AU2021106004A4

AU2021106004A4 - Device and Method for Monitoring Ecosystem Respiration of Special Plant in Alpine Grassland

Info

Publication number: AU2021106004A4
Application number: AU2021106004A
Authority: AU
Inventors: Yanfang Deng; Xueping Han; Linyong HU; Shengping Kang; Qian Li; Hongjin LIU; Li Ma; Zhen Ma; Gaowa Saren; Ping Sun; Xungang Wang; Yaosheng WANG; Shixiao XU; Tianwei Xu; Leiming Yao; Qian Zhang; Xiaoling Zhang; Liang Zhao; Na Zhao; Xinquan ZHAO
Original assignee: Northwest Institute of Plateau Biology of CAS
Current assignee: Northwest Institute of Plateau Biology of CAS
Priority date: 2021-08-19
Filing date: 2021-08-19
Publication date: 2021-10-28
Anticipated expiration: 2029-08-19

Abstract

The present disclosure provides a device and method for monitoring ecosystem respiration (ER) of a special plant in an alpine grassland. The device includes a chamber, a base, a monitoring unit and a thermometer, where a groove is formed on the base; the chamber is matched with the groove to form a closed space; a cantilever is provided on a top of the chamber; the cantilever is configured to suspend the monitoring unit; and the thermometer is provided on a sidewall of the chamber and at a same height with the monitoring unit. The present disclosure monitors the ER of the special plant in the alpine grassland ecosystem, and has the characteristics of simple structure, uniform gas production and strong stability. - 1/2 DRAWINGS FIG. 1

Description

- 1/2

DRAWINGS

FIG. 1

DEVICE AND METHOD FOR MONITORING ECOSYSTEM RESPIRATION OF SPECIAL PLANT IN ALPINE GRASSLAND TECHNICAL FIELD

[01] The present disclosure relates to the field of carbon flux monitoring, and in particular, to a device and method for monitoring ecosystem respiration (ER) of a special plant in an alpine grassland.

BACKGROUNDART

[02] With the development of civilization and industrial production in human society, the mankind is facing major environmental problems. There are a series of problems to be solved urgently, e.g., the excessive emission of greenhouse gases, sharp rise in global temperature and severe shortage of freshwater resources. In future, these problems will affect the regional or even global climate change to a great extent and will be destructive to the mankind and ecosystem. Since the industrial revolution, the burning of fossil fuels, land-use changes and other human activities have influenced the global carbon cycle significantly. Presently, the carbon dioxide is of greatest concern throughout the world because it contributes to the global warming more than other greenhouse gases with the proportion up to 70%. According to ice cores of various resolutions, the average concentration of carbon dioxide in the atmosphere was 275 ppm and only fluctuated with 5 ppm during 1,000-1,800 A.D. After that, the influences of the human activities on atmospheric concentration were increasingly prominent. During 1,750-2,011, the concentration of carbon dioxide in the atmosphere was increased by 40% from 278 ppm to 390.5 ppm; compared with the carbon dioxide gas in the ice cores, the concentration of greenhouse gas had exceeded the highest concentration over the past 800,000 years and still increased every year at 1.5-1.8 ppm; and such an average rate in increase of the concentration had never happened before over the past 20,000 years. As the main contributor to the global warming, the increase in the concentration of carbon dioxide in the atmosphere will greatly affect the future regional or global climate change. In recent decades, the human activities have led to the obvious increase in concentration of the greenhouse gases and changed the global carbon cycle radically. According to the simulation research, the global greenhouse effect has been ongoing and expanding since the last century, and the global average surface temperature has been increased by 0.6° over the past century. It is predicted by the Intergovernmental Panel on Climate Change (IPCC) that the global surface temperature will rise 1.4°C from 1,990 to 2,100. The greenhouse gas effect has become the present hotspot for climate change research. In recent decades, the human activities have led to the obvious increase in concentration of the greenhouse gases and changed the global carbon cycle radically. The research shows that the carbon dioxide has diverse sources, and except emission of the human activities, the terrestrial ecosystems (grasslands, forests, wetlands, farmlands, etc.) also serve as important emission sources. According to the existing research, about 5-20% of carbon dioxide in the atmosphere comes from soil per year, e.g., organic substances in the soil are decomposed by microbes and released to the atmosphere in the form of the carbon dioxide. At present, the grassland ecosystem has become one of the terrestrial ecosystems seriously affected by the human activities and one of the fragile terrestrial ecosystems in the ecological environment. The grassland ecosystem in China possesses an enormous potential of fixing carbon and its emission of greenhouse gas plays an important role in global climate change.

