Project Funding: 2004 - 2007

NRA: 2002 NASA: Terrestrial Ecology   

Funded by NOAA, NASA

Abstract:
Terrestrial biospheric contributions to global carbon cycling are poorly understood, particularly for Africa where we have only a few observations of fluxes and concentrations, and large uncertainty regarding ecosystem function, and the roles of fire and land use. Biogeochemical or biophysical land surface models can be used to supply time-varying, spatially distributed estimates of plant productivity, evapotranspiration, and net ecosystem exchange. However, the models surely provide an imperfect representation of the complex abiotic and biotic interactions involved in surface-atmosphere carbon, water, and energy exchanges. Analysis of observed CO2 concentrations provides additional information about the global spatial, and seasonal to interannual temporal distribution of its sources and sinks. Yet, the sparse observation network presents an incomplete picture of the true spatial and temporal patterns. The ACE project employs a multiple constraints approach that merges these techniques. Modeled land-atmosphere exchanges are merged with inverse analysis of measured [CO2] and its likely transport to provide a best estimate of regional sources/sinks and their uncertainty. The novel combination of forward and inverse approaches will lead to improved estimates of the spatial and temporal dynamics of carbon and water exchange in Africa, and enhance understanding of the impacts of climate, climate variability and land use on carbon exchange and Africa’s contributions to the global carbon cycle. We have measured fluxes of carbon, water and other gases over savanna in southern Africa for 6 years, and the Afriflux network of eddy flux stations is expanding on the continent providing datasets for parameterization and validation of model simualtions. The ACE project is also providing new very precise measurements of atmospheric CO2 in west, southern and central Africa for regional and global inverse estimates of net carbon sources and sinks.

Publications:

Akhtar-Schuster, M., P. Berliner, B. Bestelmeyer, M. Buenemann, T. Buttschardt, P. Chasek, A. Cowie, W. Critchley, N. P. Hanan, J. Herrick and S. Herrmann, et al. (2009). Monitoring and Assessment of Sustainable Land Management Understanding Desertification and Land Degradation Trends', White Papers for the First UNCCD Scientific Conference, Buenos Aires, Argentina 22-24 September 2009. Buenos Aires, Argentina.

Baccini, A., Goetz, S. J., Walker, W. S., Laporte, N. T., Sun, M., Sulla-Menashe, D., Hackler, J., Beck, P. S. A., Dubayah, R., Friedl, M. A., Samanta, S., Houghton, R. A. 2012. Estimated carbon dioxide emissions from tropical deforestation improved by carbon-density maps. Nature Climate Change. 2(3), 182-185. DOI: 10.1038/nclimate1354

Baccini, A., Laporte, N., Goetz, S. J., Sun, M., Dong, H. 2008. A first map of tropical Africa's above-ground biomass derived from satellite imagery. Environmental Research Letters. 3(4), 045011. DOI: 10.1088/1748-9326/3/4/045011

Baccini, A., Laporte, N., Goetz, S. J., Sun, M., Dong, H. 2008. A first map of tropical Africa's above-ground biomass derived from satellite imagery. Environmental Research Letters. 3(4), 045011. DOI: 10.1088/1748-9326/3/4/045011

Bucini, G., N. P. Hanan, R. Boone, S. Saatchi, I. Smit, M. A. Lefsky and G. P. Asner (2011). Woody fractional cover in Kruger National Park, South Africa: remote sensing based maps and ecological insights. Ecosystem Function in Savannas: measurement and modeling at landscape to global scales. M. J. Hill and N. P. Hanan. Boca Raton, CRC Press: 218-238.

Hanan, N. P., N. Boulain, C. A. Williams, R. J. Scholes and S. Archibald (2011). Functional convergence in ecosystem carbon exchange in adjacent savanna vegetation types of the Kruger National Park, South Africa. Ecosystem Function in Savannas: Measurement and Modeling at Landscape to Global Scales. M. J. Hill and N. P. Hanan. Boca Raton, CRC Press: 77-96.

