9
Silvi (Subject) / modelling (Lesson)
- Components of growth and yield modelling? -Mortality -Diameter increment -Recruitment -Growth
- Process based models? Characteristics? Programms? -plenty of input data and calibration -reacts and adapts to changes in the system (soil, climate...) -explains relations and maps knowledge gaps -quantifies effect of physiological and physical growth factors -process based models can often run with different time resolutions (days, months, years...) --> 3PG, BIOMASS, CABALA...
- 3PG. Characteristics? Dis-, Advantages? tree growth based on physiological principals (for many different forests) Bridges gap between mensuration based growth and yield models and process – based, C balance models Worldwide applied to many species and a wide range of forest types, good for short rotation periods, free access, can be modified and specialized for own purposes + based on wide range of conditions + applicable under changing conditions + provides explanation, aids understanding + free access - Not as widely understood as empirical growth models - Not necessarily as accurate either - can require data not available
- Statistical / empirical model (growth + yield model) -Based on statistical relations between tree / stand characters and tree / stand development → allometric relations -Multiple growth units: o Stand models o Size class models o Single tree models § Distance independent § Distance dependent --> research plots as basis
- Growth and yield tables. Practicality? Represents expected growth in evenaged stands at different ages Limited to silviculture used – interpolation between site classes and thinning regimes Not possible to take changes in growth environment into account ð Regression technique ð growth functions $ Permanent trails / experimental plots over the whole forest area
- why is it important on what kind of data the model is built on? Importance of input data type + get known of plot history (National forest inventory / permanent plots) - Maybe not representative Experiments: + Exact control & monitoring Not representative
- How to test models? - Unusual stands - Unusual treatments / measures - Is it possible to run unrealistic suggestions (planting...) - How dense can the stands become? What is the maximum stand volume?
- How to evaluate models - results? - How does the model work? - Has it been validated on independent data? Test the predictions - What are the limits for background data?
- How is growth and yield modelled? • increment • mortality •recruitment
Advertisement