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Joy B Zedler - One of the best experts on this subject based on the ideXlab platform.
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does seed availability limit Plant Establishment during salt marsh restoration
Estuaries and Coasts, 2007Co-Authors: Hem Nalini Morzarialuna, Joy B ZedlerAbstract:Patterns of seed dispersal and seed bank accumulation need to be known to predict the species that will recruit into restoration sites versus those that must be introduced. We assessed the temporal and spatial patterns of seed availability and seed accumulation on the salt marsh plain of an 8-ha resforation site, based on seedlings that emerged from tidal material, wrack, rabbit pellets, and soil samples (in controlled experiments). We compared results from the first 3 yr of restoration (2000–2002) with results from a 5-yr-old restoration and an extant marsh, all within Tijuana Estuary, California. Seed dispersal was limited for most marsh plain species. Tidal dispersal occurred mainly in winter; seedling density and richness were highest with high spring tides and after fruiting of the dominant species,Sarcocornia pacifica (>90% of emergent seedlings).S. pacifica was also common in the seedlings that emerged from soil seed banks (up to 63%) and wrack (60%), while other species common in the vegetation were present at much lower densities. Seed bank accumulation in restored sites was low and few species were abundant. Seedlings that emerged from soil samples from the youngest restoration were mostly invasive exotics (64%), those of the 5-yr restoration were mostlyS. pacifica (63%), and those from the nearby extant marsh were mostlyTriglochin concinna (70%), despite more diverse vegetation. No salt marsh seedlings emerged from rabbit pellets; all were invasives (Mesembryanthemum crystallimum andCarpobrotus edulis). Emerging seedlings were much sparser in soil from the younger restoration than from the 5-yr restoration and the extant site (32.9±5.7<4642.2±1131.5 and 4689.3±359.3 seedlings m−2, respectively). Because dispersal is limited for most species, restoring diverse vegetation will require seeding or Planting. Natural recruitment could be facilitated by completing restoration by early winter, when seeds of native Plants have maximum tidal dispersal.
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spatio temporal variation of salt marsh seedling Establishment in relation to the abiotic and biotic environment
Journal of Vegetation Science, 2001Co-Authors: Gregory B Noe, Joy B ZedlerAbstract:Contrary to our expectations, soil salinity and mois- ture explained little of the spatial variation in Plant Establishment in the upper intertidal marsh of three southern California wet- lands, but did explain the timing of germination. Seedlings of 27 species were identified in 1996 and 1997. The seedlings were abundant (maximum densities of 2143/m 2 in 1996 and 1819/m 2 in 1997) and predominantly annual species. CCAs quantified the spatial variation in seedling density that could be explained by three groups of predictor variables: (1) perennial Plant cover, elevation and soil texture (16% of variation), (2) wetland identity (14% of variation) and (3) surface soil salinity and moisture (2% of variation). Increasing the spatial scale of analysis changed the variables that best predicted patterns of species densities. Timing of germination depended on surface soil salinity and, to a lesser extent, soil moisture. Germination occurred after salinity had dropped below a threshold or, in some cases, after moisture had increased above a critical level. Between 32% and 92% of the seedlings were exotic and most of these occurred at lower soil salinity than native species. However, Parapholis incurva and Mesembryanthemum nodiflorum were found in the same envi- ronments as the native species. In 1997, the year of a strong El Nino/Southern Oscillation event with high rainfall and sea lev- els, the elevation distribution of species narrowed and densities of P. incurva and other exotic species decreased but densities of native and rare species did not change. The 'regeneration niche' of wetland Plant communities includes the effects of multiple abiotic and biotic factors on both the spatial and temporal varia- tions in Plant Establishment.
Raina M Maier - One of the best experts on this subject based on the ideXlab platform.
