3PG.d

3PG.d is an adapted version of the 3PG model to allow the defoliation simulation in forest stands. The 3PG being a model based on the efficiency of light use produces good estimates of biomass components, but estimates for the most relevant stand variables for forest management tend to be biased. To overcome this limitation, a set of empirical models based on a previous work by Tomé et al. (2004) were improved and integrated into 3PG.d allowing the estimation of the dominant height, basal area and volume as a function of one of the biomass components (Oliveira 2015). In order to develop a version of the tool that combines forest management and defoliation, the original code from the 3PGpjs 2.7 simulator (Sands 2010) implemented in Microsoft Excel was converted to Java.

This new version - 3PG.d -  includes a module that links the growth of stands to seasonal defoliation activity of G. platensis. The defoliation is calculated dynamically and applied only in the months of insect attack using the intensities predefined by the user who can still define whether the attacks occur only during spring or during spring and autumn (Rua et al. 2020).

The required inputs ( .csv format) consist of:

. 3PG Parameters
. Climatic characterization from the nearest weather station (monthly climate data for the years in which it is intended to simulate or averages of the last 30 years)
. Site characterization (soil texture, FR, ASW)
. Stand characterization (density, biomass)
. Defoliation scenario (intensity, number of attacks per year)

To run a simulation, you simply select the inputs, define the defoliation scenario and specify the number of years of simulation and the detail of the output (monthly, annual). The tool has a user-friendly interface and  comes with a small instruction manual.

3PG.d can be downloaded at Downloads after registration and login.

References:

Oliveira T. 2015. Models to support eucalyptus plantations management under a changing environment. Doctoral thesis, School of Agriculture, University of Lisbon, Portugal.

Rua J, Barreiro S, Branco M, Tomé M 2020. Estimating defoliation impact of Gonipterus platensis on Eucalyptus globulus stands productivity using a forest simulator based on 3-PG, For. Ecol. Manag., 478, 118495, https://doi.org/10.1016/j.foreco.2020.118495

Sands PJ, 2010. 3PGpjs vsn 2.7 user manual. pp. 27

Tomé M, Faias SP, Tomé J, Cortiçada A, Soares P, Araújo C, 2004. Hybridizing a stand level process-based model with growth and yield models for Eucalyptus globulus plantations in Portugal. In: Borralho NMG, Pereira JS, Marques C, Coutinho J, Madeira M, Tomé M (Eds.), Eucalyptus in a changing world. Proc. Iufro Conf., Aveiro, 11-15 Oct. (RAIZ, Instituto deInvestigação da Floresta e do Papel, Portugal), pp.290-297.