Invasive tree species can exert a profound effect on soil properties and ecosystem processes. Quercus rubra is a Northern American species that has an invader status in many European countries. ...However, the direction and magnitude of its effect on soil physicochemical and microbial properties relative to native tree species in forests are largely unknown. The aim of this study was to investigate the influence of invasive Q. rubra on physicochemical and microbial properties of soil organic and mineral horizons in comparison to native Quercus robur in a semi-natural forest. The study was performed on 23 Q. rubra and 10 Q. robur stands in the Niepołomice Forest (southern Poland). A number of soil parameters were assessed, namely moisture, water holding capacity, electrical conductivity, pH, organic C, total N, respiration, bacterial and fungal biomass and community structure (phospholipid fatty acid and ergosterol analyses). As soil properties are influenced by the quality of leaf litter deposited by trees, senesced Q. rubra and Q. robur leaves were characterized in terms of C, Ca, Mg, K, N, P, total phenolics and condensed tannins concentrations. It was found that total microbial and bacterial biomass was significantly lower under Q. rubra than Q. robur in both soil horizons. Microbial community structure of organic horizon also differed between the two Quercus species. In contrast, no differences were found in fungal biomass and soil physicochemical variables. The reduction in microbial and bacterial biomass beneath Q. rubra may be associated with the quantity and quality of its litter. Senesced Q. rubra leaves were characterized by significantly higher C/N and C/P ratios relative to those of Q. robur. Preliminary data indicate that although they had lower concentrations of phenolics and condensed tannins, the pools of these compounds supplied to the soil were higher due to higher litter production by Q. rubra.
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•Soil properties under invasive Quercus rubra and native Quercus robur were compared.•Q. rubra reduced soil total microbial and bacterial biomass relative to Q. robur.•Soil physicochemical properties did not differ between Q. rubra and Q. robur.•Leaf litter of Q. rubra had higher C/N and C/P ratios than that of Q. robur.•Q. rubra provided the soil with higher amounts of phenolics with its litter.
Although herbaceous plant layer may contribute significantly to plant diversity and nutrient turnover, its effects on the soil environment in forest ecosystems remain largely unexplored. In this ...study, we compared the effects of mono-dominant and multi-species assemblages of herb plants on soil physicochemical and microbial properties in two temperate deciduous (beech and riparian) forests. We hypothesized that the presence of herbaceous plants would increase microbial activity and biomass, and nutrient availability in soil when compared to bare soil. This increase would be the highest in multi-species assemblages as high plant diversity supports microbial performance and soil processes, and the expected patterns would be essentially similar in both forests. Allium ursinum L. and Dentaria enneaphyllos L. represented herb species forming mono-dominant patches in beech forest, while Aegopodium podagraria L. and Ficaria verna Huds. represented herb species forming mono-dominant patches in riparian forest. Our hypotheses were only partly supported by the data. We found that herb plant species affected soil microbial communities and processes, particularly in the riparian forest, but they generally did not influence soil physicochemical properties. In the beech forest, herbaceous plants increased saprotrophic fungi biomass, fungi/bacteria ratio, and arylsulfatase activity, with the highest values under D. enneaphyllos. In the riparian forest, a number of microbial parameters, namely bacteria, G+ bacteria, and saprotrophic fungi biomass, fungi/bacteria ratio, and soil respiration exhibited the lowest values in bare soil and the highest values in soil under A. podagraria. Contrary to expectations, soils under multi-species assemblages were characterized by intermediate values of microbial parameters. Concluding, herbaceous plant species largely supported soil microbial communities in deciduous temperate forests but did not affect soil chemical properties. The potential reasons for the positive influence of herb plants on soil microbes (litterfall, rhizodeposition) require further investigation.
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•The effects of herbaceous plants on soil were assessed in beech and riparian forests.•Herbaceous plants enhanced microbial parameters, mainly fungal and bacterial biomass.•Mix of species did not have beneficial effect on microbes relative to single species.•Soil physicochemical properties generally were not influenced by herbaceous plants.
Biological invasions are an important problem of human-induced changes at a global scale. Invasive plants can modify soil nutrient pools and element cycling, creating feedbacks that potentially ...stabilize current or accelerate further invasion, and prevent re-establishment of native species.
