Analysis of forest thinning strategies through the development of space–time growth–interaction simulation models

Abstract

Thinning strategies are a prime factor in generating spatial patterns in managed forests, and have a dramatic effect on stand development, and hence product yields. As trees generally have long life spans relative to the length of typical research projects, the design and analysis of complex long-term spatial-temporal experiments in forest stands is clearly difficult. This means that forest modelling is a key tool in the formulation and development of optimal management strategies. We show that the highly flexible Renshaw and Särkkä algorithm for modelling the space-time development of marked point processes is easily adapted to enable the comparative study of different thinning regimes. This procedure not only provides a powerful descriptor of forest stand growth, but there is considerable evidence that it is particularly robust to the accuracy of model choice. Two distinct thinning approaches are considered in conjunction with a variety of tree growth functions and both hard-and soft-core interaction functions. The results obtained strongly suggest that combining the immigration-growth-spatial interaction model with spatially explicit thinning algorithms produces a realistic and flexible mechanism for mimicking real forest scenarios.

Point processes statistics of stable isotopes: analysing water uptake patterns in a mixed stand of Aleppo pine and Holm oak

“…As a result, dominant tree species in Mediterranean ecosystems are ei-2 Forest science has applied numerous statistical methods belonging to point processes (Stoyan & Penttinen, 2000;Diggle, 2003;Illian et al, 2008) to tackle ecological questions (for a review, see Comas & Mateu, 2007). This includes, for instance, the study of the spatial structure of pure and mixed forest stands (Moeur, 1993;Pélissier, 1998;Mateu et al, 1998), the distribution and severity of infected trees (Shaw et al, 2005), and the space-time modelling of forest dynamics (Renshaw et al, 2009;Comas, 2009). Here we propose the use of marked point process tools to analyse the isotopic composition of xylem water as a mark associated to each tree position.…”

Characterising forest spatial structure through inhomogeneous second order characteristics

“…Distance-dependent tree-level models (i.e. trees are the basic unit of analysis) not only improve the predictive power of these formulations and permit to analyse spatially explicit silvicultural problems such as plantation and thinning strategies, but also allow the study of complex forest dynamics (Miina et al 1991;Pukkala et al 1998;Moustakas and Hristopulos 2007;Renshaw et al 2008). These models are also necessary to generate spatially explicit forest patterns (realistic synthetic data), to simulate and study realistic silvicultural operations such as thinning and regeneration strategies, and to compare inventory designs.…”

Modelling forest regeneration strategies through the development of a spatio-temporal growth interaction model

“…This would provide better understanding of the effects of distinct regeneration strategies than, for instance, other forest distance-independent formulations. This is so since a spatially explicit algorithm for silvicultural operations can be incorporated into the model, thereby providing much more ''control'' of such prescribed tools (Renshaw et al 2008). …”

“…Although marked point process theory, as applied to forestry, has focused attention on the understanding of forest patterns in order to expose possible biological and forest-ecological generating mechanisms (e.g. Comas et al 2008;Penttinen et al 1992;Rathbun and Cressie 1994;Särkkä and Tomppo 1998;Mateu et al 1998;Degenhardt 1999), rather less attention has been paid to the simulation of such patterns in order to gain a better understanding of forest space-time growth (Renshaw and Särkkä 2001;Renshaw et al 2008).…”

“…This model has been successfully used to generate spatial patterns of marked points while mimicking real forest scenarios. For instance, Renshaw et al (2008) analyse the effects of distinct forest thinning strategies under different forest scenarios based on this approach. For completeness, other formulations have been considered to model space-time point processes, including the Hawkes processes (Hawkes 1971a, b;1972), point processes conceived to generate cluster structures, and multigeneration point processes (Diggle 2003;Comas and Mateu 2006) defined to generate spatial structures evolving through discrete time.…”