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THE ALTERING OF STATES OF SOIL HUMANIFICATION IN THE BEECH AND FIR FOREST (Calamintho-Abieti-Fagetum. Ht.1938) ON THE KARST OF WESTERN CROATIA
Jakob Martinović
; Braće Domany 4, Zagreb, Hrvatska
Andrija Vranković
; Božidara Magovca 55, Zagreb, Hrvatska
Ante Kutle
; "Lijepa naša", Palmotićeva 17, Zagreb, Hrvatska
Sažetak
In the scope of authors interest is influence of forest economy on naturaly acqired production-wise power of the soil and its preservation role in environmental protection. In connection to this, periodical characterization of humisation state of soil has been done in the study (period 1965.-2008.) in beech and fir forest - economywise most productive forest ecosystem in western Croatia. Researched ecosystem has been defined pedologicaly and vegetativly by: soil which is medium deep brown soil on lime-stone and dolomite (calcicambisol), and vegetative unit which is climatogenic community Calamintho-Abiety-Fagetum (Ht. 1938). At 22 egzemplary objects (Gorski kotar, Velika i Mala Kapela i Velebit) in humus-acumulative layer of soil pH-rate has been analysed (year 2008.), concentration of humus and nitrogen, as well as C/N relation, based on average Jenny's samples and compaired with earlier research data. It was also compaired recent state of components with forest-component standards for appropriate vegetative community emphasizing the proportion of tree sorts (Table 1 and 2). Most important research results are as follows:
1. Composition of components and proportion of tree species in beech and fir forest has been determined by historical, biological and economical factors. Proportion of tree species vary from case to case with possible extremes. Complexity of ecological conditions has been substantialy changed due to vast felling of the trees after the second world war which caused opening the crowns of the trees and altered the component's climate (increased input of light and temperature, diminished soil humidity) according to Šafar and others. That reflects on phisiological decline, weak green shoot development, poor off-spring and green shoot of fir as well as insufficient resistance to technogenetic influence of atmosphere.
2. In our example (22 forest department) was found that state of components (recent average) substantialy aberrate from standards, respectivly projected optimal composition of components. Total annual average productivity of beech and fir is 6,4 m³/ha, respectivly 57-62% as per standards possible production. Sole productivity of fir is more unfavourable. Small quantity of trees in structure of components has consequence in low production, only 2,85 m³/ha average per annum which is 30-40% of standard production i.e. 9,3 respectivly 7,2 m³/ha annualy. Unfavourable is also distribution of timber according to thickness grades (Table 6b). In our components mutual proportion of beech and fir is 16:43:41 (Table 6b), and 20:30:50 is recomanded. All displayed data on structure and production of components show that they have been unsufficiently used, at least 35% below production possibility of habitat (climate and soil) and that it would remain for longer period of time.
3. In such forest-component conditions, the alterating of states of soil humisation in humus-accumulated layer of calcicambisol has been researched. By certain prevail of data decline trend of humisation has been established. In period of 44 years (1965.-2008.) according to humisation index (Ih) decline is 30 and according to humus concetration in A-horizon about 25% (Table 6). In spite of that researched soils are in group of very rich in humus.
4. Quality of humus exspressed by C/N relation in A-horizon of calcicambisol does not show significant trend of changes. Average C/N values in time periods are in range 15,2-13,1 (Table 6, 2b, 3 and 4). From the point of view of euthrophicity soils remain in same, very favourable category, although relation C/N has been narrowed.
5. In period which has been researched, proces of acidification of soil was established. Comparison of soil reaction in 1965. and 2008. shows that same type of soil (in same floral community) turn reaction from low acid to medium acid i.e. pH value has decreased from 6,4 to 5,8 (difference pH=0,6) (Table 6). It shows that concentration of H-ions in humus-accumulative A-horison of soil has increased 6 (six) times. No doubt, established proces of acidification can be explained by character and influence of perhumid climate, which causes permanent flushing of soil by precipitation as well as by input of atmospheric oxidants (S02 and NOx). Last mentioned influence has it's strongest expression in Croatia particulary in bioclimate of beech and fir.
6. Discussion on correspondence of state of humisation and human's influence on state of components is difficult due to lack of data on altering of states of components in observed period. In that regard the best picture of relations gives the comparison of condition in years 1970. and 2008. In that period the total mass of timber has diminished from 406,5 m3/ha to 366 m³/ha (Table 3, 4 and 5). Contribution of fir in timber mass has diminished from 55,5% to 51%, since the content of humus in humus-accumulative horison diminished for 25%.
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Hrčak ID:
38031
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Datum izdavanja:
20.5.2009.
Posjeta: 2.099 *