The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. http://http://dspace.unitus.it:80 2013-05-25T06:19:39Z 2013-05-25T06:19:39Z Corona, Piermaria Marziliano, Pasquale Antonio Scotti, Roberto http://hdl.handle.net/2067/2064 2011-05-03T00:35:32Z 2001-12-31T23:00:00Z

Title: Top-down growth modelling: a prototype for poplar plantations in Italy Authors: Corona, Piermaria; Marziliano, Pasquale Antonio; Scotti, Roberto Abstract: Hybrid poplar plantations are one of the most important sources of timber and wood fibres in Italy and represent a significant alternative as sustainable use of agricultural land. Effective management of such plantations requires adequate growth and yield models. In light of this, the paper presents the fundamentals of a top-down growth and yield model for hybrid poplar (I-214 clone) plantations in Italy. In the top-down approach, standing volume, basal area, or other characteristics are the primary quantities predicted and these quantities are disaggregated into size class, and, eventually, into individual tree information. The basic element of the proposed prototype is the stand basal area growth equation. Stand age, current stand basal area, and site index are considered as predictors. If the current DBH distribution is also known, a second function estimates the size-class distribution of overall stand growth, projecting the DBH distribution to the end of the considered growth period. Individual competition indices do not contribute to the explanation of the growth variation at the tree level. Prototype predictions prove to be quite accurate: they are based on readily available forest inventory data, thus extracting knowledge from the wealth of accumulated long-term observations usually carried out in forestry.

2001-12-31T23:00:00Z Marziliano, Pasquale Antonio Menguzzato, Giuliano Scuderi, Angelo Corona, Piermaria http://hdl.handle.net/2067/2332 2013-01-11T00:05:06Z 2011-12-31T23:00:00Z

Title: Simplified methods to inventory the current annual increment of forest standing volume Authors: Marziliano, Pasquale Antonio; Menguzzato, Giuliano; Scuderi, Angelo; Corona, Piermaria Abstract: The assessment of the current annual increment of forest standing volume (CAI) is a fundamental tool to support forest management and planning. A suitable approach to such an end is to rely on growth and yield models. However, this kind of models are often not available for many countries and/or locations and/or species. Furthermore, they may become obsolete due to potential changes in the environmental and silvicultural conditions. Such shortcomings may be distinctively detrimental in the context of forest inventories. Several methods have been proposed to inventory CAI on one single occasion, i.e., when repeated measurements of standing volume are not available. A wellknown family of methods, still largely exploited in Alpine and Eastern European countries, derives from the estimation of the percentage current annual increment of forest standing volume by the current annual increments of stem diameter and tree height (Δh). In this study an experimental comparison of Δh assessment by three different approaches is presented with reference to a properly designed case study: (i) Δh is measured on felled trees; (ii) Δh is estimated by dynamic height curve (i.e., diameter-height-age model); (iii) Δh is estimated by conventional height curve (i.e., diameter-height model). Under the examined experimental conditions (a pure forest of silver fir on highly fertile soils in southern Italy, aged around 60 years), both simplified approaches (ii) and (iii) have proven to underestimate height increments, with a larger underestimation by the approach based on the conventional height curve. However, the consequent error in the estimation of percentage current annual increment of forest standing volume has proved to be quite limited (4% for the approach based on the dynamic height curve and around 9% for the approach based on the conventional height curve). Hence, such simplified approaches may be rather safely considered for estimating percentage current annual increment of forest standing volume when neither Δh is directly detectable on standing trees nor sample trees can be felled, nor an appropriate model to predict Δh is available. The Δh estimation on the conventional height curve should turn out to be even more suitable in the case of uneven-aged stands, where the position of the height curve remains stationary over time. Description: L'articolo è disponibile sul sito dell'editore www.sisef.it

2011-12-31T23:00:00Z