Livestock production plays a key role in tropical Latin America in a changing economic environment. This study focuses on documenting the transformations of extensive production systems by using superior forage germplasm supplied by regional research systems. The adoption of improved Brachiaria grasses was evaluated from 1990 to 2003 to estimate its impact in terms of animal productivity and income in Central America and Mexico. Information on seed sales in the local market made it possible to estimate the areas planted and the value of additional milk and beef production attributable to adoption. Mexico presents the highest volume of marketed seed and of area established with improved pastures. Among Central America countries, Costa Rica was outstanding in terms of the high volume of seed sold and the area planted, followed by Honduras, Nicaragua, and Panama. The annual growth rate of seed sales was very high during the study period, reaching 32% in Mexico, 62% in Honduras, 45% in Nicaragua, 39% in Costa Rica, and 54% in Panama. The area planted with Brachiaria species during this period totaled 6.5% of the total surface of permanent grasses in Mexico, 12.5% in Honduras, 1.0% in Nicaragua, 18.7% in Costa Rica, and 0.1% in Panama. Excluding Nicaragua and Panama, where adoption is low, Brachiaria grasses account for 24%-55% of total annual milk production and for 5%-18% that of beef. These figures clearly demonstrate that those adopting new Brachiaria cultivars are farmers mainly oriented toward milk production and, to a lesser extent, beef. In monetary terms, the value of additional production attributable to the adoption of Brachiaria grasses in the selected study countries was estimated at US$1084 million per year, 78% corresponding to milk and 22% to beef. Due to the magnitude of the livestock sector in Mexico, adoption generates slightly more than 80% of production profits. Study results indicate that the investment of public funds in Central America and Mexico to support the International Network for Evaluation Tropical Pastures (RIEPT, its acronym in Spanish) paid off in terms of adoption of improved grasses and significant increases in the supply of milk and beef, fundamental items in the diet of consumers from all income levels in the region.

In forest harvesting process, a logging company and a forest landowner who have various goals concerning forest stands purchase value are involved. The logging company wants to maximize the profit on lower price, but forest landowner - to extract maximum income. Calculating the forest stands value prior to harvesting it is possible to achieve mutually acceptable price. This article describes question statement and primary research of prior calculated and harvested volume difference for further study of forest stands purchase value algorithm optimization. Harvested volume from feed-back data and prior calculated forest stands volume were compared to obtain the difference and understand the economical importance for optimization of harvesting sites maximal value calculation algorithm. For primary study, forest stands prior harvesting calculation model from the logging company was used. Results from prior harvesting calculations were compared with data after harvesting to achieve information about the precision of calculation model. Obtained results showed significant difference between prior calculated and harvested volumes, which in financial matter cause losses to the logging company. Compared to total harvested volume, negative cutting difference was 7% from volume, which in financial terms with annual harvesting of 1 million m**3 make loss of ~2.3 million euro.

The global population has begun to rise exponentially; therefore, the demand for bioresources including food and fibre is increasing. An increasing demand for food and fibre necessitates more sustainable use of natural resources especially for soilbased ecosystem services. In this context, Functional Land Management was developed to optimize agricultural soilbased ecosystem services to meet both agricultural and environmental targets simultaneously. The aim of the research is to evaluate unmanaged agricultural land use change impact on primary productivity function in three parishes in Latvia by using Functional Land Management framework. Evaluation of primary productivity function was accomplished for both sectors agriculture and forestry by using profit and working hours as a proxyindicators. Production of vegetables and perennial plantations has higher supply of primary productivity function comparing to other land uses. Land use changes affect all soil functions that we expect from our land, especially primary productivity function. After applying land use changes, an increase in profit is higher in Liezere parish for both areas on mineral soils (7.1%) and areas on organic soils (5.2%); while an increase in working hours is higher in Usma parish: 36.6% in areas on mineral soils and 1.0% increase in areas on organic soils. Shortterm benefits are received from agricultural land, while forest land provides long-term return which increases over time but can only be obtained after reaching the age of felling. Before applying land use changes or changes in management practices we have to consider other soil function and national commitments.

More than 17,5% of Latvian agricultural land is abondoned, therefore effective use of this land is a significant issue in national economics. One of the alternatives of how to use abandoned agricultural land is its afforestation by birch. The present research is based on the Scandinavian experience. Calculations have been made on the necessary investments and management costs. The recovery and possible impact on price changes in raw birch materials are analysed as well.