Plant Identity Research Articles

Species-specific trade-offs between regrowth and mycorrhizas in the face of defoliation and phosphorus addition

Arbuscular mycorrhizal fungi (AMF) enhance nutrient provision in exchange for carbon. However, a shift from nutrient to carbon limitation, induced by repeated or intense defoliation, can represent a trade-off between plant regrowth and the maintenance of mycorrhiza. The combined effects of AMF, phosphorus and defoliation on growth of A gropyron elongatum (C 3 grass, low mycorrhizal responsiveness) and B rachiaria brizantha (C 4 grass, high mycorrhizal responsiveness) were explored. Each species was subjected to a manipulative experiment with AMF inoculation (non-inoculated, inoculated), soluble P supply (low, high) and defoliation (non-defoliated, 60% defoliated). In A. elongatum , at low P supply, mycorrhizal plants showed increased growth rates following defoliation without substantial changes in AMF colonization. At high P supply instead, we found a clear trade-off between regrowth and the maintenance of mycorrhiza evidenced by growth depression (biomass and tillers) and lower AMF activity (reduction of arbuscules). In contrast, in B. brizantha , defoliation effects on plant regrowth were independent from AMF at any P supply (no trade-off). This indicates that cost-benefit relationship in defoliated plants is highly context-dependent and may vary with mycorrhizal responsiveness of species. This variation of responses can play a decisive role on plant recovery in pastures and natural grasslands subjected to herbivory. • First comparative study of AMF, defoliation and P supply in C 3 and C 4 grasses. • In the C 3 grass, AMF promoted recovery from defoliation at low P supply. • Mycorrhiza and defoliation trade off in the C 3 grass at high P supply. • In the C 4 grass, mycorrhizae were beneficial at all environmental contexts. • AMF effects on the recovery from defoliation depend on P supply and plant identity.

Potato seed quality control system development in Russia

The major aspects of seed potato quality control in Russia are considered in the article. The new standard ‘Seed potato specifications and methods for determining the quality’ was developed by the Lorch Potato Research Institute and widely discussed in public during 2016-2017, and approved in 2018 by Interstate Council for Standardization, Meteorology and Certification. The new standard sets out a common terminology and minimum requirements for early generation seed production (original seed), further multiplication (elite seeds) and for end-use ware potato production (reproductive seed). It covers varietal identity and purity, diseases and pests, external tuber quality, sizing and labeling. In accordance with the Standard, all seed potato must be evaluated during crop growth (field surveys) and during post-harvest control (tuber analysis). Results of the field and post-harvest control are normally be based on a visual assessment of the crop. The identification of faults may be supported by appropriate laboratory tests and comparative trials of seed potato samples when required. In 2018-2019 crop season, comparative field trials of original seed potato samples were carried out for detailed check of compliance with the normative tolerances of the standard requirements related to varietal identity and purity and, the level of viral and bacterial diseases transmitted through seed material. At the Lorch Potato Research Institute, 202 samples of original seed potatoes were evaluated to determine their varietal identity, the presence or absence of other variates and plants affected by diseases. Unification and harmonization of the Russian system of seed potato quality control with international - reference quality UNECE standard for seed potato are essential for the development of potato seed production in Russia.

Plant identity strongly structures the root-associated fungal community in a diverse subtropical forest

Revealing the relationship between plants and root-associated fungi is very important in understanding diversity maintenance and community assembly in ecosystems. However, the community assembly of root-associated fungi of focal plant species along a subtropical plant species diversity gradient is less documented. Here, we examined root-associated fungal communities associated with five ectomycorrhizal (EM) plant species (Betula luminifera, Castanea henryi, Castanopsis fargesii, C. sclerophylla, and Quercus serrate) in a Chinese subtropical woody plant species diversity (1, 2, 4, 8, 16 and 24 species) experiment, using paired-end Illumina MiSeq sequencing of the ITS2 region. In total, we detected 1933 root-associated fungal operational taxonomic units (OTUs) at a 97% sequence similarity level. Plant identity had a significant effect on total and saprotrophic fungal OTU richness, but plant species diversity level had a significant effect on saprotrophic and pathogenic fungal OTU richness. The community composition of total, saprotrophic and EM fungi was structured by plant identity and plant species diversity level. However, the community composition of pathogenic fungi was only shaped by plant identity. This study highlights that plant identity has a stronger effect on the root-associated fungal community than plant species diversity level in a diverse subtropical forest ecosystem.

