Progress 06/15/17 to 06/14/22
Outputs
Target Audience:The project's targeted audience included the scientific community, graduate and undergraduate students, postdoctoral fellows, park services and land managers. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project provided training to two graduate students, two postdoctoral fellows, one research assistant and eleven undergraduate students in establishing experimental plots in the field, processing soil samples for soil chemistry and microbial and soil carbon chemistry analysis using spectroscopy and mass spectrometry techniques and data processing. Additionally, the graduate students were trained in manuscript preparation and postdoctoral fellows were trained in proposal writing. How have the results been disseminated to communities of interest?The results have been published in high impact factor peer-reviewed journals, presented as oral presentations in scientific society meetings and university seminars, and disseminated to local land managers. The results of the project were incorporated in the graduate and undergraduate courses taught by the PI and Co-PI of the project. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
We conducted several experiments to achieve the major goals of the project. Based on our projects we elucidated the mechanisms through which NIPS input litter with distinct secondary metabolite signature that create a legacy effect through changes in soil carbon chemistry. Based on the above knowledge we developed management practices such as adding carbon amendments that reversed the legacy effect created by the NIPS and aid in the restoration of invaded habitats. Project 1: The project aimed to obtain a comprehensive understanding of the mechanisms through which invasive plants change soil carbon cycling in their invaded ranges resulting in legacy effects. Publication: Tamura M, Suseela V, Simpson M and Tharayil N. 2017. Plant invasions alter the content and molecular identity of organic carbon associated with soil mineral and aggregate fractions. Global Change Biology; 23: 4002-4018. Abstract: We hypothesized that the soils subjected to prolonged invasion by an exotic plant that input recalcitrant litter (Japanese knotweed, Polygonum cuspidatum) would have a greater proportion of plant-derived carbon (C) in the aggregate fractions, as compared with that in adjacent soil inhabited by native vegetation that input labile litter, whereas the soils under an invader that input labile litter (kudzu, Pueraria lobata) would have a greater proportion of microbial-derived C in the silt-clay fraction, as compared with that in adjacent soils that receive recalcitrant litter. At the knotweed site, the higher C content in soils under P. cuspidatum, compared with noninvaded soils inhabited by grasses and forbs, was limited to the macroaggregate fraction, which was abundant in plant biomarkers. The noninvaded soils at this site had a higher abundance of lignins in mineral and microaggregate fractions and suberin in the macroaggregate fraction, partly because of the greater root density of the native species, which might have had an overriding influence on the chemistry of the above-ground litter input. At the kudzu site, soils under P. lobata had lower C content across all size fractions at a 0-5 cm soil depth despite receiving similar amounts of Pinus litter. Our results highlight that NIPS could alter soil carbon cycle creating a legacy effect. Project 2: Specific objectives: 1. Characterize the extractable and bulk soil carbon chemistry in soils invaded by the NIPS, and how affect the extracellular enzyme activity and soil organic matter decomposition. 2. Quantify the rate of enzyme activities in invaded and non-invaded soils across multiple sites. Publication: Min K J and Suseela V. 2020. Plant invasion alters the Michaelis-Menten kinetics of microbial extracellular enzymes and soil organic matter chemistry along soil depth. Biogeochemistry, 150, 181-196. Abstract: Microbial extracellular enzymes decompose distinct components of soil organic matter (SOM), thus influencing its stability. However, we lack the knowledge about how the kinetics of individual enzymes vary when multiple substrates change simultaneously. The invasion of knotweed, which input litter rich in recalcitrant compounds, altered soil chemistry including an increase in lignin and fungal biomass compared to the adjacent non-invaded soils. The Vmax of peroxidase, the oxidative enzyme that degrades lignin, increased in the invaded soils (0-5 cm) compared to the non-invaded soils. Among the hydrolytic enzymes, the Vmax of N-acetyl-glucosaminidase which degrades chitin from fungal cell walls increased in the invaded soils (0-5 cm). However, there was no associated change in the km of peroxidase and Nacetyl-glucosaminidase under invasion, suggesting that microbes modified the enzyme production rates, not the types (isozyme) of enzymes under invasion. The Vmax of all enzymes decreased with depth, due to the reduced substrate availability. These results highlight that the addition of relatively recalcitrant substrates due to plant invasion altered the kinetics of microbial extracellular enzymes with implications for SOM chemistry in the invaded soils. Project 3.Objectives: Evaluate the effectiveness of soil amendments to reverse the legacy effect by their ability to sequester or degrade the invader induced soil carbon compounds. Publication: Zhang Z, Bhowmik P, Suseela V. 2020. Effect of soil carbon amendments in reversing the legacy effect of plant invasion. Journal of Applied Ecology, 58: 181-191. Abstract: Following the removal of knotweed biomass, we investigated the effect of two soil carbon (C) amendments (biochar and activated carbon) on the growth and establishment of newly seeded native and