Blog

LPICEA science club

About
At the LPICEA science club, the group members discuss recent published papers or update their research progresses. Early career scientists from other labs are also invited to give talks about their researches. Feel free to join us, if you’re interested.

When and where
Every Friday at 4 PM, Beijing Time
S825, MengMinwei Science Building, Tsinghua University, Beijing; or online (contact xuhy19@mails.tsinghua.edu.cn for meeting ID)

Upcoming events

23/09, paper discussion
Senapati et al. 2022 Global wheat production could benefit from closing the genetic yield gap

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Simulating wheat sowing dates based on optimality principle

Aug. 5th, 2022 by Shengchao Qiao

Sowing dates are essential input for crop models that simulate wheat production. Currently,many crop models use a pre-defined wheat calendar based on historical observations as input (Minoli et al., 2019), whereby the dates of sowing and harvest are fixed and do not respond to changes in climate, and this means that model projections are highly uncertain (Asseng et al., 2013).

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My first impression at University of Exeter

July 6th, 2022 by Huiying Xu

After such a long lockdown around the world, I finally made my way to University of Exeter (UoE) thanks to a joint PhD program between Tsinghua University (THU) and UoE partly funded by China Scholarship Council. After 2 months here, I found some difference in terms of research compared to China (Note: these are very personal ideas based on my short time here).

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What’s the thermal response of stem respiration?

Jun. 4th, 2022 by Han Zhang

Stem respiration is an important part of the autotrophic respiration in woody plants. Accounting for 14% ~ 48% of the whole plant respiration (Vose et al., 2002; Zeng et al., 2000; Xiao et al., 2005), stem respiration is a non-negligible carbon source.

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Understanding the effects of dryness stress on vegetation production

Dec. 30, 2021 by Ziqi Zhu

Dryness stress is a crucial limitation on vegetation growth (Liu et al. 2020). It can change vegetation water use efficiency, drive tree dieback and affect carbon cycle of terrestrial ecosystem (Yang et al. 2016; Humphrey et al. 2021; Zemp et al. 2017; Green et al. 2019). High vapour pressure deficit (VPD; a measure of atmospheric dryness) and low soil moisture (SM) are two main drivers of dryness stress on vegetation.

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One more successful attempt for developing more robust model based on Eco-Evolutionary Optimality (EEO) concepts

Oct. 19th, 2021 by Shengchao Qiao

Global food security is an ongoing challenge for humanity owing to the continuous growth of global population. Meanwhile, assessment of global food security contributes to the sustainable development goal of ‘No hunger’. Potential crop yields represent the biophysical ‘ceiling’ determined by variety, climate and ambient CO2. As the important part, evaluation of potential crop yields is critical for global food security assessment. Statistical modelling and process-based crop models have both been used to estimate and evaluate potential yields. However, some limitations of statistical approaches and large uncertainties of current process model-based results still remain. Therefore, a more robust way to estimate potential crop yields globally as a function of their growth environment is needed. Recently, Shengchao Qiao and his coauthors published a new paper named “Optimality-based modelling of climate impacts on global potential wheat yield” in Environmental Research Letters (https://iopscience.iop.org/article/10.1088/1748-9326/ac2e38), showing progress towards closing these gaps. The new paper extended their optimality-based wheat model (PC model) from the national to global scale to understand and predict the climatic impacts on global potential wheat yield.

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Coordination of plant hydraulic and photosynthetic traits: confronting optimality theory with field measurements

Sep. 2nd, 2021 by Huiying Xu

I have been interested in hydraulics since undergraduate. When I joined LPICEA at Tsinghua University, I was at a loss what to do about integrating my interests into my supervisor Han’s expertise. Han suggested me comprehend this optimality application in photosynthesis prediction first, which led to my first paper in Tree Physiology (https://doi.org/10.1093/treephys/tpab003) about prediction of four photosynthesis-related leaf traits along elevation. After I learned more about current photosynthesis optimality, I tried to explore hydraulics’ role in it with many helps from Han, Colin and Sandy. We made our first progress on prediction of a hydraulic trait. Our paper analysing the coordination of plant hydraulic and photosynthetic traits, using field data we collected in the Gongga Mountains in China from 2018 to 2019 and the application of eco-evolutionary optimality theory, has been accepted for publication in New Phytologist recently (https://doi.org/10.1111/nph.17656).

