Effect Of Different Plant Species Research Articles

Evaluating the Acoustic Absorption of Modular Vegetation Systems: Laboratory and Field Assessments Using an Impedance Gun

Introducing vegetation is an effective strategy for improving air quality and mitigating the heat island effect. Green modules, which consist of modules that support substrates and various plant species, integrate these elements. This study analyzes the acoustic absorption properties of a specific green wall module using an impedance gun and the Scan and Paint method for laboratory and on-site measurements. The impedance gun method is effective for in situ analysis, offering advantages over standardized techniques for inhomogeneous samples. The sound absorption coefficient of the substrate and the effects of different plant species were measured. Key findings reveal that the substrate primarily influences sound absorption, with its coefficient increasing with frequency, similar to porous materials. Vegetation enhances the acoustic absorption of the substrate, depending on coverage and thickness, with 80–90% of absorption attributed to the substrate and 4–20% to vegetation. However, not all dense plant species improve absorption; some configurations may decrease it. Improvement correlates with substrate coverage and vegetation layer thickness, while the impact of plant morphology remains unclear. These findings confirm vegetation’s potential as an acoustic absorption tool in urban settings. Additionally, green walls can enhance acoustic comfort in indoor environments such as offices and schools by reducing reverberation. They also improve air quality and provide aesthetic appeal, making them a multifunctional solution for modern architecture.

EVOLUÇÃO DE C-CO<sub>2</sub> EM SOLOS DE DIFERENTES ECOSSISTEMAS NA REGIÃO DO ALTO ACRE, ACRE, BRASIL

Different studies, developed over the years, have shown that the increase in human activities on the soil can influence the release of gases related to the increase in the greenhouse effect. In this sense, the use of methods that evaluate the evolution of C-CO2 has been considered as important indicators to detect changes in the environment, since they can be influenced by the crop and its cultivation system as a result of impacts on microbial activity. The objective of this work was to evaluate the release of C-CO2 from soils submitted to different ecosystems. Laboratory tests were carried out where soil samples, submitted to five different ecosystems, were collected in three different periods throughout the year in the municipalities of Brasiléia and Epitaciolândia, Alto Acre region, in the state of Acre, and were subsequently incubated. Subsequently, the evolution of C-CO2 was evaluated, and the readings were carried out periodically until the 500th day of incubation of the samples. The data were analyzed in order to evaluate the effect of different plant species on the evolution of C-CO2. Regarding the collection carried out in April, there was no difference in the evolution of C-CO2 between the areas. However, in the month of June, which comprises the period of the beginning of the transition between the rainy season and the dry season, and in the month of August, the dry season, it was observed that in the area of native forest occurred the highest values of C-CO2 flux, differing statistically from other areas within these months of collection. Between the collection times, only in the area of agroforestry system no significant differences were recorded in the evolution of C-CO2. The highest accumulated values of C-CO2 were recorded in the following sequence: native forest > agroforestry system > area with cassava > cultivated pasture > area with banana. It is concluded that the areas that present a greater contribution of plant material to the soil can serve as a stimulus to the development of microorganisms that, consequently, increase the flow of CO2, especially until the beginning of the dry season and that the absence of moisture negatively influences the emission of C-CO2, causing significant differences in the amount of release of C-CO2 between the study areas at the same time of evaluation.

Constructed wetlands using recycled aggregates for the improved treatment of tailwater

Recycled aggregates from the construction industry could be effective materials for constructed wetland (CW) wastewater treatment systems. However, whether the plants or which kinds of plants can survive in CWs with recycled aggregates or not is still scarce and urgent to study. The effects of different plant species, and several operation parameters on tailwater treatment from the sewage plants by CWs with different substrates (mixed construction recycled aggregate [MCRA], red brick [RB], and gravel) are systemically studied. The results showed that the average removal efficiencies of the chemical parameters in MCRA-CWs with seven plants, such as Cyperus alternifolius, were higher than those of RB-CWs and Gravel-CWs. In the MCRA-CWs, the average removal efficiencies of Typha orientalis, Cyperus alternifolius, and Phragmites australis were 77.58%, 75.09%, and 73.16%, respectively, which were higher than those of the other plants. Meanwhile, Proteobacteria had the highest relative abundances in MCRA and RB at 54.98% and 69.22%, respectively, whereas Cyanobacteria (35.21%) were the most abundant in the gravel. The influence of season on water purification was significant (p < 0.05) in the MCRA. Overall, water quality purification was dependent on season, HRT, and C/N, which accounted for 86.1%, 13%, and 7.1%, respectively. The highest average removal efficiencies of the MCRA-CWs were 71.98% (COD), 85.58% (NH4+-N), 95.01% (TN), and 84.11% (TP) when the HRT was 3 d and C/N ratio was 2.5 in the summer. This indicates that treated recycled construction aggregates could be used as substrates in CWs and have both wastewater purification and environmental improvement effects, thus achieving the purpose of “treating the wastes with wastes”.

