Article

Mulching has negative impact on fungal and plant diversity in Slovak oligotrophic grasslands

Authors:
  • Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences
  • Institute of Botany, Plant Science and Biodiversity Centre, SAS
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Abstract

Mulching (cutting of vegetation without removal of clippings) is used as a low-cost method for maintaining remote or abandoned grasslands in Slovakia. The likely consequence of mulching is seasonal nutrient enrichment resulting from decomposition of plant litter by saprotrophic organisms. The potential changes in biodiversity of the ecosystem caused by long-term application of mulching are to date only very poorly understood. In order to examine the impact of mulching on soil mycobiota, we compared six different grassland management regimes applied over nine years on a sub-montane oligotrophic Nardus pasture in the Central Slovakia. The diversity of soil fungi was assessed using DNA metabarcoding of the ITS2 regions of the nrRNA locus performed by Illumina MiSeq. We focused on a particular group of macrofungi which is characteristic of traditionally managed and undisturbed European grasslands, and which are often the dominant soil fungi in these habitats. These are collectively known as CHEGD fungi (the acronym of the constituent taxa: Clavariaceae, Hygrophoraceae, Entolomataceae, Geoglossaceae and Dermoloma). We compared the relative abundance and diversity of CHEGD fungi with the total fungal and plant diversity. CHEGD fungi were dominant across all management treatments. Although there were no statistical effects of treatments on total fungal richness and diversity, CHEGD fungi and vascular plants diversity and richness were lower on plots where mulching or no management were imposed, suggesting that such management regimes would have a negative impact on grassland fungi. However, no single treatment covered the total CHEGD diversity of the study, indicating that the localized use of mulching in addition to traditional managements can enhance overall diversity of grasslands in the area. Our results also suggest that the impact of mulching depends on the season when the grassland is mulched and it might be reduced by combination with other management treatments. The high relative abundance and sensitivity of CHEDG fungi in oligotrophic grasslands to management treatments makes them excellent indicators of grassland natural quality and is consistent with the ecological importance of this fungal group.

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... They allow, for example, the detection of invasive or endangered/rare species in a study area (Hardulak et al., 2020) or the assessment of dynamics in community composition following a disturbance event such as pollution or habitat destruction (Liu, Baker, Burridge, Jordan & Clarke, 2020;Xie et al., 2018). In a similar vein, Caboň et al. (2021) investigated the impact of mulching on plant and fungal diversity in grassland in Slovakia. Mulching, i.e., mowing without remov ing the clippings, is used as a cost-effective method of maintaining abandoned grasslands in Central Europe (Mašková, Doležal, Květ & Zemek, 2009). ...
... The decomposing plant biomass returns nutrients (N, P) to the soil, which are beneficial for vegetation regrowth and can lead to changes in soil properties and consequently to shifts in plant and insect diversity (Gaisler et al., 2019;Schmitt, 2003). Caboň et al. (2021) showed that after nine years of mulching, the diversity of vascular plants and in particular a collective of soil fungi known as CHEGD had decreased, but it made a difference whether mulching was applied in spring or fall. However, none of the other experimentally tested grassland management regimes covered the entire CHEGD diversity of the study either, suggesting that the local use of mulching in addition to traditional management can improve overall grassland diversity (Caboň et al., 2021). ...
... Caboň et al. (2021) showed that after nine years of mulching, the diversity of vascular plants and in particular a collective of soil fungi known as CHEGD had decreased, but it made a difference whether mulching was applied in spring or fall. However, none of the other experimentally tested grassland management regimes covered the entire CHEGD diversity of the study either, suggesting that the local use of mulching in addition to traditional management can improve overall grassland diversity (Caboň et al., 2021). ...