Dominant plant identity determines soil extracellular enzyme activities of its entire community in a semi-arid grassland

Dominant plants firmly affect community species composition, diversity, productivity, and belowground functions in terrestrial ecosystems. Soil extracellular enzyme activities (EEAs), as indicators for soil function, have linked the above- and belowground components and functions. However, in semi-arid grasslands, little is known about the effects of dominant plant and community type on soil EEAs, especially in the contribution of each dominant species to soil EEAs of its respective entire community. Given that, we established the comparison of the effects of three dominant herbal plants and their respective communities on soil EEAs and soil properties, determined the contribution of each dominant plant to its community-level soil EEAs, and examined key factors mediating these relationships in the Songnen grassland. Results showed that soil EEAs among the three dominant plants had more significant differences than among the three communities. This implied that dominant plant identities had significant effects on their rhizosphere soil EEAs and the difference of soil EEAs at the community level mainly depended on vegetation composition (including dominant species identity). The variations of soil EEAs at the dominant plant level and the community level were driven by different soil factors, the former being pH and electrical conductivity, and the latter being soil moisture and total carbon. Additionally, the distribution of soil EEAs was highly similar between each dominant plant and its respective community, which suggested dominant plants largely controlled soil EEAs in their respective communities. Overall, our findings expanded our understanding of the role of dominant species in soil function in semi-arid grassland ecosystems.

Efficient Cryopreservation of Populus tremula by In Vitro-Grown Axillary Buds and Genetic Stability of Recovered Plants.

Axillary buds of in vitro microshoots were successfully frozen at –196 °C by the one-step freezing method using the protective vitrification solution 2 (PVS2). Microshoots were taken from 11 transgenic lines and three wild type lines. Influence of different explant pretreatments were analyzed from the point of their influence towards recovery after cryopreservation. It was found out that the use of axillary buds as explants after removal of the apical one increases recovery on average by 8%. The cultivation on growth medium of higher density insignificantly raises the regenerants survival rate. Pretreatment of the osmotic fluid (OF) shows the greatest influence on the survival rate. It leads to the increase in survival rate by 20%. The cryopreservation technology providing regenerants average survival rate of 83% was developed. It was based on the experimental results obtained with explant pretreatment. Incubation time in liquid nitrogen did not affect the explants survival rate after thawing. After six months cryostorage of samples their genetic variability was analyzed. Six variable simple sequence repeat (SSR) loci were used to analyze genotype variability after the freezing-thawing procedure. The microsatellite analysis showed the genetic status identity of plants after cryopreservation and of the original genotypes. The presence of the recombinant gene in the transgenic lines after cryostorage were confirmed so as the interclonal variation in the growth rate under greenhouse conditions. The developed technique is recommended for long-term storage of various breeding and genetically modified lines of aspen plants, as it provides a high percentage of explants survival with no changes in genotype.

Idiosyncratic responses to simulated herbivory by root fungal symbionts in a subarctic meadow

