xine li

Followers

Following

Public Views

Interests

Uploads

Papers by xine li

The TRY Plant Trait Database - enhanced coverage and open access

Plant traits-the morphological, anatomical, physiological, biochemical and phenological character... more Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.

Download

Responses of phenology and seed production of annual Koenigia islandica to warming in a desertified alpine meadow

Agricultural and Forest Meteorology, 2017

The distribution of annual plant species greatly expands with degradation and desertification of ... more The distribution of annual plant species greatly expands with degradation and desertification of natural grasslands caused by climate change and overgrazing. However, limited understanding of how their life history traits respond to climate change limits our ability to predict their adaptive strategies in the future. Here we explored effects of warming on phenological sequences and seed production of annual Koenigia islandica using an open top chamber on the Tibetan plateau from 2014 to 2016. Our results indicate that warming significantly delayed first budding-set and complete leaf coloring, and prolonged the durations of leaf coloring and the total activity period in the alpine region. Warming significantly reduced ratio of reproductive and vegetative phases relative to nowarming in 2016. Warming significantly increased plant height at first flowering, seed number and mass, but had no significant effect on seed size in 2016. There was a positive correlation between seed germination time and seed number, and there were negative correlations between seed size and first fruiting-set and flowering duration. Soil temperatures and soil moisture in May and June had positive and negative correlations with seed number and mass per plant, respectively. Our results suggest that the annual plant primarily promotes its fitness through an increase in seed number and mass per plant due to an increase in plant height, rather than by altering phenophases or prolong duration of reproductive phase under future warming in the alpine meadow.

Download

Fungal pathogens pose a potential threat to animal and plant health in desertified and pika burrowed alpine meadow on the Tibetan Plateau

Canadian Journal of Microbiology, 2018

Intact Tibetan meadows provide significant defense against soil-borne pathogen dispersal. However... more Intact Tibetan meadows provide significant defense against soil-borne pathogen dispersal. However, dramatic meadow degradation has been observed due to climate change and pika damage, but their impacts on soil-borne pathogens are still unclear. With approximately 40% of the world’s population living in Tibetan Plateau and its downstream watersheds, this lack of knowledge should be of great concern. Here, we used Illumina amplicon sequencing to characterize the changes in potential human, domestic animal, plant, and zoonotic bacterial and fungal pathogens in nondegraded, desertified, and pika-burrowed meadows. The relative abundance of bacterial domestic animal pathogens and zoonotic pathogens were significantly increased by desertification. Pika burrowing significantly increased the relative abundance of bacterial human pathogens and zoonotic pathogens. The species richness and relative abundance of fungal pathogens was significantly increased by desertification and pika burrowing. ...

Download

Responses of biotic interactions of dominant and subordinate species to decadal warming and simulated rotational grazing in Tibetan alpine meadow

Science China. Life sciences, Jan 18, 2018

Warming increases competition among plant species in alpine communities by ameliorating harsh env... more Warming increases competition among plant species in alpine communities by ameliorating harsh environmental conditions, such as low temperatures. Grazing, as the main human activity, may mitigate the effect of warming, as previously reported. However, it is critical to refine the effects of warming on biotic interactions among species, for example, by taking the competitive ability of species into consideration. Based on a 10-year warming and grazing experiment in a Tibetan alpine meadow, we evaluated interspecific biotic interactions of dominant and subordinate species, using the approach of interspecific spatial associations. Warming significantly increased competition between subordinate and dominant species as well as among subordinate species, but not among dominant species. Moreover, facilitation of dominant-subordinate species also increased under warming. Simulated rotational grazing had similar effects to warming, with increasing interspecific competition. Our results show ...