[03] While the carbon flux in the atmosphere and ocean can be directly measured by a global environmental measurement system (GEMS), there are different estimates on carbon pools of vegetation and soil formed into the terrestrial ecosystems. Hence, the absorption and emission of the terrestrial ecosystems to the carbon dioxide become the key to research the global carbon cycle.

[04] The present hotspot in ecology is to observe and research greenhouse gases of different terrestrial ecosystems. The domestic and foreign research on the carbon cycle of the terrestrial ecosystems covers the forest ecosystem, agricultural ecosystem and grassland ecosystem, and achieves a number of achievements. Different vegetation types have different soil respiration rates. Among the grassland, forest and farmland, the grassland has the largest soil respiration rate, followed by the forest and the farmland. In spite of this, the systematic research on the carbon cycle of the grasslands in China is backward relatively. The grasslands are one of the most widely distributed vegetation types in the world, and the grassland ecosystem is also one of the leading vegetation types in our country. In China, different types of grasslands cover an area of 4,000,000 km 2 , which is about 4 times of the cultivated area and 3.6 times of the forestry area, and is up to % or more in the total land area. The domestic and foreign research on the carbon cycle of the grassland ecosystem mostly focuses on tropical grasslands and temperate grasslands in low-altitude regions. With the further research on the carbon flux and intensification of global change in the world, as major constituents of the terrestrial ecosystems, the high-altitude and high-latitude regions are most sensitive to the global climate change and function as "ecological indicators" in the global climate change. Among various grasslands throughout the country, the Qinghai-Tibet Plateau has the largest area of alpine grasslands, covering an area of 588,300 km 2, and up to 17.77% of the grasslands nationwide and 25% of the land area in China. Located on the "roof of the world", the Qinghai-Tibet Plateau lies at an average altitude of more than 4,000 m. As the highest and largest geomorphic unit on the Eurasia with the most complicated landform in the world, the plateau boasts the special climate, vegetation and soil environment that make the soil development of the grassland short and the grassland ecosystem fragile. Because of the special geographical location and climate, the Qinghai-Tibet Plateau is considered as the sensitive region for the climate change as well as the forecast region and enlarged region in global warming, with the temperature rise earlier and higher than the global average. According to the present trend of the global warming, the Qinghai-Tibet Plateau will have a temperature rise of 2.2-2.6°C every 50 years. As a key factor to affect the above-ground and below-ground biology and the biogeochemical process, the temperature change plays a vital role in carbon cycles of the terrestrial ecosystems such as the hydrothermal process, vegetation growth, physiological and populative structures and functions, and exchange and transportation of the carbon dioxide. Hence, the influences of the climate warming and terrestrial ecosystems have become the hotspot researched by the ecologists in home and abroad in recent years. Within the sensitive region to the global climate change, the terrestrial ecosystem of the Qinghai-Tibet Plateau makes a more rapid response to the global climate and environmental change than other terrestrial ecosystems due to the fragile ecological environment and frequent human activities. The alpine grassland ecosystem of the Qinghai-Tibet Plateau is the important constituent of the terrestrial ecosystem, the ecological environment of which is fragile under the action of the plateau and high mountains, is extremely sensitive to the human disturbances and global changes, makes an earlier response to these disturbances and changes and plays an important role in balance of the global greenhouse gases. With the intensification of the global warming, it is estimated that the feature of the carbon pool on the Qinghai-Tibet Plateau and the mode of the carbon cycle in the ecosystem will change. The Qinghai-Tibet Plateau possesses the huge soil carbon pool, accounting for about 2.4% in the world. Due to the temperature rise, the frozen soil is thawed, and the soil organic carbon is decomposed more quickly, such that more carbon is released in the form of the greenhouse gas, to further increase the concentration of carbon dioxide in the atmosphere, become the major carbon source for the greenhouse gases in the atmosphere and further intensify the global warming. The carbon cycle serves as a connection link for the emission of the greenhouse gases, climate warming, land utilization and other major global environmental problems, and also an important constituent in the grassland ecosystem. Hence, long-term observation and research on the carbon cycle of the alpine grassland ecosystem on the Qinghai-Tibet Plateau is of great significance to accurately assess source-sink contributions of the Qinghai-Tibet Plateau to the whole terrestrial ecosystem in China, reveal the response of the carbon cycle to the global changes, and perfect a dynamic balance mechanism of the carbon cycle. Furthermore, it also has important implications for systematically analyzing ecological values and contributions of the grassland vegetation to the global changes, and researching the terrestrial carbon cycling mechanism and the global carbon balance.