ABSTRACT Plant-associated fungi have elementary roles in ecosystem productivity. There is little information on the interactions between arbuscular mycorrhizal (AM) fungal symbiosis, fine endophytic (FE) and dark septate endophytic (DSE) fungi, and their host plants in cold climate systems. In particular, the environmental filters potentially driving the relative abundance of these root symbionts remain unknown. We investigated the interlinkage of plant and belowground fungal responses to simulated herbivory (clipping, fertilization, and trampling) in a subarctic meadow system. AM and FE frequency in the two target plant roots, Potentilla crantzii and Saussurea alpina, was unaffected by simulated herbivory, highlighting the importance and resilience of arbuscule forming mycorrhizas in a range of environmental conditions. Fertilization and trampling increased DSE colonization in P. crantzii roots although generally P. crantzii performance was reduced in these plots. The idiosyncratic responses by DSE fungal frequency in the two host plants in our experiment indicate that the host plant identity has a pivotal role in the DSE fungus–plant outcome. DSE fungal frequency did not respond to environmental manipulations in a manner similar to arbuscular mycorrhizas, suggesting that they have a different role in plant ecology.

La “Materia Médica Misionera” atribuida al jesuita Pedro de Montenegro en 1710 (II): Identificación de las plantas y sus usos contra trastornos del aparato reproductor

Se identifican las plantas empleadas para el tratamiento de los trastornos del aparato reproductor mencionadas en la “Materia Médica Misionera” (M.M.M.) atribuida al jesuita Pedro de Montenegro fechada en 1710. Se describen sus indicaciones terapéuticas en su contexto médico histórico de referencia y se discuten las relaciones de estos resultados con la etnobotánica médica folk actual de la zona de las “misiones”. Las identidades de las plantas se estimaron sobre la base de las descripciones textuales y representaciones gráficas extraídas de la fuente de datos, así como de las correspondencias botánicas de los nombres vulgares obtenidas a partir de una búsqueda exhaustiva de las mismas en 59 obras. Un total de 57 taxa empleados contra trastornos del aparato reproductor pudo ser identificado botánicamente, los cuales refieren a 102 datos etnobotánicos propiamente dichos. Aunque se evidencian pocas plantas (42,1%) y usos medicinales (5,8%) que son también compartidos entre la M.M.M. y los referidos en obras actuales, esto indicaría cierto grado de continuidad respecto a la farmacopea utilizada y a criterios etiológico-terapéuticos propios de la etnobotánica médica criolla del Paraguay.

Effects of plant invaders on rhizosphere microbial attributes depend on plant identity and growth stage

Invasive species are considered a serious threat to local biodiversity and ecosystem functioning. Invasive success is often dictated via a plant’s capacity to influence belowground processes. We considered the role of two invasive plants – Solanum elaeagnifolium Cav, a perennial, and Conyza bonariensis L, an annual species – on the rhizosphere soil microbial communities and soil functionality. This study included the cultivation of each of the invasive species and bare soil as a control, in a mesocosm experiment. Rhizosphere soil was collected at three samplings during plant growth. Phospholipid fatty acids and the activities of β-glucosidase, N-acetylglucosaminidase, urease, peroxidase, polyphenol oxidase and acid phosphomonoesterase were analysed. Soil planted with invasive plants exhibited different enzyme activities and microbial biomasses compared with controls. Also, the plant species had soil enzyme profiles that differed from each other, mostly at the vegetative stage, lesser at the maturity stage, with no difference recorded at the middle of the annual cycle. The differences between plant species were significant for microeukaryotes, actinomycetes and the fungi/bacteria and Gram-positive/Gram-negative bacteria ratios but not significant for total microbial biomass and biomasses of Gram-positive and -negative bacteria and fungi in all samplings. The network of interactions among the microbial community and enzymes was affected by plant presence, plant species as well as plant growth stage. This study suggests that life-cycle stage is important in relation to invasive species influence on belowground processes.