Phytoremediation of contaminated urban soils spiked with heavy metals

Urban environments worldwide face toxic heavy metal pollution originating from industrial discharge, municipal waste disposal, vehicular emissions, and atmospheric deposition. Kazakhstan, experiencing accelerated economic growth and extensive mining activities, contends with widespread heavy metal contamination in its soil-plant-air-water ecosystems. This study explores the potential of hyperaccumulating plants for phytoremediation in urban soils of Kazakhstan contaminated with Pb, Cd, and Co. Twelve plant species, including Korean Mint (Lamiaceae), Ornamental Cabbage (Brassica oleracea), Ageratum (Ageratum houstonianum), Coneflower (Echinacea purpurea), Amaranth (Amaranthus Perfect and Amaranthus Emerald), Fescue (Festuca glauca), Burning Bush (Kochia scoparia), Marigold (Tagetes patula nana), White Cabbage (Brassica-Cavolo cappuccino BIANKO), Tepary Bean (Phaseolus acutifolius), and Rapeseed (Brassica napus), were evaluated for growth and biomass production in urban soils spiked with two maximum permissible addition (MPA) treatments of Pb, Co, and Cd. The selected plants demonstrated varied responses to heavy metal stress, with Marigold (8.4 g shoot biomass/plant), Korean mint (10.5 g shoot biomass/plant), Rapeseed (19.9 g/shoot biomass), and Tepary bean (25.9 g shoot biomass/plant) exhibiting resilience or tolerance to Pb, Co, and Cd stresses. The results highlight the significant potential of these plants for efficient phytoremediation, showcasing their unique abilities to absorb and accumulate specific metals. Marigold, particularly, displayed noteworthy Pb accumulation (40.3 mg/kg biomass), resulting in reduced residual Pb concentrations in the soil (74.7 mg/kg). Conversely, White cabbage and Amaranth showed limited efficiency in Cd extraction, while Rapeseed and Tepary bean emerged as promising candidates for Cd phytoremediation. This study emphasizes the critical role of tailored plant species selection in designing effective phytoremediation strategies for specific metal-contaminated urban sites. A comprehensive understanding of the dynamics of metal accumulation and residual concentrations is crucial for the development of sustainable and efficient environmental remediation approaches. Further research is warranted to explore the long-term effects of different plant species on soil metal concentrations, refining and optimizing phytoremediation methods for urban soils grappling with toxic heavy metal contamination.

Mixed cropping enhances the nitrogen and phosphorus purification efficiency of sewage in wetland ecosystems

Although the water purification performance of individual species and their removal mechanisms have been thoroughly documented, the potential enhancement of sewage nitrogen and phosphorus removal rates through the combined effects of different plant species has yet to be comprehensively investigated. This study opted for Canna indica and Thalia dealbata, two characteristic wetland plants from the Three Gorges Reservoir Area, as the test subjects. The impact of cropping patterns (single-cropping and mixed-cropping) on the efficiency of nitrogen and phosphorus removal from sewage at varying concentrations was explored. The findings unveiled that the mixed-cropping pattern considerably heightened the total nitrogen (TN) absorption of plants in sewage environments, though it did not appreciably affect total phosphorus absorption. Moreover, sewage concentration influenced the nitrogen and phosphorus absorption patterns of plants, potentially exhibiting a threshold phenomenon. Mixed cropping significantly augmented the removal rates of sewage nitrogen and phosphorus. Under the single cropping arrangement, C. indica displayed superior pollutant removal performance in comparison to T. dealbata. Furthermore, the wetland plants significantly diminished the TN content of the soil matrix. The results indicated that the mixed planting pattern enhanced the purification efficiency of effluent nitrogen and phosphorus in the artificial wetland, probably due to the better purification by mixed species under competition for nutrients or the dilution effect of multiple species on effluent nitrogen and phosphorus nutrient salts following mixed planting. These results should guide planting selection for efficient and sustainable wastewater purification in wetland ecosystems.

