| 1. |
- Varenius, Kerstin, et al.
(författare)
-
Long-term effects of tree harvesting on ectomycorrhizal fungal communities in boreal Scots pine forests
- 2016
-
Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 380, s. 41-49
-
Tidskriftsartikel (refereegranskat)abstract
- Management of boreal forests with clear-cutting has a marked effect on forest biodiversity. One directly and severely affected group of species is ectomycorrhizal fungi (EMF), because of their dependence on living host trees. Key questions in nature conservation and potentially for fungal ecosystem services are whether EMF communities as regenerated stands age will develop into a similar composition as in natural stands, and whether forest regeneration method matters. We addressed these questions by analyzing EMF communities in (1) 157-174 year-old natural and about 50-year-old Scots pine forest stands regenerated by (2) clear-cutting and planting, or (3) shelterwood regeneration with naturally established seedlings. We identified 98 EMF species hypotheses (SHs) using IonTorrent sequencing of soil cores from nine forest stands. We compared these results with a sporocarp survey and an RFLP-analysis of ectomycorrhizal roots performed 18 years earlier.When testing individual SHs (in the sequencing data 2013) 13 of the 20 most frequent EMF SHs in natural forest stands were present in similar frequencies in 50-year-old managed stands whereas 7 SHs were observed at different frequencies. The overall EMF community composition differed between natural and 50-year-old managed stands both when assessing sporocarp data from 1995 to 1998 and sequencing data from 2013. One individually tested SH was found to differ between 50-year-old shelterwood and clear-cut stands and no difference in EMF overall community composition was found between the two regeneration methods. Species richness was similar in all stands. The RFLP-analysis largely identified the same common species as the current study.Our result suggests that timber harvest has a minor effect on frequent EMF in a 30-50 year perspective. However, both the current study of soil mycelia and the sporocarp survey imply the overall composition of EMF communities to be affected. A contributing factor is the higher presence of Norway spruce in the natural stands. Moreover, the majority of species were not sufficiently frequent to be statistically tested. The importance of surviving mycelia, spore bank and new spore deposition is discussed. (C) 2016 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Wallander, Håkan, et al.
(författare)
-
Uptake of N-15-labelled alanine, ammonium and nitrate in Pinus sylvestris L. Ectomycorrhiza growing in forest soil treated with nitrogen, sulphur or lime
- 1997
-
Ingår i: Plant and Soil. - 0032-079X. ; 195:2, s. 329-338
-
Tidskriftsartikel (refereegranskat)abstract
- The uptake of N-15-labelled alanine, ammonium and nitrate was studied in ectomycorrhizal morphotypes of intact Pinus sylvestris seedlings. PCR-RFLP analysis of the ITS-region of fungal rDNA was used to identify the morphotypes. Seedlings were grown in forest soil collected at an experimental site in southern Sweden. The treatments compared were a control, N fertilisation (600 kg N ha(-1) as urea), sulfur application (1200 kg S ha(-1)) and lime application (6000 kg CaCO3 ha(-1)). The forest, which had been dominated by Picea abies, was clear-cut two years before the forest soil was sampled. Soil was also collected from an adjacent standing forest. The aim of the present study was to detect changes in the ectomycorrhizal communities in forest soils and relate these changes to the functional parameter of uptake of nitrogen from organic (alanine and protein) and inorganic (ammonium and nitrate) sources. Liming resulted in the detection of a morphotype not found in other samples, and one morphotype was only found in samples from the standing forest (the fungi in these two morphotypes could not be identified). All mycorrhizal root tips showed a higher N-15 concentration after exposure to different nitrogen forms than non-mycorrhizal long roots. Uptake of N-15 from a labelled solution of alanine or ammonium was higher (about tenfold) than uptake from a N-15-labelled solution of nitrate. Uptake of ammonium and alanine varied between 0.2 and 0.5 mg N g(-1) h(-1) and between 0.1 and 0.33 mg N g(-1) h(-1), respectively, among the different morphotypes. In seedlings grown in the control soil and in soil from standing forest, alanine and ammonium were taken up to a similar degree from a supply solution by all morphotypes, whereas ammonium uptake was higher than alanine uptake in seedlings grown in lime-treated soil (about twofold) and. to a lesser extent, in the nitrogen-and sulfur-treated soils. The higher ammonium uptake by morphotypes from the limed soil was confirmed in pure culture studies. In cases where ammonium was used as the N source, an isolate of the S. variegatus morphotype collected in the limed soil produced more biomass compared with isolates of S. variegatus collected in nitrogen or sulphur-treated soil. One isolate of a silvery white morphotype produced about equal amounts of biomass on alanine and ammonium, whereas all S. variegatus isolated performed better with ammonium as their N source. Based on the results it is hypothesised that liming can induce a shift in the ectomycorrhizal community, favouring individuals that mainly utilise inorganic nitrogen over those that primarily utilise organic nitrogen
|
|
