Research
Interests:
My research focuses primarily on the ecology of tropical savannas
and forests, with special emphasis on the Cerrado region of
central Brazil. I am primarily interested in understanding
the causes of variations in tree density in tropical savannas
and the consequences of land-use change on regional climate.
Current projects involve comparative ecology of savanna and
forest trees, fire ecology, and land-atmosphere interactions.
These projects involve a range of approaches, including ecophysiology,
population dynamics, remote sensing and GCM climate modelling.
Selected
Publications:
Jackson, R.B., Farley, K.A., Hoffmann,
W.A., Jobbagy, E.G., McCulley, R.L. Vegetation
change and carbon and water dynamics. In J.
Canadell, D. Pataki, L. Pitelka (eds.) Terrestrial Ecosystems
in a Changing World, in press.
Lahoreau,
G., S. Barot, J. Gignoux, W.A. Hoffmann, S.A. Setterfield,
and P. R. Williams. 2006. Positive effect of seed
size on seedling survival in fire-prone savannas of Australia,
Brazil and West Africa. Journal of Tropical Ecology,
in press.
Hoffmann, W.A., Silva, E.R., Machado, G.C., Bucci, S.J.,
Scholz, F.G., Goldstein, G., Meinzer, F.C. 2005. Seasonal
leaf dynamics across a tree density gradient in a Brazilian
savanna. Oecologia, 145: 307-316.
Hoffmann,
W.A., Franco, A.C., Moreira, M.Z., Haridasan, M. 2005. Specific
leaf area explains differences in leaf traits between congeneric
savanna and forest trees. Functional Ecology 19:
932-940.
Sternberg,
L.S.L., Bucci, S., Franco, A.C., Goldstein, G., Hoffmann,
W.A., Moreira, M.Z., Scholz, F. 2005. Long range
lateral root activity by Neo-tropical savanna trees.
Plant and Soil, 270:169-178.
Hoffmann,
W.A., Orthen, B. and Franco, A.C. 2004. Constraints
to seedling success of savanna and forest trees across
the savanna-forest Boundary. Oecologia 140:252-260.
Hoffmann,
W.A., Lucatelli, V. M. P. C., Silva, F. J., Azeuedo, I.
N. C., Marinho, M. da S., Albuquerque, A. M. S., Lopes,
A. de O., Moreira, S. P. 2004. Impact of the invasive
grass Melinis minutiflora at the savanna-forest ecotone
in the Brazilian Cerrado. Diversity and Distributions,
10: 99-103.
Bucci
S.J., Scholz F.G., Goldstein G., Meinzer F.C , Hinojosa
J.A., Hoffmann W.A., and Franco, A.C. 2004. Processes
preventing nocturnal equilibrium between leaf and soil water
potential in tropical savanna woody species, Tree
Physiology, 24: 1119-1127.
Hoffmann, W.A.,
B. Orthen, and P.K.V. Nascimento. Comparative fire
ecology of tropical savanna and forest trees.
Functional Ecology, 17: 720-726
Hoffmann, W.A., W. Schroeder and R.B. Jackson. Regional
feedbacks among climate, fire, and tropical deforestation.
Journal of Geophysical Research – Atmospheres, 108,
DOI:2003JD003494
Hoffmann, W.A. and O.T. Solbrig. 2003. The
role of topkill in the differential response of savanna
woody species to fire. Forest Ecology and
Management, 180:273-286.
Hoffmann, W.A. and A.C. Franco. Comparative growth
analysis of tropical savanna and forest trees using phylogenetically-independent
contrasts. Journal of Ecology, 91: 475-484.
Hoffmann, W. A., W. Schroeder, and R. B. Jackson. 2002.
Positive feedbacks of fire, climate, and vegetation
change and the conversion of tropical savannas. Geophysical
Research Letters, 15: doi: 10.1029/2002GL01542
Hoffmann,
W.A. and Moreira, A.G. 2002 The Role of Fire
in Population Dynamics of Woody Plants, Pp. 159-177 in P.S.
Oliveira and R.J. Marquis (eds.) The Cerrados of Brazil:
Ecology and Natural History of a Neotropical Savanna, Columbia
University Press, New York.
Dickinson, R.E.,
J.A. Berry, G.B. Bonan, G.J. Collatz, C.B. Field, I.Y.
Fung, M. Goulden, W.A. Hoffmann, R. Jackson, R. Myneni,
P. Sellers, M. Shaikh. 2002. Nitrogen controls
on climate model evapotranspiration. Journal
of Climate, 15:278-295.
Hoffmann, W.A. and H. Poorter. 2002. Avoiding bias
in calculations of relative growth rate. Annals
of Plant Biology80:37-42 .
Hoffmann, W.A. 2002. Direct and indirect effects
of fire on radial growth of cerrado savanna trees.
Journal of Tropical Ecology 18:137-142.
Silva, G.F., R.L.C. Ferreira, W.A. Hoffmann, N.C. Fiedler,
G. Janin. 2002. Optimization applied to management
of natural forests. ETFRN News 36: 26-27.
Hoffmann, W.A., F.A. Bazzaz, N.J. Chatterton, P. Harrison,
and R.B. Jackson. 2000. Elevated CO2 enhances resprouting
of a tropical savanna tree. Oecologia, 123(3)
312-317.
Hoffmann, W. A. and R.B. Jackson. 2000. Vegetation-climate
feedbacks in the conversion of tropical savanna to grassland.
Journal of Climate 13:1593-1602.
Hoffmann, W. A. 2000. Post-establishment seedling
success of savanna and forest species in the Brazilian Cerrado.
Biotropica, 32(1):62-69
Hoffmann, W.A. 2000. The relative importance of
sexual and vegetative reproduction in cerrado woody plants.
Pp. 231-234 in T.B. Cavalcanti and B.M.T. Walter
(eds.) Tópicos Atuais em BOtânica. EMBRAPA,
Brasília.
Jackson R.B., L. A Moore, W. A. Hoffmann, W. T. Pockman,
and C. R. Linder. 1999. Ecosystem rooting depth
determined with caves and DNA. Proceedings of the
National Academy of Science 96:11387-11392.
Hoffmann, W. A. 1999. Fire and population dynamics
of woody plants in a Neotropical savanna: matrix model predictions.
Ecology 80:1354-1369.
Jackson, R. B., W. T. Pockman, and W. A. Hoffmann. 1999.
Structure and function of root systems. Pp
195-220 in: F. I. Pugnaire and F. Valladeres (eds). Handbook
of Plant Functional Ecology, Marcel Dekker, Inc.
Hoffmann, W. A. 1998. Post-burn reproduction of
woody plants in a Neotropical savanna: the relative importance
of sexual and vegetative reproduction. Journal
of Applied Ecology 35:422-433.
Archer, S., M. Coughenour, C. Dall'Aglio, C. W. Fernandez,
J. Hay, W. Hoffmann, C. Klink, J. F. Silva, and O. T. Solbrig.
1996. Savanna biodiversity and ecosystem properties.
Pp 207-215 in O. T. Solbrig, E. Medina, J. F. Silva (eds),
Biodiversity and Savanna Ecosystem Properties. Springer-Verlag,
Berlin.
Hoffmann, W. A. 1996. The effects of cover and fire
on seedling establishment in a neotropical savanna.
Journal of Ecology. 84:383-393