Effects of Different Plant Species on the Chemical and Microbial Properties of Coastal Saline-Alkaline Soils in Southeast China

Effects of Different Plant Species on the Chemical and Microbial Properties of Coastal Saline-Alkaline Soils in Southeast China

The effects of different plant species in greenwall filtration system on lakewater treatment

It is a concern when 90% of Malaysia’s water supply comes from lakes that hold moderate to bad water quality status. Greenwalls are a sustainable modern-day filtration system that proves to be a solution in tackling this lakewater quality issue. To date, there are still questions unanswered regarding the treatment performance of the greenwall filtration system used for lakewater treatment as most research conducted is related to greywater treatment in terms of water quality. Thus, this research aims to investigate the effects of different plant species, filter media ratio and lakewater flowrate on the lakewater treatment performance in a greenwall filtration system. In this work. the plant species between Epipremnum aureum and Mentha piperita as well as the filter media ratio of coir to perlite between 3:1, 1:1 and 1:3, the lakewater flowrate between 15 L/h, 30 L/h and 160 L/h with the highest treatment efficiency for lakewater was investigated and chosen. First, experimental work was conducted with a constant plant species which was Epipremnum aureum and a constant filter media ratio of 1:1 (coir:perlite) to filter lakewater at different flowrates of 15 L/h, 30 L/h and 160 L/h where the initial and final sample of the lakewater was collected. The system ran for 3 hours each time and is referred to as a cycle. The COD and pH of the lakewater were tested before and after each cycle to compare the water quality. This study aims to justify and determine how different plant species as well as the filter media ratio and lakewater flowrate affect the lakewater treatment performance. The results show that Mentha piperita with fibrous root type, filter media ratio of 3:1 of coir to perlite and lakewater flowrate of 30 L/h provide the greatest removal efficiency of pollutants from lakewater. Ultimately, this study will contribute to the ever-growing research of greenwall filtration system for lakewater treatment making this treatment method more feasible for future commercial applications.

Ex situ bioremediation of diesel fuel-contaminated soil in two different climates

The petroleum industry is often faced with accidental spills and discharges that pollute valuable natural resources such as soil. The purpose of this study was to assess bioremediation potential of an on-site landfarming unit (LU), a highly economical solution that complies with the zero-waste policy, for bioremediation of the contaminated soil after an actual diesel fuel leakage in a fuel depot. The first aim was to evaluate the effects of different climates on hydrocarbon bioremediation. For this reason, a part of the contaminated soil was moved from the initial location with a sub-Mediterranean climate to an LU at another location with a temperate continental climate. Our results demonstrated that remediation in sub-Mediterranean climate is less effective than the remediation in a temperate continental climate. The second aim of this study was to evaluate the effect of different plant species on the microbial population during bioremediation. For that purpose, 365-day monitoring of phospholipid fatty acids (PLFA) was performed. Our results support the hypothesis that plant-assisted bioremediation can diminish toxic effects of diesel-polluted soil and that the changes in plant species during bioremediation cause changes in the microbial population.

Microbial interactions play an important role in regulating the effects of plant species on soil bacterial diversity.