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Effect of Re-acidification on Buffalo Grass Rhizosphere and Bulk Microbial Communities During Phytostabilization of Metalliferous Mine Tailings
Frontiers Media S.A., 2019Co-Authors: Linnea K. Honeker, Jon Chorover, Julia W Neilson, Catherine F. Gullo, Raina M MaierAbstract:Phytostabilized highly acidic, pyritic mine tailings are susceptible to re-acidification over time despite initial addition of neutralizing amendments. Studies examining Plant-associated microbial dynamics during re-acidification of phytostabilized regions are sparse. To address this, we characterized the rhizosphere and bulk bacterial communities of buffalo grass used in the phytostabilization of metalliferous, pyritic mine tailings undergoing re-acidification at the Iron King Mine and Humboldt Smelter Superfund Site in Dewey-Humboldt, AZ. Plant-associated substrates representing a broad pH range (2.35–7.76) were sampled to (1) compare the microbial diversity and community composition of rhizosphere and bulk compartments across a pH gradient, and (2) characterize how re-acidification affects the abundance and activity of the most abundant Plant growth-promoting bacteria (PGPB; including N2-fixing) versus acid-generating bacteria (AGB; including Fe-cycling/S-oxidizing). Results indicated that a shift in microbial diversity and community composition occurred at around pH 4. At higher pH (>4) the species richness and community composition of the rhizosphere and bulk compartments were similar, and PGPB, such as Pseudomonas, Arthrobacter, Devosia, Phyllobacterium, Sinorhizobium, and Hyphomicrobium, were present and active in both compartments with minimal presence of AGB. In comparison, at lower pH (<4) the rhizosphere had a significantly higher number of species than the bulk (p < 0.05) and the compartments had significantly different community composition (unweighted UniFrac; PERMANOVA, p < 0.05). Whereas some PGPB persisted in the rhizosphere at lower pH, including Arthrobacter and Devosia, they were absent from the bulk. Meanwhile, AGB dominated in both compartments; the most abundant were the Fe-oxidizer Leptospirillum and Fe-reducers Acidibacter and Acidiphilium, and the most active was the Fe-reducer Aciditerrimonas. This predominance of AGB at lower pH, and even their minimal presence at higher pH, contributes to acidifying conditions and poses a significant threat to sustainable Plant Establishment. These findings have implications for phytostabilization field site management and suggest re-application of compost or an alternate buffering material may be required in regions susceptible to re-acidification to maintain a beneficial bacterial community conducive to long-term Plant Establishment
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environmental factors influencing the structural dynamics of soil microbial communities during assisted phytostabilization of acid generating mine tailings a mesocosm experiment
Science of The Total Environment, 2014Co-Authors: Alexis Valentinvargas, Robert A Root, Julia W Neilson, Jon Chorover, Raina M MaierAbstract:Compost-assisted phytostabilization has recently emerged as a robust alternative for reclamation of metalliferous mine tailings. Previous studies suggest that root-associated microbes may be important for facilitating Plant Establishment on the tailings, yet little is known about the long-term dynamics of microbial communities during reclamation. A mechanistic understanding of microbial community dynamics in tailings ecosystems undergoing remediation is critical because these dynamics profoundly influence both the biogeochemical weathering of tailings and the sustainability of a Plant cover. Here we monitor the dynamics of soil microbial communities (i.e. bacteria, fungi, archaea) during a 12-month mesocosm study that included 4 treatments: 2 unPlanted controls (unamended and compost-amended tailings) and 2 compost-amended seeded tailings treatments. Bacterial, fungal and archaeal communities responded distinctively to the revegetation process and concurrent changes in environmental conditions and pore water chemistry. Compost addition significantly increased microbial diversity and had an immediate and relatively long-lasting buffering-effect on pH, allowing Plants to germinate and thrive during the early stages of the experiment. However, the compost buffering capacity diminished after six months and acidification took over as the major factor affecting Plant survival and microbial community structure. Immediate changes in bacterial communities were observed following Plant Establishment, whereas fungal communities showed a delayed response that apparently correlated with the pH decline. Fluctuations in cobalt pore water concentrations, in particular, had a significant effect on the structure of all three microbial groups, which may be linked to the role of cobalt in metal detoxification pathways. The present study represents, to our knowledge, the first documentation of the dynamics of the three major microbial groups during revegetation of compost-amended, metalliferous mine tailings.