prairie species. The biomass of the prairie species was 80% higher in activated carbon and biochar amended plots than the non-amended control plots. The nitrate content of the C amended plots was five times higher than the non-amended plots indicating an increased N mineralization in the C amended plots. This could be potentially due to the amelioration of phenolic compounds by activated carbon and biochar through sorption. Our results revealed the potential of soil C amendments in reversing niche construction and legacy effects of polyphenol- rich invasive species and indicated that biochar could be a more economically feasible alternative to activated carbon in restoring invaded ecosystems. These results also emphasize that understanding the mechanisms through which invasive species create a legacy effect is pivotal in formulating suitable knowledge-based practices for restoring invaded ecosystems. Project 4. Effect of nitrogen availability on the chemical composition of soil organic carbon induced by NIPS. Publication: Zhang Z, Suseela V. 2021. Nitrogen availability modulates the impacts of plant invasion on the chemical composition of soil organic carbon. Soil Biology & Biochemistry, 156. Abstract: Compared with the noninvaded soils, the knotweed-invaded soils exhibited a 17% increase in the microbial-derived C, mainly through the accumulation of fungal residue in the form of amino sugars. The concentrations of phytosterol in the knotweed-invaded soils were 1.5-fold as that in the noninvaded soils. Fertilizer application significantly increased the retention of plant-derived compounds in the knotweed-invaded soils, but also induced 45% greater degradation of lignin. Moreover, under fertilizer application, the knotweed-invaded soils accumulated 46% more microbial-derived C, primarily due to the altered microbial biomass and community composition. Plant invasion has the potential to influence SOC chemical composition through changes in plant-derived and microbial-derived C. Furthermore, N deposition could reinforce the invasion effects on the molecular composition and accrual of SOC. Project 5.Objectives: To understand the temperature sensitivity of soil organic matter decomposition in invaded ecosystems under constant addition of labile substrates from the invasive species. Publication: Tamura M and Suseela V. 2021. Warming and labile substrate addition alter enzyme activities and composition of soil organic carbon. Frontiers in Forests and Global Change, doi.org/10.3389/ffgc.2021.691302. Abstract: After 14 months of soil incubation, the addition of labile C through kudzu extract increased the activity of b-1,4-glucosidase compared with the control. However, the activity of N-acetyl-b-D-glucosaminidase and fungal biomass (ergosterol) decreased with labile carbon addition. The activity of peroxidase increased with warming after 14 months of soil incubation. In soils that received an addition of labile C, the macro-aggregate stability was higher while the temperature sensitivity of soil C efflux was lower compared with the control. The increase in aggregate stability could enhance the physical protection of SOC from microbial decomposition potentially contributing to the observed pattern of temperature sensitivity.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Min K J and Suseela V#. 2020. Plant invasion alters the Michaelis-Menten kinetics of microbial extracellular enzymes and soil organic matter chemistry along soil depth. Biogeochemistry, 150, 181196.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Zhang Z, Bhowmik P, Suseela V#. 2020. Effect of soil carbon amendments in reversing the legacy effect of plant invasion. Journal of Applied Ecology, 58: 181-191.
|
Progress 06/15/20 to 06/14/21
Outputs
Target Audience:Scientific community Graduate and undergraduate students in lab and courses taught by the PI and Co-PI Postdoctoral fellows General Public Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project provided training to one graduate student, one postdoctoral fellow, one research assistant and four undergraduate students in establishing experimental plots in the field, processing soil samples for soil chemistry and microbial enzyme analysis and data processing. How have the results been disseminated to communities of interest?The results have been disseminated through peer reviewed journals and incorporating the results in seminars and graduate and undergrdaute classes taught by the PI and Co-PI. Publications Zhang Z*, Suseela V. 2021. Nitrogen availability modulates the impacts of plant invasion on the chemical composition of soil organic carbon. Soil Biology & Biochemistry, 156, doi.org/10.1016/j.soilbio.2021.108195. (Postdoctoral mentee). Tamura M and Suseela V. 2021. Warming and labile substrate addition alter enzyme activities and composition of soil organic carbon. Frontiers in Forests and Global Change. doi: 10.3389/ffgc.2021.691302. Tharayil, N. 2021. Physiological adaptations and organismal interactions that facilitate weediness in plants. Invited seminar at the Department of Plant Science, UC Davis. What do you plan to do during the next reporting period to accomplish the goals?Next steps for coming year(s). (1) Identify and regulate the processes through which invasive plants induce changes in soil organic matter in invaded ecosystems, (2) Predictive understanding of the potential interaction between the invasive species with soil mineralogy in creating legacy effects, (3) Understand the differential effect of roots vs aboveground tissues of invasivespecies in altering SOC chemistry and creating a legacy effect (4) Develop management practices that will restore theinvaded ecosystems based on a mechanistic understanding of the invader-induced legacy effect.
Impacts
What was accomplished under these goals?