Plant species and microbial interactions have significant impacts on the diversity of bacterial communities. However, few studies have explored interactions among these factors, such the role of microbial interactions in regulating the effects of plant species on soil bacterial diversity. We assumed that plant species not only affect bacterial community diversity directly, but also influence bacterial community diversity indirectly through changing microbial interactions. Specifically, we collected soil samples associated with three different plant species, one evergreen shrub (Rhododendron simsii) and the other two deciduous shrubs (Dasiphora fruticosa and Salix oritrepha). Soil bacterial community composition and diversity were examined by high-throughput sequencing. Moreover, soil bacterial antagonistic interactions and soil edaphic characteristics were evaluated. We used structural equation modeling (SEM) to disentangle and compare the direct effect of different plant species on soil bacterial community diversity, and their indirect effects through influence on soil edaphic characteristics and microbial antagonistic interactions. The results showed that (1) Plant species effects on soil bacterial diversity were significant; (2) Plant species effects on soil microbial antagonistic interactions were significant; and (3) there was not only a significant direct plant species effect on bacterial diversity, but also a significant indirect effect on bacterial diversity through influence on microbial antagonistic interactions. Our study reveals the difference among plant species in their effects on soil microbial antagonistic interactions and highlights the vital role of microbial interactions on shaping soil microbial community diversity.

Nitrogen Fertiliser Immobilisation and Uptake in the Rhizospheres of Wheat and Canola

Immobilisation of fertiliser nitrogen (N) by soil microorganisms can reduce N availability to crops, decreasing growth and yield. To date, few studies have focussed on the effect of different plant species on immobilisation of fertiliser N. Canola (Brassica napus) is known to influence the soil microbiome and increase mineral N in soil for future crops compared with cereals. We tested the hypothesis that canola can reduce immobilisation of fertiliser N by influencing the composition of the rhizosphere microbiome. To investigate this, we conducted a glasshouse soil column experiment comparing N fertiliser uptake between canola and wheat (Triticum aestivium) and partitioning of fertiliser N between plants and microorganisms. Plants were grown in soil to which high C:N ratio wheat residues and 15N-labelled urea fertiliser were applied. There was no difference between wheat and canola in fertiliser N uptake despite differences in fungal community composition and the carbon metabolising enzyme alpha-glucosidase in the rhizosphere. Canola obtained more soil-derived N than wheat. There was no significant difference in the rhizosphere bacterial communities present between wheat and canola and unplanted controls. Our results highlight the capacity of canola to increase mineralisation of soil N compared with wheat although the study could not describe the microbial community which facilitated this increase.

How mangrove plants affect microplastic distribution in sediments of coastal wetlands: Case study in Shenzhen Bay, South China

Microplastic pollution is common in marine and coastal ecosystems, especially in mangrove wetlands. However, factors affecting the distribution of microplastics, such as plants, have not been sufficiently studied. We investigated the effect of different plant species on the distribution of sediment microplastics in two Nature Reserves in South China, viz. Futian Mangrove and Mai Po Mangrove. In Futian Mangrove, the abundance of total microplastics among three monospecific mangrove stands dominated by Sonneratia caseolaris, Kandelia obovata, and Sonneratia apetala was similar. The abundance of microplastics in the mudflat was similar to that in the forest interior, except for the fact that more fiber was found in the mudflat than in the interior of Sonneratia apetala. This suggested that the dense pneumatophores at the fringe prevented fibers from entering the mangrove forest. The significant positive dependence (p < 0.05) between the density of Sonneratia pneumatophores and the abundance of fibers highlighted the importance of pneumatophores. The abundance of total microplastics, predominantly in the form of fibers, in sediments at the forest fringe (2835 ± 713 items/kg d.w. and 2070 ± 224 items/kg d.w. in Futian and Mai Po, respectively) was higher than that in the forest interior and mudflat. There was no difference between the two latter locations in both mangroves, which demonstrated the significance of the fringe effect. This paper reports for the first time that the spatial distribution of microplastics in mangrove sediments was affected by plant species, which provides useful information for environmental processes of microplastics in coastal wetlands.

Nitrogen Retention in Mesocosm Sediments Received Rural Wastewater Associated with Microbial Community Response to Plant Species