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Abstract The majority of Earths biodiversity is unknown. This is particularly true for the vast part of soil biodiversity, which rarely can be observed directly. Metabarcoding of DNA extracted from the environment (eDNA) has become 22 state-of-the-art in assessing soil biodiversity. Also for fungal community profiling eDNA is seen as an attractive alternative to classical surveying based on fruitbodies. However, it is unknown whether eDNA-metabarcoding provides a representative sample of fungal diversity and census of threatened species. Therefore conservation planning and assessment 26 are still based on fruitbody inventories. Based on a dataset of unprecedented width and depth, representing both soil eDNA-metabarcoding and expert inventorying of fungal fruitbodies, we document for the first time the validity of eDNA as practical inventory method and measure of conservation value for fungi. Fruitbody data identified fewer species in total and per site, and had larger variance in site richness. Focusing on macrofungi – the class Agaricomycetes, and in turn the order Agaricales – metrics of total richness and compositional similarity converged between the methods. eDNA was suboptimal for recording the non-soil dwelling fungi. β-diversity was similar between methods, but more variation in community composition could be explained by environmental predictors in eDNA data. The fruitbody survey was slightly better in finding red-listed species. We find a better correspondence between biodiversity indices derived from fungal fruitbodies and DNA-based approaches than indicated in earlier studies. We argue that (historical) fungal community data based on fruitbody forays – with careful selection of taxonomic groups – may be interpreted together with modern DNA-based approaches. Keywords: fungal fruitbodies, environmental DNA, metabarcoding, species richness, community composition, red-listed species, environmental gradients
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The encroachment of shrubs into grasslands is common in terrestrial ecosystems dominated by grass. Land abandonment and favourable climatic trends in recent decades have favoured the expansion of shrubs into subalpine grasslands in many mountainous regions across Europe. The advance of the succession from grassland to shrubland is expected to have a major impact on ecosystem functioning. We used DNA metabarcoding to assess whether the structure of soil fungal communities varied along the succession from subalpine grassland to shrubland in the Pyrenees, and investigated whether shrub encroachment was associated with changes in soil properties. The expansion of shrubs increased the soil C:N ratio and/or reduced the N, P, or K contents. Plant-driven changes in soil properties were strongly associated with the compositional turnover of fungi, including arbuscular mycorrhizal, ectomycorrhizal, ericoid, root endophytic, saprotrophic, lichenised, and pathogenic fungi. Total richness and the richness of most functional groups were correlated with soil P, N, and the C:N or N:P ratios. We show that the interplay between abiotic factors (changes in soil properties) and biotic factors (occurrence and identity of shrubs) played a key role in the structure and uniqueness of soil fungal communities along the succession.
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Grazing and mowing commonly form part of agricultural management. Nowadays, these grassland management measures – complemented by low-cost treatments such as mulching – often aim at keeping the rural landscape open and at avoiding natural succession. The evaluation of these treatments has not yet accounted for the long-term perspective particularly important for soil phosphorus (P).
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The genus Camarophyllopsis contains species with lamellate (agaricoid) basidiomes in the family Clavariaceae (Agaricales), a group otherwise dominated by club-like (clavarioid) or branched (coralloid) forms. Previous studies have suggested that species classified in Camarophyllopsis occur in two independent lineages. We reconstructed a multilocus phylogeny of the Clavaria-Camarophyllopsis-Clavicorona clade in the Clavariaceae using RNA polymerase II second largest subunit (rpb2), nuclear ribosomal 28S, and nuclear ribosomal ITS1-5.8S-ITS2 regions data and detected three independent groups of agaricoid fungi, including the genera Camarophyllopsis, Hodophilus, and Lamelloclavaria gen. nov, which distinctly differ in their pileipellis structure. In all, nine major lineages within the Clavaria-Camarophyllopsis-Clavicorona clade were recovered: Clavaria sensu stricto, Camarophyllopsis sensu stricto, Hodophilus, the Clavaria pullei clade, the Clavaria fumosa clade, Lamelloclavaria gen. nov., the Clavaria atrofusca clade, Holocoryne (= Clavaria sect. Holocoryne), and Clavicorona Clavaria is paraphyletic and represented by five clades. Additional gene sampling is necessary to determine and confirm relatedness of these lineages before splitting Clavaria into additional genera.