The aim of this study was to compare the effects of Reynoutria japonica, Rudbeckia laciniata and Solidago gigantea, invading non-forest areas located within or outside river valleys, on soil physical and chemical parameters, including soil moisture, element concentrations, organic matter content and pH. Additionally, invasion effects on plant species number and total plant cover were assessed. The concentrations of elements in shoots and roots of invasive and native plants were also measured. Split-plot ANOVA revealed that the invasions significantly reduced plant species number, but did not affect most soil physical and chemical properties. The invasions decreased total P concentration and increased N-NO3 concentration in soil in comparison to native vegetation, though the latter only in the case of R. japonica. The influence of invasion on soil properties did not depend on location (within- or outside valleys). The lack of invasion effects on most soil properties does not necessarily imply the lack of influence of invasive plants, but may suggest that the direction of the changes varies among replicate sites and there are no general patterns of invasion-induced alterations for these parameters. Tissue element concentrations, with the exception of Mg, did not differ between invasive and native plants, and were not related to soil element concentrations.
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•Effects of three invasive plants on plant diversity and soil properties were analyzed.•Plant invasions considerably reduced plant diversity.•Most soil parameters were not influenced by plant invasions.•Plant invasions decreased total P and R. japonica increased N-NO3 content in soil.•Element concentrations in soil were poorly related to those in plant tissues.
This study assessed the effects of
Reynoutria japonica
,
Rudbeckia laciniata
, and
Solidago gigantea
invading sites within and outside river valleys on activity, biomass, and composition of soil ...microbial communities. Microbial properties such as soil respiration, urease and arylsulfatase activities, microbial biomass (based on substrate-induced respiration, or SIR, and phospholipid fatty acids, or PLFA), and community composition (based on PLFA) were determined.
R. japonica
encroached on sites characterized by the lowest values of microbiological properties and
R. laciniata
on sites with the highest microbiological quality. The effect of invasion on soil microbial properties depended on the invasive plant species.
R. japonica
significantly decreased microbial biomass, determined by both SIR and total PLFA, urease activity, fungal PLFA, fungal:bacterial PLFA ratio, gram-negative bacterial PLFA, and soil respiration in comparison to soil under adjacent native plant communities. Microbial community composition also differed between soils under
R. japonica
and those under native plants. In contrast,
R. laciniata
and
S. gigantea
did not influence most microbial properties, though
S. gigantea
significantly increased fungal PLFA and
R. laciniata
and
S. gigantea
increased fungal:bacterial PLFA ratio. The effects of plant invasion on microbial properties were basically similar in soils located within and outside river valleys, probably because initially (i.e., before invasion) soils from the two locations were largely similar in terms of basic properties such as texture, moisture, pH, C:N ratio, and most microbial properties.
Reynoutria japonica is one of the most invasive plant species. Its success in new habitats may be associated with the release of secondary metabolites. The aim of this study was to compare phenolic ...concentrations in plant biomass and soils between plots with R. japonica and resident plants (control), and determine the effects of these compounds on soil microbial communities. Samples of plant shoots and rhizomes/roots, and soil were collected from 25 paired plots in fallow and riparian habitats in Poland. We measured concentrations of total phenolics, condensed tannins, catechin, chlorogenic acid, emodin, epicatechin, hyperoside, physcion, piceatannol, polydatin, procyanidin B3, quercetin, resveratrol, and resveratroloside. Soil microbial parameters were represented by acid and alkaline phosphomonoesterases, β-glucosidase, phenoloxidase, and peroxidase activity, culturable bacteria activity and functional diversity measured with Biolog Ecoplates, and microbial biomass and community structure measured with phospholipid fatty acid (PLFA) analysis. We found that concentrations of total phenolics and condensed tannins were very high in R. japonica leaves and rhizomes/roots, and concentrations of most phenolic compounds were very high in R. japonica rhizomes/roots when compared to resident plant species. Concentrations of most phenolics in mineral soil did not differ between R. japonica and control plots; the only exceptions were catechin and resveratrol which were higher and lower, respectively, under the invader. Total microbial and bacterial (G+, G–) biomass was decreased by approx. 30% and fungal biomass by approx. 25% in invaded soils in comparison to control. Among soil functional microbial parameters, only peroxidase activity and functional diversity differed between R. japonica and resident plant plots; peroxidase activity was higher, while functional diversity was lower in soil under R. japonica. The negative effects of R. japonica on microbial biomass may be related to catechin or its polymers (proanthocyanidins) or to other phenolics contained in high concentrations in R. japonica rhizomes.
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•Biomass of invasive Reynoutria japonica contained large amounts of phenolics.•Soil phenolic contents hardly differed between R. japonica and control.•Catechin was higher and resveratrol was lower in R. japonica relative to control soil.•Soil bacterial and fungal biomass were clearly reduced by invasion.•Invasion hardly affected the activity of soil microbial communities.