Experimental drought re‐ordered assemblages of root‐associated fungi across North American grasslands

AbstractPlant‐associated fungi can ameliorate abiotic stress in their hosts, and changes in these fungal communities can alter plant productivity, species interactions, community structure and ecosystem processes.We investigated the response of root‐associated fungi to experimental drought (66% reduction in growing season precipitation) across six North American grassland ecosystem types to determine how extreme drought alters root‐associated fungi, and understand what abiotic factors influence root fungal community composition across grassland ecosystems.Next generation sequencing of the fungal ITS2 region demonstrated that drought primarily re‐ordered fungal species' relative abundances within host plant species, with different fungal responses depending on host identity. Grass species that declined more under drought trended toward less community re‐ordering of root fungi than species less sensitive to drought. Host identity and grassland ecosystem type defined the magnitude of drought effects on community composition, diversity and root colonization, and the most important factor affecting fungal composition was plant species identity.Fungal diversity was less responsive to drought than fungal composition. Across ecosystems, latitude and soil pH were better predictors of fungal diversity than experimental drought. Drought significantly reduced fungal diversity and evenness only in sideoats gramaBouteloua curtipendulaand reduced root colonization only in blue gramaB. gracilis.Our results illustrate that predicting the effects of drought on root‐associated fungi will require attention to host plant identity and ecosystem type. By comparing our findings against soil microbe responses in the same experiment, we propose the hypothesis that fungi in plant roots are less sensitive to drought than fungi inhabiting soils. Our study highlights the importance of studying community‐level re‐ordering of fungal composition for understanding plant responses to climate change.

Few keystone plant genera support the majority of Lepidoptera species

Functional food webs are essential for the successful conservation of ecological communities, and in terrestrial systems, food webs are built on a foundation of coevolved interactions between plants and their consumers. Here, we collate published data on host plant ranges and associated host plant-Lepidoptera interactions from across the contiguous United States and demonstrate that among ecosystems, distributions of plant-herbivore interactions are consistently skewed, with a small percentage of plant genera supporting the majority of Lepidoptera. Plant identities critical for retaining interaction diversity are similar and independent of geography. Given the importance of Lepidoptera to food webs and ecosystem function, efficient and effective restoration of degraded landscapes depends on the inclusion of such ‘keystone’ plants.

Novel and efficient transformation of wild passion fruit (Passiflora cincinnata Mast.) using sonication-assisted Agrobacterium-mediated transformation

Passiflora cincinnata stands out among Passifloraceae because of its medicinal properties and its resistance to pathogens, which promotes its use as a rootstock for other Passiflora species. A valuable strategy for obtaining disease-resistant passion fruit plants is represented by genetic transformation; however, this requires efficient regeneration. Here, we aimed to establish an efficient protocol for generating transgenic passion fruit plants using sonication-assisted Agrobacterium-mediated transformation of somatic embryos. The latter were obtained from anthers, sonicated, and exposed to an Agrobacterium suspension for 15 or 30 s. As a comparison, non-sonicated embryos were also exposed to the same bacterial treatment, whereas non-infected embryos were used as controls. Plant identity was confirmed by PCR, qPCR, and histochemical assay. Transgenic plants were obtained at higher rates in the treatments applying sonication. Overall, 171 plantlets were regenerated, 38 of which showed stable uidA reporter gene expression. Of these 38 transgenic plants, 22 (57.89%) and 13 (34.21%) were obtained by sonication-assisted Agrobacterium-mediated transformation for 30 s and 15 s, respectively, whereas the remaining 3 (7.89%) were exposed for 30 s but without prior sonication. Our results indicate that sonication-assisted Agrobacterium-mediated transformation for 30 s enhanced transformation efficiency in P. cincinnata. We believe that this system will allow for more efficient production of transgenic passion fruit plants.

Habitat fragmentation and population features differently affect fruit predation, fecundity and offspring performance in a non-specialist gypsum plant.

