Ocena ekonomiczna retencyjnych właściwości lasu

The article attempts to calculate the economic value of the natural water storage capacity of forests. The impact of forests on the volume of the river runoff and on the delay of the water cycle from the precipitation to the runoff was an indicative measure of storage capacity of the forest. Data from long−term research aimed at determining forest−water interactions in small catchments were used. Four weakly−correlated parameters of runoff characteristics were determined, reflecting the scale of retention capacities of forested areas. These parameters included mean annual runoff (HR), coefficient of the annual runoff irregularity of (HRmax/HRmin), summer to winter half−year runoff ratio (HL/HZ) and the volume of the discharge (Wq/Sq). Equations were developed interpreting the range of changes of the parameters with the increase of forest cover from 0 to 100% (fig. 1−3), and the volume of water stored by the forest per 1% of the forest cover per year was calculated. Using simplifying assumptions, the total volume of water stored per hectare of the forest in the average year was calculated to 9.05 m³. The unit cost of 1 m³ of water was determined on the basis of the lowest price which the State Forests (in the territory of the Garwolin Forest District) spent to increase the volume of the water stored in small reservoirs. No difference was made between natural and artificial water storage in terms of utility. According to such simplified calculations, the natural storage capacity of forests was estimated at 1,089 PLN per year. Apart from the water storage function, forests provide other benefits resulting from a wide range of hydrological, water−protecting effects. Water resources safeguard, inter alia, the sustainable development of forests: affect the climatic conditions, reduce the level of environmental contamination. These functions can be intensified through the use of appropriate methods of forest management.