Puding Karst Ecosystem Research Station

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1 Puding Karst Ecosystem Research Station Guizhou, China

2 Contents Puding Karst Ecosystem Research Station Location and regional background History Scientific research Field monitoring and control experiments Experimental demonstration Research achievements Research team Collaborations 2

3 Location and regional background The Puding Karst Ecosystem Research Station (PUKERS) is located in Shawan ( N, E, 1176 m), which is 5 km north of Puding City in central Guizhou Province, southwestern China. The main station has an area of 11.2 ha. Laboratories, offices, accommodations, and meeting rooms occupy ca m 2. The meteorological station, the simulation test field for karst water and carbon research, and the eddy flux tower are facilitated by the station. The station lies in the watershed region between the Yangtze River and the Pearl River on the Guizhou Plateau, which is between 1100 and 1400 m above sea level. Influenced by the East Asian and Indian Monsoon systems and by the relatively higher altitude, the middle subtropical climate is mild and humid. According to meteorological records of the Puding weather station from 1961 to 2008, the mean annual temperature is 15.1 C, with January and July temperatures of 5.4 C and 22.9 C, respectively. The extreme maximum and minimum temperatures are 34.7 C and 11.1 C, respectively. The frost-free season lasts 289 d. The mean annual sunshine duration is h, which is relatively unfavorable to the growth of evergreen plants. The mean annual precipitation is mm, of which more than 70% falls from May to September. Karst is a highly specialized geomorphology that mainly consists of limestone and dolomite. This landscape is scattered in various areas worldwide but continuously and widely distributed in South America, the Mediterranean coast, and China. China has approximately 3.44 million km 2 of karst areas (buried, covered, and exposed carbonate rock areas), which accounts for approximately 36% of the country s total land area and 15.6% of the 22 million km 2 karst areas in the world. The extensive karst outcrops and embeddings are located in its southwestern political divisions (ca million km 2 ; 5.8% of the total land area), including the Guizhou, Guangxi, Yunnan, Guangdong, Hunan, Hubei, Sichuan, and Chongqing, especially in the first three provinces. The Guizhou Province is the center of the South China Karst; and Puding County is the center of Guizhou karst region. Within a total area of km 2 in this county, the mountainous area accounts for 34.7%, the hilly area for 49.6%, and the plain and basin areas for 14.7%. The karst morphology is a typical plateau surface type of peak-clump depression. The exposed rocks are distributed everywhere. The black limestone soil 3

4 (Rendzina, in FAO and China s soil taxonomy classifications) is shallow and discontinuous with high heterogeneity, but rich in nutrients and calcium. However, soil water easily leaks out through the rock lacunas, thereby resulting in a specific drought if sufficient rainfall is lacking. The karst topography, humid and warm monsoon climate, and specific edaphic and rocky microhabitats render the vegetation in this area different from other non-karst subtropical regions. Evergreen trees (accounting for ca. 65% of total species) mixed with a proportion of deciduous trees (35%) in the canopy and sub-canopy layers comprise the typical karst forest, a non-zonal soil climax that is widely distributed in subtropical China. However, the original evergreen deciduous broadleaved mixed forest has almost disappeared because of human disturbances. Secondary subclimax karst (short) forests remain in protected or remote areas. When forests are degraded by human activity, thorn shrublands and tussocks dominate karst hills. The bare or less vegetation-covered karst terrain usually leads to significant rocky desertification, a landscape that exhibits sand desertification in arid Central Asia but covered by large rocks. This phenomenon is a serious environmental and social disaster in the South China Karst region. History Rocky desertification cultivated land in Puding City The Puding Experimental Station of Comprehensive Karst Research as the predecessor of PUKERS was officially established in 1986 to monitor and exploit karst water resources. Previously, the station started to monitor water runoff and underground rivers since More than 20 long-term monitoring sites were established between 1980 and 1982 to investigate the time-series changes of rain water, runoff, and underground water on the karst terrain. Since 1996, the station started to explore the comprehensive 4