Download

Magnetism and microwave-absorption properties of Zn particles with magnetic shell

Materials Research Innovations, 2015

Abstract In this work, Zn particles with magnetic shell were synthesised and investigated. Zn par... more Abstract In this work, Zn particles with magnetic shell were synthesised and investigated. Zn particles with different sizes were synthesised by arc-discharge method, and then the Zn particles were put in a suitable concentration of FeSO4 solution with a surface active agent. After some time, the Zn particles with magnetic shell were produced. The particles contain oxygen shell probably in the form of FeO and ZnO, while the core material is Zn. From the saturation magnetisation at room temperature and transmission electron microscopy (TEM) images, it is noticed that the FeO was first formed on the surface of Zn and then ZnO appeared with increasing reaction time. The microwave absorption is not as good as that reported in other materials, because of the weak magnetisation and the faulty core–shell structure formed by metal core and magnetic shell.

Changes of soil microbial community under different degraded gradients of alpine meadow

Agriculture, Ecosystems & Environment, 2016

Changes in soil bacterial and fungal composition and their diversity with degradation degrees (i.... more Changes in soil bacterial and fungal composition and their diversity with degradation degrees (i.e. nondegraded (ND), moderately degraded (MD) and severely degraded (SD) meadows) were investigated in a Tibetan alpine meadow using the Illumina MiSeq. Proteobacteria,Actinobacteria, and Acidobacteria were predominant bacteria in the studied meadow soils, regardless of degradation. ND and MD exhibited no significant differences in bacterial species composition and diversity, while SD significantly altered bacterial composition and increased their diversity compared with ND and MD. Sordariomycetes was predominant fungal class in ND, however, a shift in the fungal class from it to Dothideomycetes was found with increasing degradation level. Moreover, SD apparently increased the relative abundance of pathogenic fungi compared with ND. Degradation significantly shifted fungal species composition and increased their diversity. Soil nutrient conditions could explain 33.8 and 35.6% of the variance in bacterial and fungal composition, respectively. In addition, 25.3 and 21.7% of the variance in bacterial and fungal composition, respectively, were explained by plant properties. However, neither bacterial nor fungal diversity paralleled plant diversity with degradation. Soil silt to sand ratio was the best predictor of shifts in bacterial a-diversity with degradation degrees (R 2 > 0.46), while fungal a-diversity was most closely associated with changes in soil available potassium (R 2 > 0.66). Together, these results suggest that changes of microbial diversity and plant diversity was decoupled under degradation process, and degradation could increase the potential risk of plant diseases and decrease health of the alpine ecosystem. 2016 Elsevier B.V. All rights reserved.

Download

Changes in phenological sequences of alpine communities across a natural elevation gradient

Agricultural and Forest Meteorology, 2016

Change in individual species phenology is often unsuitable for predicting change in community phe... more Change in individual species phenology is often unsuitable for predicting change in community phenology because of different responses of different species to temperature change. However, few studies have observed community phenological sequences in the field. Here we explore the changes in timing and duration of the community phenological sequence (i.e. onset of leaf-out (OLO), first flower bud (FB), first flowering (FF), first fruiting-set (FFS), post-fruiting vegetation (OPFV), first leaf-coloring (FLC) and complete leaf-coloring (CLC)) along an elevation gradient from 3200 to 3800 m in an alpine meadow on the Tibetan plateau. Our results indicate that OLO and FFS significantly advanced and other timings of phenological events significantly delayed at 3200 m compared with higher elevations (3600 and 3800 m). The flowering duration of the community was shortest and other phenological durations (except budding stage and post-fruiting vegetation stage) were longest at 3200 m. The duration of the growing season decreased as elevation increased, and the ratio of the durations of the reproductive period and growing season was smallest at 3200 m. There were negative correlations between the proportion of early-spring flowering functional group plants and FB, and the durations of leafing and post-fruiting vegetation of the community. Positive correlations were found between the proportion of midsummer flowering functional group plants in the community and these variables. There were significant negative correlations between flowering duration of the community and annual mean air temperature and soil moisture. Therefore, our results suggest that different community compositions might respond differently to climate change.