[05] For the purpose of better understanding the direction and trend of the climate change on the Qinghai-Tibet Plateau, estimates are made on the emission of the carbon dioxide greenhouse gas in the alpine grassland, so as to take better measures for the emission reduction and climate change, and alleviate the influences of the climate change. According to research on carbon exchange of different alpine grassland ecosystems on the Qinghai-Tibet Plateau, exchange capacities between the underlying surface and the atmosphere vary for different vegetation types. The mobresia humilis meadows and potentilla fruticosa shrub meadows show strong absorption capacity, while the kobresia tibetica meadows show strong emission capacity. For the grassland ecosystems under the same external environment, there is no difference in solar radiation, rainfall and landform, and the vegetation type is the major factor to affect the carbon flux of the ecosystems. The carbon fluxes of the vegetation in different grassland ecosystems vary for the different plant species and coverages. More green leaf areas are decisive to carbon dioxide absorption and organic matter accumulation of the vegetation, and the different underlying surfaces will also influence the response to evapotranspiration and net radiation. In addition, different plants also vary in above-ground biomass, below-ground biomass, litter quality and reserve, and cellulose content, all of which will affect the decomposition time and speed of soil surface microbes or fungi for anaerobic respiration. Meanwhile, different vegetation coverages further have an influence on the humidity and temperature of the soil, the soil organic matter content and other ecological environment factors, thereby indirectly affecting the soil respiration. Concerning the vegetation roots, the density and distribution depth of the root system also determine the respiration rate of the root system. In this sense, different plants vary a lot in emission and absorption of the carbon dioxide. The research on changes of ER of special plants is of importance to assess the carbon flux of the whole ecosystem. In view that the existing research only focuses on the whole ecosystem, the research on the carbon emission of the special plants in the alpine grassland ecosystem is profound to predict the future local temperature change of the Qinghai-Tibet Plateau and protect the carbon pool of the Qinghai-Tibet Plateau. Particularly, it is valuable to protect the special plants of the Qinghai-Tibet Plateau, provides bases to further reveal the evolution of grassland ecosystems on the whole Qinghai-Tibet Plateau or even high-altitude grassland ecosystems throughout the world, and scientifically assists in accurately assessing positions and functions of the special species in the global carbon-nitrogen cycle of the alpine grassland ecosystem and formulating a reasonable grazing system.