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The strategies for adapting crop production to climate warming

Jun. 30, 2021 by Shengchao Qiao

Global warming has been proved to affect significantly crop production. Several studies have reported the negative impacts of the rising temperature on crop yields(Wang et al., 2020; Zhao et al., 2017). Higher temperature can drive a faster phenological development of crops and thus shorten the length of crop growing period. It also leads to heat damages on crops growth (Asseng et al., 2015). Given the negative effects of warming and the threat to food security, it is urgent to develop adaptation strategies to deal with the negative effects of warming on crop production.

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Responses of ecosystem water use efficiency to water supply condition in Tibetan Plateau

Jun. 30, 2021 by Ziqi Zhu

Water supply has a significant impact on plant photosynthesis and water transport on the Tibetan Plateau (TP) (Huang et al., 2017), which could be reflected in the water use efficiency (WUE) of terrestrial ecosystems (Wang et al., 2020a, Sun et al., 2016). Defined as the ratio of ecosystem gross primary production (GPP) to transpiration (E) (Keenan et al., 2013, Yang et al., 2016), WUE refers to the trade-off between plant gain in carbon and cost in water. Numerous studies have shown that, lack of water suppresses both ecosystem productivity and transpiration at the same time (Lin et al., 2020, Sun et al., 2016, Wang et al., 2020b, Xue et al., 2015, Yang et al., 2016). However current studies reveal contrasting response of WUE to drought (Lin et al., 2020, Wang et al., 2020b, Yang et al., 2016). Therefore, by summarizing and comparing the following studies, we try to get a better insight into the relationship between WUE and water supply condition, which will undoubtfully benefit our understanding of how vegetation response to the future climate change in TP.

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The LPICEA Tiger Team’s Second Virtual Workshop

Jun, 29, 2021, by Wang Han

In the past two weeks, LPICEA Tiger Team held their second virtual workshop on a daily basis with Colin and Sandy on developing first-principle based vegetation models. LPICEA Tiger Team includes our PI Han Wang, our PhD students Shengchao Qiao, Huiying Xu and Ziqi Zhu, our newly coming PhD student Yanghan Ren from the Institute of Tibetan Plateau, CAS, and our ghost member Runxi Wang from Hongkong University.

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Congratulations to Huiying on her first peer-review paper!

Jun.17, 2021 by LPICEA

Recently, Huiying and her coauthors (Dr. Han Wang, Pro. I. Colin Prentice, Pro. Sandy P. Harrison, Dr. Xiangyang Sun and Pro. Genxu Wang) published a new paper on Tree Physiology about predictability of four key photosynthesis-related leaf traits based on optimality-based concepts in Gongga Mountains (Fig. 1). The maximum capacity of carboxylation standardized to 25 ˚C (Vcmax25) is a measure of photosynthesis rate for carbon fixation and the ratio of leaf-internal to ambient CO2 partial pressure (χ) represents the stomatal regulation of CO2 uptake. Leaf nitrogen content (Narea) represents the amount of enzyme responsible for photosynthesis and leaf mass per area (Ma) determines the total carbon cost of leaf construction, which further relates to the period when photosynthesis happens. These key photosynthesis-related traits determine carbon fixation and then influence vegetation production.

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Life support system: The future of ecology

Jun. 15, 2021 by Jian Zhou

Started with the survival problem in spacecrafts, life support system (LSS) has long been a fascinating and challenging field of research. Basic life-support systems for humans require the supply of food, water, and oxygen, the disposal of human wastes, and the maintenance of temperature. Primary LSSs in spaceships or space stations usually have a low recycling rate of life support materials, most of the food, water and other survival necessities are carried at the beginning of a launch mission, or replenished by cargo spaceships. But for long-distance and long-term interstellar missions, or for the establishment of bases on Moon or Mars, self-sustaining LSSs will be quite essential.