Invasive plants may modify soil properties through the release of phenolic compounds. The effects of phenolics produced by a noxious invader,
Reynoutria japonica
, on soil microorganisms have rarely ...been studied in experimental conditions. We performed a laboratory experiment to assess the influence of extracts from
R. japonica
on soil microbial activity, biomass, and community structure. Two types of extracts (shoots and rhizomes) were added in four concentrations (control—no extract, low—extract diluted 100 times, medium—extract diluted ten times, and high—undiluted extract) to soil collected under native plant species. Concentrations of 12 phenolic compounds, namely catechin, chlorogenic acid, emodin, epicatechin, hyperoside, quercetin, physcion, piceatannol, polydatin, procyanidin B3, resveratrol, and resveratroloside were analyzed in the extract and soil. We measured the activity of five enzymes, namely acid and alkaline phosphatases, β-glucosidase, phenoloxidase, peroxidase, the activity of bacteria on Biolog Ecoplates, as well as the biomass of bacteria, saprotrophic fungi, arbuscular mycorrhizal fungi (AMF), and microbial community structure using phospholipid (PLFA) and neutral (NLFA) fatty acid analysis. Many microbial parameters, namely phosphatase activities, total microbial, AMF, and G + bacterial biomass, were reduced following the addition of extracts. This was likely related to phenolics as concentrations of these compounds in soil increased with the concentration of extract added. In contrast, saprotrophic fungi and G- bacteria were largely positively affected by extract addition. Shoot and rhizome extracts had relatively similar effects on the soil properties. The changes in soil biota caused by
R. japonica
invasion may have implications for restoration of invaded areas.
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•Differences in soil abiotic properties are primarily driven by soil depth.•Q. rubra decreases the soil microbiome diversity as compared to native vegetation.•Native vegetation ...recruits greater number of unique microbial taxa than Q. rubra.•Relative abundance of unique microbial taxa is higher in Q. rubra vs native plots.•Invasion effect is stronger for fungal than bacterial/archaeal diversity.
Invasive plants can modify the diversity and taxonomical structure of soil microbiomes. However, it is difficult to generalize the underlying factors as their influence often seems to depend on the complex plant-soil-microbial interactions. In this paper, we investigated how Quercus rubra impacts on the soil microbiome across two soil horizons in relation to native woodland. Five paired adjacent invaded vs native vegetation plots in a managed forest in southern Poland were investigated. Soil microbial communities were assessed along with soil enzyme activities and soil physicochemical parameters, separately for both organic and mineral horizons, as well as forest stand characteristics to explore plant-soil-microbe interactions. Although Q. rubra did not significantly affect pH, organic C, total N, available nutrients nor enzymatic activity, differences in soil abiotic properties (except C to N ratio) were primarily driven by soil depth for both vegetation types. Further, we found significant differences in soil microbiome under invasion in relation to native vegetation. Microbial richness and diversity were lower in both horizons of Q. rubra vs control plots. Moreover, Q. rubra increased relative abundance of unique amplicon sequence variants in both horizons and thereby significantly changed the structure of the core soil microbial communities, in comparison to the control plots. In addition, predicted microbial functional groups indicated a predominant soil depth effect in both vegetation plots with higher abundance of aerobic chemoheterotrophic bacteria and endophytic fungi in the organic horizon and greater abundance of methanotrophic and methylotrophic bacteria, and ectomycorrhizal fungi in the mineral horizon. Overall, our results indicate strong associations between Q. rubra invasion and changes in soil microbiome and associated functions, a finding that needs to be further investigated to predict modifications in ecosystem functioning caused by this invasive species.
We studied the effects of invasions by three plant species:
Reynoutria japonica
,
Rudbeckia laciniata
, and
Solidago gigantea
, on arbuscular mycorrhizal fungi (AMF) communities in habitats located ...within and outside river valleys. Arbuscular mycorrhizal colonization, AMF abundance and species richness in soils were assessed in adjacent plots with invaders and native vegetation. We also quantified the performance (expressed as shoot mass, chlorophyll fluorescence, and the concentration of elements in shoots) of two common, mycorrhizal native plants,
Plantago lanceolata
and
Trifolium repens
, grown in these soils. The invasions of
R. japonica
,
R. laciniata
, and
S. gigantea
influenced AMF communities compared to native vegetation, but the changes depended on the mycorrhizal status of invaders. The effects of non-mycorrhizal
R. japonica
were the most pronounced. Its invasion reduced AMF abundance and species richness. In the plots of both mycorrhizal plants,
R. laciniata
and
S. gigantea
, we observed decreased AMF species richness in comparison to native vegetation. The AMF community alterations could be due to (i) depletion of organic C inputs to AMF in the case of
R. japonica
, (ii) plant secondary metabolites that directly inhibit or selectively stimulate AMF species, or (iii) changes in soil physicochemical properties induced by invasions. The effect of invasion on AMF abundance and species richness did not generally differ between valley and outside-valley habitats. The invasions affected photosynthetic performance and the concentrations of elements in the shoots of
P. lanceolata
or
T. repens
. However, the directions and magnitude of their response depended on both species identity and the mycorrhizal status of invaders.