[06] Presently, the closed static chamber (CSC) is one of the mainstream methods to monitor the flux of the greenhouse gas on the interface between the soil and the atmosphere. A static chamber typically includes a chamber and a base. The base is provided in the soil before test. In test, the chamber having a certain volume hoods a surface of the tested soil or crop and is inserted into a groove of the base. The chamber is sealed by water to ensure that no gas exchange exists between air in the chamber and the outside gas. A gas sample is extracted by an injection syringe from the chamber according to a certain time interval, and sent to a laboratory for analysis of a gas chromatograph, thereby calculating a release rate of the greenhouse gas. The method can provide a great deal of information on emission and influence factors of the greenhouse gas, can measure the flux of the variable gas within a large space, and has few restrictions on the measured region. However, the defects of the method lie in that the closed chamber affects a natural state of the measured surface, the monitored gas concentration is a comprehensive indication for gas concentrations of all species in the chamber, the base damages the soil to some extent and the method is only confined to the point monitoring. In addition to above defects, the existing static chamber for monitoring the greenhouse gas further has the following drawbacks: 1. The static chamber is moved, carried and transported inconveniently due to the clumsy shape, large size and heavy weight. 2. With the closed space of the static chamber, the gas sample must be collected within a short time; or otherwise, with the gas accumulation in the chamber, the pressure in the chamber increases and the air moisture is saturated, which reduces the gas release rate, cannot completely and authentically reflect the actual environment of the gas exchange on the soil-atmosphere interface and leads to a large error to the research result. 3. During extrapolation on the emission of the greenhouse gas, multiple assumptive conditions are provided. For example, when the measured value is extrapolated to the whole region, the assumption that the grasslands within the region are physicochemically and biogeochemically identical is typically provided. These drawbacks will greatly restrict the assessment on full-period emission of the greenhouse gas in the measured region.

[07] Therefore, there is an urgent need to provide a monitoring device or method for measuring carbon emission of a special plant in the alpine grassland ecosystem.

SUMMARY

[08] An objective of the present disclosure is to provide a device and method for monitoring ER of a special plant in an alpine grassland. The present disclosure monitors the ER of the special plant in the alpine grassland ecosystem, and has the characteristics of simple structure, uniform gas production and strong stability.

[09] To implement the above objectives, the present disclosure provides the following solutions:

[10] A device for monitoring ER of a special plant in an alpine grassland includes a chamber, a base, a monitoring unit and a thermometer, where

[11] a groove is formed on the base; and the chamber is matched with the groove to form a closed space;

[12] a cantilever is provided on a top of the chamber; and the cantilever is configured to suspend the monitoring unit; and

[13] the thermometer is provided on a sidewall of the chamber and at a same height with the monitoring unit.

[14] Optionally, the monitoring unit may include a housing and solid soda lime;

[15] a through hole may be formed on the housing; and

[16] the solid soda lime may be provided in the housing.

[17] Optionally, the number of thermometers and the number of monitoring units may be the same; and

[18] multiple thermometers may be uniformly arranged on the sidewall of the chamber and at the same height with the monitoring unit.

[19] Optionally, the chamber may be of a cylindrical structure; and

[20] the groove may be of a circular shape.

[21] A method for monitoring ER of a special plant in an alpine grassland includes:

[22] acquiring a special plant to be monitored;

[23] carrying out pretreatment on the special plant to be monitored, where the pretreatment includes: removing other species and a root tissue, transplanting to a flowerpot for cultivation, and placing the special plant to be monitored into an original environment for growth;

[24] placing the pretreated special plant to be monitored into a groove of a base;

[25] matching a chamber with the groove to form a closed space; and

[26] determining, after set time by using a monitoring unit, a carbon flux of the special plant to be monitored.

[27] Based on specific embodiments provided in the present disclosure, the present disclosure discloses the following technical effects:

[28] According to the device and method for monitoring ER of a special plant in an alpine grassland provided by the present disclosure, for some special species in the ecosystem, the carbon flux of the ecosystem can be decomposed by monitoring the ER of the special species to know contributions of different plants to the ER of the alpine grassland; by independently monitoring the special species, the problem of non-uniform gas emission of plants in the chamber due to different plant types and attributes is reduced; in order to avoid disordered motions of gas flow in the chamber, a fan is not provided in the chamber to uniformly mix the gas and thus the influence of the stirring of the fan on emission of greenhouse gases is avoided from the perspective of gas flowing. Therefore, the present disclosure monitors the ER of the special plant in the alpine grassland ecosystem, and has the characteristics of simple structure, uniform gas production and strong stability. Further, the long-term systematic measured results of the method can be used to guide the forage production and provide specific countermeasures or measures, thereby implementing the scientific grazing.

