Značilnosti zaraščanja in možnosti usmerjanja sukcesijskega razvoja sestojev pionirskih drevesnih in grmovnih vrst na novonastalih gozdnih površinah

Disertacija obravnavava značilnosti zaraščanja na opuščenih kmetijskih zemljiščih in učinke nege na možnost usmerjanja sukcesijskega razvoja v Halozah. Raziskava je razdeljena na dva dela. V prvem delu se proučujeta trendnaraščanja površine gozdov in zemljišč v zaraščanju ter vpliv dejavnikov okolja na zaraščanje. Vegetacijsko sestavo na zemljiščih v zaraščanju se primerja z vegetacijsko sestavo mladih razvojnih faz gozda, proučujejo se strategije zaraščanja na zemljiščih v zaraščanju ter procesi naravne obnove v gozdu. V drugem delu se proučujeta vpliv nege na zgradbo sestojev na zemljiščih v zaraščanju ter možnost usmerjanja sukcesijskega razvoja teh sestojev. Za proučevanje vegetacijske sestave in procesov naravne obnove so uporabljene gradientne metode, statistične analize, indeksi pestrosti ter izračun pomembnosti vrste, učinke nege se ugotavlja s statističnimi analizami.Rezultati analiz kažejo, da se je od leta 1985 do leta 2005 površinagozdov v Halozah povečala za 6,9 %, v naslednjem desetletju pa se pričakuje, da se bo še za dodatnih 5,5 %. Na potek zaraščanja vpliva nadmorskavišina. Opuščena kmetijska zemljišča se začnejo zaraščati z grmovnimivrstami, z napredujočo sukcesijo se povečujeta število drevesnih vrstin gostota osebkov, delež pionirskih vrst se manjša. Proces zaraščanja poteka preko stadijev Cornus sanguinea - Cornus sanguinea - Carpinus betulus . V gozdu prevladujejo drevesne vrste, s procesom razvoja gozda se gostota osebkov manjša, število vrst se bistveno ne spreminja. Proces naravne obnove poteka preko stadijev Fagus sylvatica - Fagus sylvatica - Carpinusbetulus . Z nego se pospešuje preslojevanje in rast prehodnim vrstam, zlasti plemenitim listavcem ter povečuje prsni premer izbrancem. Zaključek raziskave je, da je s pravočasnimi ukrepi nege mogoče pospešiti naravno sukcesijo in jo usmeriti v gospodarsko zanimiv in ekološko stabilen gozd. Kakovost je na teh ekološko labilnih opuščenih kmetijskih zemljiščih drugotnega pomena.The objective of this study was to examine the characteristics of the abandonment process on abandoned agricultural land in the Haloze region and the effects of young forest tending on the direction of the succession. The research consists of two parts. In the first part the tendency of increasing forest and abandoned land area, and the influence of environmental factors on the overgrowth process are studied. Species composition on abandoned land is compared to species composition of forest in young developmental phase. Also successional strategies on abandoned land and processes of natural restorationin forest are studied. In the second part the influence of young forest tending on the structure of stands on abandoned land is examined, and the potential succession process on these stands. Species composition and vegetation processes were evaluated with gradient methods, statistical analyses, variety indexes and importance values. The effects of young forest tending were analysed using statistical methods. In the period from 1985 to 2005, the forest area in Haloze increased by 6.9 %, and an increase of a further 5.5 % can be expected over the next decade. The process of succession depends on altitude. On abandoned agricultural land, the succession begins with shrub species, and in the next stage of the succession progress continueswith an increased number of tree species along with an augmentation in tree density and a decrease in the number of pioneer species. The successional process proceeds through the Cornus sanguinea - Cornus sanguinea - Carpinus betulus stages. In a dominanted by tree species, the density of individuals decreases during succession, while the number of species does not change significantly. The process of natural restoration proceeds through the Fagus sylvatica - Fagus sylvatica - Carpinus betulus stages. Young forest tending accelerated the growing process of transition species, increased the breast diameter of valuable deciduous tree species, and increased the stratification. It can be concluded that, over time, measures in young forest tending can accelerate natural succession in the direction of an economically alternative and ecologically stable forest. On this eco-labile, abandoned agricultural land quality is of secondary importance