Summary:

The aim of the present work is a description of a multi-year complex field research (hydrological, chemical and geotechnical) carried out in the area of the "Lasy Rychtalskie" Forest Promotion Complex "Lasy Rychtalskie". The work focused on characterizing the present state, forecasting future changes, as well as indicating the stability threats which the areas face. Forest promotion complexes are functional areas of a particular ecological, educational and social significance. The Lasy Rychtalskie Complex is situated within the grounds of the Syców Forest Inspectorate and its name is taken from the section called Rychtal. The area of the forests is famous for its Pinus sylvestris L ecotype, as well as unique genetic values, confirmed by scientific research. The field investigations were carried out on the marshlands of the forests in focus. Three experimental plots, microcatchments and 6 transects transverse to the forests roads, situated either within the area of the catchments or in their close neighbourhood, were selected for the detailed research. The selected catchments are situated on the marshlands. 51 groundwater measurement wells, alongside with 3 Thomson overflows situated on watercourses were installed on the experimental plots. Soil samples were collected from all drillings for standard laboratory tests of mechanical, physical, chemical and physico-chemical properties. The marshlands in focus are characteristic for their high storage capabilities. The annual outflow is relatively low, reaching about 4 % of the annual precipitation, and it occurs only in the winter half-year and May. It can be concluded on the basis of the obtained results that the Nash model delivers satisfactory results of the catchment outflow simulation for forest marshlands. The effective precipitation calculated basing on the SCS-CN model finds a limited application for marshlands. Groundwater can be found shallow at the depth of approx. 1m below ground level. Water relation changes forecast for the investigated areas, expressed by groundwater level changes, was based on the negative annual atmospheric precipitation trend. It was assumed that significant changes in marshland ecosystems would occur in the situation of at least 50 % decrease of the present mean groundwater level. It will take about 100 years. Pragmatic action to be taken should prevent from the outflow of the water from the areas. The work presents an easy to apply method of evaluating potential storage capability of forest areas. It utilizes, among other components, standard data stored in bases built during forest management practices. The carried out chemical tests did not reveal any excessive accumulation of chemical pollutants either in soil or both ground and surface waters of the Complex. Dirt roads based on marshy subsoil did not meet, in the period of the whole year, the bearing strength requirements defined for forest roads. The bearing capacity of hard paved not-improved roads depended on the groundwater table level in the subsoil.