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Abstract "Heft 19"


Freiburger Bodenkundliche Abhandlungen

Schriftenreihe des

Institut für Bodenkunde und Waldernährungslehre
der Albert-Ludwigs-Universität Freiburg i.Br.
Schriftleitung: F. Hädrich


Heft 19


Eberhard Aldinger

Elementgehalte im Boden und in Nadeln verschieden stark geschädigter
Fichten-Tannen-Bestände af Praxiskalkungsflächen im Buntsandstein - Schwarzwald


Freiburg im Breisgau 1987

ISSN 0344-2691


Summary:

Element contents in the soil and in needles of spruce/fir stands showing different degrees of damage, on limed areas in the red-sandstone Black Forest
Base losses caused by acid deposition are considered, among other reasons, to be responsible for the increasing deterioration of forest health that is visible since the seventies. Lime, which has been applied 10 to 20 years ago on large scale basis, usually wi'th blowers, counteracts base losses. If the state of health as judged by needle loss and yellowing, is connected with the lowering of base saturation, one might expect that limed stands are "healthier" than other unlimed ones. In order to examine this hypothesis, six observation plots were established in older spruce/fir stands showing different degrees of needle loss and yellowing, growing in the central Black Forest of Germany on sites of the upper red sandstone (sQ). The effect of large-scale liming on both the soil and stand was examined. On compatible sites, both the relatively "healthiest" (*) and "sick" spruci s and firs were selected on limed and unlimed areas, resulting in four comparable collectives per observation plot and tree species.
Liming was done in different years between 1963 and 1975 using varying amounts of calcium carbonate and basic slag, in addition with phosphate included in the four oldest applications.
Stand data and damage symptoms are shown in Tab. 5.1. According to the criteria used for selection (Chapter 4.1), * and + spruces and firs are distinguished from each other in terms of crown development, needle losses, and needle yellowing. On limed (Ca-) areas, spruces and firs show similar needle losses; yellowing, however, is less conspicuous than the unlimed (o-) areas (see Tab. 5.2). Liming has a lasting effect on soil-chemical conditions, but there are pronounced differences between plots. On Ca-areas, pH-values are always higher than on o-areas, with the magnitude of increase probably strongly affected by the amounts of lime that have been applied. Depth of organic matter decreases with liming. This did not bring about C-losses down to 40 cm of mineral soil, because C-loss in the humus layer has been, with one exception, compensated by an increase in C in the upper mineral soil. There has been a similar displacement of N-supplies from the organic layer into the mineral soil. No losses have been found following liming where depth of the organic layer did not exceed 1 0 cm.
Application of phosphorous results in higher P-contents and supplies, especialy in the organic layer and in mineral soils with high humus contents.
Exchangeable cations, determined on the basis of NH4Cl-extract, indicate only low base saturation of less than 4% from 0 to 40 cm; pH in CaCl2 was about 3.0 in the 0-10 cm soil depth. Base saturation increases on the Ca-plots to 8-38%; effective exchange capacity (AKe) increases significantly from 99 to 124 µeq-g-1  . There is a simultaneous increas of C-levels. The contents of cation bases Ca and Mg showed different increases corresponding with pH-values and varying with the amounts of lime that were applied. High dosages of lime had an effect beyond the 40 cm depth of mineral soil. Comparison with 0-plots showed no change of K+-contents.
Cation acids (Mn2+ , Fe3+ , Al3+ ) and protons decrease significantly as Ca2+ - and Mg2+ -contents become higher, a tendency found on all observation plots. Simple linear correlations show a Ca strong negative relationship between Ca - and Mg -contents on the one hand, and between Ca2+ -  Al3+   on the other hand.
There are no significant differences at the 10% probability level between element contents of the soil under relatively healthy spruces and firs, and under declining ones showing heavy needle losses.
Comparison of unlimed spruce and fir sites does not show any differences in the mineral soil. Only the organic layer under firs shows higher N-contents than that under spruces. On the Ca-
areas, these differences have leveled out with an increasing breakdown of humus. Therefore, it has to be assumed that soil samples taken under spruces and firs show the same element contents.