Download

Changes in phenological sequences of alpine communities across a natural elevation gradient

Agricultural and Forest Meteorology, 2016

Download

Temperature sensitivity thresholds to warming and cooling in phenophases of alpine plants

Climatic Change, 2016

The assumption of a linear relationship between temperature and phenophases may be misleading. Fu... more

Download

Responses of sequential and hierarchical phenological events to warming and cooling in alpine meadows

Nature Communications, 2016

Organisms' life cycles consist of hierarchical stages, from a single phenological stage (for exam... more Organisms' life cycles consist of hierarchical stages, from a single phenological stage (for example, flowering within a season), to vegetative and reproductive phases, to the total lifespan of the individual. Yet phenological events are typically studied in isolation, limiting our understanding of life history responses to climate change. Here, we reciprocally transfer plant communities along an elevation gradient to investigate plastic changes in the duration of sequential phenological events for six alpine species. We show that prolonged flowering leads to longer reproductive phases and activity periods when plants are moved to warmer locations. In contrast, shorter post-fruiting leaf and flowering stages led to shorter vegetative and reproductive phases, respectively, which resulted in shorter activity periods when plants were moved to cooler conditions. Therefore, phenological responses to warming and cooling do not simply mirror one another in the opposite direction, and low temperature may limit reproductive allocation in the alpine region.

Download

Soil bacterial community responses to warming and grazing in a Tibetan alpine meadow

FEMS microbiology ecology, Jan 2, 2015

Warming and grazing significantly affect the structure and function of an alpine meadow ecosystem... more Warming and grazing significantly affect the structure and function of an alpine meadow ecosystem. Yet, the responses of soil microbes to these disturbances are not well understood. Controlled asymmetrical warming (+1.2/1.7°C during daytime/nighttime) with grazing experiments were conducted to study microbial response to warming, grazing, and their interactions. Significant interactive effects of warming and grazing were observed on soil bacterial α-diversity and composition. Warming only caused significant increase in bacterial α-diversity under no-grazing conditions. Grazing induced no substantial differences in bacterial α-diversity and composition irrespective of warming. Warming, regardless of grazing, caused a significant increase in soil bacterial community similarity across space, but grazing only induced significant increases under no-warming conditions. The positive effects of warming on bacterial α-diversity and grazing on community similarity were weakened by grazing and...

Download

Effects of warming, grazing/cutting and nitrogen fertilization on greenhouse gas fluxes during growing seasons in an alpine meadow on the Tibetan Plateau

Agricultural and Forest Meteorology, 2015

Increased nitrogen (N) deposition within the context of both warming and grazing is relevant to u... more Increased nitrogen (N) deposition within the context of both warming and grazing is relevant to understand the response of greenhouse gases fluxes (GHG) (i.e. CO 2 , CH 4 and N 2 O fluxes) for alpine meadow ecosystems to projected changes in the environment. A previous controlled warming and grazing experiment only included no warming with no grazing (NWNG), no warming with grazing (NWG), warming with no grazing (WNG) and warming with grazing (WG) from 2006 to 2010. N fertilization was added to the experimental setup to determine the effects of warming, grazing and N fertilization on GHG fluxes in an alpine meadow on the Tibetan Plateau during the growing seasons from 2010 to 2012. Sheep grazing was utilized during the growing season from 2006 to 2010 and cutting was used as simulation of grazing during the non-growing seasons in 2011 and 2012. Warming significantly increased average seasonal CO 2 emission by 10%, and nitrogen addition increased average seasonal CH 4 uptake by 14% during the growing seasons in the dry years of 2011 and 2012. Warming increased average seasonal CH 4 uptake by 32-46% over the 3-year period, and grazing increased annual average N 2 O emission by 62% only in 2010. N fertilization alone did not significantly affect CO 2 and N 2 O fluxes during the experimental period. The interactive effects of warming, grazing/cutting and N fertilization effect on daily CH 4 or daily N 2 O flux depended on sampling date. Ecosystem CO 2 emission was mainly affected by soil temperature and plant aboveground net primary production (ANPP), which explained about 55% and 18% of its variation. Soil moisture and ANPP could explain 17% and 8% of the variation of CH 4 uptake in the region. Our results suggest that the stimulating effect of warming on ecosystem respiration still occurs in 2011 and 2012 after warming for seven years. Moreover, our results imply that moderate grazing/cutting may be preferred compared with no grazing or no cutting because its negative effect on GHG fluxes was small, and interactive effect of warming, grazing/cutting and increased N deposition on GHG emission could be neglected in the alpine meadow.

