R-3 Repository :: Browsing by Author "Huang, Wei"

Browsing by Author "Huang, Wei"

Now showing 1 - 13 of 13

Effects of nutrient pulses on exotic species shift from positive to neutral with decreasing water availability
(Wiley, 2024) Otieno, Evans O.; Shen, Changchao; Zhang, Kaoping; Wan, Jinlong; He, Minyan; Tao, Zhibin; Huang, Wei; Siemann, Evan
Temporal fluctuation in nutrient availability generally promotes the growth of exotic plant species and has been recognized as an important driver of exotic plant invasions. However, little is known about how the impact of fluctuating nutrients on exotic species is dependent on the availability of other resources, although most ecosystems are experiencing dramatic variations in a wide variety of resources due to global change and human disturbance. Here, we explored how water availability mediates the effect of nutrient pulses on the growth of six exotic and six native plant species. We subjected individual plants of exotic and native species to well watered or water stressed conditions. For each level of water availability, we added equivalent amounts of nutrients at a constant rate, as a single large pulse, or in multiple small pulses. Under well watered conditions, nutrient pulses promoted exotic plant growth relative to nutrients supplied constantly, while they had no significant effect on natives. In contrast, under water stressed conditions, water deficiency inhibited the growth of all exotic and native species. More importantly, nutrient pulses did not increase plant growth relative to nutrients supplied constantly and these phenomena were observed for both exotic and native species. Taken together, our study shows that the impact of fluctuating nutrient availability on the growth of exotic plant species strongly depends on the variation of other resources, and that the positive effect of nutrient pulses under well watered conditions disappears under water stressed conditions. Our findings suggest that the variation in multiple resources may have complex feedback on exotic plant invasions and, therefore, it is critical to encompass multiple resources for the evaluation of fluctuating resource availability effects on exotic plant species. This will allow us to project the invasive trajectory of exotic plant species more accurately under future global change and human disturbance.
Fluctuations in resource availability shape the competitive balance among non-native plant species
(Wiley, 2024) Tao, Zhibin; Shen, Changchao; Qin, Wenchao; Nie, Baoguo; Chen, Pengdong; Wan, Jinlong; Zhang, Kaoping; Huang, Wei; Siemann, Evan
Fluctuating resource availability plays a critical role in determining non-native plant invasions through mediating the competitive balance between non-native and native species. However, the impact of fluctuating resource availability on interactions among non-native species remains largely unknown. This represents a barrier to understanding invasion mechanisms, particularly in habitats that harbor multiple non-native species with different responses to fluctuating resource availability. To examine the responses of non-native plant species to nutrient fluctuations, we compared the growth of each of 12 non-native species found to be common in local natural areas to nutrients supplied at a constant rate or supplied as a single large pulse in a pot experiment. We found that seven species produced more biomass with pulsed nutrients compared to constant nutrients (hereafter “benefitting species”), while the other five species did not differ between nutrient enrichment treatments (hereafter “non-benefitting species”). To investigate how nutrient fluctuations influence the interactions among non-native plant species, we established experimental non-native communities in the field with two benefitting and two non-benefitting non-native species. Compared with constant nutrient supply, the single large pulse of nutrient did not influence community biomass, but strongly increased the biomass and cover of the benefitting species and decreased those of the non-benefitting species. Furthermore, the benefitting species had higher leaf N content and greater plant height when nutrients were supplied as a single large pulse than at a constant rate, whereas the non-benefitting species showed no differences in leaf N content and were shorter when nutrients were supplied as a single large pulse than at a constant rate. Our results add to the growing evidence that the individual responses of non-native species to nutrient fluctuation are species-specific. More importantly, benefitting species were favored by nutrients coming in a pulse, while non-benefitting ones were favored by nutrients coming constantly when they grew together. This suggests that nutrient fluctuations can mediate the competitive balance among non-native plants and may thus determine their invasion success in a community harboring multiple non-native plant species.
