Site Index Modeling in Poland: Its History and Current Directions Michał Zasada 1,2 and Chris J. Cieszewski 1 1 Warnell School of Forest Resources, University of Georgia, Athens, GA, USA; 2 Department of Dendrometry and Forest Productivity, Faculty of Forestry, Warsaw Agricultural University, Poland

Introduction The goal of this presentation is to: Introduce the history of site index modeling development in Poland, Show evolution of site index models using existing examples, Present current developments, and Discuss future directions of their evolution.

Background - Poland Poland – country in central Europe, surrounded by Baltic Sea and Russia (N), Germany (W), Czech Republic and Slovakia (S), Ukraine, Belarus, and Lithuania (E). Poland is a 7th largest and 6th highest populated country of the European Union. Total land area of the country is 304,465 square kilometers (>75 million acres, about twice as big as the state Georgia). Population of Poland – almost 39 million people (4.5 times more than in Georgia).

Forests occupy 8,865,000 hectares (~22 million acres), almost 29% of the total area of the country (a little bit less than in Georgia). 6th country with the highest forested area in Europe (after Sweden, Finland, France, Germany and Ukraine). The growing stock is about 1,649.6 million m 3 (58 billion cubic feet), the third largest inventory in Europe, after Germany and France (almost twice as big as in Georgia). Background - Polish Forests

Background – Polish Forestry Prevalence of coniferous forest types (~60%) Coniferous species account for ¾ of area and 80% of volume 50% stands between 20 and 60 years 6% of area and 10% of volume in stands 100 years and older Majority of public forests (>80%), mostly under the management of the State Forests

Background – Polish Forestry Based on 1997 FIA survey and Polish CSO report of 2001

Background – Polish Forestry mean volume 186m 3 /ha (~2,600 cf/ac), and differs by ownership MAI of merchantable timber 8.84 m 3 /ha (~125 cf/ac/year) harvesting ~24 million m 3 (850 million cubic feet), including almost 23 million m 3 (800 million cubic feet) from the State Forests The current harvesting level utilizes 36.5% of the ongoing annual increment

Background – Polish Forestry Scots pine: planting ~8,000-10,000 seedlings per ha (~3,000- 4,000 seedlings per ac)

Background – Polish Forestry pre-commercial thinning and a few thinnings,

Background – Polish Forestry final harvesting at the age of about 120 years (300 to 500m 3 /ha (4,300-7,150 cf/ac)

Background – Polish Forestry Semi-natural silviculture (complex cutting, seed trees, natural regeneration, multi-species and multi-story stands, etc.)

Background Traditional ties to German forestry Scientific collaboration Research (3 universities and 1 research institute), ~10-20 people in dendrometry/forest mensuration/biometrics

Site modeling in Poland 1908 – site index curves as a part of yield tables by Schwappach 1932 – site index based on age and QMD in yield tables by Jedliński 1937 – site index curves as a part of yield tables by Płoński 1949 – an adaptation of Schwappach tables to changed conditions by Szymkiewicz

Site modeling in Poland 1977 – curves modeling top height growth by Bruchwald 1986 – an anamorphic system of curves by Bruchwald 2000 – correction of the Bruchwald’s model (new data & top height definition) 2003 – a dynamic form of the Bruchwald’s model by Cieszewski and Zasada 2004 – a new, polymorphic, base-age invariant site index model by Cieszewski and Zasada

Site modeling in Poland from tables to equations, from separated curves for each site class to systems of curves, from average height to top height, from anamorphic to polymorphic models, from base age specific to base age invariant systems.

Schwappach yield tables (1908) developed by a German forester and scientist Adam Schwappach based on data from permanent sample plots established by FRI in Eberswalde still in use in Polish forestry, especially for site index class determination base of some simple models such as e.g., Socha 1997, Jarosz and Kłapeć 2002, Cieszewski and Zasada 2003, that can be used in the forest inventory data processing

Schwappach yield tables (1908) based on PSP established in XIX century one of the plots utilizing stable numbered trees 144 plots measured 1-5 times, 588 sets of data average heights from each plot formed fragments of height growth curves that were used to draw guide curves for each of distinguished site classes 5 site classes I-V (height of 28.0, 24.1, 20.3, 16.3, and 12.5m at age 100, respectively)

Schwappach yield tables (1908) Location of sample plots and Scots pine natural range in Europe

Schwappach yield tables (1908) Courtesy of Forest Research Institute, Warsaw, Poland

Schwappach yield tables (1908)

Jedliński yield tables (1932) first Polish yield tables Site index determined using age and QMD Based on data mostly from unmanaged stands in Poland Published just before World War II Never widely used in practice

Płoński yield tables (1937) first Polish yield tables using age and height for site index class determination developed using approach as described by Schwappach Based on data from unmanaged stands in eastern Poland Published just before World War II Never widely used in practice

Szymkiewicz yield tables (1949) Set of yield tables prepared in the FRI, based on previously published developments from Germany, Russia and Poland Additional site class Ia for Scots pine extrapolated by Szymkiewicz to address needs of field foresters

Separated curves (1977) The first Polish mathematical model of height growth Based on top height Site index = top height at age of 100 years Growth curve for an average site scaled up and down Model can be transformed to a linear form

Anamorphic model (1986)

Anamorphic model (2000)

Dynamic model (2002) Cieszewski & Zasada, A dynamic form of the anamorphic site index model for Scots pine in Poland. Based on anamorphic model by Bruchwald et al. from 2000 The same curves as the base model More parsimonious Site index is a special case of the overall model

Introduction of GADA Cieszewski & Zasada, Generalized Method of Algebraic Differences: deriving dynamic site index equations based on biological theories Cieszewski & Zasada, Derivation of Generic Dynamic Site Equations Using Generalized Algebraic Difference Approach

BAI based on yield tables (2003) Cieszewski & Zasada, Site index model for Scots pine based on Szymkiewicz yield tables

A new model for Scots pine Base-age invariant Polymorphic with variable asymptotes Dynamic form Based on: –Stem analysis data –Permanent sample plots

A new model 508 dominant and co-dominant dominant pine trees from 256 well-stocked, pure, even-aged pine stands located on typical pine sites in large forest complexes in Poland

A new model

Preliminary model Derived using GADA 3-parameter model based on the Schumacher function Base-age invariant Polymorphic with variable asymptotes

Future directions Site index definition New site index curves for main species (based on stem analysis data and permanent sample plots) Spatial analysis of new site index curves (regional models) Site index curves for stands under intensive management Site index in mixed stands and stands with a complex structure

Thank you!