format_quoteWarming increased seasonal CH4 uptake by 32-46% and grazing raised N2O emissions by 62% in 2010, highlighting climate effects on GHG fluxes.format_quote

Download

Design of Controlling System in Multi-function Durability Testing Device for Vehicle Vacuum Booster with Brake Master Cylinder

Lecture Notes in Electrical Engineering, 2012

The quality of vehicle vacuum booster with brake master cylinder is related to the safe of driver... more The quality of vehicle vacuum booster with brake master cylinder is related to the safe of drivers and automobiles. The testing experiment must be executed strictly before leaving factory based on the national standards .The paper introduces the controlling system of multi-function durability testing device, which is designed for doing durable testing experiments and Anti-lock braking system (ABS) performance experiments. The structure and theory of device is presented. The controlling system is illuminated in detail. To test the dynamic property, this system was identified by a recursive BP neural network. According to the character of a great deal of sensors and actuators, the high precision, capabilities and reliability, the distributed control mode (DCS) including the computer and PLC by RS-485 bus is utilized. The four channels testing experiments are achieved at the same time. The test data is directly memorized into the computer. The results of general endurance and ABS endurance testing experiments are shown to demonstrate the excellent performance of the testing device.

Patterns of species diversity and functional diversity along the southto north-facing slope gradient in a sub-alpine meadow

Community Ecology, 2011

Different components of biodiversity may vary differently since species diversity was considered ... more Different components of biodiversity may vary differently since species diversity was considered to be determined by resource availability but functional diversity was related to partitioning of niche space. Moreover, the harsh or benign conditions may result in different niche space partitioning by the coexisting species. For example, in harsh environments niche differentiation may be stronger resulting in higher functional diversity. In this study, we investigate species diversity and functional diversity along a south-to north-facing slope gradient with different resource availability in a sub-alpine meadow. Our results indicate that the patterns of species diversity and functional diversity are not consistent along this gradient. Both species richness and Shannon index of diversity increased, but functional diversity slightly decreased or changed a little from south-to north-facing slope. Moreover, these two components formed a quadratic relationship. Soil water content (SWC) was the limiting resource along this gradient. On one hand, it determined the species diversity; on the other hand, it also influenced functional diversity via affecting niche differentiation and species trait pool. In conclusion, functional diversity was determined by both species richness and niche differentiation with the influence of soil water content.

Download

Hydraulic failure and tree size linked with canopy die‐back in eucalypt forest during extreme drought

New Phytologist, 2021

Eastern Australia was subject to its hottest and driest year on record in 2019. This extreme drou... more Eastern Australia was subject to its hottest and driest year on record in 2019. This extreme drought resulted in massive canopy die-back in eucalypt forests. We examined the role of hydraulic failure and tree size on canopy die-back in three eucalypt tree species during this drought. We measured pre-dawn and midday leaf water potential (Ψleaf ), percent loss of stem hydraulic conductivity and quantified hydraulic vulnerability to drought-induced xylem embolism. We also surveyed tree size and tree health. Trees with most, or all, of their foliage dead exhibited high rates of native embolism (78-100%). This is in contrast to trees with partial canopy die-back (30-70% canopy die-back: 72-78 % native embolism), or relatively healthy trees (little evidence of canopy die-back: 25-31 % native embolism). Midday Ψleaf was significantly more negative in trees exhibiting partial canopy die-back (-2.7 to -6.3 MPa), compared to relatively healthy trees (-2.1 to -4.5 MPa). In two of the species the majority of individuals showing complete canopy die-back were in small size classes. Our results indicate that hydraulic failure is strongly associated with canopy die-back during drought in eucalypt forests. Our study provides valuable field data to help constrain models predicting mortality risk.

xine li

Uploads

Papers by xine li

Log In