Increasing flavonoid concentrations in root exudates enhance associations between arbuscular mycorrhizal fungi and an invasive plant
(Springer Nature, 2021) Tian, Baoliang; Pei, Yingchun; Huang, Wei; Ding, Jianqing; Siemann, Evan
Many invasive plants have enhanced mutualistic arbuscular mycorrhizal (AM) fungal associations, however, mechanisms underlying differences in AM fungal associations between introduced and native populations of invasive plants have not been explored. Here we test the hypothesis that variation in root exudate chemicals in invasive populations affects AM fungal colonization and then impacts plant performance. We examined flavonoids (quercetin and quercitrin) in root exudates of native and introduced populations of the invasive plant Triadica sebifera and tested their effects on AM fungi and plant performance. We found that plants from introduced populations had higher concentrations of quercetin in root exudates, greater AM fungal colonization and higher biomass. Applying root exudates more strongly increased AM fungal colonization of target plants and AM fungal spore germination when exudate donors were from introduced populations. The role of root exudate chemicals was further confirmed by decreased AM fungal colonization when activated charcoal was added into soil. Moreover, addition of quercetin into soil increased AM fungal colonization, indicating quercetin might be a key chemical signal stimulating AM fungal associations. Together these results suggest genetic differences in root exudate flavonoids play an important role in enhancing AM fungal associations and invasive plants’ performance, thus considering root exudate chemicals is critical to unveiling mechanisms governing shifting plant-soil microbe interactions during plant invasions.
Influence of Effective Modulus on Period-Doubling Bifurcation in Atomic Force Microscopy: Investigation and Implementation for Sample Characterization
(2011) Huang, Wei; Dick, Andrew J.
Atomic force microscope (AFM) is an important tool for measuring the topographical and other properties of a sample with nanometer resolution. The cantilever probe of the AFM is influenced by nonlinear interaction forces which act between the probe and the sample. For certain non-standard excitation conditions, this can result in bifurcations in the probe's response. This work numerically examines a period-doubling bifurcation observed to occur for interactions with soft materials. The influence of the sample properties and other conditions on the bifurcation is studied and a method is proposed for sample material characterization. The identified values from simulated 1-D and 2-D scans agree well with the true values. The proposed method does not require the use of special probes and it uses the control algorithm for traditional tapping mode AFM with minor modification. This proposed method could also achieve high scan speeds and prevent strong, destructive interaction forces.
Interactive effects of soils, local environmental conditions and herbivores on secondary chemicals in tallow tree
(Oxford University Press, 2024) Xiao, Li; Huang, Wei; Carrillo, Juli; Ding, Jianqing; Siemann, Evan
Plants produce secondary chemicals that may vary along with latitude due to changing abiotic and biotic stress gradients and local environmental conditions. Teasing apart the individual and combined effects of these different abiotic, such as soil nutrients, and biotic factors, such as soil biota and herbivores, on secondary chemicals is critical for understanding plant responses to changing environments. We conducted an experiment at different latitudes in China, using tallow tree (Triadica sebifera) seedlings sourced from a population at 31° N. These seedlings were cultivated in gardens located at low, middle and high latitudes, with either local soil or soil from the original seed collection site (origin soil). The seedlings were exposed to natural levels of aboveground herbivores or had them excluded. Plant secondary chemicals (both foliar and root), aboveground herbivores and soil characteristics were measured. Results showed that most leaf and root secondary metabolites depended on the interaction of the experimental site and soil type. Leaf and root phenolic and tannin concentrations were higher at the middle latitude site, especially in the origin soil. Root and foliar flavonoid concentrations increased when aboveground herbivores were excluded. Microbial communities depended strongly on soil treatment. The different responses of tannins versus flavonoids suggest that these two chemical classes differ in their responses to the varying abiotic and biotic factors in these sites along latitudes. Taken together, our results emphasize the importance of considering the interactive effects of local environmental conditions, soil properties and herbivory in regulating plant chemical defenses.
Native diversity contributes to composition heterogeneity of exotic floras
(Wiley, 2023) Chen, Pengdong; Shen, Changchao; Ren, Jie; Qin, Wenchao; Yi, Jiahui; Guan, Shuping; Tao, Zhibin; Huang, Wei; Siemann, Evan
Variation in species composition among sites (beta diversity) is generally thought to be driven by environmental filtering and dispersal limitation, but the role of biotic interactions has not been sufficiently addressed. Specifically, the early species in a local community may contribute to subsequent beta diversity patterns. Exotic assemblages within native communities provide a unique opportunity to study biotic interaction mechanisms. In this study, we conducted a field survey of plants over an approximately 1800-km transect in the middle and lower Yangtze River valley in China to study how native communities influence exotic beta diversity. The survey included 459 plots in 51 local plant communities with 40 exotic species and 103 co-occurring native species. We also investigated how 11 environmental factors involving climate conditions, soil properties, and human activity regulate the interaction between native and exotic plants. The results showed that native diversity (Shannon–Wiener index) increased exotic beta diversity. Environmental conditions, especially monthly minimum temperature, influenced exotic beta diversity indirectly through native diversity rather than directly. Our results suggest that lower native diversity driven by environmental conditions, especially warmer temperatures, led to a decrease in composition heterogeneity of the exotic flora. Our results will help to incorporate biotic interactions into the framework of beta diversity mechanisms for local community assembly.
