Stomatal and boundary-layer conductances in an Amazonian terra firme rain forest.

(1) Diurnal measurements of stomatal conductance (gs) and boundary layer conductance (ga) were made through the canopy at a primary rain forest site in the Amazon Basin, Brazil, in three experimental seasons and over a range of soil water conditions. (2) Maximum values of g, were observed near the top of the 40 m deep canopy and they declined towards the forest floor. Observed values of ga also decreased through the canopy, but a slight maximum occurred 20 m from the ground. (3) In the upper part of the tree canopy the diurnal maximum in gs occurred in the midmorning and the value declined for the remainder of the day. This peak was less marked lower in the canopy, and was not present near the forest floor. (4) g, was correlated negatively with specific humidity deficit (D) and positively with solar radiation (S). The response of gs to D increased with increasing S at all but the highest values of S. (5) The lowest values of gs occurred at the same time as the lowest soil water potentials, although these corresponded to only moderate soil water deficits.

[1]  H. Mooney,et al.  Environmental controls on stomatal conductance in a shrub of the humid tropics. , 1983, Proceedings of the National Academy of Sciences of the United States of America.

[2]  K. G. McNaughton,et al.  Stomatal Control of Transpiration: Scaling Up from Leaf to Region , 1986 .

[3]  N. Chiariello.  Leaf Energy Balance in the Wet Lowland Tropics , 1984 .

[4]  P. Tomlinson,et al.  The Study of the Physiological Ecology of Tropical Plants— Current Status and Needs , 1980 .

[5]  P. Jarvis,et al.  CHAPTER 1 – PREDICTING EFFECTS OF VEGETATION CHANGES ON TRANSPIRATION AND EVAPORATION , 1983 .

[6]  S. Oberbauer,et al.  Field water relations of a wet-tropical forest tree species, Pentaclethra macroloba (Mimosaceae) , 1987, Oecologia.

[7]  D. Doley.  CHAPTER 4 – TROPICAL AND SUBTROPICAL FORESTS AND WOODLANDS , 1981 .

[8]  J. Grace,et al.  STOMATAL CONDUCTANCE OF TWO TROPICAL TREES DURING THE WET SEASON IN NIGERIA , 1982 .

[9]  W. J. Shuttleworth,et al.  Observations of radiation exchange above and below Amazonian forest , 1984 .

[10]  W. James Shuttleworth,et al.  Eddy correlation measurements of energy partition for Amazonian forest , 1984 .

[11]  J. Norman,et al.  Crop structure and the penetration of direct sunlight , 1985 .

[12]  J. Monteith.  Evaporation and environment. , 1965, Symposia of the Society for Experimental Biology.

[13]  W. James Shuttleworth,et al.  DAILY VARIATIONS OF TEMPERATURE AND HUMIDITY WITHIN AND ABOVE AMAZONIAN FOREST , 1985 .

[14]  J. Ehleringer,et al.  Gas exchange in Schima superba a subtropical monsoonal forest tree , 1986 .

[15]  J. Grace,et al.  Boundary layer conductance of the leaves of some tropical timber trees , 1980 .

[16]  R M Gifford,et al.  Stomatal sensitivity to carbon dioxide and humidity: a comparison of two c(3) and two c(4) grass species. , 1983, Plant physiology.

[17]  D. Whitehead,et al.  STOMATAL RESPONSE TO ENVIRONMENTAL VARIABLES IN TWO TROPICAL FOREST SPECIES DURING THE DRY SEASON IN NIGERIA , 1981 .

[18]  C. J. Moore,et al.  Estimating heat storage in Amazonian tropical forest , 1986 .