Soils, water and nutrients in a forest ecosystem in Suriname

Water and nutrient flows were measured in catchments on strongly weathered loamy sediments of the Zanderij formation in Suriname under undisturbed forest and forest silviculturally treated whereby 40 % of the biomass was killed. The topography of the two catchment areas studied (each of about 150 ha) is gently undulating. The main soil is a well drained loamy Ultic Haplorthox which covers most of the plateaus and upper slopes while sandy soils occur on lower slopes and in valley bottoms.Measured data on rainfall, discharge, evaporation, groundwater levels and hydraulic conductivity were used in computer simulation of water flows. It was found that large amounts of water were available to the forest and that transpiration reduction in the dry seasons was only small. The average effective rooting depth was calculated to be 450 cm. The contribution of transpiration, interception and soil evaporation to total water use (1640 mm/y) was calculated, annual rainfall being 2140 mm.Nutrient amounts and flows were determined in both the organic matter cycle and the hydrological cycle for the treated and untreated catchments. A computer simulation of organic matter flows showed that large amounts of nutrients were liberated during the 3 years after treatment. Only a very small proportion of these nutrients left the catchment area with the discharge water. The higher nutrient influx in rainwater than nutrient losses in drainage water indicates that there was a small accumulation of nutrients in both the untreated and treated catchments. Thus it is concluded that the forest treatment did not result in unacceptable losses of nutrients from the ecosystem

Pre-advies natte bossen; verdroging, verzuring en eutrofiëring van natte bossen in Nederland: effecten en herstelmaatregelen

In dit rapport wordt een pre-advies gegeven voor herstelmaatregelen in natte bosecosystemen in het kader van het OBN, het Overlevingsplan Bos en Natuur (LNV, 1996) . Doel is het ontwikkelen van een reeks van algemeen toepasbare maatregelen gericht op het herstel van de effecten van verzuring, vermesting (beide als gevolg van luchtverontreiniging) en verdroging, in natte bossen met hoofdfunctie natuur. Een tweede doel is het inventariseren van de mogelijkheden en gevolgen van vernatting van multifunctioneel bos.Advies in het kader van OB

Soils, water and nutrients in a forest ecosystem in Suriname

Water and nutrient flows were measured in catchments on strongly weathered loamy sediments of the Zanderij formation in Suriname under undisturbed forest and forest silviculturally treated whereby 40 % of the biomass was killed. The topography of the two catchment areas studied (each of about 150 ha) is gently undulating. The main soil is a well drained loamy Ultic Haplorthox which covers most of the plateaus and upper slopes while sandy soils occur on lower slopes and in valley bottoms.Measured data on rainfall, discharge, evaporation, groundwater levels and hydraulic conductivity were used in computer simulation of water flows. It was found that large amounts of water were available to the forest and that transpiration reduction in the dry seasons was only small. The average effective rooting depth was calculated to be 450 cm. The contribution of transpiration, interception and soil evaporation to total water use (1640 mm/y) was calculated, annual rainfall being 2140 mm.Nutrient amounts and flows were determined in both the organic matter cycle and the hydrological cycle for the treated and untreated catchments. A computer simulation of organic matter flows showed that large amounts of nutrients were liberated during the 3 years after treatment. Only a very small proportion of these nutrients left the catchment area with the discharge water. The higher nutrient influx in rainwater than nutrient losses in drainage water indicates that there was a small accumulation of nutrients in both the untreated and treated catchments. Thus it is concluded that the forest treatment did not result in unacceptable losses of nutrients from the ecosystem

Simulation of growth of managed forests in the Atlantic Zone of Costa Rica and analysis of nutrient cycling to determine surpluses and shortages.

24 ilus. 9 tab. 37 ref. Sum. (En). Tambi?n como Report no. 96Growth of a managed natural forest and a forest plantation in the Atlantic Zone of Costa Rica were simulated with the TROPFOR programme and the resulting organic matter flows combined with concentrations of plant components to calculate nutrient flows. Goal of the investigations was to determine the capacities of three soil types to produce timber in managed natural forests and in plantations and to determine the sustainability of these land uses form a nutrient point of view. A climate file was constructed with 5 years of actual daily weather data: rainfall, short wave radiation, maximum and minimum temperature, vapour pressure and wind speed. Missing values of short wave radiation were calculated with the Angstrom equation, that was adjusted for the Atlantic Zone conditions. A soil file was made with hydrological characteristics for 3 representative soil types occurring in the Atlantic Zone: a well drained young soil (fertile), a poorly drained soil and a well drained old soil of low fertility. A vegetation input file was made with growth characteristics for natural forest and for a teak plantation. The climate, soil and vegetation files were used as input in the TROPFOR programme, that calculated for each day during 20 years the development of both vegetations: assimilation, maintenance respirations, formation of plant components and litter production and the influence of silvicultural activities on these processes. Simulated productions are the maximum productions that can be expected under current climatic and soil conditions when nutrient supply is not limiting. Amounts of N, P, K, Ca and Mg needded for the simulated production per year and the amounts of the same elements that are liberated by litter decomposition per year were compared in nutrient balances. Also the inputs by the atmosphere and by weathering were included in these balances, especially to compare these inputs with the exports of nutrients with harvested stemwood. It was found that the land utilization type (LUT) Managed Natural Forests with light harvests every 20 year can be sustainable on all three soil types from a nutrient point of view, both in the short and in the long run. The LUT Forest Plantation is not sustainable without input of nutrients, Large nutrient deficiencies develop during the first cycle caused by phytomass build-up. High nutrient buffering capacities are needed to take up surpluses and to supply shortages of nutrients caused by the phytomass fluctuations that are much larger in the plantation than in managed natural forest. Even on soils with extremely high nutrient buffering capacities probleMON will occur in the long run by the export of nutrients with stemwood