Seasonal variations in the net ecosystem CO<sub>2</sub> exchange of a mature Amazonian transitional tropical forest (cerradão)

Vourlitis, George L.; Filho, Nicolau Priante; Hayashi, Mauro M. S.; Nogueira, José de Souza; Caseiro, Fernando T.; Campelo, José Holanda

doi:10.1046/j.1365-2435.2001.00535.x

Cited by 80 publications

(103 citation statements)

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“…Similarly, Vourlitis et al (2002) suggest a Cerradão site was also in balance after measurements between August 1999 and July 2001. It seems worthwhile to mention those authors report a very small difference between gross ecosystem exchange -1 and ecosystem respiration, that is, 0.05 tC ha , which ultimately means a weak although significant sink exists.…”

Section: Discussionmentioning

confidence: 83%

“…Several experimental studies have adressed the carbon exchange using automatic monitoring in the Amazon rain forests as part of the LBA Project (LBA 1996;Grace et al 1996, Malhi et al 1998. Pioneer studies in Brazillian savanna were reported by Miranda et al (1997) in a Cerrado Sensu stricto in the central region, and by Vourlitis et al (2001) in a Cerradão vegetation at the ecotone between tropical savanna and rain forest in Central Brasil. Related investigations in South America about water cycle and carbon stocks in tropical savanna were developed in Venezuela (San Jose et al 2001;Szarzynsky and Anhuf et al 1999).…”

Section: Introductionmentioning

confidence: 94%

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Measurements of CO2 exchange over a woodland savanna (Cerrado Sensu stricto) in southeast Brasil

et al. 2002

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Palavras AbstractThe technique of eddy correlation was used to measure the net ecosystem exchange over a woodland savanna (Cerrado Sensu stricto) site (Gleba Pé de Gigante) in southeast Brazil. The data set included measurements of climatological variables and soil respiration using static soil chambers. Data were collected during the period from 10 to as much as 50 kgC ha day . The annual NEE sum appeared to be nearly in balance, or more exactly a small sink, equal to -1 -1 0.1 0.3 tC ha yr , which we regard possibly as a realistic one, giving the constraining conditions imposed to the turbulent flux calculation, and favourable hypothesis of succession stages, climatic variability and CO fertilization. Agosto) e na estação chuvosa, respectivamente, por um padrão de sensível correlação com a temperatura (Q =4.9) e 10 umidade do solo. Com base nos fluxos atmosféricos de CO , a PLE mostrou uma variabilidade no ciclo diurno grandemente 2 controlada pela radiação solar, umidade e temperatura do ar. Na escala sazonal, a umidade do solo foi uma variável de alta correlação com a PLE, que aparentemente induziu a queda de folhedo, redução da atividade fotossintética e da respiração -do solo. O sinal da PLE foi negativo (sumidouro) na estação chuvosa e no início da estação seca, com taxas de -25 kgChadia , e máximos de até 40 kgCha dia . Na estação seca o sinal foi positivo (emissão), o que foi revertido logo no início das chuvas. No fim da estação seca, em dias de grande estresse hídrico, ainda observou-se a resposta da fotossíntese na escala do ecossistema, mesmo tendo sido positiva a PLE. Paralelamente ao decorrer da estação seca, a PLE progressivamente

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Section: Discussionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 94%

Measurements of CO2 exchange over a woodland savanna (Cerrado Sensu stricto) in southeast Brasil

et al. 2002

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“…Thereby, for a given ecosystem when the vegetation growth is limited, the AR may be also expected to be limited and leads, therefore, to a significant reduction of the ER. This was probably the case for the savannah site during the dry periods with the ER value remarkably lower than that of the forest, the HR resulting mainly from the dissolved organic carbon or stimulation of the microorganism activities of the soil, surface litter amount, and soil organic matter pool (Vourlitis et al 2001;Davidson et al 2006a;Williams et al 2009). Fig.…”

Section: Larger Ecosystem Respiration (Er) For the Forest Than Savannahmentioning

confidence: 95%

“…The average of the CO 2 nighttime fluxes reported for the tropical forests and woodlands ranged from 3 to 8.5 μmol m −2 s −1 , with little seasonal variability (Vourlitis et al 2001;Loescher et al 2003;Merbold et al 2009;Longdoz et al 2010;Ago et al 2015). It varied between 1 and 6 μmol m −2 s −1 for the savannah sites in West Africa (Brümmer et al 2008;Merbold et al 2009;Ago et al 2014;Tagesson et al 2015; Quansah .…”

Section: Larger Ecosystem Respiration (Er) For the Forest Than Savannahmentioning

confidence: 98%

Response of CO2 fluxes and productivity to water availability in two contrasting ecosystems in northern Benin (West Africa)

