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Effects of isolation on the water status of forest patches in the Brazilian Amazon

  • Valerie Kapos (a1)
Abstract

Patterns of edge-related environmental changes and plant water relations were investigated in the isolated forest reserves of the INPA-WWF Minimum Critical Size of Eco-systems project near Manaus, Brazil early in the wet season.

Air temperature was elevated and humidity reduced in the understorey within 40 m of the reserve margins, and air temperature and vapour pressure deficit (VPD) were higher in the interiors of 1 ha reserves than in 100 ha reserves. There was increased photosynthetically active radiation penetration to understorey level up to 40 m into a 100 ha reserve.

Soil moisture was depleted in the outer 20 m of both small and large reserves, and surface soil water potentials fell below – 1.5 MPa at the margin of a 1 ha reserve.

Studies of leaf relative water contents (RWCs) in understorey shrubs revealed no appreciable saturation deficits, though RWCs were sometimes lower at the reserve margins. Studies of leaf conductances revealed no evidence of restriction of water loss in these plants, and conductances of plants near the edges were significantly higher and higher for longer.

The implications of these results for reserve design and for local and regional water budgets, as well as the possible role of water stress in increased tree mortality in isolated reserves are discussed.

Padrōes de mudanças ambientais e hídricos de plantas relacionados a bordas de matas isoladas foram investigadas no início da estação seca nas reservas de floresta do Projeto Dinâmica Biológica de Fragmentos Florestais do INPA-WWF, proximo de Manaus, Brasil.

No sub-bosque, até 40 m da borda da mata, a temperatura ambiental estava elevada e a umidade reduzida, e a temperatura do ar e o DPV estavam maiores nas reservas de 1 ha do que nas reservas de 100 ha. A penetração de radiaçao fotosintéticamente ativa no sub-bosque estava aumentada até 40 m da borda em reservas de 100 ha.

A umidade do solo baixou consideravelmente nos 20 m periféricos de reservas grandes a pequenas, e o potencial hídrico na superficie do solo baixou para menos de −1.5 MPa na margem de uma reserva de 1 ha.

Estudos do teor relativo de água (TRA) em folhas de arbustos de sub-bosque nӑo revelaram deficits de saturação apreciaveis apesar de que TRAs foram menores nas bordas das reservas. Estudos da conductancia foliar não revelaram evidência de restrições de perdas hídricas nessas plantas, e as conductancias de plantas próximas a bordas foram significativamente maiores durante um período mais longo.

As impliçõtes desses resultados para o planejamento de reservas e para o balanço hídrico local e regional, assim como as possiveis funçoes de ‘stress’ hídrico na alta mortalidade de árvores em reservas isoladas são discutidas.

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References
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Anonymous, . 1978. Projeto RADAMBRASIL Folha SA 20 Manaus. Ministerio de Minas e Energia: Departmento Nacional de Producao Mineral, Rio de Janeiro.
Curtis, J. T. 1956. The modification of mid-latitude grasslands and forests by man. Pp. 721736 in Thomas, W. L. (ed.). Man's role in changing the face of the earth. University of Chicago Press, Chicago.
Diamond, J. M. & May, R. M. 1976. Island biogeography and the design of natural reserves. Pp. 163186 in May, R. M. (ed.). Theoretical ecology: principles and applications. Saunders, Philadelphia.
Fetcher, N., Oberbauer, S. F. & Strain, B. R. 1985. Vegetation effects on microclimate in lowland tropical forest in Costa Rica. International Journal of Biometeorology 29:145155.
Fritschen, L. J., Driver, C. H., Avbery, C., Buffo, J., Edmonds, R., Kinerson, R. & Schiess, P. 1971. Dispersion of air tracers into and within a forested area: 3. Res. and Dev. Tech. Rept. ECOM-68-G8-3, US Army Elect. Command, Atmospheric Science Lab., Fort Huachuca, Arizona.
Geiger, R. 1965. The climate near the ground. Harvard University Press, Cambridge, Massachusetts.
Harris, L. D. 1980. Forest and wildlife dynamics in the southeast. Transactions of the North American Wildlife and Natural Resources Conference 45:307322.
Harris, L. D. 1984. The fragmented forest; Island biogeography theory and the preservation of biotic diversity. University of Chicago Press, Chicago. 211 pp.
Lee, R. 1978. Forest microclimatology. Columbia University Press, New York.
Lovejoy, T. E. 1980. Discontinuous wilderness: minimum areas for conservation. Parks 5(2): 1315.
Lovejoy, T. E., Bierregaard, R. O., Rankin, J. M. & Schubart, H. O. R. 1983. Ecological dynamics of forest fragments. Pp. 377384 in Sutton, S. L., Whitmore, T. C. & Chadwick, A. C. (eds). Tropical rain forests: ecology and management. Blackwell Scientific Publications, Oxford, England.
Lovejoy, T. E., Rankin, J. M., Bierregaard, R. O. Jr, Brown, K. S. Jr, Emmons, L. H. & Van Der Voort, M. E. 1984. Ecosystem decay of Amazon forest remnants. Pp. 295325 in Nitecki, M. H. (ed.). Extinctions. University of Chicago Press, Chicago.
Macarthur, R. H. & Wilson, E. O. 1967. The theory of island biogeography. Princeton University Press, Princeton.
Ranney, J. W., Bruner, M. C. & Levenson, J. B. 1981. The importance of edge in the structure and dynamics of forest islands. Pp. 6795 in Burgess, R. L. & Sharpe, D. M. (eds). Forest island dynamics in man-dominated landscapes. Springer-Verlag, New York.
Salati, E. 1985. The climatology and hydrology of Amazonia. Pp. 1848 in Prance, G. T. & Lovejoy, T. E. (eds). Key environments: Amazonia. Pergammon Press, Oxford.
Salati, E.Marques, J. & Molion, L. C. B. 1978. Origem e distribucao das chuvas na Amazonia. Interciencia 3(4):200205.
Santos, H. M. 1968. Balanco hidrico de Manaus Amazonas, Publicacao No. 1, Serie AVULSA, Conselho Nacional de Pesquisas: Instituto Nacional de Pesquisas da Amazonia.
SoulÉ, M. E. & Wilcox, B. A. (eds). 1980 Conservation biology; an evolutionary-ecological perspective. Sinauer Associates, Sunderland, Massachusetts.
Whitehead, D., Okali, D. U. U. & Fasehun, F. E. 1981. Stomatal response to environmental variables in two tropical forest species in Nigeria. Journal of Applied Ecology 18:571587.
Willis, E. O. 1974. Populations and local extinctions of birds on Barro Colorado Island, Panama. Ecological Monographs 44:153169.
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Journal of Tropical Ecology
  • ISSN: 0266-4674
  • EISSN: 1469-7831
  • URL: /core/journals/journal-of-tropical-ecology
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