Lassen sich degradierte Fichtenhochlagenwälder (Picea abies [L.] KARST.) durch organisch-ökologische Melioration stabilisieren? Ergebnisse einer Langzeitstudie

Translated title of the contribution: Can degenerated high-altitude Norway spruce forests (Picea abies [L.] KARST.) be stabilised by organic-ecological melioration? Results of a long-term study

Matthias Ulbricht, Enno Uhl, Peter Biber, Hans Pretzsch

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

While fertilisation is an effective practice for improving soil quality and stand productivity, it has been rarely applied in recent years. It could, however, play a role as a supporting measure to protective forest restoration. In this context, this study reports the results of a melioration experiment with two organic fertilisers, Biosol and Frisol, in a highland forest in the Bavarian Alps. Because of their prominent protective functions, the stability and vitality of high mountain forests is of particular importance. At the same time, many such forest stands cannot sufficiently fulfil their protective functions due to degradation, ageing and lacking natural regeneration. As an accompanying research measure within the restoration programme for protective forests in Bavaria, the experiment FUS262 has been established in 1986, and since then it is continuously maintained and observed by the Chair for Forest Growth and Yield at Technische Universität München, Germany. The experiment is located in an altimontane Norway spruce (Picea abies [L.] Karst.) forest in the Bavarian Alps near the town of Fussen. Research questions are (i) whether the increment can be increased by organic fertiliser application, (ii) whether this enhances forest vitality, and (iii) whether a higher mechanical stability of forest stands can therewith be achieved. Biosol is an organic fertiliser, which mainly contains the nutrients N, P and K. It is a granulate made from penicillin production residues. When Biosol is enriched with the organic sugarphosphoramide ACS it is called Frisol. According to the manufacturer, it improves water and nutrient uptake by plants and a general activation of the soil organisms. The experiment FUS262 consists of six parcels which are attributed to three application variants (Biosol variant, Frisol variant and 0- or control variant, each with two repetitions). Table 1 shows site and treatment information on parcel level; Table 2 presents growth and yield data on stand level, while Table 3 contains growth and yield data on single tree level based on cored trees. The main results are as follows: (i) On tree level, an explicit reaction to Frisol application appears shortly after the fertilisation. Within the entire period from 1988 to 2009 the highest radial increment is observed for the Frisol variant. In the same period, compared to the control variant, the Biosol variant also shows an increased radial increment. In contrast, the radial increment of the control variant behaves rather indifferently. Marginally increased increments can be observed at the end of the observation period only (Figures 1 and 2). On stand level, total volume production (GWL) and average periodic increment (MPZ) react analogously: The increment of the Frisol variant is located clearly above the other both other variants, while the increment of the Biosol variant contrasts with the control variant to a minor extent only (section 3.2 and Figure 3). These results indicate that tree and stand increment can be increased by the application of Biosol and Frisol, at which Frisol is by far the more potent fertiliser. (ii) Taking foliage percentage as an indicator for vitality, the most auspicious development can be found on the Frisol variant. With approx. 70 % it remains nearly constant since 1986. The foliage percentage on the Biosol variant is approximately on a level with the Frisol variant at the beginning, but decreases over time. At the end of the observation (2009), however, it is barely below the foliage percentage of the Frisol variant. The control variant shows the most adverse development. Its foliage percentage keeps consistently below both other variants. Thus, the foliage percentage shows a positive reaction to the fertilisation, similar to the radial increment (Figures 4 and 5). Another proxy for vitality, the leaf area index (LAI), was adjusted with absolute foliage percentage (Table 4). The adjusted LAI and the correlation between tree-wise radial increment and foliage percentage indicate that especially the dominant and relatively vital spruces profit from the fertilisation; this results in a decreasing crown transparency (Figures 6 and 7). (iii) Selected crown shape parameters that were used as stability indicators do not show any noticeable influence of the fertilisation with Biosol or Frisol (Table 6). In summary, the application of Biosol and Frisol is an option for a long-term revitalisation of high-altitude Norway spruce forests. This finding is in accordance with several other studies that report a positive influence of organic-ecological fertilisation on growth and vitality in degraded high-altitude Norway spruce forests.

Translated title of the contributionCan degenerated high-altitude Norway spruce forests (Picea abies [L.] KARST.) be stabilised by organic-ecological melioration? Results of a long-term study
Original languageGerman
Pages (from-to)144-159
Number of pages16
JournalAllgemeine Forst- und Jagdzeitung
Volume183
Issue number7-8
StatePublished - 2012
Externally publishedYes

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