Project 1: To understand the interactive effects of nitrogen deposition and plant invasion on the chemical composition of soil organiccarbon Abstract: Plant invasion can dramatically impact soil carbon (C) cycling and sequestration while, other global change factors, such as nitrogen (N) deposition, are predicted to promote plant invasion. However, questions remain as to whether the chemical composition of soil organic C (SOC) may alter with plant invasion and how N availability modulates the invasion effects on SOC. In this study, we conducted a 10-year mesocosm experiment simulating the invasion of Japanese knotweed (Polygonum cuspidatum) into a fallow soil, coupled with a simultaneous mineral fertilizer application scheme for the invasive plants. We investigated the invasion effects on the chemical composition of various SOC components at the molecular level, and examined how these effects responded to changes in soil N availability. Compared with the noninvaded soils, the knotweed-invaded soils exhibited a 17% increase in the microbial-derived C, mainly through the accumulation of fungal residue in the form of amino sugars. Despite receiving leaf litter which was abundant in polyphenolic compounds (40% and 3- times higher in lignin and tannins per unit biomass, respectively), the knotweed-invaded soils did not differ in the concentration of plant lipids and lignin monomers compared to the noninvaded soils inhabited by grasses. However, the concentrations of phytosterol in the knotweed-invaded soils were 1.5-fold as that in the noninvaded soils. Fertilizer application significantly increased the retention of plant-derived compounds in the knotweed-invaded soils, but also induced 45% greater degradation of lignin. Moreover, under fertilizer application, the knotweed-invaded soils accumulated 46% more microbial-derived C, primarily due to the altered microbial biomass and community composition. Collectively, our findings suggest that plant invasion has the potential to influence SOC chemical composition through changes in plant-derived and microbial-derived C. Furthermore, N deposition could reinforce the invasion effects on the molecular composition and accrual of SOC. Our results also highlight the need to understand the impacts of biological invasion in the context of other global change drivers that both affect invasion and modulate their effects. The manuscript related to this project is published in Soil Biology and Biochemistry in 2021. Project 2: To understand the interactive effects of global changes such as climate warming and invasion on the composition of soil organic carbon and microbial functional activity Abstract:Warming can increase the efflux of carbon dioxide (CO2) from soils and can potentially feedback to climate change. In addition to warming, the input of labile carbon can enhance the microbial activity by stimulating the co-metabolism of recalcitrant soil organic matter (SOM). This is particularly true with SOM under invaded ecosystems where elevated CO2 and warming may increase the biomass of invasive species resulting in higher addition of labile substrates.We hypothesized that the input of labile carbon would instigate a greatersoil organic carbon (SOC) loss with warming compared to the ambient temperature.We investigated this by incubating soils collected from a native pine (Pinus taeda) forest to which labile carbon from the invasive species kudzu (Pueraria lobata) was added.We evaluated the microbial extracellular enzyme activity, molecular composition of SOC and the temperature sensitivity of soil CO2 efflux under warming and labile carbon addition.After 14 months of soil incubation, the addition of labile C through kudzu extract increased the activity of b-1,4-glucosidase compared with the control. However, the activity of N-acetyl-b-D-glucosaminidase and fungal biomass (ergosterol) decreased with labile carbon addition. The activity of peroxidase increased with warming after 14 months of soil incubation. Although the carbon content of incubated soils did not vary with substrate and temperature treatments, the molecular composition of SOM indicated a general decrease in biopolymers such as cutin, suberin, long-chain fatty acids, and phytosterol with warming and an increasing trend of microbial-derived compounds with labile substrate addition. In soils that received an addition of labile C, the macro-aggregate stability was higher while the temperature sensitivity of soil C efflux was lower compared with the control. The increase in aggregate stability could enhance the physical protection of SOC from microbial decomposition potentially contributing to the observed pattern of temperature sensitivity. Our results suggest that warming could preferentially accelerate the decomposition of recalcitrant compounds while the addition of labile substrates could enhance microbial-derived compounds that are relatively resistant to further decomposition. Our study further emphasizes that global change factors such as plant invasion and climate change can differentially alter soil microbial activity and the composition of SOM. The manuscript related to this projectis pulished in Frontiers in Forests and Global Changes in 2021. Project 3 Objectives: Evaluate the effectiveness of soil amendments to reverse the legacy effect by their ability to sequester or degradethe invader induced soil carbon compounds. In this study, we hypothesized that the management practices that can restore soil C and nutrient cycling in invadedecosystems can facilitate the rapid restoration of the invaded sites. We predicted that adding soil carbon amendments canrevert the microbial composition and functional activity leading to changes in C and nutrient cycling similar to the pre-invasionstages. The study site was selected in Amherst, Massachusetts as this site has been under knotweed invasion for more than 20 years. The study site for the restoration experiment was prepared by first clearing the above ground growth of the knotweed and the decomposing stems from the site. All the remaining rhizomes in the soil up to 30 cm depth were also removed. A total of 30 plots were set up with 5 treatments and 6 replicates in a randomized block design (2 m x 2 m).The plots were assigned as (1) control, (2) activated carbon, (3) sugar, (4) biochar, and (5) activated carbon and sugar. After mixing top 10 cm of soil and leveling it evenly, treatments except sugar, were added to designated plots and soils were raked again. Our results suggest that these soil carbon amendments are very effective in reversing the niche construction by knotweed. The studyis currently ongoing. Project 4: To evaluate the effect of different invasive species on creating a soil legacy effect and the impact of soil carbon amendments in reversing the legacy effect. The objective of this project is to understand the impact of several invasive species belonging to different plant functional types in altering the soil carbon chemistry and microbial biomass and activity. Further, the objective is to formulate different soil amendment practices to reverse the carbon chemistry and microbial activity. Seeds of native plants will be added to this soil with and without carbon amendments to evaluate the effectiveness of active soil interventions in restoring the invaded soils. The study is now undertaken as a greenhouse experiment and is ongoing.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Zhang Z, Suseela V. 2021. Nitrogen availability modulates the impacts of plant invasion on the chemical composition of soil organic carbon. Soil Biology & Biochemistry, 156, doi.org/10.1016/j.soilbio.2021.108195.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Tamura M and Suseela V#. 2021. Warming and labile substrate addition alter enzyme activities and composition of soil organic carbon. Frontiers in Forests and Global Change. doi: 10.3389/ffgc.2021.691302
- Type:
Other
Status:
Other
Year Published:
2021
Citation:
Tharayil, N. 2021. Physiological adaptations and organismal interactions that facilitate weediness in plants. Invited seminar at the Department of Plant Science, UC Davis.