The effects of habitat fragmentation on plant populations are complex, as it might disrupt many ecological processes, including plant reproduction and plant-animal interactions. Gypsum specialist plants may be resilient to fragmentation due to their evolutionary history in fragmented landscapes, but the effects on non-specialist plants occurring in gypsum are unknown. We conducted a study focusing on different aspects of the reproductive cycle of Astragalus incanus subsp. incanus, a plant facultatively linked to gypsum soils. We focused on plant fecundity and pre-dispersal predation, obtained from field observations, and offspring performance, assessed in a common garden. Beyond fragment size and connectivity, we also considered habitat quality, population size and density and plant size as predictors. Fragment size and connectivity had no effect on plant fecundity, but jointly determined fruit predation, while fragment size was positively related to offspring growth. Population density, rather than population size, had a positive effect on predation but negatively affected plant fecundity and offspring performance. Habitat quality reduced both plant fecundity and predation incidence. In this non-specialist species, habitat fragmentation, population features and habitat quality affect different facets of plant performance. Predation was the only process clearly affected by fragmentation variables, fecundity mainly depended on population features and offspring performance and was better explained by mother plant identity. Our results show the need to consider habitat and population features together with fragment size and connectivity in order to assess the effects of fragmentation. Importantly, these effects can involve different aspects of plant reproduction, including plant-animal interactions.

Community composition of arctic root-associated fungi mirrors host plant phylogeny.

ABSTRACTThe number of plant species regarded as non-mycorrhizal increases at higher latitudes, and several plant species in the High-Arctic Archipelago Svalbard have been reported as non-mycorrhizal. We used the rRNA ITS2 and 18S gene markers to survey which fungi, as well as other micro-eukaryotes, were associated with roots of 31 arctic plant species not usually regarded as mycorrhizal in Svalbard. We assessed to what degree the root-associated fungi showed any host preference and whether the phylogeny of the plant hosts may mirror the composition of root-associated fungi. Fungal communities were largely structured according to host plant identity and to a less extent by environmental factors. We observed a positive relationship between the phylogenetic distance of host plants and the distance of fungal community composition between samples, indicating that the evolutionary history of the host plants plays a major role for which fungi colonize the plant roots. In contrast to the ITS2 marker, the 18S rRNA gene marker showed that chytrid fungi were prevalently associated with plant roots, together with a wide spectrum of amoeba-like protists and nematodes. Our study confirms that arbuscular mycorrhizal (AM) fungi are present also in arctic environments in low abundance.

Neighbor identity affects growth and survival of Mediterranean plants under recurrent drought.

The increasing intensity and frequency of droughts predicted for the Mediterranean basin with ongoing climate change will impact plant communities and ecosystem functioning. This study investigated the effect of severe recurrent droughts and the role of the neighbor plant identity on the growth and survival of three abundant and co-existing species of a typical Mediterranean shrubland. Two juvenile plants, either of the same species or in all possible combinations of the two woody species Quercus coccifera and Cistus albidus and the perennial grass species Brachypodiumretusum were grown together in rhizotrons under controlled watering regimes for two years. Compared to a treatment with only one drought cycle, three successive droughts reduced the relative growth rates (RGR) of shoots and roots in B. retusum, but not in woody species, and increased the mortality of the woody species, but not that of the grass. The survival of C. albidus and of B.retusum, but not of Q. coccifera, increased when the neighbor individual was a different species than when it was the same species. Our data suggest that both species composition and frequency of drought events will impact the dynamics of plant communities in Mediterranean shrublands under ongoing climate change. The abundance of dehydration sensitive woody species will likely decrease under more frequent drought events at the expense of dehydration-tolerant grass species, resulting in potentially strong changes in the functioning of these ecosystems.

Plant species and season influence soil physicochemical properties and microbial function in a semi-arid woodland ecosystem

This research investigated the effects of woody plant identity and season on soil physicochemical properties and microbiological function in the semi-arid Zagros forest, one of the old-growth semi-arid oak forests in the world. Soil sampling was conducted beneath the canopy of six woody (tree and shrub) species in spring and winter. Microbial variables analysed included soil basal respiration (BR), microbial biomass C and N (MBC and MBN), microbial entropy index (MIE), substrate induced respiration (SIR) and enzymatic activities (i.e., urease and alkaline phosphatase). Soil physicochemical properties were also analysed and included pH, electrical conductivity (EC), available calcium and magnesium (Ca2+ and Mg2+), organic carbon (OC), total nitrogen (Ntot), lime, water content (WC), bulk density (BD), clay, silt and sand. Results demonstrated significant differences among the woody species (Pseudo-F = 56.31; p = 0.001), season (Pseudo-F = 97.37; p = 0.001) and their interaction (Pseudo-F = 2.96; p = 0.005) for the matrix of microbiological soil parameters. Differences were species-specific for shrubs and trees with a marked effect for tree species such as Quercus brantii. Microbial parameters were consistently higher in spring when higher temperature and lower moisture were recorded. Soil OC, Ntot, BD, and WC were important drivers of the soil microbial function. Our results evidenced a strong effect of season and plant species on soil physicochemical and microbiological soil properties in a semi-arid forest ecosystem. Higher values of microbiological soil parameters, including urease and phosphatase activities, were recorded for tree species during spring season.