Vegetated drainage ditches (eco-ditches) have drawn much attention in recent years for the ability to remediate diffuse contaminants in rural wastewater through sediment retention, plant uptake and interception, and microbial metabolic activities. However, the effect of plant species on microbial community structure and nitrogen (N) retention in ditch sediment remains poorly understood. In this study, mesocosm plastic drums were planted with eight plant species commonly found in ditches and nurtured with wastewater for 150 days. Sediment total nitrogen (TN) was greatly increased after 150-day nurturing with rural wastewater, from 296.03 mg∙kg−1 (Iris japonica Thunb) to 607.88 mg∙kg−1 (Acorus gramineusO). This study also presents the effect of different plant species on sediment microbial communities, thus providing insight into N removal mechanisms in eco-ditch. Fifty-eight differentially abundant taxa were identified, and sediment microbial community structure for no plant (CK), Acg, Canna indica (Cai), and Typha latifolia L. (Tyl) was primarily linked to sediment NH4+-N and TN. Extremely small proportions of ammonia oxidizing bacteria (AOB) and nitrifying bacteria were detected for all treatments, but large proportions of Crenarchaeota, which comprises the widely existent ammonium oxidized archaea (AOA), were found in CK, Acg and Cai. The abundance of Nitrosotalea from Crenarchaeota presented positive correlations with sediment NH4+-N contents and ammonia oxidation function predicted by Faprotax, indicating Nitrosotalea might be the dominant ammonium-oxidizing microbes in sediment samples. The probable NH4+-N removal pathway in wastewater sediment was through a combined effect of AOA, nitrifying bacteria, and anammox.

English

The investigation of allelopathic effects of different plant species is important to prevent serious crop losses that would arise. The usage of such materials as mulch, cover crops or residues will be useful to implement in integrated weed management strategies of agricultural fields. Therefore, this study was conducted to screen the allelopathic effect of selected plant species using seedlings growth of lettuce (Lactuca sativa L.) as an indicator. The sandwich method was used and 20 mg of dried plant material, resembling the leaf litter, from 27 species were placed in petri dishes. Twenty-eight treatments including the control treatment were arranged in a Completely Randomized Design (CRD). On the fifth day after the establishment of lettuce seeds, hypocotyl length (cm), radicle length (cm) and total height (cm) of seedlings were measured. The inhibitory percentage was calculated and a dendrogram with single linkage was developed. Results revealed that the lowest hypocotyl and radicle lengths with the highest inhibitory percentage were recorded for Ageratum conyzoides, Cassia occidentals and Clidemia hirta when compared to the control treatment (p&lt;0.05). Weed species expressed varying degree of inhibitory effects on growth performances of lettuce seedlings. Further studies need to be carried out to explore the effects of allelopathy on crop plants. Key words: Inhibitory percentage, lettuce, seedling growth, hypocotyl, radicle. &nbsp

Soil mutualists modify priority effects on plant productivity, diversity, and composition

AbstractQuestionThe importance of priority effects on community assembly is well recognized, as is, increasingly, the role of environmental context in shaping those priority effects. Distinguishing the effects of soil nutrients and soil mutualists may be critical in the context of restoration, but remains poorly understood. Additionally, we asked whether pioneer species and soil conditions influenced trade‐offs or complementarities between vegetation production and species diversity.LocationPlant Growth Center, Montana State University, Bozeman, MT, US.MethodsUsing experimental seed addition in mesocosms, we investigated how the priority effects of different plant species influenced productivity, diversity and composition of the resulting plant community. We also experimentally manipulated soil nutrients and mycorrhizae to determine how they modified those priority effects.ResultsWe found that species‐specific priority effects of pioneers strongly governed the productivity, diversity and species composition of the resulting community. Pioneer grasses, one native and one non‐native species, both preempted light and space, prevented the colonization and growth of the subsequent community and restricted community dispersion (i.e. differences in species composition among mesocosms). By contrast, the pioneer forb species had little influence on the recruitment and establishment of the later colonizing species, and supported the assembly of divergent communities. We found evidence to suggest that amendments of soil mutualists, but not soil nutrients, modified the influence of one pioneer species on characteristics of the resulting community by enhancing community productivity and diversity in mesocosms with non‐native grass pioneers. Across all treatments, species diversity declined as vegetation production increased, indicating an overall trade‐off between productivity and diversity. However, relationships between productivity and diversity varied among pioneer treatments and mycorrhizal amendments.ConclusionsOur results emphasize important interactions between priority effects and the use of soil mycorrhizal amendments in restoration, as well as highlight how pioneer species and mycorrhizae influence potential trade‐offs between restoration objectives aimed at enhancing productivity vs species diversity.