|
Progress 06/15/19 to 06/14/20
Outputs
Target Audience:Scientific community Graduate and undergraduate students Postdoctoral fellows Public Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project provided training to one graduate student, twopostdoctoral fellows, one research assistant and four undergraduate students in establishing experimental plots in the field, processing soil samples for soil chemistry and microbial enzyme analysis and data processing. How have the results been disseminated to communities of interest?The results have been disseminated through peer reviewed journals and national meetings. Min K J* and Suseela V. 2020. Plant invasion alters the Michaelis-Menten kinetics of microbial extracellular enzymes and soil organic matter chemistry along soil depth. Biogeochemistry; https://doi.org/10.1007/s10533-020-00692.(*Postdoctoral mentee). Zhang Z*, Bhowmik P, Suseela V. 2020. Effect of soil carbon amendments in reversing the legacy effect of plant invasion. Journal of Applied Ecology; DOI: 10.1111/1365-2664.13757.(*Postdoctoral mentee). Zhang, Z*., Bhowmik, P. C., & Suseela, V. (2020). Data from: Effect of soil carbon amendments in reversing the legacy effect of plant invasion. Dryad Digital Repository, https://doi.org/10.5061/dryad.crjdfn327 (*Postdoctoral mentee) Zhang Z*,Tharayil, N, Suseela V. 2020. Nitrogen availability modulates the impacts of plant invasion on the chemical composition of soil organic carbon. Annual Meeting of the Ecological Society of America, Utah, USA. (*Postdoctoral mentee). What do you plan to do during the next reporting period to accomplish the goals?Next steps for coming year(s). (1) Identify and regulate the processes through which invasive plants induce changes in soil organic matter in invaded ecosystems, (2) Predictive understanding of the potential interaction between the invasive species with soil mineralogy in creating legacy effects, (3) Understand the differential effect of roots vs aboveground tissues of invasive species in altering SOC chemistry and creating a legacy effect (4)Develop management practices that will restore the invaded ecosystems based on a mechanistic understanding of the invader-induced legacy effect.
Impacts
What was accomplished under these goals?
Project 1.Plant invasion alters the Michaelis-Menten kinetics of microbial extracellular enzymes and soil organic matter chemistry along soil depth Specific objectives: 1. Characterize the extractable and bulk soil carbon chemistry in soils invaded by the NIPS, and how it extracellular enzyme activity and soil organic matter decomposition. 2. Quantify the rate of enzyme activities in invaded and non-invaded soils across multiple sites. We did additional analysis and revisions of themanuscript related to this project and is now published in the journal Biogeochemsitry (impact factor: 4.61). Results:The Vmax of peroxidase, the oxidative enzyme that degrades lignin, increased in the invaded soils (0-5 cm) compared to the non-invaded soils. Among the hydrolytic enzymes, the Vmax of N-acetyl-glucosaminidase which degrades chitin from fungal cell walls increased in the invaded soils (0-5 cm). However, there was no associated change in the km of peroxidase and Nacetyl-glucosaminidase under invasion, suggesting that microbes modified the enzyme production rates, not the types (isozyme) of enzymes under invasion. The Vmax of all enzymes decreased with depth, due to the reduced substrate availability. These results highlight that the addition of relatively recalcitrant substrates due to plant invasion altered the kinetics of microbial extracellular enzymes with implications for SOM chemistry in the invaded soils. Project 2.Effect of soil carbon amendments in reversing the legacy effect of plant invasion Objectives: Evaluate the effectiveness of soil amendments to reverse the legacy effect by their ability to sequester or degrade the invader induced soil carbon compounds. In this study, we hypothesized that the management practices that can restore soil C and nutrient cycling in invaded ecosystems can facilitate the rapid restoration of the invaded sites. We predicted that adding soil carbon amendments can revert the microbial composition and functional activity leading to changes in C and nutrient cycling similar to the pre-invasion stages. The manuscript related to this project is revised and is now published in the Journal of Applied Ecology (impact factor: 5.84). The abstract is as follows Abstract: We conducted this study in an old-field in Massachusetts, USA that has been invaded by Japanese knotweed (Polygonum cuspidatum) for >20 years. We chose knotweed as a model system as it alters soil chemistry and microbial community through the input of polyphenols such as tannins and creates a legacy effect. We investigated the effect of two soil carbon (C) amendments (biochar and activated carbon) on the growth and establishment of native and prairie species that were seeded after removing the knotweed above- and below-ground biomass. We measured the percent plant cover and above-ground biomass to assess the establishment of the native and prairie species. We also measured soil and microbial characteristics including nutrient availability, extracellular enzyme activities, and fungal biomass to elucidate the effect of carbon amendments in reversing the legacy effect. Our results revealed that activated carbon and biochar amended plots had 80% more biomass of the prairie species than the control plots. The nitrate content of C amended plots was five times higher than the non-amended plots indicating an increased nitrogen mineralization in the C amended plots. This could be potentially due to the sorption of phenolic compounds by activated carbon and biochar, which makes them unavailable. The phenol peroxidase activity also increased in the activated carbon and biochar amended plots potentially due to the less inhibition by phenolic compounds such as tannins. The fungal biomass decreased in C amended plots that may have resulted in faster nutrient cycling and increased availability of soil nitrogen. Synthesis and applications: Our results revealed the potential of soil C amendments in reversing niche construction and legacy effects of polyphenol-rich invasive species and indicated that biochar could be a more economically feasible alternative to activated carbon in restoring invaded ecosystems. These results also emphasize that understanding the mechanisms through which invasive species create a legacy effect is pivotal in formulating suitable knowledge-based practices for the restoration of invaded ecosystems. Project 3.Nitrogen availability modulates the impacts of plant invasion on the chemical composition of soil organic carbon Objectives:Plant invasion can impact soil carbon (C) cycling