BRIEF DESCRIPTION OF THE DRAWINGS

[29] To describe the technical solutions in the embodiments of the present disclosure or in the prior art more clearly, the accompanying drawings required for the embodiments are briefly described below. Apparently, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and a person of ordinary skill in the art may still derive other accompanying drawings from these accompanying drawings without creative efforts.

[30] FIG. 1 is a schematic structural view of a device for monitoring ER of a special plant in an alpine grassland according to the present disclosure.

[31] FIG. 2 is a flow chart of a method for monitoring ER of a special plant in an alpine grassland according to the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[32] The technical solutions of the embodiments of the present disclosure are clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are merely a part rather than all of the embodiments of the present disclosure. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

[33] An objective of the present disclosure is to provide a device and method for monitoring ER of a special plant in an alpine grassland. The present disclosure monitors the ER of the special plant in the alpine grassland ecosystem, and has the characteristics of simple structure, uniform gas production and strong stability.

[34] To make the above-mentioned objectives, features, and advantages of the present disclosure clearer and more comprehensible, the present disclosure will be further described in detail below with reference to the accompanying drawings and the specific implementations.

[35] FIG. 1 is a schematic structural view of a device for monitoring ER of a special plant in an alpine grassland according to the present disclosure. The device for monitoring ER of a special plant in an alpine grassland includes: a chamber 1, a base 2, a monitoring unit 3 and a thermometer 4.

[36] A groove 6 is formed on the base 2; and the chamber 1 is matched with the groove 6 to form a closed space. The chamber 1 is of a cylindrical structure, and the groove 6 is of a circular shape.

[37] A cantilever 5 is provided on a top of the chamber 1; and the cantilever 5 is configured to suspend the monitoring unit 3. The cantilever 5 is arranged spirally. The spirally arranged monitoring unit 3 avoids the problem of the non-uniform gas in the chamber 1 and the gas extraction pipe, thereby improving the sampling accuracy of the gas in the static chamber, and ) improving the repeatability of the test result.

[38] The thermometer 4 is provided on a sidewall of the chamber 1 and at a same height with the monitoring unit 3.

[39] The base 2 is made of a plastic plate, the groove is a U-shaped groove, and the U-shaped groove is provided on an upper surface of the base.

[40] The chamber 1 is made of a cylindrical polyvinyl chloride (PVC) pipe. As the common material in the building industry, this material is cheap, easily available, fixed in diameter and convenient for volume calculation; and compared with other materials such as the organic glass or algam, the weight of the device can be effectively reduced. With the light-tight PVC plastic, it is ensured that the gas in the chamber 1 is not affected by solar radiation and the temperature in the chamber is kept stable. The PVC plastic can be completely used as a replacement of the foam insulation layer and the reflective film, guarantees normal release and collection of the greenhouse gas, and avoids the change of the gas temperature in the chamber 1 due to the solar radiation to affect the gas density and other parameters.

[41] The conventional static chamber lacks a pressure balance function. With the gas accumulation in the chamber, the pressure in the small-volume chamber 1 rises sharply to affect the gas exchange on the soil-gas interface. In order to solve the above problem, an alkali absorption method of the CSC is used. Through timely emission and timely absorption, the increase of the gas pressure in the chamber 1 is avoided, i.e., the monitoring unit 3 includes a housing and solid soda lime.

[42] A through hole is formed on the housing.

[43] The solid soda lime is provided in the housing.

[44] The solid soda lime may absorb a large amount of accumulated water vapor in the chamber 1 while absorbing the gas.

[45] The small-volume measurement chamber 1 facilitates the uniformly mixing of the gas in the chamber 1 within a short time. In view of the spatio-temporal non-uniformity during emission of the greenhouse gas, the solid soda lime is provided spirally in the chamber 1 to absorb the gas hierarchically. This method may avoid the problem of non-uniform gas emission due to different plant traits at different ecological heights, and release and absorb the gas at the same time.

[46] The number of thermometers 4 and the number of monitoring units 3 are the same.

