Simulator rasta šumskih stabala i sastojina „RASTko“: razvoj i parametrizacija za bukvu u zapadnoj Srbiji

Abstract

Simulator rasta šumskih stabala i sastojina „RASTko“ razvijen je i parametrizovan na osnovu podataka o rastu bukve u zapadnoj Srbiji. Istraživanja strukture sastojina i modelovanje rasta stabala realizovani su za ogledne površine u GJ „Istočna Boranja“, Loznica i GJ „MZ Rača“, NP Tara. Analizirana baza podataka sastoji se od detaljnog premera ukupno 66 oglednih polja (OP) odnosno 2,27 ha visokih bukovih šuma. Pored izvrtaka uzetih svim stablima na OPa, rekonstruisani su i tokova rasta i prirasta kod 52 dominantna stabla. Prikupljeni su podaci o rastu bukve na tri geološke podloge- granodioritu, krečnjaku i filitu, a pokrivaju i preko 600 m vertikalne distribucije bukovih sastojina (395-1020 m n.v.), odražavajući na taj način dinamiku rasta stabala i sastojina bukve u gornjim delovima niže brdske zone vegetacije i u celokupnoj nižoj planinskoj zoni. Istraživanja starosne strukture OPa pokazala su da se u 75% slučajeva radi o jednodobnim (25/66) i približno jednodobnim sastojinama (25/66), dok je raznodobna starosna struktura evidentirana kod četvrtine analiziranih OPa (16/66). Pokazano je da iskustvena procena starosti u bukovim sastojinama nije pouzdan metod i da u preko 50% slučajeva dovodi do greške koja je veća od polovine dobnog razreda jednodobnih sastojina. Na formiranje pogrešnog utiska o sastojinskoj starosti najviše utiče gustina sastojine iskazana preko broja stabala. Analizom podataka o dostignutim visinama utvrđeno je da bukva na istraživanom području u zrelim sastojinama dostiže visine preko 40 m, što ova staništa svrstava u jedna od najproizvodnijih za ovu vrstu drveća kod nas i u Evropi. U svrhu kvantifikacije tokova visinskog rasta na istraživanom području testirana je mogućnost primene 7 različitih formi modela dobijenih generalizovanim algebarsko diferencijalnim postupkom (GADA). Nakon postupka višekritrijumskog izbora najbolje dinamične GADA funkcije, formirane su krive stanišnih indeksa. Na osnovu iznosa stanišnog indeksa u 100. godini (SI100) utvrđeno je da bukva na staništima najvećeg proizvodnog potencijala na području ŠG ''Boranja'', Loznica dostižu veće visine u odnosu na bukvu na području NP ''Tara''. Šire posmatrano, bukva na najboljim staništima u zapadnoj Srbiji ima i do 8 m veće iznose SI100 nego na području istočne i centralne Srbije. Dostupni podaci nisu pokazali da postoje statistički značajne razlike u ostvarenim visinama na tipovima staništa mapiranim u okviru GJ „Istočna Boranja“. Da bi se omogućile simulacije rasta stabala bukve izvršena je i kalibracija modela 1) maksimalnog rasta prečnika, 2) promene širine krošnje i 3) rasta početka krošnje. RASTko je formiran kao hibridni simulatora rasta šumskih stabala i sastojina čiji izvršni je napisan u programskom jeziku R. Operativna verzija sa odgovarajućim interfejsom predstavljena je korisnicima u formi interaktivne shiny internet aplikacije. Povezanost modula simulatora prikazana je odgovarajućim algoritmom, a pored toga detaljno su predstavljene i dostupne funkcionalnosti programa. Pokazano je da je primena GADA pristupa prilikom konstrukcije modela visinskog rasta prikladnija je za razvrstavanje staništa po proizvodnosti u odnosu na pristup koji je korišćen prilikom izrade polimorfnih stanišnih indeksa u sklopu simulatora SILVA (Nemačka) i SYBILA (Slovačka). Prva testiranja su pokazala da RASTko funkcioniše na očekivani način i da može da simulira rast stabala i sastojina bukve na području na kojem je vršena parametrizacija modela.

The growth simulator of forest trees and stands "RASTko" was developed and parameterized based on data reflecting the beech growth in western Serbia. Investigations of the stand's structure and modelling of tree growth were carried out for sample areas in GJ "Istočna Boranja", Loznica and GJ "MZ Rača", NP Tara. The studied database consists of a detailed survey of 66 sample fields (SP) in total, i.e. 2.27 ha of high beech forests. In addition to the core samples taken from all the trees at the SPs, the growth of 52 dominant trees was also reconstructed. Data were collected on three geological substrates - granodiorite, limestone and phyllite, and they cover over 600 m of the vertical distribution of beech stands (395-1020 m a.s.l.), thus showing the dynamics of beech growth in the upper parts of the lower hilly vegetation zone and the entire lower mountain zone. Investigations of the age structure showed that in 75% of cases, SPs are even-aged (25/66) and approximately same-age stands (25/66), while uneven age structure was recorded in a quarter of the investigated SPs (16/66). It has been shown that the experiential assessment of age in beech forests isn’t a reliable approach, which leads in more than 50% of cases to an error greater than half of the age class for even-aged stands. The wrong impression is primarily influenced by the stand density expressed through the number of trees. The analysis of the heights reached revealed that the beech in the researched area in mature stands reaches a height of over 40 m, which ranks these habitats as one of the most productive for this type of tree in our country and Europe. To quantify the height growth patterns in the researched area, the possibility of applying 7 different forms of models obtained by the generalized algebraic differential procedure (GADA) was tested. After the multi-criteria selection of the best dynamic GADA function, site index curves were formed. Based on the value of the site index in the 100th year (SI100), it was determined that beech at the most productive sites in the area of ŠG "Boranja", Loznica reached greater heights compared to the beech in the area of NP "Tara". More broadly, beech growth at the best sites in western Serbia is up to 8 m higher than SI100 values in Eastern and Central Serbia. The available data did not show statistically significant differences in heights along site types mapped for GJ "Istočna Boranja". To enable simulations of the beech growth, the model of 1) maximum growth of diameter, 2) changes in crown width and 3) growth of the crown base was calibrated. RASTko was formed as a hybrid individual tree growth simulator coded in the R programming language. The operational version with the appropriate interface is presented to users as an interactive shiny internet application. The relation between simulator modules is shown with the descriptive algorithm, and in addition, the available functionalities of the program are presented in detail. It has been discussed that the GADA approach in the height growth modelling is more suitable for classifying habitats by productivity compared to the approach used during the creation of polymorphic habitat indices as part of the SILVA (Germany) and SYBILA (Slovakia) simulators. The first tests showed that RASTko works expectedly and can simulate the growth of trees and beech stands in the area where the model was parameterized.