Ago

Agbossou

Cohard

et al. 2016

Annals of Forest Science

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& Key message CO 2 fluxes were measured during 18 months in a forest and a savannah in northern Benin. Higher values of carbon fluxes were found during the wet season at each site. A strong dependency of carbon fluxes on water relations was found in two contrasting sites. The forest sequestered 640 ± 50 and the savannah 190 ± 40 g C m −2 year −1 . & Context In West Africa, the main mechanisms or factors governing the dynamics of ecosystems, especially the dynamics of the carbon fluxes and productivity, still remain less known. This study reports the carbon fluxes over two contrasting ecosystems, notably a protected forest (lat 9.79°N, long 1.72°E, alt 414 m) and a cultivated savannah (lat 9.74°N, long 1.60°E, alt 449 m) in northern Benin. The two sites were among those equipped by the AMMA-CATCH observatory and Ouémé 2025 project. & Aims Flux data were analyzed at the daily and seasonal scales in order to understand their controlling variables. We discussed the patterns of CO 2 fluxes and the characteristics of the two ecosystems. The study also focused on the different water usage strategies developed by the two ecosystems since the alternation between dry and wet seasons highly influenced the seasonal dynamics. Finally, the annual carbon sequestration was estimated together with its uncertainty. & Methods The carbon fluxes were measured during 18 months (July 2008-December 2009) by an eddy-covariance system over two contrasting sites in northern Benin. Fluxes data were computed following the standard procedure. The responses of CO 2 fluxes to the principal climatic and edaphic factors, and the canopy conductance were studied. & Results A clear CO 2 fluxes response to main environmental factors was observed, however with difference according to the seasons and vegetation types. The ecosystem respiration showed the highest values during the wet season and a progressive decrease from wet to dry periods. Also, the carbon uptake values were high during the wet period, but Handling Editor: Erwin DreyerContribution of the co-authors Expédit Evariste Ago conducted mainly the data analysis and prepared the manuscript with contributions from all co-authors. The field work with the eddy-covariance technique was carried out by Jean-Martial Cohard and Sylvie Galle who processed the raw data of fluxes. Marc Aubinet and Euloge Kossi Agbossou assisted in the data analyses. All authors read and approved the final manuscript which was submitted. low during the dry period. However, the CO 2 fluxes for the protected forest were always higher than that for the cultivated savannah within each defined period. This was due to the seasonal changes not only in phenology and physiology but also to the acclimation to environmental conditions, especially to the soil water availability. The water use efficiency was influenced by VPD during the day conditions for two ecosystems. However, the VPD response curve of water usage was relatively constant for the protected forest during the transitional and wet seasons. In contrary, for t...

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“…It provides a unique contribution to the study of the environmental, biological and climatological controls of net surface exchange between vegetation and the atmosphere [4][5][6][7][8] . However, eddy covariance technique is limited to use and easily related to measurement errors by many factors, such as vegetation height, footprint area, boundary-layer stability, sensor heights and separation, frequency response, alignment problems, and interference from tower or instrument-mounting structures.…”

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confidence: 99%

A preliminary study on the heat storage fluxes of a tropical seasonal rain forest in Xishuangbanna

Dou

Zhang

et al. 2006

SCI CHINA SER D

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In order to discuss the values and daily variation characteristics of heat storage fluxes in a tropical seasonal rain forest in Xishuangbanna, the sensible and latent heat storage flux within air column, canopy heat storage flux, energy storage by photosynthesis and ground heat storage above the soil heat flux plate, as well as the ratios of these heat storage fluxes to the net radiation in the cool-dry, hot-dry and rainy season were compared and analyzed based on the observation data of carbon fluxes, meteorological factors and biomass within this tropical seasonal rain forest from January 2003 to December 2004. The findings showed that heat storage terms ranged significantly in the daytime and weakly in the nighttime, and the absolute values of sensible and latent heat storage fluxes were obviously greater than other heat storage terms in all seasons. In addition, the absolute values of total heat storage fluxes reached the peak in the hot-dry season, then were higher in the rainy season, and reached the minimum in the cool-dry season. The ratios of heat storage fluxes to net radiation generally decreased with time in the daytime, moreover, the sensible and latent heat storage dominated a considerable fraction of net radiation, while other heat storage contents occupied a smaller fraction of the net radiation and the peak value was not above 3.5%. In the daytime, the ratios of the total heat storage to net radiation were greater and differences in these ratios were distinct among seasons before 12:00, and then they became lower and differences were small among seasons after 12:00. The energy closure was improved when the storage terms were considered in the energy balance, which indicated that heat storage terms should not been neglected. The energy closure of tropical seasonal rain forest was not very well due to effects of many factors. The results would help us to further understand energy transfer and mass exchange between tropical forest and atmosphere. Moreover, they would supply a research basis for studying energy closure at other places.

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Seasonal variations in the net ecosystem CO₂ exchange of a mature Amazonian transitional tropical forest (cerradão)

Cited by 80 publications

References 46 publications

Measurements of CO2 exchange over a woodland savanna (Cerrado Sensu stricto) in southeast Brasil

Measurements of CO2 exchange over a woodland savanna (Cerrado Sensu stricto) in southeast Brasil

Response of CO2 fluxes and productivity to water availability in two contrasting ecosystems in northern Benin (West Africa)

A preliminary study on the heat storage fluxes of a tropical seasonal rain forest in Xishuangbanna

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Seasonal variations in the net ecosystem CO2 exchange of a mature Amazonian transitional tropical forest (cerradão)

Cited by 80 publications

References 46 publications

Measurements of CO2 exchange over a woodland savanna (Cerrado Sensu stricto) in southeast Brasil

Measurements of CO2 exchange over a woodland savanna (Cerrado Sensu stricto) in southeast Brasil

Response of CO2 fluxes and productivity to water availability in two contrasting ecosystems in northern Benin (West Africa)

A preliminary study on the heat storage fluxes of a tropical seasonal rain forest in Xishuangbanna

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Seasonal variations in the net ecosystem CO₂ exchange of a mature Amazonian transitional tropical forest (cerradão)