Hanan, N. P. and C. E. R. Lehmann (2011). Tree-grass interactions in savannas: paradigms, contradictions and conceptual models. Ecosystem Function in Savannas: measurement and modeling at landscape to global scales. M. J. Hill and N. P. Hanan. Boca Raton, CRC Press: 39-56.

Hanan, N. P., Sea, W. B., Dangelmayr, G., Govender, N. 2008. Do Fires in Savannas Consume Woody Biomass? A Comment on Approaches to Modeling Savanna Dynamics. The American Naturalist. 171(6), 851-856. DOI: 10.1086/587527

Hill, M. J. and N. P. Hanan (2011). Current approaches to measurement, remote sensing and modeling in savannas: a synthesis. Ecosystem Function in Savannas: measurement and modeling at landscape to global scales. M. J. Hill and N. P. Hanan. Boca Raton, CRC Press: 515-546.

Hill, M. J. and N. P. Hanan, Eds. (2011). Ecosystem Function in Savannas: measurement and modeling at landscape to global scales. Boca Raton, CRC Press.

Hill, M. J., Roman, M. O., Schaaf, C. B., Hutley, L., Brannstrom, C., Etter, A., Hanan, N. P. 2011. Characterizing vegetation cover in global savannas with an annual foliage clumping index derived from the MODIS BRDF product. Remote Sensing of Environment. 115(8), 2008-2024. DOI: 10.1016/j.rse.2011.04.003

Mitchard, E. T. A., Saatchi, S. S., Lewis, S. L., Feldpausch, T. R., Woodhouse, I. H., Sonke, B., Rowland, C., Meir, P. 2011. Measuring biomass changes due to woody encroachment and deforestation/degradation in a forest-savanna boundary region of central Africa using multi-temporal L-band radar backscatter. Remote Sensing of Environment. 115(11), 2861-2873. DOI: 10.1016/j.rse.2010.02.022

Niu, S., Luo, Y., Fei, S., Yuan, W., Schimel, D., Law, B. E., Ammann, C., Altaf Arain, M., Arneth, A., Aubinet, M., Barr, A., Beringer, J., Bernhofer, C., Andrew Black, T., Buchmann, N., Cescatti, A., Chen, J., Davis, K. J., Dellwik, E., Desai, A. R., Etzold, S., Francois, L., Gianelle, D., Gielen, B., Goldstein, A., Groenendijk, M., Gu, L., Hanan, N., Helfter, C., Hirano, T., Hollinger, D. Y., Jones, M. B., Kiely, G., Kolb, T. E., Kutsch, W. L., Lafleur, P., Lawrence, D. M., Li, L., Lindroth, A., Litvak, M., Loustau, D., Lund, M., Marek, M., Martin, T. A., Matteucci, G., Migliavacca, M., Montagnani, L., Moors, E., William Munger, J., Noormets, A., Oechel, W., Olejnik, J., U, K. T. P., Pilegaard, K., Rambal, S., Raschi, A., Scott, R. L., Seufert, G., Spano, D., Stoy, P., Sutton, M. A., Varlagin, A., Vesala, T., Weng, E., Wohlfahrt, G., Yang, B., Zhang, Z., Zhou, X. 2012. Thermal optimality of net ecosystem exchange of carbon dioxide and underlying mechanisms. New Phytologist. 194(3), 775-783. DOI: 10.1111/j.1469-8137.2012.04095.x

Saatchi, S., Marlier, M., Chazdon, R. L., Clark, D. B., Russell, A. E. 2011. Impact of spatial variability of tropical forest structure on radar estimation of aboveground biomass. Remote Sensing of Environment. 115(11), 2836-2849. DOI: 10.1016/j.rse.2010.07.015

Sea, W. B., Hanan, N. P. 2011. Self-thinning and Tree Competition in Savannas. Biotropica. 44(2), 189-196. DOI: 10.1111/j.1744-7429.2011.00789.x

Williams, C. A. (2011). Integration of remote sensing and modeling to understand carbon fluxes and climate interactions in Africa. Ecosystem Function in Savannas: measurement and modeling at landscape to global scales. M. J. Hill and N. P. Hanan. Boca Raton, CRC Press: 327-346.

