Forest microsite effects on community composition of ectomycorrhizal fungi on seedlings of Picea abies and Betula pendula.
ABSTRACT Niche differentiation in soil horizons, host species and natural nutrient gradients contribute to the high diversity of ectomycorrhizal fungi in boreal forests. This study aims at documenting the diversity and community composition of ectomycorrhizal fungi of Norway spruce (Picea abies) and silver birch (Betula pendula) seedlings in five most abundant microsites in three Estonian old-growth forests. Undisturbed forest floor, windthrow mounds and pits harboured more species than brown- and white-rotted wood. Several species of ectomycorrhizal fungi were differentially represented on either hosts, microsites and sites. Generally, the most frequent species in dead wood were also common in forest floor soil. Ordination analyses suggested that decay type determined the composition of EcM fungal community in dead wood. Root connections with in-growing mature tree roots from below affected the occurrence of certain fungal species on seedling roots systems in dead wood. This study demonstrates that ectomycorrhizal fungi differentially establish in certain forest microsites that is attributable to their dispersal and competitive abilities. Elevated microsites, especially decayed wood, act as seed beds for both ectomycorrhizal forest trees and fungi, thus affecting the succession of boreal forest ecosystems.
- SourceAvailable from: Leho Tedersoo[Show abstract] [Hide abstract]
ABSTRACT: In the fungal kingdom, the ectomycorrhizal (EcM) symbiosis has evolved independently in multiple groups that are referred to as lineages. A growing number of molecular studies in the fields of mycology, ecology, soil science, and microbiology generate vast amounts of sequence data from fungi in their natural habitats, particularly from soil and roots. However, as the number and diversity of sequences has increased, it has become increasingly difficult to accurately identify the fungal species in these samples and to determine their trophic modes. In particular, there has been significant controversy regarding which fungal groups form ectomycorrhizas, the morphological “exploration types” that these fungi form on roots, and the ecological strategies that they use to obtain nutrients. To address this problem, we have synthesized the phylogenetic and taxonomic breadth of EcM fungi by using the wealth of accumulated sequence data. We also compile available information about exploration types of 143 genera of EcM fungi (including 67 new reports) that can be tentatively used to help infer the ecological strategies of different fungal groups. Phylogenetic analyses of ribosomal DNA ITS and LSU sequences enabled us to recognize 20 novel lineages of EcM fungi. Most of these are rare and have a limited distribution. Five new lineages occur exclusively in tropical and subtropical habitats. Altogether 46 fungal genera were added to the list of EcM fungal taxa and we anticipate that this number will continue to grow rapidly as taxonomic works segregate species-rich genera into smaller, monophyletic units. Three genera were removed from the list of EcM groups due to refined taxonomic and phylogenetic information. In all, we suggest that EcM symbiosis has arisen independently in 78–82 fungal lineages that comprise 251–256 genera. The EcM fungal diversity of tropical and southern temperate ecosystems remains significantly understudied and we expect that these regions are most likely to reveal additional EcM taxa.Fungal Biology Reviews 12/2013; 27(s 3–4):83–99.
- [Show abstract] [Hide abstract]
ABSTRACT: Coarse woody debris (CWD)is an important nursery environment for many tree species. Understanding the communities of ectomycorrhizal fungi (ECMF)and the effect of ECMF species on tree seedling condition in CWD will elucidate the potential for ECMF-mediatedeffects on seedling dynamics. In hemlock-dominatedstands, we characterized ECMF communities associated with eastern hemlock (Tsuga canadensis (L.) Carr) and yellow birch (Betula alleghaniensis Britt) seedling pairs growing on CWD. Seedling foliage and CWD were analyzed chemically, and seedling growth, canopy cover, and canopy species determined. Thirteen fungal taxa, 12 associated with birch, and 6 with hemlock, were identified based on morphology and ITS sequencing. Five species were shared by co-occurringbirch and hemlock, representing 75 % of ectomycorrhizal root tips. Rarified ECMF taxon richness per seedling was higher on birch than hemlock. Nonmetric multidimensional scaling revealed significant correlations between ordination axes, the mutually exclusive ECMF Tomentella and Lactarius spp., foliar N and K, CWD pH, and exchangeable Ca and Mg. Seedlings colonized by Lactarius and T. sublilacina differed significantly in foliar K and N, and CWD differed in exchangeable Ca and Mg. CWD pH and nutrient concentrations were low but foliar macro-nutrientconcentrations were not. We hypothesize that the dominant ECMF are adapted to low root carbohydrate availability typical in shaded environments but differ in their relative supply of different nutrients.Mycorrhiza 08/2014; · 2.96 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Numerous species of ectomycorrhizal (ECM) fungi coexist under the forest floor. To explore the mechanisms of coexistence, we investigated the fine-scale distribution of ECM fungal species colonizing root tips in the root system of Tsuga diversifolia seedlings in a subalpine forest. ECM root tips of three seedlings growing on the flat top surface of rocks were sampled after recording their positions in the root system. After the root tips were grouped by terminal-restriction fragment length polymorphism (T-RFLP) analysis of ITS rDNA, the fungal species representing each T-RFLP group were identified using DNA sequencing. Based on the fungal species identification, the distribution of root tips colonized by each ECM fungus was mapped. Significant clustering of root tips was estimated for each fungal species by comparing actual and randomly simulated distributions. In total, the three seedlings were colonized by 40 ECM fungal species. The composition of colonizing fungal species was quite different among the seedlings. Twelve of the 15 major ECM fungal species clustered significantly within a few centimeters. Some clusters overlapped or intermingled, while others were unique. Areas with high fungal species diversity were also identified in the root system. In this report, the mechanisms underlying generation of these ECM root tip clusters in the root system are discussed.Mycorrhiza 11/2013; · 2.96 Impact Factor