Native Plant Diversity Generates Microbial Legacies That Either Promote or Suppress Non-Natives, Depending on Drought History
(Wiley, 2024) Tao, Zhibin; Zhang, Kaoping; Callaway, Ragan M.; Siemann, Evan; Liu, Yanjie; Huang, Wei
Diverse native plant communities resist non-native plants more than species-poor communities, in part through resource competition. The role of soil biota in diversity–invasibility relationships is poorly understood, although non-native plants interact with soil biota during invasions. We tested the responses of non-native plants to soil biota generated by different native plant diversities. We applied well-watered and drought treatments in both conditioning and response phases to explore the effects of ‘historical’ and ‘contemporary’ environmental stresses. When generated in well-watered soils, the microbial legacies from higher native diversity inhibited non-native growth in well-watered conditions. In contrast, when generated in drought-treated soils, the microbial legacies from higher native diversity facilitated non-native growth in well-watered conditions. Contemporary drought eliminated microbial legacy effects on non-native growth. We provide a new understanding of mechanisms behind diversity–invasibility relationships and demonstrate that temporal variation in environmental stress shapes relationships among native plant diversity, soil biota and non-native plants.
Nonlinear Dynamics in Atomic Force Microscopy for Various Excitation Conditions
(2015-05-11) Huang, Wei; Dick, Andrew J.; O' Malley, Marcia K.; Clark, John W.
The atomic force microscopy (AFM) is a high-resolution measurement tool for measuring sample topography and material properties in micro-scale and nano-scale research. The dynamics of the cantilever probe in AFM is influenced by the intrinsically nonlinear interaction between the probe tip and the surface of the sample. Previous work has shown that in off-resonance excited intermittent-contact AFM, a period-doubling bifurcation can occur as a result of the nonlinearity. The amplitude of the resulting sub-harmonic frequency component of the response has been identified as a source of contrast to measure the Young's modulus of the sample. This dissertation details the continued work in this area and includes three parts. In the first part, the focus is to investigate the performance of a material characterization method, proposed to use the relationship between the sample modulus and the sub-harmonic frequency component, to study material property transitions for one-dimensional samples. In the second part, the focus is on the effect of the inclusion of the explicit dissipative interaction force in the system model on the numerical simulation on the AFM. Both resonant and off-resonant excitation conditions are discussed. In the third part, the focus is on the generation of the sub-harmonic amplitude for an unique dual-frequency excitation condition. The influence of this excitation condition is numerically investigated and experimental studies are conducted with a macro-scale constrained cantilevered beam system to qualitatively verify the numerically predicted behavior. The work in this dissertation brings a wider understanding for these nonstandard excitation methods and their applications in AFM.
Phase diagram structures in a periodic one-dimensional exclusion process
(American Physical Society, 2013) Jiang, Rui; Wang, Yu-Qing; Kolomeisky, Anatoly B.; Huang, Wei; Hu, Mao-Bin; Wu, Qing-Song
This paper studies a periodic one-dimensional exclusion process composed of a driven part and a biased diffusive part in a mesoscopic limit. It is shown that, depending on the biased diffusion parameter δ, rich phase diagram structures appear in which diverse phases have been exhibited and the density profile in the diffusive part is qualitatively different. This is because the domain wall is behaving differently. Our analytical results are in good agreement with Monte Carlo simulations.
Soil bacterial communities and co-occurrence changes associated with multi-nutrient cycling under rice-wheat rotation reclamation in coastal wetland
(Elsevier, 2022) Zhang, Kaoping; Shi, Yu; Lu, Haiying; He, Minyan; Huang, Wei; Siemann, Evan
Coastal reclamation is a global threat to coastal wetland ecosystems, but the impacts of coastal reclamation on belowground biodiversity and their consequences for ecosystem nutrient cycling remain poorly understood. In this study, we examined soil bacterial communities, bacterial co-occurrence pattern and soil multi-nutrient cycling index after natural vegetated coastal wetlands were converted for 6-year and 30-year rice-wheat rotation fields. The soil multi-nutrient cycling index was higher in 6-year and 30-year rice-wheat rotation fields than natural vegetated coastal wetlands. For bacterial community, rice-wheat rotation reclamation increased soil bacterial alpha diversity but decreased beta diversity and co-occurrence network complexity than those in the vegetated coastal wetland. Rice-wheat rotation reclamation also changed soil bacterial community assemblages by increasing the relative abundance of Actinobacteriota and Desulfobacterota while decreasing the relative abundance of Alphaproteobacteria and Gammproteobacteria. Changes in the relative importance of dispersal limitation and homogenizing dispersal mainly controlled the variations in soil bacterial community assemblages. Soil bacterial community variations induced by rice-wheat reclamation were strongly related to soil multi-nutrient cycling, especially bacterial connection complexity. Our results provide experimental support that belowground microbial interactions are crucial for maintaining ecosystem functioning.