Williams, C. A., Hanan, N. P. 2011. ENSO and IOD teleconnections for African ecosystems: evidence of destructive interference between climate oscillations. Biogeosciences. 8(1), 27-40. DOI: 10.5194/bg-8-27-2011

Williams, C. A., Hanan, N., Scholes, R. J., Kutsch, W. 2009. Complexity in water and carbon dioxide fluxes following rain pulses in an African savanna. Oecologia. 161(3), 469-480. DOI: 10.1007/s00442-009-1405-y

Yi, C., Ricciuto, D., Li, R., Wolbeck, J., Xu, X., Nilsson, M., Aires, L., Albertson, J. D., Ammann, C., Arain, M. A., de Araujo, A. C., Aubinet, M., Aurela, M., Barcza, Z., Barr, A., Berbigier, P., Beringer, J., Bernhofer, C., Black, A. T., Bolstad, P. V., Bosveld, F. C., Broadmeadow, M. S. J., Buchmann, N., Burns, S. P., Cellier, P., Chen, J., Chen, J., Ciais, P., Clement, R., Cook, B. D., Curtis, P. S., Dail, D. B., Dellwik, E., Delpierre, N., Desai, A. R., Dore, S., Dragoni, D., Drake, B. G., Dufrene, E., Dunn, A., Elbers, J., Eugster, W., Falk, M., Feigenwinter, C., Flanagan, L. B., Foken, T., Frank, J., Fuhrer, J., Gianelle, D., Goldstein, A., Goulden, M., Granier, A., Grunwald, T., Gu, L., Guo, H., Hammerle, A., Han, S., Hanan, N. P., Haszpra, L., Heinesch, B., Helfter, C., Hendriks, D., Hutley, L. B., Ibrom, A., Jacobs, C., Johansson, T., Jongen, M., Katul, G., Kiely, G., Klumpp, K., Knohl, A., Kolb, T., Kutsch, W. L., Lafleur, P., Laurila, T., Leuning, R., Lindroth, A., Liu, H., Loubet, B., Manca, G., Marek, M., Margolis, H. A., Martin, T. A., Massman, W. J., Matamala, R., Matteucci, G., McCaughey, H., Merbold, L., Meyers, T., Migliavacca, M., Miglietta, F., Misson, L., Molder, M., Moncrieff, J., Monson, R. K., Montagnani, L., Montes-Helu, M., Moors, E., Moureaux, C., Mukelabai, M. M., Munger, J. W., Myklebust, M., Nagy, Z., Noormets, A., Oechel, W., Oren, R., Pallardy, S. G., Paw U, K. T., Pereira, J. S., Pilegaard, K., Pinter, K., Pio, C., Pita, G., Powell, T. L., Rambal, S., Randerson, J. T., von Randow, C., Rebmann, C., Rinne, J., Rossi, F., Roulet, N., Ryel, R. J., Sagerfors, J., Saigusa, N., Sanz, M. J., Mugnozza, G., Schmid, H. P., Seufert, G., Siqueira, M., Soussana, J., Starr, G., Sutton, M. A., Tenhunen, J., Tuba, Z., Tuovinen, J., Valentini, R., Vogel, C. S., Wang, J., Wang, S., Wang, W., Welp, L. R., Wen, X., Wharton, S., Wilkinson, M., Williams, C. A., Wohlfahrt, G., Yamamoto, S., Yu, G., Zampedri, R., Zhao, B., Zhao, X. 2010. Climate control of terrestrial carbon exchange across biomes and continents. Environmental Research Letters. 5(3), 034007. DOI: 10.1088/1748-9326/5/3/034007

More details may be found in the following project profile(s):

• NASA Terrestrial Ecology (TE) Project Profile
• North American Carbon Program (NACP) Project Profile