Effect of different plant species on nutrient removal and rhizospheric microorganisms distribution in horizontal-flow constructed wetlands

Three macrophyte species, Phragmites australis, Arundo donax L., and Typha latifolia L. have been separately grown in a horizontal-flow (HF) constructed wetland (CW) fed with domestic wastewater to investigate effects of plant species on nutrient removal and rhizospheric microorganisms. All the three mesocosms have been in operation for eight months under the loading rates of 1.14 g N m−2 d−1 and 0.014 g P m−2 d−1. Appropriately 34–43% phosphorus (P) was removed in HF CWs, and no distinct difference was found among the plants. In the growing season, A. donax L. removed 31.19 g m−2 of nitrogen (N), followed by P. australis (29.96 g m−2), both of which were significantly higher than T. latifolia L. (7.21 g m−2). Depending on the species, plants absorbed 1.73–7.15% of the overall N, and 0.06–0.56% of the P input. At least 10 common dominant microorganisms were found in the rhizosphere of all the three plants, and 6 of the 10 kinds of bacteria had close relationship with denitrifying bacteria, implying that denitrifiers were dominant microorganism distributed in rhizosphere of wetland plants.

Effect of different plant species in pilot constructed wetlands for wastewater reuse in agriculture

In this paper the first results of an experiment carried out in Southern Italy (Sicily) on the evapotranspiration (ET) and removal in constructed wetlands with five plant species are presented. The pilot plant used for this study is made of twelve horizontal sub-surface flow constructed wetlands (each with a surface area of 4.5 m2) functioning in parallel, and it is used for tertiary treatment of part of the effluents from a conventional municipal wastewater treatment plant (trickling filter). Two beds are unplanted (control) while ten beds are planted with five different macrophyte species: Cyperus papyrus, Vetiveria zizanoides, Miscanthus x giganteus, Arundo donax and Phragmites australis (i.e., every specie is planted in two beds to have a replication). The influent flow rate is measured in continuous by an electronic flow meter. The effluent is evaluated by an automatic system that measure the discharged volume for each bed. Physical, chemical and microbiological analyses were carried out on wastewater samples collected at the inlet of CW plant and at the outlet of the twelve beds. An automatic weather station is installed close to the experimental plant, measuring air temperature, wind speed and direction, rainfall, global radiation, relative humidity. This allows to calculate the reference Evapotranspiration (ET0) with the Penman-Monteith formula, while the ET of different plant species is measured through the water balance of the beds. The first results show no great differences in the mean removal performances of the different plant species for TSS, COD and E.coli, ranged from, respectively, 82% to 88%, 60% to 64% and 2.7 to 3.1 Ulog. The average removal efficiency of nutrient (64% for TN; 61 for NH4-N, 31% for PO4-P) in the P.australis beds was higher than that other beds. From April to November 2012 ET measured for plant species were completely different from ET0 and ETcontrol, underlining the strong effect of vegetation. The cumulative evapotranspiration highest value was measured in the CWs vegetated with P.australis (4,318 mm), followed by A.donax (2,706 mm), V.zizanoides (1,904), M.giganteus (1,804 mm), C.papyrus (1,421 mm).

Effect of different plant species in pilot constructed wetlands for wastewater reuse in agriculture

In this paper the first results of an experiment carried out in Southern Italy (Sicily) on the evapotranspiration (ET) and removal in constructed wetlands with five plant species are presented. The pilot plant used for this study is made of twelve horizontal sub-surface flow constructed wetlands (each with a surface area of 4.5 m2) functioning in parallel, and it is used for tertiary treatment of part of the effluents from a conventional municipal wastewater treatment plant (trickling filter). Two beds are unplanted (control) while ten beds are planted with five different macrophyte species: Cyperus papyrus, Vetiveria zizanoides, Miscanthus x giganteus, Arundo donax and Phragmites australis (i.e., every specie is planted in two beds to have a replication). The influent flow rate is measured in continuous by an electronic flow meter. The effluent is evaluated by an automatic system that measure the discharged volume for each bed. Physical, chemical and microbiological analyses were carried out on wastewater samples collected at the inlet of CW plant and at the outlet of the twelve beds. An automatic weather station is installed close to the experimental plant, measuring air temperature, wind speed and direction, rainfall, global radiation, relative humidity. This allows to calculate the reference Evapotranspiration (ET0) with the Penman-Monteith formula, while the ET of different plant species is measured through the water balance of the beds. The first results show no great differences in the mean removal performances of the different plant species for TSS, COD and E.coli, ranged from, respectively, 82% to 88%, 60% to 64% and 2.7 to 3.1 Ulog. The average removal efficiency of nutrient (64% for TN; 61 for NH4-N, 31% for PO4-P) in the P.australis beds was higher than that other beds. From April to November 2012 ET measured for plant species were completely different from ET0 and ETcontrol, underlining the strong effect of vegetation. The cumulative evapotranspiration highest value was measured in the CWs vegetated with P.australis (4,318 mm), followed by A.donax (2,706 mm), V.zizanoides (1,904), M.giganteus (1,804 mm), C.papyrus (1,421 mm).

