Modeling Type 1 and Type 2 growth responses in plantations after application of fertilizer or other silvicultural treatments

摘要

The concepts of Type 1 and Type 2 responses to silvicultural treatment are presented. Type 1 responses, which result from treatments such as weed control or application of N-fertilizer at the time of thinning, advance the stage of stand development but do not change the inherent productivity of the site. Type 2 responses occur to treatments, such as correction of P-deficiency, which result in a long-term change in site properties. Schumacher yield and projection models incorporating these concepts are developed. The models are tested with data from field experiments and compared with the model advocated by Pienaar and Rhency [Forest Science 41 (1995) 629]. The new models performed better than the Pienaar-Rheney model in yield form but the Pienaar-Rheney model tended to perform best in projection form. Many experiments provide insufficient data to use curve-fitting methods to calibrate the models. To overcome this defect a direct method of estimating the advance in stand development due to Type 1 responses is suggested. The consequences of the concepts of Type 1 and Type 2 responses for experimental design, optimal measurement regimes, model development, and subsequent application of models are discussed. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 42]