and sequestration. Meanwhile, other global change factors such as nitrogen (N) deposition is predicted to promote plant invasion. However, questions remain as to whether the chemical composition of soil organic C (SOC) alter with plant invasion and how N availability modulates the invasion effects on SOC. We carried out a 10-year mesocosm experiment simulating the invasion of Polygonum cuspidatum into a fallow soil, coupled with an N fertilization scheme for the invasive plants. Weinvestigated the invasion effects on the chemical composition of various SOC components and examined how the effects of plant invasion respond to changes in soil N availability. We investigated the invasion effects on the chemical composition of various SOC components (i.e., plant- and microbial-derived C) at the molecular level. We further examined how these effects of plant invasion responded to altered soil N availability. We also quantified the soil microbial biomass, community composition, and enzyme activities to elucidate potential mechanisms driving the variation of SOC compositions. Abstract: In this study, we carried out a 10-year mesocosm experiment simulating the invasion of Polygonum cuspidatum (Japanese knotweed) into a fallow soil, coupled with a contemporary N fertilization scheme for the invasive plants. Using paired invaded and noninvaded treatments as well as paired invaded and invaded + fertilized treatments, we investigated the invasion effects on the chemical composition of various SOC components at the molecular level. We further examined how the effects of plant invasion responded to changes in soil N availability. Compared with noninvaded soils, knotweed-invaded soils exhibited a 17% increase in the microbial-derived C, mainly through the accumulation of fungal residue in the form of amino sugars.N fertilization increased the retention of plant-derived compounds in knotweed-invaded soils, but also stimulated the degradation of lignin monomers. Moreover, knotweed-invaded soils accumulated 46% more microbial-derived C under N enrichment, primarily due to the altered microbial biomass and community composition. Collectively, our findings suggest that plant invasion has the potential to influence SOC chemical composition, with microbial-derived C fractions showing a higher sensitivity relative to plant-derived C. Furthermore, N fertilization could modulate the invasion effects on the molecular composition and accrual of SOC. Our results also highlight the need to understand the impacts of biological invasion in the context of other global change drivers that both affect invasion and modulate their effects. The manuscript issubmitted to Soil Biology and Biochemistry. Project 4. Objective: To understand the effect of root vs above ground tissues in altering SOC chemistry in invaded ecosystems. We have planted Lonicera japonica under greenhouse settings to collect the aboveground tissues and roots. These tissues will be analyzed for tissue chemistry using LC and GC based mass spectrometry analysis. The root tissues and aboveground tissues will be added to soils with different minerology in an incubation study to understand the effect of root tissues and aboveground tissues on the plant-derived and microbial derived soil biomarker and hence on soil organic carbon chemsitry. This study is ongoing.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Min K J* and Suseela V. 2020. Plant invasion alters the Michaelis-Menten kinetics of microbial extracellular enzymes and soil organic matter chemistry along soil depth. Biogeochemistry; https://doi.org/10.1007/s10533-020-00692.(*Postdoctoral mentee).
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Zhang Z*, Bhowmik P, Suseela V. 2020. Effect of soil carbon amendments in reversing the legacy effect of plant invasion. Journal of Applied Ecology; DOI: 10.1111/1365-2664.13757.(*Postdoctoral mentee).
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Zhang Z*,Tharayil, N, Suseela V. 2020. Nitrogen availability modulates the impacts of plant invasion on the chemical composition of soil organic carbon. Annual Meeting of the Ecological Society of America, Utah, USA. (*Postdoctoral mentee).
- Type:
Other
Status:
Published
Year Published:
2020
Citation:
Zhang, Z*., Bhowmik, P. C., & Suseela, V. (2020). Data from: Effect of soil carbon amendments in reversing the legacy effect of plant invasion. Dryad Digital Repository, https://doi.org/10.5061/dryad.crjdfn327 (*Postdoctoral mentee)
|
Progress 06/15/18 to 06/14/19
Outputs
Target Audience:Scientific community Graduate and undergraduate students Postdoctoral research fellows Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project provided training to one graduate student, twopostdoctoral fellows, one research assistant and five undergraduate students in establishing experimental plots in the field, processing soil samples for soil chemistry and microbial enzyme analysis and data processing. How have the results been disseminated to communities of interest?The results have been disseminated through peer reviewed journals and national meetings. Min K J. and Suseela V. Plant invasion alters the Michaelis-Menten kinetics of microbial extracellular enzymes and soil organic matter chemistry along soil depth. Biogeochemistry (In Review) Tamura M, Tharayil N, Suseela V. Warming and labile substrate addition alters enzyme activity and the composition of soil organic matter. Biogeochemistry (In Review) K. Min*, N. Tharayil, P. C. Bhowmik, V. Suseela. 2019. Linking the invasion of weedy species to atered functional adaptations of soil microbes. Oral Presentation at the Annual Meeting of the Weed Science Society of America, New Orleans. (*Postdoctoral Mentee) K. Min*, J Bodenheimer#, V. Suseela. 2019. Plant invasion alters the Michaelis-Menten kinetics of microbial exo-enzymes and soil organic matter chemistry along soil depth. Oral Presentation at the Annual Meeting of the Ecological Society of America, Louisville, Kentucky, August 11-16. (*Postdoctoral Mentee, #undergraduate mentee) What do you plan to do during the next reporting period to accomplish the goals?Next steps for coming year(s). (1) Conduct experiments ininvaded sites along eastern US that differ in native vegetation and soil mineral properties, (2) Identify and regulate the processes through which invasive plants induce changes in soil organic matter in invaded ecosystems, (3) Predictive understanding of the potential interaction between the invasive species with soil mineralogy in creating legacy effects, (4) Identify the suitability of soil amendments in reversing invader-induced changes in soil organic matter cycling, (5) Develop management practices that will restore the invaded ecosystems based on a mechanistic understanding of the invader-induced legacy effect.