5 management of karst environments and water resources. A complete new station was established in 2007 by the Institute of Geochemistry of the Chinese Academy of Sciences and the Science and Technology Agency of Guizhou Province. As approved by the Chinese Academy of Sciences, PUKERS was formally established in 2009 and is managed by the Chinese Ecological Research Network (CERN). The main building of the station in Shawan was constructed in September PUKERS officially became one of the 44 ecological stations of CERN in July Monitoring, research, and demonstration are three major tasks for each CERN station. Satellite image around Puding city (A. Shawan B. Tianlongshan C. Chenqi D. Zhaojiatian E. Chenjiazhai) Scientific research The PUKERS, as one of the only two monitoring and research stations of karst ecosystems of CERN, generally aims to provide long-term, permanent monitoring and investigation of karst ecosystems in 3D and comprehensive approaches. A technical standard of ecosystem monitoring for karst landscape will then be established. The structure, functions, patterns, and processes of karst ecosystems on the Guizhou Plateau will be revealed by long-term monitoring and control experiments of the material cycles and 5

6 energy flows at different spatial and temple scales and under various perturbations by human activities. The mechanism of self-maintenance and its key driving forces of karst ecosystems under global change and human disturbances will be explored. Such research will be used to predict the successional trend, to establish the optimal management model, and to enhance ecological function of karst ecosystems. The karst biogeochemical cycles (long-term), the ecological restoration of rocky desertification land (short-term), and the dynamics of the karst carbon cycle and its management (short-term) are the three key research tasks based on long-term and short-term goals. 1. Karst biogeochemical cycles The fluxes and cycling processes of C, N, P, Ca, S, and water in karst ecosystems will be investigated and monitored at various scales from the plot or site to the catchment, watershed, and region, with long-term control experiments by focusing on key life elements and water cycle. The effect of global change and human perturbations on the karst ecosystem elements and water cycles will be explored. With multi-tracers of stable isotopes (e.g., 13 C, 18 O, 15 N, and 36 S), methods of ecological stoichiometry, and measurements of plant ecophysiology, we will investigate the biogeochemical cycles of water and nutrients in karst ecosystems among multi-spheres of the hydrosphere, lithosphere, pedosphere, atmosphere, and biosphere. The driving forces and control mechanisms of material cycles of karst ecosystems will also be analyzed. The dynamic changes of structure, functions, processes, and patterns of karst ecosystems in the Guizhou Plateau will be revealed through regional syntheses. Regional material cycles and energy flows, as well as their driving forces, will be further integrated. The major research issues include the following: spatiotemporal patterns and variations of elements and the water cycle; biogeochemical processes of multi-sphere boundaries; responses and feedback of material cycles to climate change and land use/land cover changes; and biological (plants and microbes) and geological driving forces of biogeochemical cycles in karst ecosystems. 6

7 Karst microhabitat 2. Ecological restoration of rocky desertification land Through long-term investigation and monitoring of degraded karst ecosystems, as well as comparisons with regional ecosystem climaxes, we will analyze the degradation and restoration processes of the structure and functions of karst ecosystems and their key controlling factors and mechanisms. Potential and optimal ways of natural restoration and artificial recovery of degraded karst ecosystems will be tested and selected to better construct a paradigm of the comprehensive treatment of karst rocky desertification. We will further predict the future trends of structures and functions of restored karst ecosystems under the circumstance of global change. The major research issues include the following: features and maintenances of karst ecosystem structures and functions; spatial and temporal processes and driving forces of soil and water erosions under karst ecosystem degradation; assessments of ecological health and successional trends of degraded karst ecosystems; methods and mechanisms of ecological restoration of structures and functions of degraded karst ecosystems; responses and adaption of degraded karst ecosystems to global change; and 7

8 optimal models and management (water, nutrients, and species arrangement) of ecological restoration of degraded karst ecosystems. Karst soil profile and cultivated land 3. Dynamics of karst carbon cycle and its management We will quantitatively analyze carbon fluxes and the driving forces of different components of karst ecosystems based on observations of changes in the carbon storage of vegetation, soils and water bodies, as well as the processes of ecosystem degradation, maintenance, and restoration. To evaluate and predict contribution and time point of restored karst ecosystems to China s carbon sink, major research issues include the following: current status and spatial pattern of carbon in karst ecosystems; changes of various carbon pools in karst ecosystems and their responses to global change; carbon transformation through multi-sphere boundaries of karst ecosystems and its driving mechanisms; carbon pool potential of degraded karst ecosystems; methods and techniques of carbon enhancement for degraded karst ecosystems; and type, model, and regulatory management of the carbon cycle in the karst region. 8