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Widespread land degradation has strengthened the urgent need to restore overgrazing grasslands. China has implemented the program ‘Returning Grazing Land to Grassland’ (RGLG) through grazing exclusion by fence since 2003. Despite a lot of field experiments, there is still controversy on the effects of grazing exclusion on rangeland restoration, highlighting the need for synthetic analysis. We conducted a meta-analysis of 447 entries from 78 papers to analyze the spatiotemporal effects of grazing exclusion on plant diversity, productivity and soil carbon sequestration in the major RGLG-implemented provinces of China. Our results showed that, compared with the grazed sites, grazing exclusion significantly increased carbon stored in aboveground biomass, litter mass, belowground biomass and soils by 84.7%, 111.6%, 25.5% and 14.4%, respectively. Plant coverage, soil available nitrogen, soil available phosphorus and soil microbial biomass carbon increased by 52.0%, 21.7% 22.8% and 26.3%, respectively. However, grazing exclusion had little effects on recovering plant diversity in China’s grasslands. Of the factors examined, climatic factors strongly modified the effects of grazing exclusion on ecosystem carbon stocks, for example, precipitation significantly amplified the positive effects. Grazing exclusion played a positive role in soil carbon sequestration in most grassland types except in temperate desert-steppe. But annual soil carbon sequestration rates decayed rapidly over time in both alpine meadow and temperate steppe. Short-term (≤5 years) grazing exclusion remarkably increased species richness, but not significantly in the long run. The threshold from neutral to negative effects of grazing exclusion on species evenness occurs after approximately ten years. Our findings provide evidence that grazing exclusion is an effective way to restore vegetation and sequestrate carbon in degraded grasslands, but not beneficial to plant diversity maintenance. The benefits of grazing exclusion are more effective in humid area than arid area. We suggest that grazing exclusion should be ceased after about six to ten years. Additionally, grazing exclusion should integrate with other appropriate management practices instead of operating on a stand-alone basis.
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In the Czech Republic, the number of cattle has decreased by about 60% between the years 1990 and 2010 and one major question is therefore, how to manage mountain grasslands with reduced livestock and demand for forage. One possible alternative is low-cost mulching, which is defined as the crushing of aboveground biomass, which is then evenly spread onto the ground. In view of a lack of data on the effects of mulching, we established an experiment with different cutting and mulching regimes on mountain Festuca rubra grassland in 1997 and monitored plant species composition over twelve years. Treatments with a similar response of plant species composition were (i) unmanaged control and grassland mulched once a year in September; (ii) grassland mulched once a year in May and in July; (iii) grassland mulched twice a year in June and August and grassland mulched three times a year in May, July and September; (iv) grassland cut twice a year with biomass removal in June and August. We concluded that mulching performed at least twice a year can substitute for cutting management in low productive grassland, without substantial loss of plant species richness and diversity. Mulching only in September affected plant species composition of the grassland in a similar way to no management, therefore, mulching performed only in September can be used only for prevention of grassland encroachment by shrubs and trees. The majority of changes in plant species composition developed during the first five years, thus, experiments to study the effects of management on grasslands must be performed for at least this length. (c) 2013 Elsevier B.V. All rights reserved.
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Studies were conducted to determine the effects on herbage yield of removing mulch and standing dead plant litter during dormancy for up to 3 or more consecutive years. This information is required to obtain a better understanding of the implications of dormant season grazing on forage production. In 2 studies, mulch and standing litter were harvested at 3 or more annual frequencies from 2 × 2 m plots. One study was repeated in both the Fescue Prairie and Mixed Prairie communities and plant response was measured annually as the yield of herbage produced from treated and control plots. The second study was conducted in the Fescue Prairie on 3 sites and designed as a 3 × 3 Latin square. The treatments consisted of removing mulch and standing litter, removing and replacing this material, and a control. Estimates were made of the yield, species composition, and morphological characteristics of the grasss. A third study was made, in the Fescue Prairie, by defoliating individual rough fescue (Festuca scabrella Torr. var. major Vasey) plants a single time, at 5 and 15 cm above ground, and comparing them with a control. Herbage yields decreased as the annual frequency of mulch and litter harvests increased in the Mixed Prairie but not in the Fescue Prairie. In the Mixed Prairie, yields declined to 43% of the control after 3 years of treatment. Removing mulch and standing litter from rough fescue plants resulted in shorter but a greater number of tillers than in the control. The results were similar after 1 or 3 years of treatment.
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Aboveground-belowground interactions exert critical controls on the composition and function of terrestrial ecosystems, yet the fundamental relationships between plant diversity and soil microbial diversity remain elusive. Theory predicts predominantly positive associations but tests within single sites have shown variable relationships, and associations between plant and microbial diversity across broad spatial scales remain largely unexplored. We compared the diversity of plant, bacterial, archaeal and fungal communities in one hundred and forty-five 1 m(2) plots across 25 temperate grassland sites from four continents. Across sites, the plant alpha diversity patterns were poorly related to those observed for any soil microbial group. However, plant beta diversity (compositional dissimilarity between sites) was significantly correlated with the beta diversity of bacterial and fungal communities, even after controlling for environmental factors. Thus, across a global range of temperate grasslands, plant diversity can predict patterns in the composition of soil microbial communities, but not patterns in alpha diversity. © 2014 John Wiley & Sons Ltd/CNRS.