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bacterial community changes during Plant Establishment at the san pedro river mine tailings site
Journal of Environmental Quality, 2007Co-Authors: Karyna Rosario, Sadie L Iverson, David A Henderson, Shawna Chartrand, Casey Mckeon, Edward P Glenn, Raina M MaierAbstract:Mine tailings are moderately to severely impacted sites that lack normal Plant cover, soil structure and development, and the associated microbial community. In arid and semiarid environments, tailings and their associated contaminants are prone to eolian dispersion and water erosion, thus becoming sources of metal contamination. One approach to minimize or eliminate these processes is to establish a permanent vegetation cover on tailings piles. Here we report a revegetation trial conducted at a moderately impacted mine tailings site in southern Arizona. A salt and drought-tolerant Plant, fourwing saltbush [Atriplex canescens (Pursh) Nutt.], was chosen for the trial. A series of 3 by 3 m plots were established in quadruplicate on the test site to evaluate growth of four-wing saltbush transPlants alone or with compost addition. Results show that >80% of the transPlanted saltbush survived after 1.5 yr in both treatments. Enumeration of heterotrophs and community structure analysis were conducted to monitor bacterial community changes during Plant Establishment as an indicator of Plant and soil health. Th e bacterial community was evaluated using denaturing gradient gel electrophoresis (DGGE) analysis of 16S rDNA PCR gene products from tailings samples taken beneath transPlant canopies. Signifi cant diff erences in heterotrophic counts and community composition were observed between the two treatments and unPlanted controls throughout the trial, but treatment eff ects were not observed. Th e results suggest that compost is not necessary for Plant Establishment at this site and that Plants, rather than added compost, is the primary factor enhancing bacterial heterotrophic counts and aff ecting community composition.
Mark Van Kleunen - One of the best experts on this subject based on the ideXlab platform.
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determinants of Plant Establishment success in a multispecies introduction experiment with native and alien species
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Anne Kempel, Thomas Chrobock, Markus Fischer, Rudolf P Rohr, Mark Van KleunenAbstract:Determinants of Plant Establishment and invasion are a key issue in ecology and evolution. Although Establishment success varies substantially among species, the importance of species traits and extrinsic factors as determinants of Establishment in existing communities has remained difficult to prove in observational studies because they can be confounded and mask each other. Therefore, we conducted a large multispecies field experiment to disentangle the relative importance of extrinsic factors vs. species characteristics for the Establishment success of Plants in grasslands. We introduced 48 alien and 45 native Plant species at different seed numbers into multiple grassland sites with or without experimental soil disturbance and related their Establishment success to species traits assessed in five independent multispecies greenhouse experiments. High propagule pressure and high seed mass were the most important factors increasing Establishment success in the very beginning of the experiment. However, after 3 y, propagule pressure became less important, and species traits related to biotic interactions (including herbivore resistance and responses to shading and competition) became the most important drivers of success or failure. The relative importance of different traits was environment-dependent and changed over time. Our approach of combining a multispecies introduction experiment in the field with trait data from independent multispecies experiments in the greenhouse allowed us to detect the relative importance of species traits for early Establishment and provided evidence that species traits—fine-tuned by environmental factors—determine success or failure of alien and native Plants in temperate grasslands.
Richard N Knowles - One of the best experts on this subject based on the ideXlab platform.