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Estimating land-surface evapotranspiration derived from the P model

Jun. 15, 2021 by TanShen

Evapotranspiration (ET) is a critical process in the global terrestrial water cycle, which describes the actual water consumption from land surface. ET comprises the biotic process of transpiration (T) via stomata, and the abiotic processes of evaporation from wet leaves (interception) and bare soil. The Penman-Monteith (PM) equation, together with the surface energy balance theory, provides a direct way to estimate the ET. In the PM equation, the surface conductance is an important variable that cannot be detected by remote sensing. Traditional methods estimate the surface conductance by empirical or parameterization methods, which requires calibration and, therefore, produces uncertainty during model application.

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Understand the thermal response of carbon use efficiency from respiration acclimation

Jun. 12, 2021 by Yanghang

Carbon use efficiency (CUE), defined as the proportion of net primary productivity (NPP) to gross primary production (GPP), is increasingly recognized as an important parameter describing ecosystem carbon storage (Collalti et al. 2020). As plant respiration (Ra) responds positively to temperature, a warming world may result in additional respiratory CO2 release, and hence further atmospheric warming. An accelerate positive feedback between climate warming and carbon cycle is therefore expected.

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First science meeting of the LEMONTREE project

May 28 by LPICEA

The joint LEMONTREE science meeting and Tsinghua’s 110th anniversary celebration meeting was held online on May 13th, 2021. The theme of this forum is “ The overview of eco-evolutionary optimality theory and its application”.  

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Gather online at vEGU21

Jan. 7th

LPICEA is involved in convening two sessions at vEGU this year! One emphasizes the principles of general organization and optimality in ecophydrological systems, which is the core concept driving the research work carried out in LPICEA. The other session is about plant traits with almost all sorts of aspects one can think about traits. This is one of the core subjects LPICEA people are looking at.

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The big picture of LPICEA research

Jan. 1st 2021 by Han Wang

It has been 2.5 years since this small research group of plant ecology was built up at DESS, Tsinghua in the spring of 2018. The group has expanded from one PI working on core carbon cycle processes and leaf economic traits at the first beginning, to additional two PhD students, Shengchao and Huiying, and two postdocs Shen and Wenjie by the end of 2019. Considering their backrgound and interests, they lead quite different projects on crop modelling, the coordination between photosynthetic and hydraulic traits, evoportranspiration and phenology. In the third year, we have two new PhD candidates Ziqi and Yanghang (still as external member) and one new postdoc Jian, who expand the research areas of LPICEA to optimality-based understanding/modelling of carbon allocation, carbon-climate feedback and functional diversity. The scale of LPICEA research also expands from the leaf or plant level, to the canopy and ecosystem level, and eventually and hopefully to the earth system level.

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Farewell Wenjie! And welcome Jian!

Jan. 1st 2021 by Han Wang

After doing a postcod research on phenology for almost 1.5 years in LPICEA, wenjie successfully found a position in Nanjing University of Information Science & Technology. He is going to conitnue carrying out scientific research but also to do some administration work. We wish Wenjie and his family settle down well in Nanjing and have a wonderful new journey there 😉

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Will Unmanned Aerial System (UAS) Change the Way of Field Observation?

Dec. 29th 2020 by Shen Tan

DJI published their newest product: DJI-L1 and P1, early this year. The former one is a UAS with LiDAR camera. The new product would be available in April, 2021. So, if the UAS with LiDAR (P1 is equipped with LiDAR and RGB together) has the potential to improve the way of field observation in the next 5 years?

