Humus conditions of stands with different proportion of Douglas fir in the Hůrky Training Forest District and Křtiny Training Forest Enterprise

Abstract

A long-term deviation from the natural species composition of our forests resulted in marked changes in the relative tree species composition where coniferous species began to predominate in the species composition at the expense of broadleaved species. The changes mostly affected the natural distribution of beech, the proportion of which decreased from the original 40.2% to the present 6.9%. On the other hand, the proportion of spruce increased from the original 11.2% to the present 52.8% (MZE 2008).Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) is evidently rightly considered to be the most important and perspective introduced species in the Czech Republic. It is given by more than 150-year tradition of its growing in this country and its potential to grow up very well at acid, mesotrophic and gleyed sites of the 2 nd to the 5 th forest vegetation zone. As a rule, Douglas fir also naturally regenerates there creating mixtures with a number of autochthonous species. For its dynamic intensive growth (Bušina 2007) it is an optimum species for repair or enrichment planting already at an early age. Above all, it is necessary to stress its quite exceptional production potential markedly exceeding all domestic conifers AbsTRAcT: The paper presented evaluates reserves and chemical composition of forest floor of three stands of Douglas fir, spruce and spruce with beech at acid sites (3K) in the Hůrky Training Forest District (TFD) and at a mesotrophic site (4H) in the Křtiny Training Forest Enterprise (TFE). The aim of the study was to evaluate: (i) reserves of forest floor, (ii) soil reaction, (iii) total content of carbon and nitrogen for the forest floor layers, (iv) C/N ratio, and (v) the content of dissolved organic carbon (DOC). The lowest reserve occurs in the Douglas fir stand at a mesotrophic site (25.0 t/ha), the highest accumulation occurs in the spruce stand and in the spruce/beech stand at an acid site (79.4-79.6 t/ha). The soil reaction is strongly acid to acid. The most favourable values of pH for forest floor and soil at acid (4.6 ± 0.4) and mesotrophic sites (5.2 ± 0.4) occur in the Douglas fir stand. It also corresponds to C/N ratio (23-26). The highest reserve of carbon in forest floor occurs at the acid site 34.7 t/ha (1.3 t/ha nitrogen). The lowest reserve of carbon in forest floor at the mesotrophic site amounts to 8.5 t/ha (0.4 t/ha nitrogen). The higher content of DOC in stands at acid sites can result in a higher risk of soil acidification.

Effect of agricultural lands afforestation and tree species composition on the soil reaction, total organic carbon and nitrogen content in the uppermost mineral soil profile

“…TOC contents in agricultural lands shifted from 1.6-1.8% to 4.24% (LA)-15.16% (AL) (Figure 2). The main source of TOC is the humified litter of the tree species, mixed by bioturbation into deeper horizons (Menšík et al 2009). …”

“…Potentiometric determination of pH (KCl) was conducted according to ISO 10390 (1996). Cation-exchange capacity (CEC) and exchangeable cations (H, Al, Ca, Mg, and K) was leached in BaCl 2 solution and measured by AAS-Varian240 (ISO 13536 1995).This practice is commonly used for evaluating of not fully comprehensive data sets (Menšík et al 2009). …”

“…Both review ) and original articles have documented a very high potential of the afforested agricultural soil to capture carbon in the surface humus and also in the uppermost mineral soil horizon. The yearly surface humus accumulation exceeded often 1 t/ha and the carbon content in the uppermost layer of the mineral soil frequently doubled (Podrázský & Remeš 2008;Menšík et al 2009;Podrázský & Procházka 2009;Podrázský et al , 2010Hatlapatková & Podrázský 2011). Processes of nutrient misbalances are leading to insufficient nutrient supply and foliage yellowing in many regions (Vacek et al 2009).…”

Effects of afforestation on soil structure formation in two climatic regions of the Czech Republic

“…Broadleaved species and Pseudotsuga menziesii particularly promote humus establishment and development (Menšík et al 2009;Kupka, Podrázský 2011). Similar trends were also documented in other regions of the Czech Republic, such as the Krušné hory Mts.…”

Soil-forming effect of Douglas fir at lower altitudes - a case study

“…Large introduction of Norway spruce is considered also as one cause of broad acidification of the forest environment (Borůvka et al 2005;Oulehle, Hruška 2005 (Ferron, Douglas 2010;Larson 2010) for its fast growth and technical characteristics of very valuable timber. Also in the Czech conditions, it was recognized as the most productive species (Kantor et al 2001a, b;Martiník 2003;Martiník, Kantor 2007;Kantor 2008;Kantor, Mareš 2009;Podrázský et al 2009;Remeš et al 2010) with relatively favourable effects on the forest soil -at least comparing to native conifers (Podrázský et al 2002(Podrázský et al , 2009Podrázský, Remeš 2008;Menšík et al 2009;Podrázský, Kupka 2011).…”