Dynamic site index model and trends in changes of site productivity for Alnus glutinosa (L.) Gaertn. in southern Poland

Abstract

Black alder is naturally widespread across all of Europe and has an increasing importance for forest ecosystems. Thanks to the considerable tolerance to adverse climatic and edaphic environmental conditions black alder is important both in open landscapes and can also be involved in the rehabilitation of disturbed soils. Assessment of site productivity is essential for providing a frame of reference for silvicultural diagnosis and prescription in order to ensure the sustainability of existing and newly established ecosystems. The most accepted method of evaluating site productivity is the site index (SI). The aim of the presented research was to develop the SI model for black alder in southern Poland. The developed SI model was used as a tool in order to test the research hypothesis assuming the increase in site productivity for black alder in southern Poland. The research material for development of SI model were stem analysis data from 180 research plots. Both, the local model parameter, which was estimated individually for every tree, and the other parameters estimated globally for the whole data set were estimated simultaneously. Changes in site productivity were analyzed on research plots and a set of 12,974 stands from the forest inventory database. Site indices calculated using the developed model are negatively correlated with age/ positively correlated with establishment year of the stands. This confirms the existence of the phenomenon of increasing site productivity for black alder. During the last century site productivity measured with site index increased on average 5 m. Therefore, black alder that belongs to the fast-growing tree species should be considered of the increasing importance for forest management.

Height growth rate of Scots pine in Central Europe increased by 29% between 1900 and 2000 due to changes in site productivity

“…The SI estimated using an individual growth series of Scots pine trees was found to be linearly dependent on the year of germination. The correlation between the SI and stand age or year of germination has been reported previously, and in most cases, an age trend has been interpreted as being driven by changes in site conditions (Albert and Schmidt, 2010;Bravo-Oviedo et al, 2010;Elfving and Tegnhammar, 1996;Kiviste, 1999;Nilson et al, 1999;Nothdurft et al, 2012;Sharma et al, 2012;Socha, 2008;Socha and Ochał, 2017;C. Yue et al, 2014).…”

A Method for the Development of Dynamic Site Index Models Using Height–Age Data from Temporal Sample Plots

“…Therefore, the NFE method was selected for fitting the model to chronosequences obtained from TSP data. To simultaneously calculate the site and global parameters of Equation (1), we used a nested iterative procedure (NIP) [8,17,28]. The NIP starts with the calibration of the global parameters of the equation, using the preliminary values of site index (H 1 ) determined by the mean height at the base age estimated for the whole empirical material.…”

Modeling Diameter Distribution of Black Alder (Alnus glutinosa (L.) Gaertn.) Stands in Poland

“…The collected data were used to calculate the basic stand variables widely used for the construction of diameter distribution models, that is, quadratic mean diameter (QMD; cm), stand density (SD; trees•ha −1 ), Reineke stand density index (SDI; trees•ha −1 ), Lorey's mean height (HL; m), and basal area (BA; m 2 •ha −1 ). Furthermore, site index (SI; m) was estimated by means of a formula developed for alder stands in Poland, assuming a base age of 100 years [44].…”