Unraveling Arbuscular Mycorrhiza-Induced Changes in Plant Primary and Secondary Metabolome.

Arbuscular mycorrhizal fungi (AMF) is among the most ubiquitous plant mutualists that enhance plant growth and yield by facilitating the uptake of phosphorus and water. The countless interactions that occur in the rhizosphere between plants and its AMF symbionts are mediated through the plant and fungal metabolites that ensure partner recognition, colonization, and establishment of the symbiotic association. The colonization and establishment of AMF reprogram the metabolic pathways of plants, resulting in changes in the primary and secondary metabolites, which is the focus of this review. During initial colonization, plant–AMF interaction is facilitated through the regulation of signaling and carotenoid pathways. After the establishment, the AMF symbiotic association influences the primary metabolism of the plant, thus facilitating the sharing of photosynthates with the AMF. The carbon supply to AMF leads to the transport of a significant amount of sugars to the roots, and also alters the tricarboxylic acid cycle. Apart from the nutrient exchange, the AMF imparts abiotic stress tolerance in host plants by increasing the abundance of several primary metabolites. Although AMF initially suppresses the defense response of the host, it later primes the host for better defense against biotic and abiotic stresses by reprogramming the biosynthesis of secondary metabolites. Additionally, the influence of AMF on signaling pathways translates to enhanced phytochemical content through the upregulation of the phenylpropanoid pathway, which improves the quality of the plant products. These phytometabolome changes induced by plant–AMF interaction depends on the identity of both plant and AMF species, which could contribute to the differential outcome of this symbiotic association. A better understanding of the phytochemical landscape shaped by plant–AMF interactions would enable us to harness this symbiotic association to enhance plant performance, particularly under non-optimal growing conditions.

Diversity and community structure of ericoid mycorrhizal fungi in European bogs and heathlands across a gradient of nitrogen deposition.

Despite the ecological significance of ericoid mycorrhizal fungi, little is known about the abiotic and biotic factors driving their diversity and community composition. To determine the relative importance of abiotic and biotic filtering in structuring ericoid mycorrhizal fungal communities, we established 156 sampling plots in two highly contrasting environments but dominated by the same Ericaceae plant species: waterlogged bogs and dry heathlands. Plots were located across 25 bogs and 27 dry heathlands in seven European countries covering a gradient in nitrogen deposition and phosphorus availability. Putatively ericoid mycorrhizal fungal communities in the roots of 10 different Ericaceae species were characterized using high-throughput amplicon sequencing. Variation in ericoid mycorrhizal fungal communities was attributed to both habitat and soil variables on the one hand and host plant identity on the other. Communities differed significantly between bogs and heathlands and, in a given habitat, communities differed significantly among host plant species. Fungal richness was negatively related to nitrogen deposition in bogs and phosphorus availability in bogs and heathlands. Our results demonstrate that both abiotic and biotic filtering shapes ericoid mycorrhizal fungal communities and advocate an environmental policy minimizing excess nutrient input in these nutrient-poor ecosystems to avoid loss of ericoid mycorrhizal fungal taxa.

Higher host plant specialization of root-associated endophytes than mycorrhizal fungi along an arctic elevational gradient.