Direct and indirect bottom-up and top-down forces shape the abundance of the orb-web spider Argiope bruennichi

Species abundance in local communities is determined by bottom-up and top-down processes, which can act directly and indirectly on the focal species. Studies examining these effects simultaneously are rare. Here we explore the direct top-down and direct and indirect bottom-up forces regulating the abundance and predation success of an intermediate predator, the web-building spider Argiope bruennichi (Araneae: Araneidae). We manipulated plant diversity (2, 6, 12 or 20 sown species) in 9 wildflower strips in a region of intensive farmland. To identify the major factors regulating the distribution and abundance of A. bruennichi, we quantified three characteristics of vegetation (species diversity, composition and vegetation structure) as well as the spider's prey community and natural enemies. The distribution and abundance of A. bruennichi was regulated by combined bottom-up and top-down processes as well as by direct and indirect interactions between trophic levels. Four main factors were identified: (1) the strong direct effect of vegetation structure, (2) the positive effect of plant species diversity, which affected spider abundance directly and indirectly through increased densities and size of flower-visiting prey species, (3) the positive or negative direct effects of different plant species, and (4) the strongly negative direct effect of predacious hornets. The advantage of taking a global approach to understand the regulation of species abundance is highlighted first by the quantification of the relative importance of factors, with a surprisingly strong effect of hornet predators, and second by the discovery of a direct effect of plant diversity, which raises intriguing questions about habitat selection by this spider.

Soils development in opencast coal mine spoils reclaimed for 1–13 years in the West-Northern Loess Plateau of China

Soil development is the key process of mine spoil reclamation. To investigate the effects of different plant species and reclamation time on the soil development, 9 plots in the reclaimed spoils of Pingshuo opencast coal mine in Shanxi, China were established and the physical, chemical and microbiological properties of the soils were analyzed. The results showed that, soil bulk density and field capacity in plots with longer reclamation time were statistically different from plots with younger vegetation in both the 0–20 cm and 20–40 cm soil layers. Accordingly, values of organic matter and available nitrogen levels showed a significant increase in both 0–20 cm and 20–40 cm depth with reclamation time increasing and the top layer marked higher value except for some individual data. The organic matter in plot 8 in 0–20 cm depth with 13-year old vegetation reached 9.45 g kg−1, about 2.5-, 2.0- and 3.1-fold higher than the plots of 1-, 3- and 4-year old vegetation respectively. Total microbial amount showed a positive correlation with contents of organic matter which reached 1436.72 × 105 g−1 in plot 8 with 13-years old vegetation, about 11.3-fold greater than plot 1 of 1-yr old vegetation. Plots planted with sea buckthorn (Hippophae rhamnoides ssp. sinensis) singly or mixed with other species tend to develop better soil aggregation and microbiological properties than other plots, which may be due to its particular biological characteristics, developed root system and high growth rate in the first 4–6 year and 8–10 year, indicating that sea buckthorn may be a good species choice for activating soil development in the early stage of reclamation.

Effects of plant rhizosphere on mercury methylation in sediments

Purpose This research investigates the effects of different plant species on Hg methylation rates, examines the difference in mercury (Hg) methylation rates in the plant rhizospheres, and shows the trend in methylmercury (MeHg) content of sediment in the Second Songhua River (SSR) of China, thereby providing the basis for estimating the ecological risk of this area.