Tw. Berger et H. Hager, Physical top soil properties in pure stands of Norway spruce (Picea abies)and mixed species stands in Austria, FOREST ECOL, 136(1-3), 2000, pp. 159-172
This study was done to evaluate the impact of pure Norway spruce stands on
physical soil properties of top soil in comparison to mixed species stands
on comparable sites. It was hypothesized that the flat root system of spruc
e causes soil compaction, which would have a negative impact on the soil ae
ration and hydraulic properties and consequently on seedbed quality, as wel
l as early tree growth and seedling establishment. Hence, this topic is imp
ortant for forest restoration, especially converting secondary pure spruce
stands to mixed species stands. Forty-eight sites (24 pairs pure spruce sta
nd/mixed species stand) of different stand development stages (mature stage
, pole stage) were selected on two different bedrock materials (Molasse, Fl
ysch). Undisturbed soil cores were taken from 0-4 and 4-8 cm soil depth and
the following soil parameters were determined: (total) bulk density, remai
ning fine soil bulk density, dry masses of coarse fragments, roots and fore
st floor, organic carbon content, total soil pore volume as well as macropo
re volumes (after free drainage for 24 h and after water desorption at 10 k
Pa). The remaining fine soil bulk density was a useful parameter for charac
terization of the state of compactness. Pure spruce stands caused a lower b
ulk density of the upper mineral soil due to lifting and loosening of the s
oil above the root system. Results of calculated macropore volumes after wa
ter desorption at 10 kPa were exactly conform with those obtained for the r
emaining fine soil bulk density, indicating significant differences for the
grouping variables bedrock material and species composition. It is conclud
ed from this study that changes of soil physical properties of the upper mi
neral soil (0-8 cm soil depth) by Norway spruce will not reduce germination
and growth of mixed species trees. However, chemical and nutritional chang
es were not subject of this study, which are expected to limit the success
of forest restoration. (C) 2000 Elsevier Science B.V. All rights reserved.