DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 11-12/1997 str. 12 <-- 12 --> PDF |
B. Prpić, Z. Seletković i I. Tikvić: O UTJECAJU KANALA DUNAV - SAVA NA ŠUMSKE EKOSUSTAVE Šumarski list br. 11-12. CXXI (1997), 579-592 Table 1. Decline of pedunculate oak, conditions, causes and consequences, improvement measures B. Prpić, 1996. Site, range and ways of tree decline Dieback causes of groups and stands in ali pedunculate oak sites, survival of marsh species - white vvillow, black alder, narrovv-leaved ash. Dieback of pedunculate oak in different sites along water reservoirs (hydro-power stations, artifical lakes, potable and technical vvater storages, etc. First, dieback of individual trees, followed by group and entire štand dieback after 3 to 5 years, ali middle- aged and old stands. Trees under the age of 30 survive. A decline inthe increment. Ali pedunculate oak sites. Seedlings and young group die. Hydrophyte plants occur in ground storev. Ali pedunculate oak sites except drained micro-elevations. Death after final, but also regeneraton cut. Extensive death of forests in ali sites of pedunculate oak ecosystems. Observed acidic emisions pH values less than 4 in the accumulative soil horizont. Pests and discases occur. Ali tree species decline. Extent of dieback assumes the caracter of an ecological catastropfe. Dieback causes Precipitation and flood vvater during vegetation period remain on soil surface. Lack of oxygen and build-up of C02 in the rhizosphere. Death of roots due to C02 build-up and general roots necrosis. Insect and fungi attack on weakened trees. Permanent rise in groudwater levels, absence of oscillations in water- table. Slovved movement of groundvvater, bild-up of C02 in the rhizosphere accompained with lack of ozvgen, root necrosis. Permanent fali in groundvvater levels during vvegvvtation period by more than 0,5 m compared to previous mean values. After regeneration felling, štand rejuvenates poorlv. Soil is waterlogged due to vvater surplus in the site, which had previously been transpired and intercepted by old pedunculate trees. Synergetic action of swamping, lovvered vvater-table, climatic excesses, pest and disease attacks emission of harmful substances into the air and vvater, regulated monocultures. Svvamping is most dangerous (floods and excessive precipitation in vegetation period), together vvith a drop in vvater-table by more than 0.5 mmin 1-2 years. Measures aimed at improving the condition Surface dreinage, building drains in roads. Prevention of change in vvater- table. After drainage, regenerate štand vvith adequate tree species. But pedunculate oak monocultures shouldbeestablished. Present tehnical possibilities cannot improve the situation. Štand regeneration vvith tree species which correspond to a particular site. Surface drainage and introduction of pedunculate oak ond other tree species responding to the site. Stop emissions by installing devices for cleansing industrial gases and polluted industrial and urban vvater. Drainage of marshy sites. Treatment of polluted forest soils with zeoli substances. Introduction of species responding to nevv site conditions. |