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Effects of Elevated CO2 on vegetation in Tibetan Plateau

Dec. 18th 2020 by Ziqi Zhu

At present, effects of climate change on the Tibetan Plateau, characterized mainly by elevated CO2, slightly increased precipitation and significant increased temperature (0.16 to 0.67°C decade-1 since the 1950s) (Kuang and Jiao, 2016) on plant growth, have already been concerned by scientists(Fu et al., 2018, Zhao et al., 2019). And as an important part of atmospheric change, elevated CO2 can improve primary productivity(Zhao et al., 2020, Kuzyakov et al., 2019) and has a critical impact on ecosystem biomass and species diversity on the Tibetan Plateau(Zhao et al., 2020, Zhu et al., 2020).

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What Huber Value can tell us about the traits coordination

Dec. 16th 2020 by Huiying Xu

Around 500 years ago, one mystery of tree architecture has been observed by a great mind, Leonardo da Vinci. He wrote in his notebook about ‘Rule of Trees’: “All the branches of a tree at every stage of its height when put together are equal in thickness to the trunk.” To put it in another way, if you squeeze all the daughter branches into one, like closing a folding fan, you would observe that it’s as thick as the trunk at every height (Fig. 1). This fabulous observation hasn’t been moved forward until 1928 by Bruno Huber who measured the xylem area of branch and expressed it per weight of leaves supported by this branch, called Huber Value (Huber 1928). This definition makes it possible to compare the conducting area between different branches. With the development of technology, it’s easier to measure leaf area. Nowadays, we use leaf area instead of weight to calculate Huber Value (Tyree and Ewers 1991).

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The role of CO2 on closing yield gap

Dec. 15th 2020 by Shengchao Qiao

Over the past few decades, a dramatic increase in crop yield has been achieved as a consequence of management practices and breeding technology, and to meet the food demand resulting from population growth. However, a stronger increase in crop grain demand is expected because of the increasing population and changing diet (Neumann et al., 2010). Therefore, understanding how much crop potential needs to excavate is crucial to the food supply.

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What is the yield gap? How to calculate the yield gap?

Nov. 9th 2020 by Shengchao Qiao

Food is necessary for our life and directly or indirectly from crops. To keep food security, we need to know how many crop productions have achieved and how much crop potential need to excavate. Here I introduced the relavent variables involved in estimating yield gap and visualized the links among those variables and yield gap in Figure 1. Figure 2 and 3 are then exploited to illustrate the key logic of two extensively used methods on estimating yield gap.

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Congratulations to Shengchao and Huiying on passing the PhD Candidacy Examination!

3rd Nov. 2020 by LPICEA

To test the student’s breadth and depth of knowledge in earth system science, the second- or third-year students in DESS are required to do an PhD Candidacy Examination before they are quantified to conduct their research as a PhD candidate. In this examination, the students are required to give a presentation on the literature they reviewed, the courses they took, and possibly their on-going research projects as well.

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Collaboration with University Utrecht on Mapping Regional Canopy Nitrogen Content.

3rd Nov. by Tan Shen

Canopy nitrogen (N) content plays important role in plant growth and other ecosystem processes. More specifically, Leaf nitrogen concentration links to several leaf traits associated with photosynthesis, including photosynthetic capacity, light use efficiency, specific leaf area and thus the primary productivity. Current Global Vegetation Models (GVMs) based prediction of carbon assimilation could be improved by accurate canopy N map….

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The possible way to improve the photosynthesis module in Noah MP

3rd Nov. by Yanghang Ren

Last month, I passed the PhD application at DESS, Tsinghua University. I’m very excited that I can continue my study at Tsinghua University next year as a member of LPICEA. Considering my educational background and the development of LPICEA,I will focus on the improvement of vegetation dynamics in Noah MP (a land surface model) (Niu et al. 2011) and this is also my research proposal at THU.

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The timescale of plant acclimation

2nd Nov. by Huiying Xu

When you climb a mountain, you would notice that there may exist the same species all along the way. Do you ever wonder if there are some differences between them? For example, leaf nitrogen content of Abies fabri increases almost 90% more along elevation (data collected in Gongga Mountain, China). Why’s that?