Species-specific defence responses facilitate conspecifics and inhibit heterospecifics in above-belowground herbivore interactions
(Macmillan Publishers Limited, 2014) Huang, Wei; Siemann, Evan; Xiao, Li; Yang, Xuefang; Ding, Jianqing
Conspecific and heterospecific aboveground and belowground herbivores often occur together in nature and their interactions may determine community structure. Here we show how aboveground adults and belowground larvae of the tallow tree specialist beetle Bikasha collaris and multiple heterospecific aboveground species interact to determine herbivore performance. Conspecific aboveground adults facilitate belowground larvae, but other aboveground damage inhibits larvae or has no effect. Belowground larvae increase conspecific adult feeding, but decrease heterospecific aboveground insect feeding and abundance. Chemical analyses and experiments with plant populations varying in phenolics show that all these positive and negative effects on insects are closely related to root and shoot tannin concentrations. Our results show that specific plant herbivore responses allow herbivore facilitation and inhibition to co-occur, likely shaping diverse aboveground and belowground communities. Considering species-specific responses of plants is critical for teasing apart inter- and intraspecific interactions in aboveground and belowground compartments.
Species-specific plant-mediated effects between herbivores converge at high damage intensity
(Wiley, 2022) Wan, Jinlong; Yi, Jiahui; Tao, Zhibin; Ren, Zhikun; Otieno, Evans O.; Tian, Baoliang; Ding, Jianqing; Siemann, Evan; Erb, Matthias; Huang, Wei
Plants are often exposed to multiple herbivores and densities of these attackers (or corresponding damage intensities) often fluctuate greatly in the field. Plant-mediated interactions vary among herbivore species and with changing feeding intensity, but little is known about how herbivore identity and density interact to determine plant responses and herbivore fitness. Here, we investigated this question using Triadica sebifera (tallow) and two common and abundant specialist insect herbivores, Bikasha collaris (flea beetle) and Heterapoderopsis bicallosicollis (weevil). By manipulating densities of leaf-feeding adults of these two herbivore species, we tested how variations in the intensity of leaf damage caused by flea beetle or weevil adults affected the performance of root-feeding flea beetle larvae and evaluated the potential of induced tallow root traits to predict flea beetle larval performance. We found that weevil adults consistently decreased the survival of flea beetle larvae with increasing leaf damage intensities. In contrast, conspecific flea beetle adults increased their larval survival at low damage then decreased larval survival at high damage, resulting in a unimodal pattern. Chemical analyses showed that increasing leaf damage from weevil adults linearly decreased root carbohydrates and increased root tannin, whereas flea beetle adults had opposite effects as weevil adults at low damage and similar effects as them at high damage. Furthermore, across all feeding treatments, flea beetle larval survival correlated positively with concentrations of carbohydrates and negatively with concentration of tannin, suggesting that root primary and secondary metabolism might underlie the observed effects on flea beetle larvae. Our study demonstrates that herbivore identity and density interact to determine systemic plant responses and plant-mediated effects on herbivores. In particular, effects are species-specific at low densities, but converge at high densities. These findings emphasize the importance of considering herbivore identity and density simultaneously when investigating factors driving plant-mediated interactions between herbivores, which advances our understanding of the structure and composition of herbivore communities and terrestrial food webs.
Temporal effects of cell adhesion on the mechanical characteristics of the single chondrocyte
(2001) Huang, Wei; Athanasiou, Kyriacos A.
Cell adhesion to material surfaces is a fundamental phenomenon in tissue response to implanted devices, and an important consideration in tissue engineering. The first objective of this study was to measure the mechanical adhesiveness characteristics of rabbit articular chondrocytes as a function of seeding time to provide further understanding of the cell adhesion process. The second objective was to quantify the tether formation force and tether stiffness as a function of seeding time. With increasing time of seeding up to 6 hours, chondrocytes exhibited increasing mechanical adhesiveness, tether formation force and tether stiffness, as measured using the cytodetacher and optical tweezers system. Concomitantly, cell contact area and cell height, as measured using inverted microscope and confocal imaging, were found to increase and decrease respectively.

Browsing by Author "Huang, Wei"

Results Per Page

Sort Options