Impacts
What was accomplished under these goals?
Project 1 Specific objectives: 1.Characterize the extractable and bulk soil carbon chemistry in soils invaded by the NIPS, and how it extracellular enzyme activity and soil organic matter decomposition. 2.Quantify the rate ofenzyme activities in invaded and non-invaded soils across multiple sites. Methodology We selected three sites in Massachusettssubjected to prolonged invasion byjapanese knotweed. Using a transect sampling, we collected six soil cores (5 cm diameter) from 0-5, 5-10, and 10-15 cm ininvaded and adjacent non-invaded zones. We characterized the total soil organic matter, dissolved organic matter, soil phenolics, soil phosphorus, cellulose, chitin,lignin, fungal biomass (ergosterol) and we characterizedthe Michaelis-Menten kinetics of four microbial extracellular enzymes relevant to soil Cdynamics such as β-glucosidase, N-acetyl-glucosaminidase, acid phosphatase and peroxidase. Notable fingings Microbial extracellular enzyme activity (EEA) decomposes distinct components of soil organic matter (SOM), thusregulating the stability of SOM.We hypothesizedthat invasion will increase the Vmax and km of oxidative enzymes, but decrease the Vmax and km of hydrolytic enzymesand that increasing soil depth will alleviate the invasion effects on the enzyme kinetics. Plant invasion increased theabundance of SOM and chitin at 0-5 cm and lignin at 0-5 and 5-10 cm. At top 5 cm, invasion generally increased theVmax of hydrolytic enzymes, while at deeper soils (5-10 and 10-15 cm), the Vmax of hydrolytic enzymes generallydecreased. The Vmax of peroxidase was higher under invasion across depth. In contrast to the varying responses ofVmax under invasion, we found no invasion effect on km of any enzymes, suggesting that microbes modified enzymeproduction rates, not the types (isozyme) of enzymes under invasion. These results highlight that plant invasioninduced microbes to preferentially allocate resources for the production of enzymes that depolymerize therecalcitrant compounds and that the effects of plant invasion on EEA are not confined to surface, but penetrated intodeeper soils.The results suggest that the stabilityof individual SOM components under plant invasion is not equal and that the input of relatively recalcitrantsubstrates may result in the production of extracellular enzymes that disproportionately decay recalcitrant C morethan the labile C. The manuscript iscurrently under review and the results are dissiminated via national scientific meetings. Project 2. Objectives: To understand the temperature sensitivity of soil organic matter decomposition in invaded ecosystems under constant addition of labile substrates from the invasive species.Warming is projected to increase the efflux of CO2 from soil organic carbon (SOC) pool which can induce a positive feedback to climate change. Along with warming, microbial metabolism can also be enhanced by the addition of labile carbon that could stimulate the co-metabolism of recalcitrant SOC. This is particularly true with SOC under invaded ecosystems where a greater biomass production of invaders with elevated CO2 and warming may increase the input of labile substrates and subsequent decomposition of recalcitrant carbon leading to the loss of SOC. We hypothesized that compared to ambient temperature, the input of labile carbon would instigate a greater SOC loss with warmer temperature, while the temperature sensitivity of CO2 efflux would be lower in soils receiving an input of labile carbon. Methodology The study investigated the combined effect of warming and addition of labile C substrates on microbial biomass (fungal and bacterial biomass), microbial extracellular enzyme activity,soil C content and molecular level composition of soil carbon by quantifyingcutin, suberin, long chain fattyacids, phytosterol, and shortchain fatty acids and soil aggregate stability. In this study, the difference in C quality between the labile substrate and the soil was achieved by adding labile litter-extracts (C:N= 19) from kudzu, an N-fixing leguminous invasive species (Pueraria lobata) to a pine (Pinus taeda) forest soil (C:N=128) that was relatively enriched in recalcitrant compounds. Notable findings After 14 months of soil incubation, the addtion of labile C increased β-glucosidase and peroxidase activity than the control. The molecular composition of SOM showed a decrease in plant biopolymers with warming and an increasing trend of microbial-derived compounds with labile substrate addition. Temperature sensitivity of soil C efflux was higher in control than soils that received the input of labile C. The greater macro-aggregate stability observed in soils that received labile C which in turn provides physical protection of SOC from microbial decomposition could potentially contribute to the observed pattern of temperature sensitivity. Our results suggests that warming would preferentially accelerate the decomposition of recalcitrant compounds while addition of labile substrates could enhance microbial-derived compounds that are relatively resistant to further decomposition. This further indicates that the interaction of global change factors such as plant invasion and climate change can differentially alter enzyme activity and the composition of SOC. The manuscript is being currenlty under review and the results are dissiminated via national scientific meetings. Project 3 Objectives:Evaluate the effectiveness of soil amendments to reverse the legacy effect by their ability to sequester or degrade the invader induced soil carbon compounds. In