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The Department of Earth System Science of Tsinghua University held the 610th Doctoral Forum

2nd Nov. by Ziqi Zhu

On the afternoon of the October 16th, the Department of Earth System Science held a doctoral forum with the theme of ” A community of shared destiny for human-beings under global climate change “.  And thanks to my tutor, Wang Han’s guidance, after several days’ preparation and revision, I have a good fortune to be selected to attend this form

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The significant impact of earlier leaf-out on hydrological circulation over the North Hemisphere

4th Sep. 2020. By Wenjie Zhang

My first year Postdoc project was developing a novel approach coupling remote sensing big data techniques to uncover the impact of advanced leaf-out on hydrology. Although widely advanced leaf-out has been unambigously reported over north hemisphere, much of focus remains largely on the impact on the carbon balance with few on the hydrological cycle. Evapotranspiration (ET) is one of the most important component in hydrological circle, directly effects on precipitation and soil moisture, rivers and lakes. Therefore, We explored the impact of earlier leaf-out on hydrological circulation over the North Hemisphere: a case study on ET. Our results show advanced leaf-out mainly effect on spring Etvariation, accounting for 29%, yet only 2% in summer. Besides, the advanced leaf-out contribution of -0.282 mm day-1 to the ET changes along 3-days sos gradient in spring future indicates its key role on hydrology, which also varing with vegetation species (Fig 1 and Fig 2).

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Exploration of plant traits – My first year of PhD at LPICEA

1st Sep. 2020. By Huiying Xu

Though I just finished my first year of PhD, I’ve done some trait analysis with Dr. Wang for two years. Now I reflected on my past two years, it seems I have gained some knowledge of plant traits but with more unknown things to explore in the future.

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The Study on the Adaptability of Vegetation to Climate Change in Tibetan Plateau

26th Aug. 2020. By Ziqi Zhu

In order to develop Pmodel, proposed by Wang et al. (Wang, Prentice et al. 2017), from a diagnostic model to a prognostic model, we need to predict the FPAR value (An input parameter in the model). However, the understanding of what kind of climatic factors control vegetation greenness is still very limited (Iio, Hikosaka et al. 2014), which is also reflected in the huge uncertainty of existing vegetation models for simulation (Cui, Huang et al. 2019). Therefore, we need to use remote sensing data to analyze the impact of climate factors on FPAR.

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A scheme for simulating sustainable leaf area index based on mass-balance equation

19th Aug. 2020. By Shengchao Qiao

It has been confirmed that the universal productivity model proposed by Wang et al. (named Pmodel) can well simulate the gross primary productivity (GPP) on the monthly scale. However, if we want to drive this model, we need the information of plant canopy coverage, such as leaf area index (LAI), as the input. This model can not be used to predict the future GPP because of the dependence for observation of canopy coverage at present. Now, we are working on proposing a scheme starting from the first-principles, such as mass-balance and optimality, to predict the dynamic of LAI. Then we incorporate this LAI scheme into Pmodel, and the diagnostic Pmodel is developed into the prognostic Pmodel. Here, we attempt to project a scheme starting from carbon mass-balance.

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The limitation of soil moisture on GPP

5th Jul. 2020. By Yanghang Ren

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Applying an a priori primary production model to estimate land-surface evapotranspiration

11th Jun. 2020. By Shen Tan

Evapotranspiration (ET) links the water and carbon cycles in the atmosphere, hydrosphere and biosphere. Models based on energy-balance principles have been widely used to estimate ET and its spatio-temporal pattern. Many uncertainties remain, however, in particular because of incomplete understanding of stomatal regulation. Here we evaluate an ET modelling framework embodying the hypothesis that canopy conductance acclimates to plant growth conditions according to the least-cost hypothesis, that is, minimizing the combined costs of maintaining carboxylation and transpiration capacities.

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Good luck to Yunke Peng on his PhD journey at ETH!

30th Mar. 2020. By Han Wang

After suffering the anxiety of waiting for more than half year, our ghost member Yunke Peng got a PhD offer from ETH! He is going to work with our collaborator Beni Stocker at ETH (https://stineb.github.io) to understand and predict the dynamics of global carbon and nitrogen cycles based on the optimality principles.

