Current issue: 53(4)
In this study we determined the effect of transformation of a mature sessile oak forest stand into a coppiced forest, and of thinning and throughfall reduction in a coppice stand on soil water content (SWC) and soil CO2 efflux. The precipitation reduction was induced by installing parallel drainage channels in both unthinned and thinned coppice stands. The driving factor for temporal dynamics of soil CO2 efflux in all plots was soil temperature. The other factor was soil water content but only up to about 15%. Above this threshold, there was no more effect on CO2 efflux. We found no clear difference in SWC or soil CO2 efflux between the mature and coppiced stand eight years after harvesting. On the other hand, thinning of the coppice stand resulted in increase in SWC up to 22% in proportion, which we assume to be a result of increased gap fraction of the canopy. However, no effect on soil CO2 efflux was observed two years after the thinning. Installation of the drainage channels in two plots covering 30% of the ground area resulted in decrease in SWC up to a proportional 30.5% and thus contributed up to 50.7% reduction in soil CO2 efflux.
We describe here a study based on analysis of vegetation indices and land surface temperatures, which provides relevant information for estimating soil moisture at regional scales. Through an analysis of MODIS satellite imagery and in situ moisture data, the triangle method was used to develop a conceptual land surface temperature−vegetation index model, and spatial temperature-vegetation dryness index (TVDI) values to describe soil moisture relationships for a broad landscape. This study was situated mainly within two states of the southern United States (Georgia and South Carolina). The total study area was about 30 million hectares. The analyses were conducted using information gathered from the 2009 growing season (from the end of March to September). The results of the study showed that soil moisture content was inversely proportional to TVDI, and that TVDI based on the normalized difference vegetation index (NDVI) had a slightly higher correlation with soil moisture than TVDI based on the enhanced vegetation index (EVI).
Various environmental conditions (heat waves and drought events) strongly affect leaf and xylem phenology. Disentangling the influence of temperature, precipitation and soil moisture content (AWR) on the forest productivity remains an important research area. We analyzed the impact of climate variability on the leaf phenology (10 sample trees) and radial growth (17 sample trees) of European beech (Fagus sylvatica L.). The study was conducted on 130-year-old European beech trees growing in a temperate forest stand in the Czech Republic. Detailed 20-year phenological monitoring was performed at the study site (1992–2011). As expected, leaf phenological events were mainly driven by the growing season temperatures. Leaf unfolding was highly affected positively by spring temperatures and the top-layer (to 40 cm) AWR in March. The correlation of tree-ring width with the interpolated climate data was positive significant for the growing season AWR and precipitation signal. Furthermore, the water availability in the top soil layer was found to be an important predictor of tree growth and extremely low growth occurrence. The extended phenological growing season, which was caused by a temperature increase, was not followed by an increased tree-ring width. The examined relationships point out the significance of the water availability in the top soil layer in European beech stands.
Five ploughed research areas from Finnish Norther Karelia were selected for comparison studies of plough ridges and untouched soil. Measurements were made at a depth of 10 cm in sample plots on both mineral and paludified mineral soil and peatland parts of these areas. In summer 1987 daily soil water matric potential was measured using tensiometers, and volumetric soil moisture content and density were determined from soil samples at two dates during the summer. Water characteristics of the core samples were also determined. On paludified mineral and peat soils the water table depth from the soil surface was measured.
The results indicated that in plough ridges matric potential was lowest. Plough ridges were also seen to dry and wet faster and to a greater degree than untouched soils. In untouched soils, soil water relations and aeration were not affected by the distance to the furrow. The effect of the plough ridge was smallest on peatland, where there was a good capillary connection from plough ridge to the ground water, if the ditches were not very effective. The soil in the ridges did not dry too much to restrict seedling growth. The untouched surface soil in poorly drained peat and paludified minear soil was, at least in a rainy growing season, often and also for long times so wet that 10% minimum air space required for good seedling root growth was not available.
The PDF includes an abstract in English.
The structure and functional responses of roots in planted seedlings when acclimatizing at the planting site are reviewed. A wide range of methods for classifying roots has been employed, and the terminology used is not uniform. Roots can be classified by their morphology, origin, and function. The temporal and spatial variation of soil temperature, moisture, structure, and concentration of nutrients are among the most important properties to which root systems acclimatize. In order to reliably describe the function of the root system, several parameters usually have to be measured. Studies on the root-soil interface have indicated that roots are not necessarily in continuous contact with soil. The control mechanism of root growth is inadequately known and theoretically formulated. Generally, only the mass needed for water and nutrient uptake has been allocated to the roots. However, the amount of photosynthates allocated to the roots is high. Acclimatization of seedlings out at the planting site is a complicated process which is influenced by the growing conditions at both the nursery and at the site. The function, distribution and structure of roots are controlled by the environment in a way similar to the shoot, but the control mechanism is imperfectly known.
The PDF includes an abstract in English.