Comparison of the data obtained from foliar anaylsis of older spruces from the observation plots, considering known threshold values for sufficient nutrient element supplies, shows sufficient to low N-levels, but high P- and K-contents of the trees on the 0-plots. There appears to be an overall sufficient Ca-Supply, but an insufficient Mg one. In 4-year-old needles contents of Ca and especially of Mg decrease, while in 1-year-old needles a relative increase is found. When both elements do not become available in sufficient amounts younger needles are apparently better supplied with both Ca and Mg than older ones. A rapid decrease of these levels with increasing needle age thus indicates an insufficient supply of nutrient elements. There is no danger of Mn-deficiency in acid soils; Zn-levels, however, are low, but probably not within the range of acute deficiency.
In spruce needles, the contents of Ca, Mg, and Zn, especiaxly from unlimed trees, are near the threshold values for latent deficiency and are closely interrelated.
Limed spruces show higher foliar Ca-contents than unlimed ones. Also, Zn-values increase, but K-contents of the 1-year-old needles of the first whirl (1.1) decreas significantly. Spruce needles from areas which had been supplied with lime containing Mg and phosphate, showed higher contents of these elements. There is a strong correlation between Ca- and Mg-levels of 4-year-old spruce needles and Ca - and Mg -contents of the unlimed soil. The 0-plots especially show the antagonistic effect of Mn and Al on the Ca. and Mg-uptake. The nutrient supply of spruce trees with potentially deficient elements Ca, Mg, and Zn may therefore be improved by application of basic slag and phophate.
In fir needles, contents of the investigated elements were frequently higher than that of spruce needles from the same site. With similar foliar amounts of C in both tree species, P-contents are approximately 1/3 higher in fir needles. Levels of Mg, Ca,
Mn, and Zn are twice as high; Al-contents are more than 3 times higher. Only N-contents were at a similar level.
Foliar analysis data of the firs show optimum to sufficient supply with N, K, Ca, Mn, and Zn; P, in any case, indicates optimum nutritional levels. Only Mg-contents point to latent deficiency on some areas.
There is a decreas of Mg-contents in the needles of unlimed firs with increasing Al -levels in the soil. Liming of firs brings about increased Ca-levels only in older needles (IV.2 and 4). The increase of Zn-levels is less distinct than that with spruce. K-contents decrease distinctly and also those of Mn. No differences could be found in N- and Al-contents of needles from 0- and Ca-plots.
Obviously, levels of these elements are not influenced by liming. As with spruce, foliar Mg-levels of firs have increased only on the areas which received lime containing Mg. P-contents, too are higher only on respective areas. Application of basic slag by itself leads to decreasing foliar P-levels.
Foliar Ca- and Mg-levels on limed areas are not correlated with the corresponding soil values. Given sufficient foliar levels, Ca-uptake seems to depend not only on its level in the soil. Needles of declining firs frequently show higher Ca-levels than healthy firs. There may also be higher foliar Mg-levels associated with low levels in the soil. However, following the application of lime containing Mg, foliar Mg-levels were higher on limed areas than on the controls. Mg-deficiency may therefore be remedied by apply basic slag.
Differences in foliar contents between * and + spruces and firs are only minor; they also vary frone are to another.
As a symptom for decline needle loss is similar with spruces from both 0- and Ca-areas. Liming has not been able to stop needle losses, neither of spruce nor that of * firs, on the research areas. Limed + firs have denser foliage than those receiving no lime, although no differences in foliar element levels can  be
recognized. Thus needle losses are not correlated with nutrient element levels in needles or in the soil. Needle loss obviously is a non-specific symptom, independent from the nutrient element supply.
Considering the average in all observation plots, yellowing of spruce needles increases with needle losses. On individual plots, however, yellowing may be minor even if heavy needle losses occur. Thus needle losses and yellowing may go together, but this is   not   necesaarily   so.
In contrast to needle loss, yellowing largely disappears on Ca-plots. Especially the more heavily discolored declining spruces show less yellowing on the Ca-plots. This is confirmed by correlations between soil and foliar element contents from limed spruces.
As with spruce, minor needle discoloration of firs decreases after liming. Since this symptom is only weakly expressed, there is hardly any correlation between soil and foliar element contents. Application of lime containing Mg basic slag improves insufficient Mg-supplies of spruces and firs, leading to a decrease in needle yellowing.


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