How community‐level specialization differs among groups of organisms, and changes along environmental gradients, is fundamental to understanding the mechanisms influencing ecological communities. In this paper, we investigate the specialization of root‐associated fungi for plant species, asking whether the level of specialization varies with elevation. For this, we applied DNA barcoding based on the ITS region to root samples of five plant species equivalently sampled along an elevational gradient at a high arctic site. To assess whether the level of specialization changed with elevation and whether the observed patterns varied between mycorrhizal and endophytic fungi, we applied a joint species distribution modeling approach. Our results show that host plant specialization is not environmentally constrained in arctic root‐associated fungal communities, since there was no evidence for changing specialization with elevation, even if the composition of root‐associated fungal communities changed substantially. However, the level of specialization for particular plant species differed among fungal groups, root‐associated endophytic fungal communities being highly specialized on particular host species, and mycorrhizal fungi showing almost no signs of specialization. Our results suggest that plant identity affects associated mycorrhizal and endophytic fungi differently, highlighting the need of considering both endophytic and mycorrhizal fungi when studying specialization in root‐associated fungal communities.

Dominance by Spartina densiflora slows salt marsh litter decomposition

AbstractQuestionsCoastal vegetated systems are known to play a fundamental role in climate change mitigation as a result of their efficiency sequestering and storing atmospheric CO2. While most of the work evaluating carbon sequestration capacity has focused on global change factors that can affect carbon release from plant litter decomposition through changes in (large‐scale) environmental conditions, less is known about the possible effects of the loss (or replacement) of dominant species. We hypothesized that dominant marsh plants can influence decomposition not only through changes in litter quality but also through changes in (microscale) soil environmental conditions such as humidity, soil temperature or solar radiation.LocationWe performed a field manipulative experiment in a southwestern (SW) Atlantic salt marsh in Argentina.MethodsWe simulate a selective disturbance (i.e., removal of the dominant grass species Spartina densiflora) thus allowing removal plots to develop an alternative plant community. To evaluate the effect of the dominant grass species on litter decomposition, in an experiment we performed a litterbag approach three years after the establishment of the removal plots.ResultsResults showed that the presence of S. densiflora significantly decreased litter decomposition directly by producing less labile litter, but also by effects that seem to be related to its structure as standing dominant vegetation. The experimental removal of S. densiflora led to an alternative plant community, formed by otherwise subordinate species, which is less densely packed, allowing higher radiation incidence on the soil and elevated midday soil temperature.ConclusionsOur results suggest that salt marsh litter decomposition, and thus C sequestration, is determined in part by the identity of the dominant plant, not only because of the quality of the produced litter but also as a consequence of the vegetation structure . Changes in species diversity, above all changes in the dominant species in these coastal systems, could have large impacts on the carbon turnover and mitigation capacity of these ecosystems.

The effect of vineyard groundcover on the abundance of naturally occurring entomopathogenic fungi isolated using a quantitative Galleria bait method

Although sold commercially as myco-insecticides, naturally occurring soil borne entomopathogenic fungi (EPF) pose a unique opportunity for regulating soil-dwelling insect herbivore populations via conservation biological control. Plant identity has a significant effect on soil borne fungi, which may includee EPF. We asked whether the choice of covercrops could affect the diversity and infectivity of EPF in a vineyard. We studied the effect of different mixtures of groundcover vegetation on the infectivity and community composition of the naturally occurring EPF community in a semi-arid vineyard in British Columbia, Canada. Soil was collected from a groundcover field trial and used in a quantitative laboratory bioassay with the model insect, Galleria mellonella. Death by mycosis was greater when Galleria was exposed to soil collected from groundcovers containing native versus exotic grasses. EPF communities isolated from Galleria cadavers also differed among groundcovers. This study presents the first evidence that manipulating vegetative identity can alter the composition and infectivity of soil-dwelling EPF. Future work should investigate the potential for groundcovers and cover crops to increase conservation biological control of soil-dwelling insect pests via changes to EPF communities in specific crop-pest scenarios.