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correlative changes in proteases and protease inhibitors during mobilisation of protein from potato solanum tuberosum seed tubers
Functional Plant Biology, 2010Co-Authors: Sarah M Weeda, G Mohan N Kumar, Richard N KnowlesAbstract:Potato tubers (Solanum tuberosum L.) contain protease inhibitors that function in Plant defence and as storage proteins. A multi-domain cysteine protease inhibitor, potato multicystatin (PMC), has also been implicated in regulating protein accumulation in developing tubers by inhibiting proteases. Unlike developing tubers, sprouting tubers mobilise protein reserves to support growth of developing Plants and, therefore, show an increase in protease activity. Using single-eye containing cores (seedcores) from seed tubers, we characterised the relative changes in patatin, PMC, proteases and serine (Ser) protease inhibitors, as a prerequisite to further research on their potential roles in protein mobilisation from tubers during Plant Establishment. Approximately 63% of seedcore dry matter was mobilised over a 29-day period of Plant Establishment (1.7 mg seedcore dry matter mobilised for every mg increase in Plant dry matter). The gelatinolytic protease isoforms induced in seedcores during Plant Establishment differed from those characterised previously in developing tubers. Total protease activity increased progressively in seedcores and reached a maximum 23 days after Planting. Conversely, seedcore soluble protein content declined, with patatin accounting for the greatest decrease in the soluble protein fraction during Plant Establishment. PMC also decreased 44% and Ser (trypsin) protease inhibitors decreased to levels barely detectable in seedcores over the 29-day growth interval. Moreover, the temporal changes in PMC, protease activity and patatin content were highly correlated. As PMC decreased from 6 to 4 ng core–1, protease activity increased 9-fold, patatin decreased 2.6-fold and total soluble protein decreased by 58%. These results suggest that catabolism of protease inhibitors may facilitate protein mobilisation from seed tubers. Further work to define unequivocally the role of protease inhibitors in modulating the activity of proteases during protein mobilisation from tubers is warranted.
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modelling the effects of potato seed tuber age on Plant Establishment
Canadian Journal of Plant Science, 1991Co-Authors: Richard N Knowles, Gabor I BotarAbstract:Four physiological ages of potato (Solanum tuberosum L. 'Russet Burbank') seed-tubers were produced by varying the time of storage at 15 °C. Age was quantified as the accumulated degree-days (dd) above 4 °C over the 199-d storage interval, and Plant emergence and Establishment were then modelled in controlled environment studies. As age advanced, time to 50% sprout emergence decreased, reaching a minimum at 589 dd, and then increased with further aging. Apical dominance was also reduced, as evident from a linear increase in the number of sprouts per seedpiece with advancing age. Earlier emergence from older seed-tubers led to significantly more leaves, leaf area, and leaf and stem dry weights per Plant compared with younger seed-tubers early in the study; however, this advantage in Plant Establishment was eventually lost as time progressed through 33 d, resulting in significant age by time interactions on each yield component. Unit leaf rate, and relative growth rates with respect to leaf area and Plant d...
Jeremy J James - One of the best experts on this subject based on the ideXlab platform.
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a modelling framework for improving Plant Establishment during ecological restoration
Ecological Modelling, 2017Co-Authors: Matthew J Rinella, Jeremy J JamesAbstract:Abstract Plants seeded during ecological restoration sometimes persist but more often fail to establish. Biodiversity has been shown to stabilize a number of ecological processes, suggesting biodiverse seed mixes could be designed to stabilize Plant Establishment outcomes. In particular, it may be possible to design seed mixes to increase chances at least some seeded species will be adapted to whatever environmental conditions arise during Establishment. To explore this possibility, we developed a modelling framework and applied it to data from 30 field experiments (15 sites × 2 seeding years) conducted in a big sagebrush (Artemisia tridentata Nutt.) ecosystem. In each experiment, three native and one nonnative grass were sown (600 seeds m−2) in separate plots, and we estimated the probability each species germinated and survived through two growing seasons post-seeding. Applying an optimization algorithm to these survival probabilities allowed us to assign species identities to 600 seeds m−2 in a manner maximizing the number of experimental conditions yielding ≥5 Plants m−2, a common Plant density goal in grassland restoration. Allocating 353 (216, 555) [point estimate (95% CI)] seeds to Poa secunda J. Presl and 247 (11, 378) seeds to Pseudoroegneria spicata (Pursh) A. Love) maximized our native Plant density goal (goal achieved in 12 (10, 14) of 30 experiments), and the allocation to >1 species supports the hypothesis biodiverse seed mixes could be designed to reduce Establishment failures. Averaged over experiments, P. spicata survival was roughly half of P. secunda survival, but P. spicata nevertheless contributed to the density goal by compensating for low P. secunda survival in certain experiments. Strategically combining species with different seed/seedling traits can increase chances of achieving adequate Plant Establishment during ecological restoration.