this study, we hypothesized that the management practices that can restore soil C and nutrient cycling in invaded ecosystems can facilitate the rapid restoration of the invaded sites. Wepredicted that adding soil carbon amendments can revert the microbial composition and functional activity leading to changes in C and nutrient cycling similar to the pre-invasion stages. Methodology The study site was selected in Amherst, Massachusettsas this site has been under knotweed invasion for more than 20 years.The study site for the restoration experiment was preparedby first clearing the above ground growth of the knotweed and the decomposing stems from the site.All the remaining rhizomes in the soil up to 30 cm depth were also removed.A total of 30 plots were set up with 5 treatments and 6 replicates in a randomized block design (2 m x 2 m) in November and December 2018. Each block had the same distance from the invading front, because soil phenolics concentration increased with the distance from the invading front due to longer duration of invasion history. The first block was 3 m away from the invading front and the subsequent blocks were separated each other by 26 cm wide plank.Planks (26 cm wide x 3 cm thick x 3 m length) were vertically inserted into soil around the site to block the spread of rhizomes from surroundings. Within the vertical planks, we put two layers of planks horizontally to minimize edge effects. Treatments The plots were assigned as (1) control, (2) activated carbon, (3) sugar, (4) biochar, and (5) activated carbonand sugar. After mixing top 10 cm of soil and leveling it evenly, treatments except sugar, were added to designated plots and soils were raked again. We added sugar in April 2019 to avoid the dissolution-out of the site during rain-snow events in winter and early spring. Mixture of grassland seeds was sprinkled to the site (22 g of medium red clover per plot, 28 g of orchard grass, 22 g of perennial rye grass, 80 g of hariy vetch), and soils were mildly raked again. We started taking obervations regarding both plant and soil starting spring season and and is currently ongoing.
Publications
- Type:
Journal Articles
Status:
Under Review
Year Published:
2019
Citation:
Min K J. and Suseela V. Plant invasion alters the Michaelis-Menten kinetics of microbial extracellular enzymes and soil organic matter chemistry along soil depth. Biogeochemistry (In Review)
- Type:
Journal Articles
Status:
Under Review
Year Published:
2019
Citation:
Tamura M, Tharayil N, Suseela V. Warming and labile substrate addition alters enzyme activity and the composition of soil organic matter. Biogeochemistry (In Review)
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
K. Min*, N. Tharayil, P. C. Bhowmik, V. Suseela. 2019. LINKING THE INVASION OF WEEDY SPECIES TO ATERED FUNCTIONAL ADAPTATIONS OF SOIL MICROBES. Oral Presentation at the Annual Meeting of the Weed Science Society of America, New Orleans. (*Postdoctoral Mentee)
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2019
Citation:
K. Min*, J Bodenheimer#, V. Suseela. 2019. Plant invasion alters the Michaelis-Menten kinetics of microbial exo-enzymes and soil organic matter chemistry along soil depth. Oral Presentation at the Annual Meeting of the Ecological Society of America, Louisville, Kentucky, August 11-16. (*Postdoctoral Mentee, #undergraduate mentee)
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Progress 06/15/17 to 06/14/18
Outputs
Target Audience:Scientific community Graduate and undergraduate students Postdoctoral fellows Park services Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The project provided training to onegraduate student, one postdoctoral fellow, one research assistant and twoundergraduate students in establishing experimental plots in the field, processing soil samples for soil chemistry and microbial enzyme analysis anddata processing. How have the results been disseminated to communities of interest?The results have been dissimiated to the scientific community through the SSSA meeting and a publication in the journal Global Change Biology Suseela, V. Tharayil. N. 2017. Using Biomarker Approaches to Predict the Chemical Attributes of Organic Matter That Facilitates Soil Carbon Sequestration. Symposium "New Insights on Biogeochemical Processes in Terrestrial Ecosystems As Revealed By Isotopic and Biomarker Approaches II" Crop Science Society of America Annual Meeting. October 24, 2017, Tampa FL. M Tamura*, V Suseela*, M Simpson, B Powell, N Tharayil . 2017. Plant litter chemistry alters the content and composition of organic carbon associated with soil mineral and aggregate fractions in invaded ecosystems. Global Change Biology, 23: 4002-4018. (*co-first authors) The results have also been incorporated into the undergraduate/ graduatecourses taught by the PI and Co-PI at Clemson University. What do you plan to do during the next reporting period to accomplish the goals?Next steps for coming year(s). (1) Establish more invaded sites along eastern US that differ in native vegetation and soil mineral properties, (2) Identify and regulate the processes through which invasive plants induce changes in soil organic matter in invaded ecosystems, (3) Predictive understanding of the potential interaction between the invasive species with soil mineralogy in creating legacy effects, (4) Identify the suitability of soil amendments in reversing invader-induced changes in soil organic matter cycling, (5) Develop management practices that will restore the invaded ecosystems based on a mechanistic understanding of the invader-induced legacy effect.
