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Microbiological Characteristics of the Soils and Natural Regeneration of Forest Gaps within Damaged Forest Ecosystems of the Silver Fir (Abies alba Mill.) in Gorski Kotar

Damir Ugarković orcid id ; Šumarski fakultet Sveučilišta u Zagrebu
Ivica Tikvić ; Šumarski fakultet Sveučilišta u Zagrebu
Zvonko Seletković ; Hrvatski šumarski institut Jastrebarsko
Milan Oršanić ; Šumarski fakultet Sveučilišta u Zagrebu
Ivan Seletković ; Hrvatski šumarski institut Jastrebarsko
Mihaela Blažinkov ; Agronomski fakultet Sveučilišta u Zagrebu
Mirna Mrkonjić Fuka ; Agronomski fakultet Sveučilišta u Zagrebu
Sulejman Redžepović ; Agronomski fakultet Sveučilišta u Zagrebu

Puni tekst: hrvatski pdf 102 Kb

str. 99-110

preuzimanja: 976



Silver fir (Abies alba Mill.) is the most damaged forest tree species in Republic of Croatia. As a result of changes in natural biotope fac­tors tree degradation and sudden decline is manifested. Intensive tree decline leads to canopy degradation and creating smaller or larger forest gaps. These advents cause changes in microclimatic and microbiological conditions, and regeneration problems. Researchers are carried out in Gorski kotar, in beech-fir and fir forest areal. The main aim of this research was to determine chan­ges in chemical and microbiological composition of forest gap soil, and natural regeneration within gaps. Chemical and microbiological analyses of forest soil were done. Soil microbiological analyses included determination of total fungi and bacteria count, and presence of microorganism functional groups. According to chemical parameters higher values were found in con­trol plots (canopy) than in large forest gaps. Exception was small forest gap where values of chemical variables were higher than in corresponding control plot (table 2).
In large beech-fir forest gap was found smaller number of asymbiotic nitro­gen fixators and cellulose decomposition fungi than in control plot (table 3).
Small forest gap in beech-fir forest had higher value of individual soil functional microorganism groups than corresponding control plot, except cel­lulose decomposition fungi. The highest soil biogenity was found in small fo­rest gap (table 4).
In large fir with hard fern forest gap regarding control plot was found si­gnificantly smaller total fungi count and amount of cellulose decomposition fungi (table 5).
Comparing gaps between themselves total fungi count in O1 and O2 beech-fir forest gaps was significantly higher than in O3 fir with hard fern gap. Amount of asymbiotic nitrogen fixators and ammonia forming bacteria was significantly the highest in small gap O2, then in large gap O1 in beech-fir forest, and the lowest in O3 fir with hard fern forest gap (table 6).
Amount of asymbiotic nitrogen fixators, cellulose decomposition fungi and ammonia forming bacteria was significantly higher in beech-fir forest than in fir with hard fern forest (table 7).
The highest number of seedlings was found in gap O1, while other two gaps have had equal plant number. Regarding control plots gap O1 had two times more plants than control. In gap O2 was found two times lower plants number regarding control, while gap O3 had equal plants number as control. Considering plants age in all gaps and control plots was found the highest number of biennial plants (table 8).
Considering percentage of tree species younger than three years, in gaps was found the highest proportion of silver fir, then mountain maple, and the lowest common beech (table 9).
Considering the number of older trees good regeneration with deciduous tree species was found within gaps namely with mountain maple and common beech (tables 10, 11 and 12).
Considering amount of different functional microorganism groups small forest gap O2 has medium, while large gaps have lower soil biogenity. Com­paring large gaps in different forest associations, large gap O1 in beech-fir fo­rest regarding large gap O3 in fir with hard fern forest has significantly higher total fungi count, amount of asymbiotic nitrogen fixatros and ammonia for­ming bacteria. In this research was found different amount of soil individual microorganism groups comparing beech-fir forest and fir with hard fern fo­rest. As in larger forest gaps were found certain changes in soil microbiologi­cal characteristics regarding small gap it can be concluded that large gaps represent specific microbiotops. Namely in forest gaps are found young silver fir plants, while there is lack of older ones. According to height in gaps there are no silver fir plants higher than 50 cm. As large forest gaps are enlarging and not getting smaller, also are good regenerated with common beech and mountain maple plants, were are believe that forest gaps are biotops with exc­hanging tree species.
Soil chemical characteristics in small beech-fir forest gap had higher va­lues, and large gap lower values than control plots. Soil chemical characteri­stics in large fir with hard fern gap had smaller values than in control plots, except soil pH value. In all gaps was found significantly lower amount of cel­lulose decomposition fungi than in control canopies. In large forest gaps was found low, and in small forest gap medium soil biogenity. Microbiological characteristics of soils in beech-fir forests have higher values than in fir with hard fern forest gaps.
Proportion of deciduous tree species (mountain maple and common beech) younger than three years was higher in large beech-fir forest gap, while in small gap was same. In large fir with hard fern forest gap dominate silver fir plants younger than three years.
According to number of plants younger than three years in forest gaps and control plots are dominating mountain maple and common beech plants, while proportion of silver fir plants was small.

Ključne riječi

forest gaps, microbiological characteristics of the soils, microorganism functional groups in the soil, natural rege­neration, Silver fir, tree decline

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Podaci na drugim jezicima: hrvatski

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