A new concept to estimate matter budgets in heterogeneous forest stands : Forest Ecosystem Restoration. Ecological and Economical Impacts of Restoration Processes in Secondary Coniferous Forests

2000

S. 44-48

3 Abb., 6 Lit. Ang.

Unselbständiges Werk

200072790

The monitoring of element fluxes in heterogeneous forest stands is essential for an integrated evaluation of silvicultural practices. The key variables to calculate matter fluxes are (i) the amount of precipitation, (ii) the water tension in various soil depth, and (iii) the chemical composition of the soil solution. The most common method to gain these parameters is the installation of permanent plots with lysimeters, tensiometers and precipitation samplers. However, the data gained are spatially autocorrelated, and the costs are high. Based upon the assumptions, that the main driving forces of the fluxes through forests are (i) the amount and composition of the throughfall, and (ii) the temperature, and that this primary factos were (iii) modified by the crown density, we develop a new extensive procedure to determine all key variables to calculate matter budgets in heterogeneous forest stands. On randomized selected plots in a stand (the elementary unit is 2,25 m¬), the precipitation (amount and composition) is determined for 2 weeks. The water tension is measured and soil samples were taken with an auger. Afterwards the equipment is transferred to the next plot. The soil solution is gained by desorption of the soil water from the field moist soil by applying 17 kPa in a pressure chamber. The chemical analyses were done with capillary electrophoresis (cations, anions), which require only small sample volumes. For each plot the sky obsuration factor is determined with the fisheye photography (2 times a year). The results from the randomized moving plots can be combined with the time series from a stationary plot by means of a regression model.