[47] On the sidewall of the chamber 1 and at the same height with the monitoring unit 3, multiple thermometers 4 are uniformly arranged.

[48] As a specific embodiment, there are three thermometers 4 and three monitoring units 3.

[49] With the thermometer 4, the temperature in the chamber 1 is collected uniformly to perfect the function of the conventional greenhouse gas collection device.

[50] FIG. 2 is a flow chart of a method for monitoring ER of a special plant in an alpine grassland according to the present disclosure. As shown in FIG. 2, the method for monitoring ER of a special plant in an alpine grassland includes the following steps:

[51] S201: Acquire a special plant to be monitored.

[52] S202: Carry out pretreatment on the special plant to be monitored, where the pretreatment includes: removing other species and a root tissue, transplanting to a flowerpot for cultivation, and placing the special plant to be monitored into an original environment for growth, i.e., the pretreated special plant to be monitored receives the same illumination, rainfall and temperature like the community where the plant is located originally, such that the plant in the flowerpot can well simulate the external environment of the community where the plant is located.

[53] S203: Place the pretreated special plant to be monitored into a groove 6 of a base 2.

[54] S204: Match a chamber 1 with the groove 6 to form a closed space; and add water in the circular groove 6 of the base 2, and hood the chamber 1 in the water groove of the base 2, such that a gas path between the base 2 and the chamber 1 is sealed and free exchange between inside air and outside air of the chamber 1 is cut off.

[55] S205: Monitor, after set time by using a monitoring unit 3, ER of the special plant to be monitored.

[56] Solid soda lime particles are used for absorption to form carbonate radicals, and a rest content of the soda lime is calculated with a titration method, thereby inferring the ER of the ecosystem formed by some special plant within a certain time. The method has the advantages of multipoint measurement for a long time, simple operation, low cost, convenience for field measurement and repeated measurement.

[57] Each embodiment of the present specification is described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts between the embodiments may refer to each other. Since the system disclosed in the embodiments corresponds to the method disclosed in the embodiments, the description is relatively simple, and reference can be made to the method description.

[58] In this specification, several specific embodiments are used for illustration of the principles and implementations of the present disclosure. The description of the foregoing embodiments is used to help illustrate the method of the present disclosure and the core ideas thereof. In addition, those of ordinary skill in the art can make various modifications in terms of specific implementations and the scope of application in accordance with the ideas of the present disclosure. In conclusion, the content of this specification shall not be construed as a limitation to the present disclosure.

Claims

WHAT IS CLAIMED IS:

1. A device for monitoring ecosystem respiration (ER) of a special plant in an alpine grassland, comprising a chamber, a base, a monitoring unit and a thermometer, wherein a groove is formed on the base; and the chamber is matched with the groove to form a closed space; a cantilever is provided on a top of the chamber; and the cantilever is configured to suspend the monitoring unit; and the thermometer is provided on a sidewall of the chamber and at a same height with the monitoring unit.

2. The device for monitoring ER of a special plant in an alpine grassland according to claim 1, wherein the monitoring unit comprises a housing and solid soda lime; a through hole is formed on the housing; and the solid soda lime is provided in the housing.

3. The device for monitoring ER of a special plant in an alpine grassland according to claim 1, wherein the number of thermometers and the number of monitoring units are the same; and multiple thermometers are uniformly arranged on the sidewall of the chamber and at the same height with the monitoring unit.

4. The device for monitoring ER of a special plant in an alpine grassland according to claim 1, wherein the chamber is of a cylindrical structure; and the groove is of a circular shape.

5. A method for monitoring ecosystem respiration (ER) of a special plant in an alpine grassland, comprising: acquiring a special plant to be monitored; carrying out pretreatment on the special plant to be monitored, wherein the pretreatment comprises: removing other species and a root tissue, transplanting to a flowerpot for cultivation, and placing the special plant to be monitored into an original environment for growth; placing the pretreated special plant to be monitored into a groove of a base; matching a chamber with the groove to form a closed space; and monitoring, after set time by using a monitoring unit, ER of the special plant to be monitored.