Impacts
What was accomplished under these goals?
Project 1 Objectives: The project aims to obtain a comprehensive understanding of the mechanisms through which invasive plants change soil carbon cycling in their invaded ranges resulting in legacy effects. Further, based on these identified plant-soil feedbacks, knowledge based management practices will be formulated that reverse the legacy effect and restore theinvaded ecosystems. Methodology: We selected two sites along the eastern US that were subjected to prolonged invasion by exotic species that input contrasting litter chemistry compared to the resident native species. Japanese knotweed (Polygonum cuspidatum) that produce recalcitrant litter was invading an old-field ecosystem dominated by grasses and forbs that produced relativelylabile litter, whereas Pueraria lobata (kudzu) that produce labile litter was invading a Pinus forest with recalcitrant-rich litter. Soils were collected to 30 cm depth both in invaded and adjacent non-invaded stands. To understand the influence of litter chemistry on finer-level sequestration of soil carbon, the bulk soils were separated into different size fractions such asmacroaggregates (250-2000 μm), microaggregate (53-250 μm), and silt-clay (<53 μm) fraction. We analyzed the chemistry of different fractions of soil carbon associated with these size-fractions using FTIR and NMR spectroscopy, base hydrolysis and CuO oxidation followed gas chromatography- mass spectrometry analysis to obtain the plant and microbial biomarkersand lignin monomers, respectively. Notable findings: At the knotweed site, the higher C content in soils under P. cuspidatum, compared with non-invaded soils inhabited by grasses and forbs, was limited to the macroaggregate fraction, which was abundant in plant biomarkers. The non-invaded soils at this site had a higher abundance of lignins in mineral and microaggregate fractions and suberin in the macroaggregate fraction, partly because of the greater root density of the native species, which might have had an overriding influence on the chemistry of the above ground litter input. At the kudzu site, soils under P. lobata had lower C content across all size fractions at a 0-5 cm soil depth despite receiving similar amounts of Pinus litter. Contrary to our prediction, the non-invaded soils receiving recalcitrant Pinus litter had a similarabundance of plant biomarkers across both mineral and aggregate fractions, potentially because of the higher surface area of soil minerals at this site. The plant biomarkers were lower in the aggregate fractions of the P. lobata invaded soils, compared with non-invaded pine stands, potentially suggesting a microbial co-metabolism of pine-derived compounds.These results highlight the complex interactions among litter chemistry, soil biota, and minerals in mediating soil C storage in natural ecosystems; these interactions are particularly important under global changes that may alter plant species composition and hence, the quantity and chemistry of litter inputs in terrestrial ecosystems. Project 2 We aim to understand soil carbon, nitrogen, and phosphorus cyclings in the invaded ecosystems in the context of plant-microbe-soil interaction. The knowledge about biogeochemical processes under plant invasion obtained from our field and lab studies will be used to develop management practices to reverse legacy effects of plant invasion. We selected three Japanese Knotweed invaded sites in Amherst, MA. Soils were collected from 0-5, 5-10, 10-15, and 15-30 cm from invaded and adjacent non-invaded stands. We chose five microbial extracellular enzymes targeting common organic compounds in soil: beta-glucosidase for cellulose, N-acetylglucosaminidase for chitin, acid phosphate for organic P, protease for proteins, and peroxidase for lignin. The Michaelis-Menten parameters were determined for each enzyme using fluorogenic and colorimetric methods. Notable findings: Japanese Knotweed invasion differentially influenced distinct soil microbial extracellular enzyme activities and their catalytic efficiencies at 0-5 cm depth. Peroxidase and N-acetylglucosaminidase exhibited lower activities in the invaded stand than those in the non-invaded stand. In contrast, activities of acid phosphatase and beta-glucosidase did not differ between the non-invaded and the invaded stands. Plant invasion reduced catalytic efficiencies of peroxidase and beta-glucosidase compared to the adjacent non-invaded stand. Similar catalytic efficiencies of N-acetylglucosaminidase between the non-invaded and the invaded stands suggest that the apparently low activity of N-acetylglucosaminidase in the invaded stand is due to decreases in total enzyme production, not due to reductions in enzyme performance. In contrast, beta-glucosidase with low catalytic efficiency but similar enzyme activity under invasion compared to the non-invaded stand implies that soil microbial communities in the invaded stand produced more beta-glucosidase. These results highlight that invasion modifies soil microbial biogeochemical processes via changes in the amounts of extracellular enzyme production and enzyme performance, which in turn may distinctly alter the stability of individual compound in soil organic matter under plant invasion.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
M Tamura, V Suseela, M Simpson, B Powell, N Tharayil . 2017. Plant litter chemistry alters the content and composition of organic carbon associated with soil mineral and aggregate fractions in invaded ecosystems. Global Change Biology, 23: 4002-4018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2017
Citation:
Suseela, V. Tharayil. N. 2017. Using Biomarker Approaches to Predict the Chemical Attributes of Organic Matter That Facilitates Soil Carbon Sequestration. Symposium "New Insights on Biogeochemical Processes in Terrestrial Ecosystems As Revealed By Isotopic and Biomarker Approaches II" Crop Science Society of America Annual Meeting. October 24, 2017, Tampa FL.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2017
Citation:
Tharayil, N. 2017. Organismal- & ecosystem-level roles of plant metabolites in facilitating resilience in weedy and invasive species. Dept. of Plant science. University of California Davis.
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