This study discovers and surveys sites left by former Zn–Pb mining in western Małopolska (S Poland), focusing on old heaps of mining waste rock located in agricultural land and suburban wasteland. ...Topsoil samples were taken from 73 heaps and described using many parameters, including heavy metal contamination (the content of total, EDTA-extractable, BaCl2-extractable and water-extractable metals), macronutrient content, pH and texture. At five sites, a short transect was delineated from heaps towards their surroundings to estimate the impact of the heaps on the adjacent agricultural soil. The total heavy metal concentration in the heap soil varied greatly across sites, ranging from 5 to 522mgCdkg−1, from 94 to 23,006mgPbkg−1, from 6 to 51mgTlkg−1 and from 394 to 70,435mgZnkg−1. These values were very high compared to that measured in the soil of the control areas: 2–5mgCdkg−1, 13–67mgPbkg−1, 1–17mgTlkg−1 and 63–476mgZnkg−1. The extractability of heavy metals from heap soil decreased in the following order: Cd>Pb>Zn>Tl (EDTA) and Cd>Zn>Pb~Tl (BaCl2). For the most mobile metal (Cd), the extractability averaged 43% and 5% for the EDTA and BaCl2 extractants, respectively. A factor analysis reduced 33 soil physicochemical parameters to five factors that explained 72% of the variance in the data. Factor 1 represented heavy metal contamination (concentrations of both total and mobile Cd, Pb and Zn), factor 2 represented organic matter accumulation, reflecting the most likely age of a heap, factor 3 represented the total concentration of Ca, Mg and Tl derived from weathering of the waste material — mostly dolomite and calcite, factors 4 and 5 represented soil particles of different sizes. In the transect study, the amount of total and EDTA-extractable heavy metals in soil generally decreased when increasing the distance from the heaps, but still remained high in agricultural soil sampled 10m from the foot of the heaps. The results of this study suggest that remnants of the historical Zn–Pb ore mining are “hot spots” of persistent soil contamination and may pose an environmental problem, especially those located in the inhabited areas; their status should be monitored by the local authorities.
•Small heaps left by historical Zn–Pb mining are hot spots of soil contamination.•Heap soil has up to 0.5, 23, 0.05 and 70gkg−1 of Cd, Pb, Tl and Zn, respectively.•Agricultural soil around the heaps clearly exceeds the contamination standards.•The most polluted sites nearby human settlements should be monitored.
This study examined the effects of soil heavy metals, macronutrients, texture and pH as well as plant species richness and composition on soil respiration, enzymatic activity, microbial biomass, ...metabolic quotient (qCO2) and arbuscular mycorrhizal fungi (AMF) at sites of historical Zn–Pb mining. The study was conducted both on a large scale (65 heaps scattered over the area of 750 km2) and on a small scale (25 plots along two 48 m transects extending from heaps to adjacent fallow fields). Total concentrations of metals exceeded 400 (Cd), 20,000 (Pb) and 80,000 (Zn) mg kg−1 at the most polluted sites. Although they decreased along the heap-fallow direction, they still remained above environmental standards in fallow soils. In contrast, some soluble metal forms increased with the increasing distance from heaps. Soil organic matter had the strongest positive effect on most microbial parameters. Total and/or available heavy metals exhibited significant negative effects on microbial biomass, enzymatic activity and AMF, and a positive effect on qCO2. Organic matter alleviated negative effects of heavy metals on microorganisms; they were not observed where the increase in the contamination was accompanied by the increase in organic matter content. Plant species richness affected positively enzymatic activity and mycorrhization level. Plant species composition possibly contributed to the formation of soil microbial communities, but its effect was entangled in that of heavy metals as plant communities changed along pollution gradients (from metal-tolerant grasslands dominated by Festuca ovina to calcareous grasslands and ruderal communities at less polluted sites).
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•Mining waste heaps and surrounding fallows were highly polluted with Cd, Pb and Zn.•Total or available heavy metals affected negatively soil microbial communities.•Organic matter and nutrient availability had strongest positive effects on microbes.•Plant species richness correlated positively with soil enzymes and mycorrhizal fungi.
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