As we know, forest management is a long-term process that can project forward for more than a hundred years. A sound forest management scheme is a significant precondition to promote sustainable use of forests. Forest management strategies, therefore, should be formulated with great care before they are applied. Knowledge of forest dynamics as well as the ways forests respond to management practices (e.g., thinning, fertilizing) must be considered when formulating a management strategy. In addition obtaining forest resource information at different level of resolution is essential for making both national forest policies and enterprise-level forest management plans. Field measurements can provide accurate information but they are time-consuming and expensive. We need more efficient ways to update forest resource information.
Growth and yield models that produce estimates of stand characteristics at specified points in time provide knowledge for forest management decision making. The primary uses of growth and yield information are: production forecasting, inventory updating, evaluation of silvicultural alternatives, management planning, and harvest scheduling. This topic looks at the models currently used, the whole stand-level, size-class and individual-tree models according to the modeling entity (stand, size class, tree), and discusses their fundamental features such as scope of application, specific usability, and limitations. Some of the prevailing models will be introduced and discussed. I will introduce some of them in my lectures but I would encourage you to explore more on your own.
View the following video lectures:
2.2.1 Overview of forest growth and yield modeling
2.2.2 Whole stand model
2.2.3 Size class model
2.2.4 Individual tree model
- Weiskittel, A. R., Hann, D. W., Kershaw Jr, J. A., &Vanclay, J. K. (2011). Forest growth and yield modeling. John Wiley & Sons.ISBN-13: 978-0470665008; ISBN-10: 0470665009
- Burkhart, H. E., & Tomé, M. (2012). Modeling forest trees and stands. Springer. Retrieved from http://link.springer.com/book/10.1007%2F978-90-481-3170-9
The previous two books provide readers with a comprehensive summary of the current approaches for modeling forest dynamics. In addition they include the preliminaries for producing forest growth and yield models such as forest site evaluation, indices of competition, stand density quantification and growth functions.
- Van Laar, A., &Akça, A. (Eds.). (2007).Forest mensuration(Vol. 13). Springer. Retrieved from http://link.springer.com/book/10.1007%2F978-1-4020-5991-9
This book explains the basic knowledge of forest mensuration which are essential for producing forest growth and yield model.
- Peng, C. (2000). Growth and yield models for uneven-aged stands: past, present and future. Forest ecology and management, 132(2), 259-279. Retrieved from http://www.sciencedirect.com/science/article/pii/S0378112799002297
This article focuses on uneven-aged forest growth and yield modeling. It discusses basic types of models and also demonstrates future trends for modeling uneven-aged forests.
- Liang, J., & Picard, N. (2013). Matrix model of forest dynamics: an overview and outlook. Forest Science, 59(3), 359-378. Retrieved from http://jiliang.forestry.wvu.edu/r/download/167726
This article provides a review of matrix model which are applied over a wide number areas. It introduces the general structure of matrix models, summarizes their key properties, evaluates their advantages and limitations and, finally, gives an overview of major challenges and future possibilities.
- Etiënne Thomassen. (2015). Forest Growth Modules [Models]. Retrieved from http://models.etiennethomassen.com
A collection of links to sites which contain information on forest growth models.
- BWINPro: An Individual-tree growth and yield simulator. Retrieved from http://www.nw-fva.de/index.php?id=194&no_cache=1&sword_list=bwinpro#c682
BWINPro is a free individual-tree based simulator that can be downloaded from the above link. This website is in German however the simulator supports English GUI.
Self-test for Topic 2
- What is the reason for constructing forest growth and yield models?
- What are the main approaches to modeling forest stands?
- How do you determine the biological rotation age of an even-aged pure forest stand to get the maximum volume according to growth and yield relationships?
- When do you use a space state model? Please describe its advantage over yield tables and compatible growth and yield equations.
- What is a matrix model and what are its limitations?
- What is an individual-tree model and when is it used?
- How do you categorize individual-tree models?
After formulating your answers, you may post them online at the Knowledge Café for this course as a way to share your ideas and glean knowledge from other students’ responses.