9 Field works in plots Furthermore, construction of an appropriate observational system of karst ecosystems considering the CERN criteria is another key task of the Puding Station. Four key principles are taken into account when observing the material cycles and energy flow of karst ecosystems: Holistic: based on the basic unit of the small watershed and development features of the karst surface zone Three-dimensional: vertically and horizontally according to water movement routes High frequency: key observations after rainfall Multi-boundary: concentrating on interface interactions of the hydrosphere, lithosphere, pedosphere, atmosphere, and biosphere 9

10 Karst environments in Puding city Field monitoring and control experiments The monitoring network of the station is mainly set in the Houzhai River Watershed, a karst peak-depression landform in the central Guizhou Plateau with a total area of 82 km 2 : one primary site at Tianlongshan (evergreen and deciduous broadleaved mixed forest permanent plot) and four subsidiary sites (six human-disturbed plots at Chenqi, a clear cutting plot at Zhaojiatian, and an abandoned crop plot at Shawan). Another demonstration site is built in the Gaoyang River Watershed: one subsidiary site with nine vegetation restoration plots at Chenjiazhai. Various investigation plots and sites are widely distributed in these two watersheds and in other regions of the Guizhou Plateau. Satellite image of Houzhai River Watershed 10

11 The key monitoring sites of the station are distributed in the Houzhai River Watershed, which is representative of the karst morphology, hydrology, soil, and ecosystem on the Guizhou Plateau surface. The basic lithology is carbonate rock (mainly limestone and dolomite). The black limestone soil is very shallow and discontinuous but rich in nutrients and calcium. Under intensive human disturbances (fire, grazing, cutting, and firewood collection), the original azonal evergreen deciduous broadleaved mixed forest no longer exists in this region. Secondary mixed forests and low forests only grow in small areas with less human disturbances. The thorn scrubland and tussock cover mostly of the karst terrain. 1. Hydrological and hydrochemical monitoring sites in Houzhai River Watershed We set up six surface or underground hydrological monitoring sites in the entire Houzhai River Watershed (a total of seven stations): three stations in upstream mountainous areas (Chenqi, Dengzhanhe, and Yangpizhai), two stations in the midstream (Jiaguan and Laoheitan), and two more stations in the downstream surface and underground outlets (Houzhai). Research infrastructure includes an array of sensors to quantify water and energy fluxes, thereby providing high-frequency data on the atmospheric, hydrologic, and vegetation dynamics in the watershed. In conjunction with geophysical, geochemical and hydrochemical analyses, and geospatial/remote sensing observations, these data will be further used to study carbon and water changes in this karst landscape. Several vegetation plots with different land use/land cover types are also built to investigate the effect of land use change on carbon and water dynamics, especially in the Chenqi small catchment (see below for more details). 2. Tianlongshan primary plot This plot occupies 2 ha, which was built and fully investigated in 2012 according to the protocol of big plot of worldwide forest biodiversity monitoring before it was re-investigated in The plant community of the key plot is an abzonal soil climax of a secondary evergreen deciduous broadleaved mixed forest, which is dominated by Platycarya longipes (deciduous tree), Lithocarpus confinis (evergreen tree), Machilus cavaleriei (evergreen tree), Carpinus pubescens (deciduous tree), and Itea yunnanensis (evergreen tree). Key researches include vegetation dynamics of a secondary evergreen deciduous broadleaved forest in the karst plateau surface, as well 11

