Solution of ecological problems is an urgent and extremely important task at the present stage of social economic development of Ukraine. Unreasonably high degree of economic (mostly agricultural) reclaiming of area causes spreading and intensification of degradation processes in ecosystems. Conservation of lands, including the one carried out by means of foresting of degraded lands, is the principal way to renature environment. The article concerns an issue of land conservation in the context of ecosystem services of forests.

Land degradation is a topical issue not only in Latvia, but also in Europe. Even the real estate additional tax rate of 1.5% does not prevent agricultural land from overgrowing, and there is no other legal mechanism to control it. One of the mechanisms of prevention of land degradation process is reconstruction of drainage systems, change of worthless agricultural land (less than 25 points) to forest land or improvement and return of agricultural land (more than 25 points) to economic production.

The research work presented in this doctoral thesis is devoted to the study of land use. The question is examined from two angles: i) land use within the farm (the choice of crops, pastures), and ii) land use between economic sectors (forests, urban, agriculture, etc.). Two methods were employed: mathematical programming models for the agriculture and forestry sectors and econometric methods. The supply-side agricultural model, AROPAj, allows us to model farmers’ decision in terms of crops and nitrogen input quantities.

Global climate and land use changes could strongly affect soil erosion and the capability of soils to sustain agriculture and in turn impact regional or global food security. The objective of our study was to develop a method to assess soil sustainability to erosion under changes in land use and climate.

In many regions of the world, soil erosion is one of the main land degradations processes that reduce the soil productivity by removing fertile topsoil layers, thus decreasing levels of organic matter and the nutrients. Therefore erosion researches constitute an important part of the research on the soils. The erosion risk of soils can be evaluated directly carried out in the field, greenhouses or laboratory by means of some experiments or indirectly based on developing and applying models that gives risk expectations for large areas.