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Congratulations on our Pmodel GMD paper!

29th Mar. 2020

The model paper on our Pmodel was published in Geoscientific Model Development this week (https://doi.org/10.5194/gmd-13-1545-2020). Different from the theory paper of Pmodel (Wang et al., 2017), this model paper is aiming to archive and clarify the technical details of Pmodel, and evaluate …

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Congratulations to Shengchao Qiao on his new paper on AFM!

20th Feb. 2020

Recently, Shengchao and his coauthors (Dr. Han Wang, Pro. I. Colin Prentice and Pro. Sandy P. Harrison) published a new paper on Agricultural and Forest Meteorology to introduce their novel, simply formulated crop model (PC model).

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Evaluation about how key photosynthetic traits response to environmental gradient (Chinese version)

6th Feb. 2020

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Congratulations to Dr. Han Wang on her new paper on GCB!

10th Jan. 2020

Based on the optimality concept, Dr. Han Wang and her coauthors (Owen Atkin, Trevor Keenan, Nick Smith, Ian Wright, Jens Kettge, Keith Bloonfield, Peter Reich and Colin Prentice) proposed a novel theory on leaf respiration acclimation that are largely neglected, but can be directly implemented, in the state-of-the-art land surface models.

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Colin & Sandy visit LPICEA!

31st Oct. 2019

This autumn, we were honored to have Professor Iain Colin Prentice (https://www.imperial.ac.uk/people/c.prentice) and Professor Sandra Patricia Harrison (https://research.reading.ac.uk/palaeoclimate/) in our lab and work with us, as part of ongoing Chinese High End Expert Program. During this time, three students in our lab have worked closely with Colin and Sandy and made great progress on their researches.

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Introduction to Linear Algebra and More

3rd Jul. 2019

Linear algebra has been widely used in a variety of fields in mathematics and science. Starting from the simple questions of solving linear equations, the methods and ideas in linear algebra are also applied in some advanced topics of math, such as group representation theory and differential equations. Here in this article, I am trying to give a brief introduction to linear algebra and its basic application with simplest languages and hopefully least number of equations.

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Press relase of EGU

31st May 2019

Last week the General Assembly 2019 of EGU was held in Vienna Austria. Four of our lab, Han Wang, Shengchao Qiao, Huiying Xu and Yunke Peng, took part in this meeting. In this meeting, Han Wang worked as one of the co-conveners of session ‘Plant traits, adaptation and biogeochemical cycles-from measurements to models’, with her project ‘Quantitative prediction of leaf economic’ presented by I. Colin Prentice.

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Workshop at XTBG, an opportunity to present, to learn, to connect

19th Apr. 2019

The workshop about the carbon, nitrogen and water cycle during the last 4 days in XiShuangBanNa Tropical Botanic Garden (XTBG), Yunnan was amazing. I did my first presentation about predictability of leaf traits, knew some great scientists and their spirits, last but not the least, enjoyed the splendid view of tropical rainforest.

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On Interdisciplinary Cooperating Principles

1st Apr. 2019

In his autobiography, Richard Feynman tells his experience in the lab of Watson and Crick during his professorship in Caltech. He guested in the lab and performed a series of experiments on DNA —— it is quite reasonable for someone like Feynman to try something out of his field, and indeed he had some fruits working in a biochemistry lab.

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Lecture on vegetation models at itp-CAS

21st Mar. 2019

Dr. Han Wang gives a lecture on the history and future of vegetation models at the Institite of Tibetian Pleteau Research, CAS.

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Visiting South China Botanical Garden, Guangzhou

18th Mar. 2019

During last week (18th – 20th, March), the LPICEA group visited Professor YE Qing in South China Botanical Garden (SCBG), Chinese Academy of Science. Professor Ye shares the common interests in plant functional traits with LPICEA group and has been working on the responses of plant eco-physiological processes and forest community assemblage to global environmental changes for many years.

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