12 as the effect and feedback of the structure, functions, processes, patterns, and material cycles of this forest to global change. Landscape of Tianlongshan primary plot 3. Chenqi subsidiary plots The entire Chenqi Catchment, with a total area of 1.3 km 2, is an ideal place to monitor karst hydrology and water chemistry. The plot has a typical hill peak cluster depression landform, with an elevation of m. We set up four meteorological stations, six large runoff fields with different land use and land cover types, one karst dry valley runoff monitoring station, three spring stations, five bore holes, and three soil CO 2 hydrochemistry automatic monitoring systems within forest, cropland, and paddy field areas. By building such infrastructures, we emphasize the quantitative prediction of the karst critical zone evolution and structure by focusing on understanding the surface and underground pathways and fluxes of water, solutes, and sediments. We particularly emphasize regolith structure and evolution, including all relevant geochemical, hydrological, biological, and geomorphological processes that operate in this mixed land use and land cover landscape. Six subsidiary vegetation plots in an area of m 2 each are set up to monitor long-term changes of the water, soil, climate, and biota of karst ecosystems in different successional stages and under major human disturbances (grazing, fire, cutting, and forest conversion from cropland). These six plant communities are (1) secondary mixed evergreen deciduous broadleaved low forest under natural restoration, (2) shrubland under cow grazing, (3) low forest and shrubland after firewood cutting, (4) economic forest (orchard) after land conversion from agricultural field, (5) tussock restored naturally after fire, and (6) tussock controlled after fire by cutting once a year. Successional processes, material cycles, and their control factors of such degraded vegetation, which are driven by global change and human 12

13 disturbances, will be explored. Runoff pool in the Chenqi small catchment 4. Zhaojiatian subsidiary plots One clear cutting plot and one reference plot with 1000 m 2 each are located at Zhaojiatian. The vegetation is almost a climax of an evergreen deciduous broadleaved mixed forest with richer evergreen trees than the forest at the Tianlongshan plot. The tree species are dominated by the taller trees of Cinnamomum bodinieri, Populus adenopoda, and Itea ilicifolia. The plot is used to monitor and investigate the spatial and temporal changes and the processes of water loss and soil erosion, as well as the speed and processes of vegetation restoration after forest clear cutting. Landscape of Tianlongshan primary plot 5. Shawan subsidiary plot A plot of natural restored vegetation after the abandonment of cropland (maize) with an area of 1200 m 2 was set up in the main station in This plot is used to monitor the governing factors in water and soil during natural vegetation restoration, as well as the stages and processes of vegetation restoration. 13

14 Vegetation restoration for four years at Shawan subsidiary plot 6. Control experiments Several controlled experiments are established in the main station at Shawan, including one microbe experiment site, five rainfall simulation experimental fields, one biochar experimental site, one soil water conservation site, and one fertilization experimental plot. The largest infrastructure is the simulation test field for karst carbon and water fluxes. This experiment mainly aims to investigate carbon transportation and transformation through water flow under processes of vegetation soil rock interactions and to analyze the carbon sink effect of karstification quantitatively under land use changes. 14

15 The simulation test field for karst carbon and water fluxes Experimental demonstration The ecological demonstration was set up at Chenjiazhai, a small catchment in the Gaoyang River Watershed. This field is an observational, experimental, and demonstrational field in an area of 1.5 km 2. Nine subsidiary plots were built in The karst slope was vertically classified into three belts, namely, the natural vegetation restoration in the upper rocky slope (upper belt), the orchard plantation taking account of both ecological and economic benefits in the middle earthy and rocky slope (middle belt), and the agricultural development in high efficiency in the lower rocky and earthy slope. Plots were separated based on their lithology (i.e., limestone and dolomite): four vegetation plots for reformation of ecological forest plantation (cypress forest) in dolomite slope and five vegetation plots for ecological restoration by artificially planting local tree, shrub, and herb species with various collocations after land abandonment of the orchard. In the basin, specific vegetables and traditional Chinese medicinal herbs are planted to provide higher income to the locals. Pond collecting water for irrigating vegetables in Chenjiazhai 15

