the total volume of growing forest trees before harvest. Tree volume cannot be easily measured. Therefore, volume functions that express the stem volume based on tree diameter at breast height (DBH) and total height are needed. In Finland, the currently applied volume functions were published already 40 years ago. Since that, the form of tree stems has changed because of forest management practices and tree breeding, for example and new models are needed. Tree stems are three-dimensional objects, and their shape is somewhere between a cone and a cylinder. Based on this, I develop a theoretically justified volume function and fit it to a data set. The data includes the trees used in the old volume models (collected by climbing to the trees in 1970’s), a data collected in 1990 by felling the trees, and a recent data set based on terrestrial laser scanning of standing trees. The data includes a total of 8500 trees. Comparison to an data-driven model formulation based on empirically found functions is also presented.
Bio: Lauri Mehtätalo works currently as research professor in mathematical modelling for forest planning at Natural Resources Institute Finland (Luke). Before moving to Luke, he worked as professor in applied statistics at UEF. He did his PhD in forest mensuration and has also worked as senior researcher in forest planning at UEF. He is the main author of a recent textbook monograph Mehtätalo and Lappi 2020. Biometry for Forestry and Environmental Data: With Examples in R.
Further information: Annamari Laurén, email ari.lauren@uef.fi.
