Restoration of Aboveground Ectomycorrhizal Flora in Stands of Pinus sylvestris (Scots Pine) in The Netherlands by Removal of Litter and Humus

Abstract

Species richness and sporocarp density of ectomycorrhizal fungi in stands of Pinus sylvestris (Scots pine) in The Netherlands have decreased during the last decades. The lowest species diversity was found in P. sylvestris stands situated in areas with high atmospheric deposition of nitrogen originating from intensive livestock industry. In these stands, litter and humus have accumulated into thick layers, and the herbaceous understory vegetation is dominated by the grass Deschampsia flexuosa (wavy hair grass). Earlier investigations showed negative correlations between the number of species of ectomycorrhizal fungi above ground and the depth of humus layers. Our aim was to investigate whether removal of litter, humus layers, and herbaceous vegetation (sods)—so‐called “sod cutting”—increased species diversity above ground and sporocarp density of ectomycorrhizal fungi in P. sylvestris stands of different age. Therefore, three P. sylvestris stands of different ages (planted in 1987, 1963, and 1924) on Haplic Arenosol were selected. In 1990, litter, humus layers, and herbaceous vegetation were removed to create nutrient‐poor sandy soils without overlying litter and humus layers. Untreated plots served as controls. Surveys conducted in 1991, 1992, and 1993 indicated that sod cutting enhanced the species diversity and sporocarp density of ectomycorrhizal fungi. These results suggest that sod cutting is a way to restore ectomycorrhizal flora in medium‐aged and old stands of P. sylvestris where litter and humus have accumulated.

Ectomycorrhizal Fungal Protein Degradation Ability Predicted by Soil Organic Nitrogen Availability

“…Hence, the presence of S. variegatus may depend on the development of an organic layer in the forest soil, where its protein degradation ability would give a competitive advantage for N uptake. Moreover, S. bovinus was also stimulated by litter removal in pine stands that exposed mineral soil (26). Interestingly, S. luteus, which is classified as a species characteristic of young trees on mineral soils, does occur in older stands as well, but its root tips and mycelium are located in the mineral rather than the organic layer (27,28).…”

Using experimental manipulation to assess the roles of leaf litter in the functioning of forest ecosystems

“…Mean chronic nitrogen deposition in Europe amounts to approximately 17 kg ha x1 yr x1 and in the USA to around 7.7 kg ha x1 yr x1 (Stevens et al, 2004) and would therefore 'replace ' much of the nitrogen being removed with the litter, or even exceed annual nitrogen export (Table 1). Litter removal has been proposed as a forest management practice for the amelioration of eutrophicated forests in the Netherlands on the basis of similar calculations (Baar & Kuyper, 1998). Nitrogen deposition was initially thought to reverse the most important effects of long-term litter removal (Prietzel et al, 1997), but other effects of litter removal and soil acidification with atmospheric nitrogen deposition remain a problem.…”

Post-fire, seasonal and annual dynamics of the ectomycorrhizal community in a Quercus ilex L. forest over a 3-year period

“…However, most of the studies on the post-fire dynamics of the ECM community have been performed in conifer forests (Baar and Kuyper 1998;Baar et al 1999;Dahlberg et al 2001;Danielson 1984b;Grogan et al 2000;Mah et al 2001;Purdy et al 2002;Stendell et al 1999;Visser 1995), with one exception, a study carried out in a Eucalyptus regnans forest (Launonen et al 1999).…”