16 Research achievements More than 120 papers based on observational and experimental data from the Puding Station have been published in English and Chinese journals, such as Geochimica et Cosmochimica Acta, Earth-Science Reviews, Chemical Geology, Solid Earth, Journal of Hydrology, Science in China, and the Chinese Science Bulletin, during the past five years. Key achievements include the soil formation and erosion in karst hill slopes to reveal the mechanism of rocky desertification, the hydrological and hydrochemical features of karst water in small catchments for improved water resource management, the karst vegetation structures and functions (especially root biomass) to aid the ecological restoration of degraded karst forests, and the new carbon cycle that is specifically for carbonate rocks and water interactions. A dozen key projects have been and are being implemented in the studied region of the Puding Station. Two priority key projects were funded by the Ministry of Science and Technology (MOST) of China: the Rocky Desertification and Adaptive Ecosystem Management in Karst Mountainous Regions of Southwest China ( ), and the Karst Carbon Cycle Model and its Regulated Management based on Interactions among Hydrosphere, Lithosphere, Pedosphere, Atmosphere, and Biosphere ( ). A demonstration project of Benefiting People from Science and Technology named, Governance of Rocky Desertification and Cultivation of Ecological Industry, was also funded by MOST and recently implemented in the station. This project aimed to control rocky desertification, improve regional ecological environments, overcome the problem of poverty, and safeguard national solidarity via social harmony. In addition, a considerable amount of data from biological, soil, atmospheric and hydrological measurements, and experiments has been collected according to the standards of national field stations by considering the unique features of karst ecosystems. Most of the data and databases have been made publically available at the Karst Science Research Center ( and the Scientific Databases of Rocky Desertification in South China Karst ( 16

17 Paper published and datasets available at two websites Research team A total of 19 staff members work in the station, including 12 research scientists, 3 technicians, 2 administrators, and 2 assistants. This multi-disciplinary research team includes scientists and technicians who specialize in geochemistry, karst environmental science, hydrogeology, ecology, soil science, agriculture, botany, forestry, geography, and geology. The lead scientists include the following: Professor Congqiang Liu is the Director of the Academic Committee of the Puding Station, Academician of the Chinese Academy of Sciences, and Vice-President of the National Science Foundation of China. He is engaged in scientific research on the geochemistry of the Earth s surface and the environmental effects of trace elements and stable isotopes in karst landscapes. Professor Shijie Wang is the Director of the Puding Station, Vice-Director of the Institute of Geochemistry, and the Director of the State Key Laboratory of Environmental Geochemistry. He works on the biogeochemistry of karst ecosystems and comprehensive treatments of karst rocky desertification. 17

18 Professor Zaihua Liu is an awardee of the Hundred Talents Program of the Chinese Academy of Sciences. He works on karst carbon cycles and karstification under global changes and human disturbances. Professor Jian Ni is also an awardee of the Hundred Talents Program of the Chinese Academy of Sciences. He works on karst vegetation science and global change, karst carbon synthesis and modeling, and the paleoecology based on large-scale pollen data collection. From left to right, Congqiang Liu, Shijie Wang, Zaihua Liu and Jian Ni Collaborations Based on the philosophy of alliance, openness, collaboration, and win win solutions, the station has rules on the open management and data sharing of all infrastructure and scientific resources. Successful research has been achieved under collaborations with domestic and international scientists and students. We have long-term scientific cooperation with geologists and ecologists from the Institute of Botany (Beijing), South China Botanical Garden (Guangzhou), and Institute of Subtropical Agriculture (Changsha) of the Chinese Academy of Sciences, Hohai University, Nanjing Agricultural University, Guangxi Teacher and Education University, Guizhou University, Guizhou Normal University, and Anshun College, as well as those from the University of Southern Mississippi, University of Florida, Texas A&M University, University of Exeter, University of Edinburgh, University of McMaster, Forschungszentrum Jülich, and University of Bremen. Several national and international conferences have been organized by the Puding Station, including the 22nd Annual Conference of the CERN in

19 Domestic and international Scholars and visitors How to contact us Guiyang Office Institute of Geochemistry, Chinese Academy of Sciences Lincheng West Road 99,Guanshanhu District, Guiyang Guizhou Province, China Puding Office Puding Karst Ecosystem Research Station Shawan, Longga Village, Chengguan District, Puding Guizhou Province, China Tel: 0086-(0)

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